Fix external links in related content

.gitignore

@@ -2,3 +2,4 @@ config.json
 .build
 .swiftpm
 Package.resolved
+Issues.md

Sources/Generator/Content/DefaultValueProvider.swift

@@ -0,0 +1,6 @@
+import Foundation
+
+protocol DefaultValueProvider {
+
+    static var defaultValue: Self { get }
+}

Sources/Generator/Content/Element+LocalizedMetadata.swift

@@ -57,7 +57,7 @@ extension Element {
          - Note: If this value is inherited from the parent, if it is not defined. There must be at least one
          element in the path that defines this property.
          */
-        let moreLinkText: String
+        let moreLinkText: String?
 
         /**
          The text on the back navigation link of **contained** elements.
@@ -140,82 +140,71 @@ extension Element {
          This property is mandatory at root level, and is propagated to child elements.
          */
         let navigationTextAsPreviousPage: String
+
+        /**
+         The text to display above a slideshow for most recent items.
+         Only used for elements that define `showMostRecentSection = true`
+         */
+        let mostRecentTitle: String?
+
+        /**
+         The text to display above a slideshow for featured items.
+         Only used for elements that define `showFeaturedSection = true`
+         */
+        let featuredTitle: String?
     }
 }
 
 extension Element.LocalizedMetadata {
 
-    init?(atRoot folder: URL, data: GenericMetadata.LocalizedMetadata) {
+    init?(atRoot folder: URL, data: GenericMetadata.LocalizedMetadata, log: MetadataInfoLogger) {
         // Go through all elements and check them for completeness
         // In the end, check that all required elements are present
-        var isComplete = true
+        var isValid = true
-        func markAsIncomplete() {
+
-            isComplete = false
-        }
         let source = "root"
-        self.language = log
+        self.language = log.required(data.language, name: "language", source: source, &isValid)
-            .required(data.language, name: "language", source: source)
+        self.title = log.required(data.title, name: "title", source: source, &isValid)
-            .ifNil(markAsIncomplete) ?? ""
-        self.title = log
-            .required(data.title, name: "title", source: source)
-            .ifNil(markAsIncomplete) ?? ""
         self.subtitle = data.subtitle
         self.description = data.description
         self.linkPreviewTitle = data.linkPreviewTitle ?? data.title ?? ""
-        self.linkPreviewImage = log
+        self.linkPreviewImage = data.linkPreviewImage
-            .linkPreviewThumbnail(customFile: data.linkPreviewImage, for: language, in: folder, source: source)
         let linkPreviewDescription = data.linkPreviewDescription ?? data.description ?? data.subtitle
-        self.linkPreviewDescription = log
+        self.linkPreviewDescription = log.required(linkPreviewDescription, name: "linkPreviewDescription", source: source, &isValid)
-            .required(linkPreviewDescription, name: "linkPreviewDescription", source: source)
+        self.moreLinkText = data.moreLinkText
-            .ifNil(markAsIncomplete) ?? ""
+        self.backLinkText = log.required(data.backLinkText, name: "backLinkText", source: source, &isValid)
-        self.moreLinkText = data.moreLinkText ?? Element.LocalizedMetadata.moreLinkDefaultText
-        self.backLinkText = log
-            .required(data.backLinkText, name: "backLinkText", source: source)
-            .ifNil(markAsIncomplete) ?? ""
         self.parentBackLinkText = "" // Root has no parent
-        self.placeholderTitle = log
+        self.placeholderTitle = log.required(data.placeholderTitle, name: "placeholderTitle", source: source, &isValid)
-            .required(data.placeholderTitle, name: "placeholderTitle", source: source)
+        self.placeholderText = log.required(data.placeholderText, name: "placeholderText", source: source, &isValid)
-            .ifNil(markAsIncomplete) ?? ""
-        self.placeholderText = log
-            .required(data.placeholderText, name: "placeholderText", source: source)
-            .ifNil(markAsIncomplete) ?? ""
         self.titleSuffix = data.titleSuffix
         self.thumbnailSuffix = log.unused(data.thumbnailSuffix, "thumbnailSuffix", source: source)
         self.cornerText = log.unused(data.cornerText, "cornerText", source: source)
-        self.externalUrl = log.unexpected(data.externalUrl, name: "externalUrl", source: source)
+        self.externalUrl = log.unused(data.externalUrl, "externalUrl", source: source)
-        self.relatedContentText = log
+        self.relatedContentText = log.required(data.relatedContentText, name: "relatedContentText", source: source, &isValid)
-            .required(data.relatedContentText, name: "relatedContentText", source: source) ?? ""
+        self.navigationTextAsNextPage = log.required(data.navigationTextAsNextPage, name: "navigationTextAsNextPage", source: source, &isValid)
-        self.navigationTextAsNextPage = log
+        self.navigationTextAsPreviousPage = log.required(data.navigationTextAsPreviousPage, name: "navigationTextAsPreviousPage", source: source, &isValid)
-            .required(data.navigationTextAsNextPage, name: "navigationTextAsNextPage", source: source) ?? ""
+        self.mostRecentTitle = data.mostRecentTitle
-        self.navigationTextAsPreviousPage = log
+        self.featuredTitle = data.featuredTitle
-            .required(data.navigationTextAsPreviousPage, name: "navigationTextAsPreviousPage", source: source) ?? ""
 
-        guard isComplete else {
+        guard isValid else {
             return nil
         }
     }
 
-    init?(folder: URL, data: GenericMetadata.LocalizedMetadata, source: String, parent: Element.LocalizedMetadata) {
+    init?(folder: URL, data: GenericMetadata.LocalizedMetadata, source: String, parent: Element.LocalizedMetadata, log: MetadataInfoLogger) {
         // Go through all elements and check them for completeness
         // In the end, check that all required elements are present
-        var isComplete = true
+        var isValid = true
-        func markAsIncomplete() {
+
-            isComplete = false
-        }
         self.language = parent.language
-        self.title = log
+        self.title = log.required(data.title, name: "title", source: source, &isValid)
-            .required(data.title, name: "title", source: source)
-            .ifNil(markAsIncomplete) ?? ""
         self.subtitle = data.subtitle
         self.description = data.description
         self.linkPreviewTitle = data.linkPreviewTitle ?? data.title ?? ""
-        self.linkPreviewImage = log
+        self.linkPreviewImage = data.linkPreviewImage
-            .linkPreviewThumbnail(customFile: data.linkPreviewImage, for: language, in: folder, source: source)
         let linkPreviewDescription = data.linkPreviewDescription ?? data.description ?? data.subtitle
-        self.linkPreviewDescription = log
+        self.linkPreviewDescription = log.required(linkPreviewDescription, name: "linkPreviewDescription", source: source, &isValid)
-            .required(linkPreviewDescription, name: "linkPreviewDescription", source: source)
+        self.moreLinkText = log.required(data.moreLinkText ?? parent.moreLinkText, name: "moreLinkText", source: source, &isValid)
-            .ifNil(markAsIncomplete) ?? ""
-        self.moreLinkText = log.moreLinkText(data.moreLinkText, parent: parent.moreLinkText, source: source)
         self.backLinkText = data.backLinkText ?? data.title ?? ""
         self.parentBackLinkText = parent.backLinkText
         self.placeholderTitle = data.placeholderTitle ?? parent.placeholderTitle
@@ -227,33 +216,11 @@ extension Element.LocalizedMetadata {
         self.relatedContentText = data.relatedContentText ?? parent.relatedContentText
         self.navigationTextAsPreviousPage = data.navigationTextAsPreviousPage ?? parent.navigationTextAsPreviousPage
         self.navigationTextAsNextPage = data.navigationTextAsNextPage ?? parent.navigationTextAsNextPage
+        self.mostRecentTitle = data.mostRecentTitle ?? parent.mostRecentTitle
+        self.featuredTitle = data.featuredTitle ?? parent.featuredTitle
 
-        guard isComplete else {
+        guard isValid else {
             return nil
         }
     }
 }
-
-// MARK: Thumbnails
-
-extension Element {
-
-    static let defaultThumbnailName = "thumbnail.jpg"
-
-    static func localizedThumbnailName(for language: String) -> String {
-        "thumbnail-\(language).jpg"
-    }
-
-    static func findThumbnail(for language: String, in folder: URL) -> String? {
-        let localizedThumbnail = localizedThumbnailName(for: language)
-        let localizedThumbnailUrl = folder.appendingPathComponent(localizedThumbnail)
-        if localizedThumbnailUrl.exists {
-            return localizedThumbnail
-        }
-        let defaultThumbnailUrl = folder.appendingPathComponent(defaultThumbnailName)
-        if defaultThumbnailUrl.exists {
-            return defaultThumbnailName
-        }
-        return nil
-    }
-}

Sources/Generator/Content/Element.swift

@@ -65,7 +65,7 @@ struct Element {
     let sortIndex: Int?
 
     /**
-     All files which may occur in content but is stored externally.
+     All files which may occur in content but are stored externally.
 
      Missing files which would otherwise produce a warning are ignored when included here.
      - Note: This property defaults to an empty set.
@@ -85,6 +85,15 @@ struct Element {
      */
     let images: [ManualImage]
 
+    /**
+     The path to the thumbnail file.
+
+     This property is optional, and defaults to ``GenericMetadata.defaultThumbnailName``.
+     Note: The generator first looks for localized versions of the thumbnail by appending `-[lang]` to the file name,
+     e.g. `customThumb-en.jpg`. If no file is found, then the specified file is tried.
+     */
+    let thumbnailPath: String
+
     /**
      The style of thumbnail to use when generating overviews.
 
@@ -117,6 +126,19 @@ struct Element {
      */
     let headerType: HeaderType
 
+    /**
+     Indicate that the overview section should contain a `Newest Content` section before the other sections.
+     - Note: If not specified, this property defaults to `false`
+     */
+    let showMostRecentSection: Bool
+
+    /**
+     Indicate that the overview section should contain a `Featured Content` section before the other sections.
+     The elements are the page ids of the elements contained in the feature.
+     - Note: If not specified, this property defaults to `false`
+     */
+    let featuredPages: [String]
+
     /**
      The localized metadata for each language.
      */
@@ -148,120 +170,183 @@ struct Element {
      - Parameter folder: The root folder of the site content.
      - Note: Uses global objects.
      */
-    init?(atRoot folder: URL) {
+    init?(atRoot folder: URL, log: MetadataInfoLogger) {
         self.inputFolder = folder
         self.path = ""
 
         let source = GenericMetadata.metadataFileName
-        guard let metadata = GenericMetadata(source: source) else {
+        guard let metadata = GenericMetadata(source: source, log: log) else {
             return nil
         }
 
+        var isValid = true
+
         self.id = metadata.customId ?? Element.defaultRootId
-        self.author = log.required(metadata.author, name: "author", source: source) ?? "author"
+        self.author = log.required(metadata.author, name: "author", source: source, &isValid)
-        self.topBarTitle = log
+        self.topBarTitle = log.required(metadata.topBarTitle, name: "topBarTitle", source: source, &isValid)
-            .required(metadata.topBarTitle, name: "topBarTitle", source: source) ?? "My Website"
+        self.date = log.castUnused(metadata.date, "date", source: source)
-        self.date = log.unused(metadata.date, "date", source: source)
+        self.endDate = log.castUnused(metadata.endDate, "endDate", source: source)
-        self.endDate = log.unused(metadata.endDate, "endDate", source: source)
+        self.state = log.cast(metadata.state, "state", source: source)
-        self.state = log.state(metadata.state, source: source)
         self.sortIndex = log.unused(metadata.sortIndex, "sortIndex", source: source)
         self.externalFiles = metadata.externalFiles ?? []
         self.requiredFiles = metadata.requiredFiles ?? [] // Paths are already relative to root
-        self.images = metadata.images?.compactMap { ManualImage(input: $0, path: "") } ?? []
+        self.images = metadata.images?.compactMap { ManualImage(input: $0, path: "", log: log) } ?? []
-        self.thumbnailStyle = log.unused(metadata.thumbnailStyle, "thumbnailStyle", source: source) ?? .large
+        self.thumbnailPath = metadata.thumbnailPath ?? Element.defaultThumbnailName
-        self.useManualSorting = log.unused(metadata.useManualSorting, "useManualSorting", source: source) ?? true
+        self.thumbnailStyle = log.castUnused(metadata.thumbnailStyle, "thumbnailStyle", source: source)
+        self.useManualSorting = log.unused(metadata.useManualSorting, "useManualSorting", source: source)
         self.overviewItemCount = metadata.overviewItemCount ?? Element.overviewItemCountDefault
-        self.headerType = log.headerType(metadata.headerType, source: source)
+        self.headerType = log.cast(metadata.headerType, "headerType", source: source)
-        self.languages = log.required(metadata.languages, name: "languages", source: source)?
+        self.showMostRecentSection = metadata.showMostRecentSection ?? false
+        self.featuredPages = metadata.featuredPages ?? []
+        self.languages = log.required(metadata.languages, name: "languages", source: source, &isValid)
             .compactMap { language in
-                    .init(atRoot: folder, data: language)
+                    .init(atRoot: folder, data: language, log: log)
-            } ?? []
+            }
         // All properties initialized
         guard !languages.isEmpty else {
-            log.add(error: "No languages found", source: source)
+            log.error("No languages found", source: source)
             return nil
         }
 
-        files.add(page: path, id: id)
+        guard isValid else {
-        self.readElements(in: folder, source: nil)
+            return nil
         }
 
-    mutating func readElements(in folder: URL, source: String?) {
+        //files.add(page: path, id: id)
+        self.readElements(in: folder, source: nil, log: log)
+    }
+
+    mutating func readElements(in folder: URL, source: String?, log: MetadataInfoLogger) {
         let subFolders: [URL]
         do {
             subFolders = try FileManager.default
                 .contentsOfDirectory(at: folder, includingPropertiesForKeys: [.isDirectoryKey])
                 .filter { $0.isDirectory }
         } catch {
-            log.add(error: "Failed to read subfolders", source: source ?? "root", error: error)
+            log.error("Failed to read subfolders: \(error)", source: source ?? "root")
             return
         }
         self.elements = subFolders.compactMap { subFolder in
             let s = (source.unwrapped { $0 + "/" } ?? "") + subFolder.lastPathComponent
-            return Element(parent: self, folder: subFolder, path: s)
+            return Element(parent: self, folder: subFolder, path: s, log: log)
         }
     }
 
-    init?(parent: Element, folder: URL, path: String) {
+    init?(parent: Element, folder: URL, path: String, log: MetadataInfoLogger) {
         self.inputFolder = folder
         self.path = path
 
         let source = path + "/" + GenericMetadata.metadataFileName
-        guard let metadata = GenericMetadata(source: source) else {
+        guard let metadata = GenericMetadata(source: source, log: log) else {
+            return nil
+        }
+        let state: PageState = log.cast(metadata.state, "state", source: source)
+        guard state != .ignored else {
             return nil
         }
 
+        var isValid = true
+
         self.id = metadata.customId ?? folder.lastPathComponent
         self.author = metadata.author ?? parent.author
-        self.topBarTitle = log
+        self.topBarTitle = log.unused(metadata.topBarTitle, "topBarTitle", source: source)
-            .unused(metadata.topBarTitle, "topBarTitle", source: source) ?? parent.topBarTitle
+        self.date = metadata.date.unwrapped { log.cast($0, "date", source: source) }
-        let date = log.date(from: metadata.date, property: "date", source: source).ifNil {
+        self.endDate = metadata.endDate.unwrapped { log.cast($0, "endDate", source: source) }
-            if !parent.useManualSorting {
-                log.add(error: "No 'date', but parent defines 'useManualSorting' = false", source: source)
-            }
-        }
-        self.date = date
-        self.endDate = log.date(from: metadata.endDate, property: "endDate", source: source).ifNotNil {
-            if date == nil {
-                log.add(warning: "Set 'endDate', but no 'date'", source: source)
-            }
-        }
-        let state = log.state(metadata.state, source: source)
         self.state = state
-        self.sortIndex = metadata.sortIndex.ifNil {
+        self.sortIndex = metadata.sortIndex
-            if state != .hidden, parent.useManualSorting {
-                log.add(error: "No 'sortIndex', but parent defines 'useManualSorting' = true", source: source)
-            }
-        }
         // TODO: Propagate external files from the parent if subpath matches?
         self.externalFiles = Element.rootPaths(for: metadata.externalFiles, path: path)
         self.requiredFiles = Element.rootPaths(for: metadata.requiredFiles, path: path)
-        self.images = metadata.images?.compactMap { ManualImage(input: $0, path: path) } ?? []
+        self.images = metadata.images?.compactMap { ManualImage(input: $0, path: path, log: log) } ?? []
-        self.thumbnailStyle = log.thumbnailStyle(metadata.thumbnailStyle, source: source)
+        self.thumbnailPath = metadata.thumbnailPath ?? Element.defaultThumbnailName
+        self.thumbnailStyle = log.cast(metadata.thumbnailStyle, "thumbnailStyle", source: source)
         self.useManualSorting = metadata.useManualSorting ?? false
         self.overviewItemCount = metadata.overviewItemCount ?? parent.overviewItemCount
-        self.headerType = log.headerType(metadata.headerType, source: source)
+        self.headerType = log.cast(metadata.headerType, "headerType", source: source)
+        self.showMostRecentSection = metadata.showMostRecentSection ?? false
+        self.featuredPages = metadata.featuredPages ?? []
         self.languages = parent.languages.compactMap { parentData in
             guard let data = metadata.languages?.first(where: { $0.language == parentData.language }) else {
-                log.add(info: "Language '\(parentData.language)' not found", source: source)
+                log.warning("Language '\(parentData.language)' not found", source: source)
                 return nil
             }
-            return .init(folder: folder, data: data, source: source, parent: parentData)
+            return .init(folder: folder, data: data, source: source, parent: parentData, log: log)
         }
         // Check that each 'language' tag is present, and that all languages appear in the parent
-        log.required(metadata.languages, name: "languages", source: source)?
+        log.required(metadata.languages, name: "languages", source: source, &isValid)
-            .compactMap { log.required($0.language, name: "language", source: source) }
+            .compactMap { log.required($0.language, name: "language", source: source, &isValid) }
             .filter { language in
                 !parent.languages.contains { $0.language == language }
             }
             .forEach {
-                log.add(warning: "Language '\($0)' not found in parent, so not generated", source: source)
+                log.warning("Language '\($0)' not found in parent, so not generated", source: source)
             }
 
         // All properties initialized
 
-        files.add(page: path, id: id)
+        if self.date == nil, !parent.useManualSorting {
-        self.readElements(in: folder, source: path)
+            log.error("No 'date', but parent defines 'useManualSorting' = false", source: source)
+        }
+        if date == nil {
+            log.unused(self.endDate, "endDate", source: source)
+        }
+        if self.sortIndex == nil, state != .hidden, parent.useManualSorting {
+            log.error("No 'sortIndex', but parent defines 'useManualSorting' = true", source: source)
+        }
+
+        guard isValid else {
+            return nil
+        }
+
+        self.readElements(in: folder, source: path, log: log)
+
+        if showMostRecentSection {
+            if elements.isEmpty {
+                log.error("Page has no children", source: source)
+            }
+            languages.filter { $0.mostRecentTitle == nil }.forEach {
+                log.error("'showMostRecentSection' = true, but 'mostRecentTitle' not set for language '\($0.language)'", source: source)
+            }
+        }
+
+        if !featuredPages.isEmpty {
+            if elements.isEmpty {
+                log.error("'featuredPages' contains elements, but page has no children", source: source)
+            }
+            languages.filter { $0.featuredTitle == nil }.forEach {
+                log.error("'featuredPages' contains elements, but 'featuredTitle' not set for language '\($0.language)'", source: source)
+            }
+        }
+    }
+
+    func getExternalPageMap(language: String, log: MetadataInfoLogger) -> [String : String] {
+        var result = [String : String]()
+        if let ext = getExternalLink(for: language) {
+            result[id] = ext
+        } else {
+            result[id] = path + Element.htmlPagePathAddition(for: language)
+        }
+        elements.forEach { element in
+            element.getExternalPageMap(language: language, log: log).forEach { key, value in
+                if result[key] != nil {
+                    log.error("Page id '\(key)' is used twice", source: value)
+                }
+                result[key] = value
+            }
+        }
+        return result
+    }
+
+    private func getExternalLink(for language: String) -> String? {
+        languages.first { $0.language == language }?.externalUrl
+    }
+
+    var needsFirstSection: Bool {
+        showMostRecentSection || !featuredPages.isEmpty
+    }
+
+    var hasVisibleChildren: Bool {
+        !elements.filter { $0.state == .standard }.isEmpty
     }
 }
 
@@ -288,7 +373,7 @@ extension Element {
     }
 
     var hasNestingElements: Bool {
-        elements.contains { $0.containsElements }
+        elements.contains { $0.hasVisibleChildren }
     }
 
     func itemsForOverview(_ count: Int? = nil) -> [Element] {
@@ -299,6 +384,20 @@ extension Element {
         }
     }
 
+    func mostRecentElements(_ count: Int) -> [Element] {
+        guard self.thumbnailStyle == .large else {
+            return []
+        }
+        guard self.containsElements else {
+            return [self]
+        }
+        let all = shownItems
+            .reduce(into: [Element]()) { $0 += $1.mostRecentElements(count) }
+            .filter { $0.thumbnailStyle == .large && $0.state == .standard && $0.date != nil }
+            .sorted { $0.date! > $1.date! }
+        return Array(all.prefix(count))
+    }
+
     var sortedItems: [Element] {
         if useManualSorting {
             return shownItems.sorted { $0.sortIndex! < $1.sortIndex! }
@@ -333,6 +432,9 @@ extension Element {
      - Returns: The relative url from a localized page of the element to the target file.
      */
     func relativePathToOtherSiteElement(file: String) -> String {
+        guard !file.hasPrefix("/"), !file.hasPrefix("https://"), !file.hasPrefix("http://") else {
+            return file
+        }
         // Note: The element `path` is missing the last component
         // i.e. travel/alps instead of travel/alps/en.html
         let ownParts = path.components(separatedBy: "/")
@@ -340,7 +442,7 @@ extension Element {
 
         // Find the common elements of the path, which can be discarded
         var index = 0
-        while pageParts[index] == ownParts[index] {
+        while index < pageParts.count && index < ownParts.count && pageParts[index] == ownParts[index] {
             index += 1
         }
         // The relative path needs to go down to the first common folder,
@@ -420,17 +522,6 @@ extension Element {
 
 extension Element {
 
-    /**
-     Get the full path of the thumbnail image for the language (relative to the root folder).
-     */
-    func thumbnailFilePath(for language: String) -> String {
-        guard let thumbnailFile = Element.findThumbnail(for: language, in: inputFolder) else {
-            log.add(error: "Missing thumbnail", source: path)
-            return Element.defaultThumbnailName
-        }
-        return pathRelativeToRootForContainedInputFile(thumbnailFile)
-    }
-
     /**
      The full url (relative to root) for the localized page
      - Parameter language: The language of the page where the url should point
@@ -497,7 +588,7 @@ extension Element {
     }
 
     func linkPreviewImage(for language: String) -> String? {
-        localized(for: language).linkPreviewImage
+        localized(for: language).linkPreviewImage ?? thumbnailFileName(for: language)
     }
 }
 
@@ -541,21 +632,14 @@ extension Element {
 
 extension Element {
 
-    private var additionalHeadContentPath: String {
+    var additionalHeadContentPath: String {
         path + "/head.html"
     }
 
-    func customHeadContent() -> String? {
+    var additionalFooterContentPath: String {
-        files.contentOfOptionalFile(atPath: additionalHeadContentPath, source: path)
-    }
-
-    private var additionalFooterContentPath: String {
         path + "/footer.html"
     }
 
-    func customFooterContent() -> String? {
-        files.contentOfOptionalFile(atPath: additionalFooterContentPath, source: path)
-    }
 }
 
 // MARK: Debug
@@ -582,14 +666,14 @@ extension Element {
 
         let desiredHeight: Int?
 
-        init?(input: String, path: String) {
+        init?(input: String, path: String, log: MetadataInfoLogger) {
             let parts = input.components(separatedBy: " ").filter { !$0.isEmpty }
             guard parts.count == 3 || parts.count == 4 else {
-                log.add(error: "Invalid image specification, expected 'source dest width (height)", source: path)
+                log.error("Invalid image specification, expected 'source dest width (height)", source: path)
                 return nil
             }
             guard let width = Int(parts[2]) else {
-                log.add(error: "Invalid width for image \(parts[0])", source: path)
+                log.error("Invalid width for image \(parts[0])", source: path)
                 return nil
             }
 
@@ -601,7 +685,7 @@ extension Element {
                 return
             }
             guard let height = Int(parts[3]) else {
-                log.add(error: "Invalid height for image \(parts[0])", source: path)
+                log.error("Invalid height for image \(parts[0])", source: path)
                 return nil
             }
             self.desiredHeight = height
@@ -663,3 +747,53 @@ extension Element {
         return node
     }
 }
+
+// MARK: Thumbnails
+
+extension Element {
+
+    static let defaultThumbnailName = "thumbnail.jpg"
+
+    /**
+     Find the thumbnail for the element.
+
+     This function uses either the custom thumbnail path from the metadata or the default name
+     to find a thumbnail. It first checks if a localized version of the thumbnail exists, or returns the
+     generic version. If no thumbnail image could be found on disk, then an error is logged and the
+     generic path is returned.
+
+     - Parameter language: The language of the thumbnail
+     - Returns: The thumbnail (either the localized or the generic version)
+     */
+    func thumbnailFilePath(for language: String) -> (source: String, destination: String) {
+        let localizedThumbnail = thumbnailPath.insert("-\(language)", beforeLast: ".")
+        let localizedThumbnailUrl = inputFolder.appendingPathComponent(localizedThumbnail)
+
+        if localizedThumbnailUrl.exists {
+            let source = pathRelativeToRootForContainedInputFile(localizedThumbnail)
+            let ext = thumbnailPath.lastComponentAfter(".")
+            let destination = pathRelativeToRootForContainedInputFile("thumbnail-\(language).\(ext)")
+            return (source, destination)
+        }
+        let source = pathRelativeToRootForContainedInputFile(thumbnailPath)
+        let ext = thumbnailPath.lastComponentAfter(".")
+        let destination = pathRelativeToRootForContainedInputFile("thumbnail.\(ext)")
+        return (source, destination)
+    }
+
+    private func thumbnailFileName(for language: String) -> String? {
+        let localizedThumbnailName = thumbnailPath.insert("-\(language)", beforeLast: ".")
+        let localizedThumbnail = pathRelativeToRootForContainedInputFile(localizedThumbnailName)
+        let localizedThumbnailUrl = inputFolder.appendingPathComponent(localizedThumbnail)
+
+        if localizedThumbnailUrl.exists {
+            return localizedThumbnailName
+        }
+
+        let thumbnailUrl = inputFolder.appendingPathComponent(thumbnailPath)
+        if !thumbnailUrl.exists {
+            return nil
+        }
+        return thumbnailPath
+    }
+}

Sources/Generator/Content/GenericMetadata+Localized.swift

@@ -14,8 +14,8 @@ extension GenericMetadata {
         let language: String?
 
         /**
-         - Note: This field is mandatory
          The title used in the page header.
+         - Note: This field is mandatory
          */
         let title: String?
 
@@ -133,6 +133,18 @@ extension GenericMetadata {
          This property is mandatory at root level, and is propagated to child elements.
          */
         let navigationTextAsNextPage: String?
+
+        /**
+         The text to display above a slideshow for most recent items.
+         Only used for elements that define `showMostRecentSection = true`
+         */
+        let mostRecentTitle: String?
+
+        /**
+         The text to display above a slideshow for featured items.
+         Only used for elements that define `showFeaturedSection = true`
+         */
+        let featuredTitle: String?
     }
 }
 
@@ -158,6 +170,8 @@ extension GenericMetadata.LocalizedMetadata: Codable {
             .relatedContentText,
             .navigationTextAsPreviousPage,
             .navigationTextAsNextPage,
+            .mostRecentTitle,
+            .featuredTitle,
         ]
     }
 
@@ -190,7 +204,9 @@ extension GenericMetadata.LocalizedMetadata {
             externalUrl: nil,
             relatedContentText: nil,
             navigationTextAsPreviousPage: nil,
-            navigationTextAsNextPage: nil)
+            navigationTextAsNextPage: nil,
+            mostRecentTitle: nil,
+            featuredTitle: nil)
     }
 
     /**
@@ -214,7 +230,9 @@ extension GenericMetadata.LocalizedMetadata {
               externalUrl: nil,
               relatedContentText: "",
               navigationTextAsPreviousPage: "",
-              navigationTextAsNextPage: "")
+              navigationTextAsNextPage: "",
+              mostRecentTitle: nil,
+              featuredTitle: nil)
     }
 
     static var full: GenericMetadata.LocalizedMetadata {
@@ -235,6 +253,8 @@ extension GenericMetadata.LocalizedMetadata {
               externalUrl: "",
               relatedContentText: "",
               navigationTextAsPreviousPage: "",
-              navigationTextAsNextPage: "")
+              navigationTextAsNextPage: "",
+              mostRecentTitle: "",
+              featuredTitle: "")
     }
 }

Sources/Generator/Content/GenericMetadata.swift

@@ -84,6 +84,15 @@ struct GenericMetadata {
      */
     let images: Set<String>?
 
+    /**
+     The path to the thumbnail file.
+
+     This property is optional, and defaults to ``Element.defaultThumbnailName``.
+     Note: The generator first looks for localized versions of the thumbnail by appending `-[lang]` to the file name,
+     e.g. `customThumb-en.jpg`. If no file is found, then the specified file is tried.
+     */
+    let thumbnailPath: String?
+
     /**
      The style of thumbnail to use when generating overviews.
 
@@ -116,6 +125,19 @@ struct GenericMetadata {
      */
     let headerType: String?
 
+    /**
+     Indicate that the overview section should contain a `Newest Content` section before the other sections.
+     - Note: If not specified, this property defaults to `false`
+     */
+    let showMostRecentSection: Bool?
+
+    /**
+     Indicate that the overview section should contain a `Featured Content` section before the other sections.
+     The elements are the page ids of the elements contained in the feature.
+     - Note: If not specified, this property defaults to `false`
+     */
+    let featuredPages: [String]?
+
     /**
      The localized metadata for each language.
      */
@@ -136,10 +158,13 @@ extension GenericMetadata: Codable {
             .externalFiles,
             .requiredFiles,
             .images,
+            .thumbnailPath,
             .thumbnailStyle,
             .useManualSorting,
             .overviewItemCount,
             .headerType,
+            .showMostRecentSection,
+            .featuredPages,
             .languages,
         ]
     }
@@ -159,8 +184,8 @@ extension GenericMetadata {
      - Note: The decoding routine also checks for unknown properties, and writes them to the output.
      - Note: Uses global objects
      */
-    init?(source: String) {
+    init?(source: String, log: MetadataInfoLogger) {
-        guard let data = files.dataOfOptionalFile(atPath: source, source: source) else {
+        guard let data = log.readPotentialMetadata(atPath: source, source: source) else {
             return nil
         }
 
@@ -186,8 +211,7 @@ extension GenericMetadata {
         do {
             self = try decoder.decode(from: data)
         } catch {
-            print("Here \(data)")
+            log.failedToDecodeMetadata(source: source, error: error)
-            log.failedToOpen(GenericMetadata.metadataFileName, requiredBy: source, error: error)
             return nil
         }
     }
@@ -207,10 +231,13 @@ extension GenericMetadata {
             externalFiles: [],
             requiredFiles: [],
             images: [],
+            thumbnailPath: "",
             thumbnailStyle: "",
             useManualSorting: false,
             overviewItemCount: 6,
             headerType: "left",
+            showMostRecentSection: false,
+            featuredPages: [],
             languages: [.full])
     }
 }

Sources/Generator/Content/HeaderType.swift

@@ -17,3 +17,19 @@ enum HeaderType: String {
      */
     case none
 }
+
+extension HeaderType: StringProperty {
+
+    init?(_ value: String) {
+        self.init(rawValue: value)
+    }
+
+    static var castFailureReason: String {
+        "Header type must be 'left', 'center' or 'none'"
+    }
+}
+
+extension HeaderType: DefaultValueProvider {
+
+    static var defaultValue: HeaderType { .left }
+}

Sources/Generator/Content/PageState.swift

@@ -15,6 +15,11 @@ enum PageState: String {
      Generate the page, but don't include it in overviews of the parent.
      */
     case hidden
+
+    /**
+     Completely ignore the element.
+     */
+    case ignored
 }
 
 extension PageState {
@@ -23,7 +28,7 @@ extension PageState {
         switch self {
         case .standard, .draft:
             return true
-        case .hidden:
+        case .hidden, .ignored:
             return false
         }
     }
@@ -32,10 +37,24 @@ extension PageState {
         switch self {
         case .standard:
             return true
-        case .draft:
+        case .draft, .hidden, .ignored:
-            return false
-        case .hidden:
             return false
         }
     }
 }
+
+extension PageState: StringProperty {
+
+    init?(_ value: String) {
+        self.init(rawValue: value)
+    }
+
+    static var castFailureReason: String {
+        "Page state must be 'standard', 'draft', 'hidden', or 'ignored'"
+    }
+}
+
+extension PageState: DefaultValueProvider {
+
+    static var defaultValue: PageState { .standard }
+}

Sources/Generator/Content/StringProperty.swift

@@ -0,0 +1,8 @@
+import Foundation
+
+protocol StringProperty {
+
+    init?(_ value: String)
+
+    static var castFailureReason: String { get }
+}

Sources/Generator/Content/ThumbnailStyle.swift

@@ -33,3 +33,19 @@ enum ThumbnailStyle: String, CaseIterable {
 extension ThumbnailStyle: Codable {
 
 }
+
+extension ThumbnailStyle: StringProperty {
+
+    init?(_ value: String) {
+        self.init(rawValue: value)
+    }
+
+    static var castFailureReason: String {
+        "Thumbnail style must be 'large', 'square' or 'small'"
+    }
+}
+
+extension ThumbnailStyle: DefaultValueProvider {
+
+    static var defaultValue: ThumbnailStyle { .large }
+}

Sources/Generator/Extensions/Array+Extensions.swift

@@ -0,0 +1,6 @@
+import Foundation
+
+extension Array: DefaultValueProvider {
+
+    static var defaultValue: Array<Element> { [] }
+}

Sources/Generator/Extensions/Bool+Extensions.swift

@@ -0,0 +1,6 @@
+import Foundation
+
+extension Bool: DefaultValueProvider {
+
+    static var defaultValue: Bool { true }
+}

Sources/Generator/Extensions/Date+Extensions.swift

@@ -0,0 +1,26 @@
+import Foundation
+
+extension Date: StringProperty {
+
+    private static let metadataDate: DateFormatter = {
+        let df = DateFormatter()
+        df.dateFormat = "dd.MM.yy"
+        return df
+    }()
+
+    init?(_ value: String) {
+        guard let date = Date.metadataDate.date(from: value) else {
+            return nil
+        }
+        self =  date
+    }
+
+    static var castFailureReason: String {
+        "Date string format must be 'dd.MM.yy'"
+    }
+}
+
+extension Date: DefaultValueProvider {
+
+    static var defaultValue: Date { .init() }
+}

Sources/Generator/Extensions/Int+Extensions.swift

@@ -0,0 +1,13 @@
+import Foundation
+
+extension Int: StringProperty {
+
+    static var castFailureReason: String {
+        "The string was not a valid integer"
+    }
+}
+
+extension Int: DefaultValueProvider {
+
+    static var defaultValue: Int { 0 }
+}

Sources/Generator/Extensions/Optional+Extensions.swift

@@ -3,7 +3,7 @@ import Metal
 
 extension Optional {
 
-    func unwrapped<T>(_ closure: (Wrapped) -> T) -> T? {
+    func unwrapped<T>(_ closure: (Wrapped) -> T?) -> T? {
         if case let .some(value) = self {
             return closure(value)
         }

Sources/Generator/Extensions/String+Extensions.swift

@@ -20,6 +20,11 @@ extension String {
             .joined(separator: "\n")
     }
 
+    /**
+     Remove the part after the last occurence of the separator (including the separator itself).
+
+     The string is left unchanges, if it does not contain the separator.
+     */
     func dropAfterLast(_ separator: String) -> String {
         guard contains(separator) else {
             return self
@@ -51,6 +56,11 @@ extension String {
         return parts.dropLast().joined(separator: separator) + content + separator + parts.last!
     }
 
+    /**
+     Remove everything behind the first separator.
+
+     Also removes the separator itself. If the separator is not contained in the string, then the full string is returned.
+     */
     func dropAfterFirst<T>(_ separator: T) -> String where T: StringProtocol {
         components(separatedBy: separator).first!
     }
@@ -62,10 +72,25 @@ extension String {
 
 extension Substring {
 
+    func dropBeforeFirst(_ separator: String) -> String {
+        guard contains(separator) else {
+            return String(self)
+        }
+        return components(separatedBy: separator).dropFirst().joined(separator: separator)
+    }
+
     func between(_ start: String, and end: String) -> String {
         components(separatedBy: start).last!
             .components(separatedBy: end).first!
     }
+
+    func between(first: String, andLast last: String) -> String {
+        dropBeforeFirst(first).dropAfterLast(last)
+    }
+
+    func last(after: String) -> String {
+        components(separatedBy: after).last!
+    }
 }
 
 extension String {
@@ -74,3 +99,8 @@ extension String {
         try data(using: .utf8)!.createFolderAndWrite(to: url)
     }
 }
+
+extension String: DefaultValueProvider {
+
+    static var defaultValue: String { "" }
+}

Sources/Generator/Extensions/URL+Extensions.swift

@@ -50,4 +50,23 @@ extension URL {
         let attributes = try? FileManager.default.attributesOfItem(atPath: path)
         return (attributes?[.size] as? NSNumber)?.intValue
     }
+
+    func resolvingFolderTraversal() -> URL? {
+        var components = [String]()
+        absoluteString.components(separatedBy: "/").forEach { part in
+            if part == ".." {
+                if !components.isEmpty {
+                    _ = components.popLast()
+                } else {
+                    components.append("..")
+                }
+                return
+            }
+            if part == "." {
+                return
+            }
+            components.append(part)
+        }
+        return URL(string: components.joined(separator: "/"))
+    }
 }

Sources/Generator/Files/Configuration.swift

@@ -16,22 +16,35 @@ struct Configuration: Codable {
     let pageImageWidth: Int
 
     /**
-     Automatically minify all `.css` and `.js` resources which are copied
+     The maximum width (in pixels) for images shown full screen.
+     */
+    let fullScreenImageWidth: Int
+
+    /**
+     Automatically minify all `.css` resources which are copied
      to the output folder.
-     - Note: This option requires the `uglifyjs` and `clean-css` tools,
+     - Note: This option requires the `clean-css` tool,
      which can be installed using the `install.sh` script in the root folder of the generator.
      */
-    let minifyCSSandJS: Bool
+    let minifyCSS: Bool
+
+    /**
+     Automatically minify all `.js` resources which are copied
+     to the output folder.
+     - Note: This option requires the `uglifyjs` tool,
+     which can be installed using the `install.sh` script in the root folder of the generator.
+     */
+    let minifyJavaScript: Bool
 
     /**
      The path to the directory where the root element metadata is located.
      */
-    let contentPath: String
+    var contentPath: String
 
     /**
      The path where the generated website should be written.
      */
-    let outputPath: String
+    var outputPath: String
 
     /**
      Create .md files for content pages, if they don't exist.
@@ -56,4 +69,23 @@ struct Configuration: Codable {
     var outputDirectory: URL {
         .init(fileURLWithPath: outputPath)
     }
+
+    mutating func adjustPathsRelative(to folder: URL) {
+        if !contentPath.hasPrefix("/") {
+            contentPath = folder.appendingPathComponent(contentPath).resolvingFolderTraversal()!.path
+        }
+        if !outputPath.hasPrefix("/") {
+            outputPath = folder.appendingPathComponent(outputPath).resolvingFolderTraversal()!.path
+        }
+    }
+
+    func printOverview() {
+        print("         Source folder: \(contentDirectory.path)")
+        print("         Output folder: \(outputDirectory.path)")
+        print("            Page width: \(pageImageWidth)")
+        print("     Full-screen width: \(fullScreenImageWidth)")
+        print("     Minify JavaScript: \(minifyJavaScript)")
+        print("            Minify CSS: \(minifyCSS)")
+        print(" Create markdown files: \(createMdFilesIfMissing)")
+    }
 }

Sources/Generator/Files/FileSystem.swift

@@ -1,426 +0,0 @@
-import Foundation
-import CryptoKit
-import AppKit
-
-final class FileSystem {
-
-    private static let tempFileName = "temp.bin"
-
-    private let input: URL
-
-    private let output: URL
-
-    private let source = "FileSystem"
-
-    private let images: ImageGenerator
-
-    private var tempFile: URL {
-        input.appendingPathComponent(FileSystem.tempFileName)
-    }
-
-    /**
-     All files which should be copied to the output folder
-     */
-    private var requiredFiles: Set<String> = []
-
-    /**
-     The files marked as external in element metadata.
-
-     Files included here are not generated, since they are assumed to be added separately.
-     */
-    private var externalFiles: Set<String> = []
-
-    /**
-     The files marked as expected, i.e. they exist after the generation is completed.
-
-     The key of the dictionary is the file path, the value is the file providing the link
-     */
-    private var expectedFiles: [String : String] = [:]
-
-    /**
-     All pages without content which have been created
-     */
-    private var emptyPages: Set<String> = []
-
-    /**
-     All pages which have `status` set to ``PageState.draft``
-     */
-    private var draftPages: Set<String> = []
-
-    /**
-     All paths to page element folders, indexed by their unique id.
-
-     This relation is used to generate relative links to pages using the ``Element.id`
-     */
-    private var pagePaths: [String: String] = [:]
-
-    /**
-     The image creation tasks.
-
-     The key is the destination path.
-     */
-    private var imageTasks: [String : ImageOutput] = [:]
-
-    /**
-     The paths to all pages which were changed
-     */
-    private var generatedPages: Set<String> = []
-
-    init(in input: URL, to output: URL) {
-        self.input = input
-        self.output = output
-        self.images = .init(input: input, output: output)
-
-    }
-
-    func urlInOutputFolder(_ path: String) -> URL {
-        output.appendingPathComponent(path)
-    }
-
-    func urlInContentFolder(_ path: String) -> URL {
-        input.appendingPathComponent(path)
-    }
-
-    private func exists(_ url: URL) -> Bool {
-        FileManager.default.fileExists(atPath: url.path)
-    }
-
-    func dataOfRequiredFile(atPath path: String, source: String) -> Data? {
-        let url = input.appendingPathComponent(path)
-        guard exists(url) else {
-            log.failedToOpen(path, requiredBy: source, error: nil)
-            return nil
-        }
-
-        do {
-            return try Data(contentsOf: url)
-        } catch {
-            log.failedToOpen(path, requiredBy: source, error: error)
-            return nil
-        }
-    }
-
-    func dataOfOptionalFile(atPath path: String, source: String) -> Data? {
-        let url = input.appendingPathComponent(path)
-        guard exists(url) else {
-            return nil
-        }
-
-        do {
-            return try Data(contentsOf: url)
-        } catch {
-            log.failedToOpen(path, requiredBy: source, error: error)
-            return nil
-        }
-    }
-
-    func contentOfOptionalFile(atPath path: String, source: String, createEmptyFileIfMissing: Bool = false) -> String? {
-        let url = input.appendingPathComponent(path)
-        guard exists(url) else {
-            if createEmptyFileIfMissing {
-                try? Data().write(to: url)
-            }
-            return nil
-        }
-
-        do {
-            return try String(contentsOf: url)
-        } catch {
-            log.failedToOpen(path, requiredBy: source, error: error)
-            return nil
-        }
-    }
-
-    func writeDetectedFileChangesToDisk() {
-        images.writeDetectedFileChangesToDisk()
-    }
-    
-    // MARK: Images
-
-    @discardableResult
-    func requireImage(source: String, destination: String, requiredBy path: String, width: Int, desiredHeight: Int? = nil)  -> NSSize {
-        images.requireImage(at: destination, generatedFrom: source, requiredBy: path, width: width, height: desiredHeight)
-    }
-
-    func createImages() {
-        images.createImages()
-    }
-
-    // MARK: File copying
-
-    /**
-     Add a file as required, so that it will be copied to the output directory.
-     */
-    func require(file: String) {
-        let url = input.appendingPathComponent(file)
-        guard url.exists, url.isDirectory else {
-            requiredFiles.insert(file)
-            return
-        }
-        do {
-            try FileManager.default
-                .contentsOfDirectory(atPath: url.path)
-                .forEach {
-                    // Recurse into subfolders
-                    require(file: file + "/" + $0)
-                }
-        } catch {
-            log.add(error: "Failed to read folder \(file): \(error)", source: source)
-        }
-    }
-
-    /**
-     Mark a file as explicitly missing.
-
-     This is done for the `externalFiles` entries in metadata,
-     to indicate that these files will be copied to the output folder manually.
-     */
-    func exclude(file: String) {
-        externalFiles.insert(file)
-    }
-
-    /**
-     Mark a file as expected to be present in the output folder after generation.
-
-     This is done for all links between pages, which only exist after the pages have been generated.
-     */
-    func expect(file: String, source: String) {
-        expectedFiles[file] = source
-    }
-
-    func copyRequiredFiles() {
-        var copiedFiles = Set<String>()
-        for file in requiredFiles {
-            let cleanPath = cleanRelativeURL(file)
-            let sourceUrl = input.appendingPathComponent(cleanPath)
-            let destinationUrl = output.appendingPathComponent(cleanPath)
-            guard sourceUrl.exists else {
-                if !isExternal(file: file) {
-                    log.add(error: "Missing required file", source: cleanPath)
-                }
-                continue
-            }
-            if copyFileIfChanged(from: sourceUrl, to: destinationUrl) {
-                copiedFiles.insert(file)
-            }
-        }
-        try? tempFile.delete()
-        for (file, source) in expectedFiles {
-            guard !isExternal(file: file) else {
-                continue
-            }
-            let cleanPath = cleanRelativeURL(file)
-            let destinationUrl = output.appendingPathComponent(cleanPath)
-            if !destinationUrl.exists {
-                log.add(error: "Missing \(cleanPath)", source: source)
-            }
-        }
-        guard !copiedFiles.isEmpty else {
-            print("No required files copied")
-            return
-        }
-        print("\(copiedFiles.count) required files copied:")
-        for file in copiedFiles.sorted() {
-            print("  " + file)
-        }
-    }
-
-    private func copyFileIfChanged(from sourceUrl: URL, to destinationUrl: URL) -> Bool {
-        guard configuration.minifyCSSandJS else {
-            return copyBinaryFileIfChanged(from: sourceUrl, to: destinationUrl)
-        }
-        switch sourceUrl.pathExtension.lowercased() {
-        case "js":
-            return minifyJS(at: sourceUrl, andWriteTo: destinationUrl)
-        case "css":
-            return minifyCSS(at: sourceUrl, andWriteTo: destinationUrl)
-        default:
-            return copyBinaryFileIfChanged(from: sourceUrl, to: destinationUrl)
-        }
-    }
-
-    private func copyBinaryFileIfChanged(from sourceUrl: URL, to destinationUrl: URL) -> Bool {
-        do {
-            let data = try Data(contentsOf: sourceUrl)
-            return writeIfChanged(data, to: destinationUrl)
-        } catch {
-            log.add(error: "Failed to read data at \(sourceUrl.path)", source: source, error: error)
-            return false
-        }
-    }
-
-    private func minifyJS(at sourceUrl: URL, andWriteTo destinationUrl: URL) -> Bool {
-        let command = "uglifyjs \(sourceUrl.path) > \(tempFile.path)"
-        do {
-            _ = try safeShell(command)
-            return copyBinaryFileIfChanged(from: tempFile, to: destinationUrl)
-        } catch {
-            log.add(error: "Failed to minify \(sourceUrl.path): \(error)", source: source)
-            return false
-        }
-    }
-
-    private func minifyCSS(at sourceUrl: URL, andWriteTo destinationUrl: URL) -> Bool {
-        let command = "cleancss \(sourceUrl.path) -o \(tempFile.path)"
-        do {
-            _ = try safeShell(command)
-            return copyBinaryFileIfChanged(from: tempFile, to: destinationUrl)
-        } catch {
-            log.add(error: "Failed to minify \(sourceUrl.path): \(error)", source: source)
-            return false
-        }
-    }
-
-    private func cleanRelativeURL(_ raw: String) -> String {
-        let raw = raw.dropAfterLast("#") // Clean links to page content
-        guard raw.contains("..") else {
-            return raw
-        }
-        var result: [String] = []
-        for component in raw.components(separatedBy: "/") {
-            if component == ".." {
-                _ = result.popLast()
-            } else {
-                result.append(component)
-            }
-        }
-        return result.joined(separator: "/")
-    }
-
-    /**
-     Check if a file is marked as external.
-
-     Also checks for sub-paths of the file, e.g if the folder `docs` is marked as external,
-     then files like `docs/index.html` are also found to be external.
-     - Note: All paths are either relative to root (no leading slash) or absolute paths of the domain (leading slash)
-     */
-    func isExternal(file: String) -> Bool {
-        // Deconstruct file path
-        var path = ""
-        for part in file.components(separatedBy: "/") {
-            guard part != "" else {
-                continue
-            }
-            if path == "" {
-                path = part
-            } else {
-                path += "/" + part
-            }
-            if externalFiles.contains(path) {
-                return true
-            }
-        }
-        return false
-    }
-
-    func printExternalFiles() {
-        guard !externalFiles.isEmpty else {
-            return
-        }
-        print("\(externalFiles.count) external resources needed:")
-        for file in externalFiles.sorted() {
-            print("  " + file)
-        }
-    }
-
-    // MARK: Pages
-
-    func isEmpty(page: String) {
-        emptyPages.insert(page)
-    }
-
-    func printEmptyPages() {
-        guard !emptyPages.isEmpty else {
-            return
-        }
-        print("\(emptyPages.count) empty pages:")
-        for page in emptyPages.sorted() {
-            print("  " + page)
-        }
-    }
-
-    func isDraft(path: String) {
-        draftPages.insert(path)
-    }
-
-    func printDraftPages() {
-        guard !draftPages.isEmpty else {
-            return
-        }
-        print("\(draftPages.count) drafts:")
-        for page in draftPages.sorted() {
-            print("  " + page)
-        }
-    }
-
-    func add(page: String, id: String) {
-        if let existing = pagePaths[id] {
-            log.add(error: "Conflicting id with \(existing)", source: page)
-        }
-        pagePaths[id] = page
-    }
-
-    func getPage(for id: String) -> String? {
-        pagePaths[id]
-    }
-
-    func generated(page: String) {
-        generatedPages.insert(page)
-    }
-
-    func printGeneratedPages() {
-        guard !generatedPages.isEmpty else {
-            print("No pages modified")
-            return
-        }
-        print("\(generatedPages.count) pages modified")
-        for page in generatedPages.sorted() {
-            print("  " + page)
-        }
-    }
-
-
-    // MARK: Writing files
-
-    @discardableResult
-    func writeIfChanged(_ data: Data, to url: URL) -> Bool {
-        // Only write changed files
-        if url.exists, let oldContent = try? Data(contentsOf: url), data == oldContent {
-            return false
-        }
-        do {
-            try data.createFolderAndWrite(to: url)
-            return true
-        } catch {
-            log.add(error: "Failed to write file", source: url.path, error: error)
-            return false
-        }
-    }
-
-    @discardableResult
-    func write(_ string: String, to url: URL) -> Bool {
-        let data = string.data(using: .utf8)!
-        return writeIfChanged(data, to: url)
-    }
-
-    // MARK: Running other tasks
-
-    @discardableResult
-    func safeShell(_ command: String) throws -> String {
-        let task = Process()
-        let pipe = Pipe()
-
-        task.standardOutput = pipe
-        task.standardError = pipe
-        task.arguments = ["-cl", command]
-        task.executableURL = URL(fileURLWithPath: "/bin/zsh")
-        task.standardInput = nil
-
-        try task.run()
-
-        let data = pipe.fileHandleForReading.readDataToEndOfFile()
-        let output = String(data: data, encoding: .utf8)!
-
-        return output
-    }
-}

Sources/Generator/Files/FileUpdateChecker.swift

@@ -3,14 +3,10 @@ import CryptoKit
 
 final class FileUpdateChecker {
 
-    private static let hashesFileName = "hashes.json"
+    private let hashesFileName = "hashes.json"
 
     private let input: URL
     
-    private var hashesFile: URL {
-        input.appendingPathComponent(FileUpdateChecker.hashesFileName)
-    }
-    
     /**
      The hashes of all accessed files from the previous run
 
@@ -25,35 +21,41 @@ final class FileUpdateChecker {
      */
     private var accessedFiles: [String : Data] = [:]
 
-    private var source: String {
+    var numberOfFilesLoaded: Int {
-        "FileUpdateChecker"
+        previousFiles.count
+    }
+
+    var numberOfFilesAccessed: Int {
+        accessedFiles.count
     }
 
     init(input: URL) {
         self.input = input
-        guard hashesFile.exists else {
+    }
-            log.add(info: "No file hashes loaded, regarding all content as new", source: source)
+
-            return
+    enum LoadResult {
+        case notLoaded
+        case loaded
+        case failed(String)
+    }
+
+    func loadPreviousRun(from folder: URL) -> LoadResult {
+        let url = folder.appendingPathComponent(hashesFileName)
+        guard url.exists else {
+            return .notLoaded
         }
         let data: Data
         do {
-            data = try Data(contentsOf: hashesFile)
+            data = try Data(contentsOf: url)
         } catch {
-            log.add(
+            return .failed("Failed to read hashes from last run: \(error)")
-                warning: "File hashes could not be read, regarding all content as new",
-                source: source,
-                error: error)
-            return
         }
         do {
             self.previousFiles = try JSONDecoder().decode(from: data)
         } catch {
-            log.add(
+            return .failed("Failed to decode hashes from last run: \(error)")
-                warning: "File hashes could not be decoded, regarding all content as new",
-                source: source,
-                error: error)
-            return
         }
+        return .loaded
     }
 
     func fileHasChanged(at path: String) -> Bool {
@@ -73,16 +75,18 @@ final class FileUpdateChecker {
         accessedFiles[path] = SHA256.hash(data: data).data
     }
 
-
+    func writeDetectedFileChanges(to folder: URL) -> String? {
-    func writeDetectedFileChangesToDisk() {
+        let url = folder.appendingPathComponent(hashesFileName)
         do {
             let encoder = JSONEncoder()
             encoder.outputFormatting = .prettyPrinted
             let data = try encoder.encode(accessedFiles)
-            try data.write(to: hashesFile)
+            try data.write(to: url)
+            return nil
         } catch {
-            log.add(warning: "Failed to save file hashes", source: source, error: error)
+            return "Failed to save file hashes: \(error)"
+        }
     }
 }
 
-}
+var notFound = 0

Sources/Generator/Files/ImageGenerator.swift

@@ -1,287 +0,0 @@
-import Foundation
-import AppKit
-import CryptoKit
-
-private struct ImageJob {
-
-    let destination: String
-
-    let width: Int
-
-    let path: String
-}
-
-final class ImageGenerator {
-
-    /**
-     The path to the input folder.
-     */
-    private let input: URL
-
-    /**
-     The path to the output folder
-     */
-    private let output: URL
-
-    /**
-     The images to generate.
-
-     The key is the image source path relative to the input folder, and the values are the destination path (relative to the output folder) and the required image width.
-     */
-    private var imageJobs: [String : [ImageJob]] = [:]
-
-    /**
-     The images which could not be found, but are required for the site.
-
-     The key is the image path, and the value is the page that requires it.
-     */
-    private var missingImages: [String : String] = [:]
-
-    /**
-     All warnings produced for images during generation
-     */
-    private var imageWarnings: Set<String> = []
-
-    /**
-     All images required by the site.
-
-     The values are the destination paths of the images, relative to the output folder
-     */
-    private var requiredImages: Set<String> = []
-
-    /**
-     All images modified or created during this generator run.
-     */
-    private var generatedImages: Set<String> = []
-
-    /**
-     A cache to get the size of source images, so that files don't have to be loaded multiple times.
-
-     The key is the absolute source path, and the value is the image size
-     */
-    private var imageSizeCache: [String : NSSize] = [:]
-
-    private var fileUpdates: FileUpdateChecker
-
-    init(input: URL, output: URL) {
-        self.fileUpdates = FileUpdateChecker(input: input)
-        self.input = input
-        self.output = output
-    }
-
-    func writeDetectedFileChangesToDisk() {
-        fileUpdates.writeDetectedFileChangesToDisk()
-    }
-
-    private func getImageSize(atPath path: String) -> NSSize? {
-        if let size = imageSizeCache[path] {
-            return size
-        }
-        guard let image = getImage(atPath: path) else {
-            return nil
-        }
-        let size = image.size
-        imageSizeCache[path] = size
-        return size
-    }
-
-    private func getImage(atPath path: String) -> NSImage? {
-        guard let data = getData(atPath: path) else {
-            log.add(error: "Failed to load file", source: path)
-            return nil
-        }
-        guard let image = NSImage(data: data) else {
-            log.add(error: "Failed to read image", source: path)
-            return nil
-        }
-        return image
-    }
-
-    private func getData(atPath path: String) -> Data? {
-        let url = input.appendingPathComponent(path)
-        guard url.exists else {
-            return nil
-        }
-        do {
-            let data = try Data(contentsOf: url)
-            fileUpdates.didLoad(data, at: path)
-            return data
-        } catch {
-            log.add(error: "Failed to read data", source: path, error: error)
-            return nil
-        }
-    }
-
-    func requireImage(at destination: String, generatedFrom source: String, requiredBy path: String, width: Int, height: Int?) -> NSSize {
-        requiredImages.insert(destination)
-        let height = height.unwrapped(CGFloat.init)
-        let sourceUrl = input.appendingPathComponent(source)
-        guard sourceUrl.exists else {
-            missingImages[source] = path
-            return .zero
-        }
-
-        guard let imageSize = getImageSize(atPath: source) else {
-            missingImages[source] = path
-            return .zero
-        }
-        let scaledSize = imageSize.scaledDown(to: CGFloat(width))
-
-        // Check desired height, then we can forget about it
-        if let height = height {
-            let expectedHeight = scaledSize.width / CGFloat(width) * height
-            if abs(expectedHeight - scaledSize.height) > 2 {
-                addWarning("Invalid height (\(scaledSize.height) instead of \(expectedHeight))", destination: destination, path: path)
-            }
-        }
-
-        let job = ImageJob(destination: destination, width: width, path: path)
-
-        guard let existingSource = imageJobs[source] else {
-            imageJobs[source] = [job]
-            return scaledSize
-        }
-
-        guard let existingJob = existingSource.first(where: { $0.destination == destination}) else {
-            imageJobs[source] = existingSource + [job]
-            return scaledSize
-        }
-
-        if existingJob.width != width {
-            addWarning("Multiple image widths (\(existingJob.width) and \(width))", destination: destination, path: "\(existingJob.path) and \(path)")
-        }
-        return scaledSize
-    }
-
-    func createImages() {
-        for (source, jobs) in imageJobs.sorted(by: { $0.key < $1.key }) {
-            create(images: jobs, from: source)
-        }
-        printMissingImages()
-        printImageWarnings()
-        printGeneratedImages()
-        printTotalImageCount()
-    }
-
-    private func printMissingImages() {
-        guard !missingImages.isEmpty else {
-            return
-        }
-        print("\(missingImages.count) missing images:")
-        for (source, path) in missingImages {
-            print("  \(source) (required by \(path))")
-        }
-    }
-
-    private func printImageWarnings() {
-        guard !imageWarnings.isEmpty else {
-            return
-        }
-        print("\(imageWarnings.count) image warnings:")
-        for imageWarning in imageWarnings {
-            print(imageWarning)
-        }
-    }
-
-    private func printGeneratedImages() {
-        guard !generatedImages.isEmpty else {
-            return
-        }
-        print("\(generatedImages.count) images generated:")
-        for image in generatedImages {
-            print("  " + image)
-        }
-    }
-
-    private func printTotalImageCount() {
-        print("\(requiredImages.count) images")
-    }
-
-    private func addWarning(_ message: String, destination: String, path: String) {
-        let warning = "  \(destination): \(message) required by \(path)"
-        imageWarnings.insert(warning)
-    }
-
-    private func addWarning(_ message: String, job: ImageJob) {
-        addWarning(message, destination: job.destination, path: job.path)
-    }
-
-    private func isMissing(_ job: ImageJob) -> Bool {
-        !output.appendingPathComponent(job.destination).exists
-    }
-
-    private func create(images: [ImageJob], from source: String) {
-        // Only load image if required
-        let imageHasChanged = fileUpdates.fileHasChanged(at: source)
-        guard imageHasChanged || images.contains(where: isMissing) else {
-            return
-        }
-
-        guard let image = getImage(atPath: source) else {
-            missingImages[source] = images.first?.path
-            return
-        }
-        let jobs = imageHasChanged ? images : images.filter(isMissing)
-        // Update all images
-        jobs.forEach { job in
-            // Prevent memory overflow due to repeated NSImage operations
-            autoreleasepool {
-                create(job: job, from: image, source: source)
-            }
-        }
-    }
-
-    private func create(job: ImageJob, from image: NSImage, source: String) {
-        let destinationUrl = output.appendingPathComponent(job.destination)
-
-        // Ensure that image file is supported
-        let ext = destinationUrl.pathExtension.lowercased()
-        guard ImageType(fileExtension: ext) != nil else {
-            fatalError()
-        }
-
-        let destinationExtension = destinationUrl.pathExtension.lowercased()
-        guard let type = ImageType(fileExtension: destinationExtension)?.fileType else {
-            addWarning("Invalid image extension \(destinationExtension)", job: job)
-            return
-        }
-
-        let desiredWidth = CGFloat(job.width)
-
-        let sourceRep = image.representations[0]
-        let destinationSize = NSSize(width: sourceRep.pixelsWide, height: sourceRep.pixelsHigh)
-            .scaledDown(to: desiredWidth)
-
-        // create NSBitmapRep manually, if using cgImage, the resulting size is wrong
-        let rep = NSBitmapImageRep(bitmapDataPlanes: nil,
-                                   pixelsWide: Int(destinationSize.width),
-                                   pixelsHigh: Int(destinationSize.height),
-                                   bitsPerSample: 8,
-                                   samplesPerPixel: 4,
-                                   hasAlpha: true,
-                                   isPlanar: false,
-                                   colorSpaceName: NSColorSpaceName.deviceRGB,
-                                   bytesPerRow: Int(destinationSize.width) * 4,
-                                   bitsPerPixel: 32)!
-
-        let ctx = NSGraphicsContext(bitmapImageRep: rep)
-        NSGraphicsContext.saveGraphicsState()
-        NSGraphicsContext.current = ctx
-        image.draw(in: NSMakeRect(0, 0, destinationSize.width, destinationSize.height))
-        ctx?.flushGraphics()
-        NSGraphicsContext.restoreGraphicsState()
-
-        // Get NSData, and save it
-        guard let data = rep.representation(using: type, properties: [.compressionFactor: NSNumber(0.7)]) else {
-            addWarning("Failed to get data", job: job)
-            return
-        }
-        do {
-            try data.createFolderAndWrite(to: destinationUrl)
-        } catch {
-            addWarning("Failed to write image (\(error))", job: job)
-            return
-        }
-        generatedImages.insert(job.destination)
-    }
-}

Sources/Generator/Files/ImageJob.swift

@@ -0,0 +1,14 @@
+import Foundation
+
+struct ImageJob {
+
+    let destination: String
+
+    let width: Int
+
+    let path: String
+
+    let quality: Float
+
+    let alwaysGenerate: Bool
+}

Sources/Generator/Files/ImageReader.swift

@@ -0,0 +1,66 @@
+import Foundation
+import AppKit
+
+final class ImageReader {
+
+    /// The content folder where the input data is stored
+    let contentFolder: URL
+
+    private let fileUpdates: FileUpdateChecker
+
+    let runDataFolder: URL
+
+    init(in input: URL, runFolder: URL, fileUpdates: FileUpdateChecker) {
+        self.contentFolder = input
+        self.runDataFolder = runFolder
+        self.fileUpdates = fileUpdates
+    }
+
+    var numberOfFilesLoaded: Int {
+        fileUpdates.numberOfFilesLoaded
+    }
+
+    var numberOfFilesAccessed: Int {
+        fileUpdates.numberOfFilesAccessed
+    }
+
+    func loadData() -> FileUpdateChecker.LoadResult {
+        fileUpdates.loadPreviousRun(from: runDataFolder)
+    }
+
+    func writeDetectedFileChangesToDisk() -> String? {
+        fileUpdates.writeDetectedFileChanges(to: runDataFolder)
+    }
+
+    func imageHasChanged(at path: String) -> Bool {
+        fileUpdates.fileHasChanged(at: path)
+    }
+
+    func getImage(atPath path: String) -> NSImage? {
+        guard let data = getData(atPath: path) else {
+            // TODO: log.error("Failed to load file", source: path)
+            return nil
+        }
+        guard let image = NSImage(data: data) else {
+            // TODO: log.error("Failed to read image", source: path)
+            return nil
+        }
+        return image
+    }
+
+    private func getData(atPath path: String) -> Data? {
+        let url = contentFolder.appendingPathComponent(path)
+        guard url.exists else {
+            return nil
+        }
+        do {
+            let data = try Data(contentsOf: url)
+            fileUpdates.didLoad(data, at: path)
+            return data
+        } catch {
+            // TODO: log.error("Failed to read data: \(error)", source: path)
+            return nil
+        }
+    }
+
+}

Sources/Generator/Files/ImageType.swift

@@ -4,6 +4,8 @@ import AppKit
 enum ImageType: CaseIterable {
     case jpg
     case png
+    case avif
+    case webp
 
     init?(fileExtension: String) {
         switch fileExtension {
@@ -11,6 +13,10 @@ enum ImageType: CaseIterable {
             self = .jpg
         case "png":
             self = .png
+        case "avif":
+            self = .avif
+        case "webp":
+            self = .webp
         default:
             return nil
         }
@@ -20,7 +26,7 @@ enum ImageType: CaseIterable {
         switch self {
         case .jpg:
             return .jpeg
-        case .png:
+        case .png, .avif, .webp:
             return .png
         }
     }

Sources/Generator/Files/ValidationLog.swift

@@ -46,123 +46,7 @@ final class ValidationLog {
         add(info: .init(reason: reason, source: source, error: error))
     }
 
-    @discardableResult
-    func unused<T, R>(_ value: Optional<T>, _ name: String, source: String) -> Optional<R> {
-        if value != nil {
-            add(info: "Unused property '\(name)'", source: source)
-        }
-        return nil
-    }
-
-    func unknown(property: String, source: String) {
-        add(info: "Unknown property '\(property)'", source: source)
-    }
-
-    func required<T>(_ value: Optional<T>, name: String, source: String) -> Optional<T> {
-        guard let value = value else {
-            add(error: "Missing property '\(name)'", source: source)
-            return nil
-        }
-        return value
-    }
-
-    func unexpected<T>(_ value: Optional<T>, name: String, source: String) -> Optional<T> {
-        if let value = value {
-            add(error: "Unexpected property '\(name)' = '\(value)'", source: source)
-            return nil
-        }
-        return nil
-    }
-
-    func missing(_ file: String, requiredBy source: String) {
-        print("[ERROR] Missing file '\(file)' required by \(source)")
-    }
-
     func failedToOpen(_ file: String, requiredBy source: String, error: Error?) {
         print("[ERROR] Failed to open file '\(file)' required by \(source): \(error?.localizedDescription ?? "No error provided")")
     }
-
-    func state(_ raw: String?, source: String) -> PageState {
-        guard let raw = raw else {
-            return .standard
-        }
-        guard let state = PageState(rawValue: raw) else {
-            add(warning: "Invalid 'state' '\(raw)', using 'standard'", source: source)
-            return .standard
-        }
-        return state
-    }
-
-    func headerType(_ raw: String?, source: String) -> HeaderType {
-        guard let raw = raw else {
-            return .left
-        }
-        guard let type = HeaderType(rawValue: raw) else {
-            add(warning: "Invalid 'headerType' '\(raw)', using 'left'", source: source)
-            return .left
-        }
-        return type
-    }
-
-    func thumbnailStyle(_ raw: String?, source: String) -> ThumbnailStyle {
-        guard let raw = raw else {
-            return .large
-        }
-        guard let style = ThumbnailStyle(rawValue: raw) else {
-            add(warning: "Invalid 'thumbnailStyle' '\(raw)', using 'large'", source: source)
-            return .large
-        }
-        return style
-    }
-
-    func linkPreviewThumbnail(customFile: String?, for language: String, in folder: URL, source: String) -> String? {
-        if let customFile = customFile {
-            let customFileUrl: URL
-            if customFile.starts(with: "/") {
-                customFileUrl = URL(fileURLWithPath: customFile)
-            } else {
-                customFileUrl = folder.appendingPathComponent(customFile)
-            }
-            guard customFileUrl.exists else {
-                missing(customFile, requiredBy: "property 'linkPreviewImage' in metadata of \(source)")
-                return nil
-            }
-            return customFile
-        }
-        guard let thumbnail = Element.findThumbnail(for: language, in: folder) else {
-            // Link preview images are not necessarily required
-            return nil
-        }
-        return thumbnail
-    }
-
-    func moreLinkText(_ elementText: String?, parent parentText: String?, source: String) -> String {
-        if let elementText = elementText {
-            return elementText
-        }
-        let standard = Element.LocalizedMetadata.moreLinkDefaultText
-        guard let parentText = parentText, parentText != standard else {
-            add(error: "Missing property 'moreLinkText'", source: source)
-            return standard
-        }
-
-        return parentText
-    }
-
-    func date(from string: String?, property: String, source: String) -> Date? {
-        guard let string = string else {
-            return nil
-        }
-        guard let date = ValidationLog.metadataDate.date(from: string) else {
-            add(warning: "Invalid date string '\(string)' for property '\(property)'", source: source)
-            return nil
-        }
-        return date
-    }
-
-    private static let metadataDate: DateFormatter = {
-        let df = DateFormatter()
-        df.dateFormat = "dd.MM.yy"
-        return df
-    }()
 }

Sources/Generator/Files/VideoType.swift

@@ -3,6 +3,7 @@ import Foundation
 enum VideoType: String, CaseIterable {
     case mp4
     case m4v
+    case webm
 
     var htmlType: String {
         switch self {
@@ -10,6 +11,8 @@ enum VideoType: String, CaseIterable {
             return "video/mp4"
         case .m4v:
             return "video/mp4"
+        case .webm:
+            return "video/webm"
         }
     }
 }

Sources/Generator/Generators/HTMLElementsGenerator.swift

@@ -1,11 +1,9 @@
 import Foundation
 
+typealias SVGSelection = (x: Int, y: Int, width: Int, height: Int)
+
 struct HTMLElementsGenerator {
 
-    init() {
-
-    }
-
     func make(title: String, suffix: String) -> String {
         "\(title)<span class=\"suffix\">\(suffix)</span>"
     }
@@ -37,20 +35,18 @@ struct HTMLElementsGenerator {
         "\(text)<span class=\"icon-next\"></span>"
     }
 
-    func svgImage(file: String) -> String {
+    func image(file: String, width: Int, height: Int, altText: String) -> String {
-        """
+        let ratio = Float(width) / Float(height)
+        return """
         <span class="image">
-            <img src="\(file)"/>
+            <img src="\(file)" loading="lazy" style="aspect-ratio:\(ratio)" alt="\(altText)"/>
         </span>
         """
     }
 
-    func svgImage(file: String, x: Int, y: Int, width: Int, height: Int) -> String {
+    func svgImage(file: String, part: SVGSelection, altText: String) -> String {
-        """
+        let path = "\(file)#svgView(viewBox(\(part.x), \(part.y), \(part.width), \(part.height)))"
-        <span class="image">
+        return image(file: path, width: part.width, height: part.height, altText: altText)
-            <img src="\(file)#svgView(viewBox(\(x), \(y), \(width), \(height)))" style="aspect-ratio:\(Float(width)/Float(height))"/>
-        </span>
-        """
     }
 
     func downloadButtons(_ buttons: [(file: String, text: String, downloadName: String?)]) -> String {
@@ -103,8 +99,11 @@ struct HTMLElementsGenerator {
         """
     }
 
-    func scriptInclude(path: String) -> String {
+    func scriptInclude(path: String, asModule: Bool) -> String {
-        "<script src=\"\(path)\"></script>"
+        if asModule {
+            return "<script type=\"module\" src=\"\(path)\"></script>"
+        }
+        return "<script src=\"\(path)\"></script>"
     }
 
     func codeHighlightFooter() -> String {

Sources/Generator/Generators/MarkdownProcessor.swift

@@ -1,297 +0,0 @@
-import Foundation
-import Ink
-import Splash
-
-struct PageContentGenerator {
-
-    private let factory: TemplateFactory
-
-    private let swift = SyntaxHighlighter(format: HTMLOutputFormat())
-
-    init(factory: TemplateFactory) {
-        self.factory = factory
-    }
-
-    func generate(page: Element, language: String, content: String) -> (content: String, includesCode: Bool) {
-        var hasCodeContent = false
-
-        let imageModifier = Modifier(target: .images) { html, markdown in
-            processMarkdownImage(markdown: markdown, html: html, page: page, language: language)
-        }
-        let codeModifier = Modifier(target: .codeBlocks) { html, markdown in
-            if markdown.starts(with: "```swift") {
-                let code = markdown.between("```swift", and: "```").trimmed
-                return "<pre><code>" + swift.highlight(code) + "</pre></code>"
-            }
-            hasCodeContent = true
-            return html
-        }
-        let linkModifier = Modifier(target: .links) { html, markdown in
-            handleLink(page: page, language: language, html: html, markdown: markdown)
-        }
-        let htmlModifier = Modifier(target: .html) { html, markdown in
-            handleHTML(page: page, language: language, html: html, markdown: markdown)
-        }
-
-        let parser = MarkdownParser(modifiers: [imageModifier, codeModifier, linkModifier, htmlModifier])
-        return (parser.html(from: content), hasCodeContent)
-    }
-
-    private func handleLink(page: Element, language: String, html: String, markdown: Substring) -> String {
-        let file = markdown.between("(", and: ")")
-        if file.hasPrefix("page:") {
-            let pageId = file.replacingOccurrences(of: "page:", with: "")
-            guard let pagePath = files.getPage(for: pageId) else {
-                log.add(warning: "Page id '\(pageId)' not found", source: page.path)
-                // Remove link since the page can't be found
-                return markdown.between("[", and: "]")
-            }
-            let fullPath = pagePath + Element.htmlPagePathAddition(for: language)
-            // Adjust file path to get the page url
-            let url = page.relativePathToOtherSiteElement(file: fullPath)
-            return html.replacingOccurrences(of: file, with: url)
-        }
-
-        if let filePath = page.nonAbsolutePathRelativeToRootForContainedInputFile(file) {
-            // The target of the page link must be present after generation is complete
-            files.expect(file: filePath, source: page.path)
-        }
-        return html
-    }
-
-    private func handleHTML(page: Element, language: String, html: String, markdown: Substring) -> String {
-        #warning("Check HTML code in markdown for required resources")
-        //print("[HTML] Found in page \(page.path):")
-        //print(markdown)
-        // Things to check:
-        // <img src=
-        // <a href=
-        //
-        return html
-    }
-
-    private func processMarkdownImage(markdown: Substring, html: String, page: Element, language: String) -> String {
-        // Split the markdown ![alt](file title)
-        // There are several known shorthand commands
-        // For images: ![left_title](file right_title)
-        // For videos: ![option1,option2,...](file)
-        // For svg with custom area: ![x,y,width,height](file.svg)
-        // For downloads: ![download](file1, text1; file2, text2, ...)
-        // For a simple boxes: ![box](title;body)
-        // A fancy page link: ![page](page_id)
-        // External pages: ![external](url1, text1; url2, text2, ...)
-        let fileAndTitle = markdown.between("(", and: ")")
-        let alt = markdown.between("[", and: "]").nonEmpty
-        if let alt = alt, let command = ShorthandMarkdownKey(rawValue: alt) {
-            return handleShortHandCommand(command, page: page, language: language, content: fileAndTitle)
-        }
-
-        let file = fileAndTitle.dropAfterFirst(" ")
-        let title = fileAndTitle.contains(" ") ? fileAndTitle.dropBeforeFirst(" ").nonEmpty : nil
-
-        let fileExtension = file.lastComponentAfter(".").lowercased()
-        if let _ = ImageType(fileExtension: fileExtension) {
-            return handleImage(page: page, file: file, rightTitle: title, leftTitle: alt)
-        }
-        if let _ = VideoType(rawValue: fileExtension) {
-            return handleVideo(page: page, file: file, optionString: alt)
-        }
-        if fileExtension == "svg" {
-            return handleSvg(page: page, file: file, area: alt)
-        }
-        return handleFile(page: page, file: file, fileExtension: fileExtension)
-    }
-
-    private func handleShortHandCommand(_ command: ShorthandMarkdownKey, page: Element, language: String, content: String) -> String {
-        switch command {
-        case .downloadButtons:
-            return handleDownloadButtons(page: page, content: content)
-        case .externalLink:
-            return handleExternalButtons(page: page, content: content)
-        case .includedHtml:
-            return handleExternalHTML(page: page, file: content)
-        case .box:
-            return handleSimpleBox(page: page, content: content)
-        case .pageLink:
-            return handlePageLink(page: page, language: language, pageId: content)
-        }
-    }
-
-    private func handleImage(page: Element, file: String, rightTitle: String?, leftTitle: String?) -> String {
-        let imagePath = page.pathRelativeToRootForContainedInputFile(file)
-
-        let size = files.requireImage(
-            source: imagePath,
-            destination: imagePath,
-            requiredBy: page.path,
-            width: configuration.pageImageWidth)
-
-        let imagePath2x = imagePath.insert("@2x", beforeLast: ".")
-        let file2x = file.insert("@2x", beforeLast: ".")
-        files.requireImage(
-            source: imagePath,
-            destination: imagePath2x,
-            requiredBy: page.path,
-            width: 2 * configuration.pageImageWidth)
-
-        let content: [PageImageTemplate.Key : String] = [
-            .image: file,
-            .image2x: file2x,
-            .width: "\(Int(size.width))",
-            .height: "\(Int(size.height))",
-            .leftText: leftTitle ?? "",
-            .rightText: rightTitle ?? ""]
-        return factory.image.generate(content)
-    }
-
-    private func handleVideo(page: Element, file: String, optionString: String?) -> String {
-        let options: [PageVideoTemplate.VideoOption] = optionString.unwrapped { string in
-            string.components(separatedBy: " ").compactMap { optionText in
-                guard let optionText = optionText.trimmed.nonEmpty else {
-                    return nil
-                }
-                guard let option = PageVideoTemplate.VideoOption(rawValue: optionText) else {
-                    log.add(warning: "Unknown video option \(optionText)", source: page.path)
-                    return nil
-                }
-                return option
-            }
-        } ?? []
-        #warning("Check page folder for alternative video versions")
-        let sources: [PageVideoTemplate.VideoSource] = [(url: file, type: .mp4)]
-
-        let filePath = page.pathRelativeToRootForContainedInputFile(file)
-        files.require(file: filePath)
-        return factory.video.generate(sources: sources, options: options)
-    }
-
-    private func handleSvg(page: Element, file: String, area: String?) -> String {
-        let imagePath = page.pathRelativeToRootForContainedInputFile(file)
-        files.require(file: imagePath)
-
-        guard let area = area else {
-            return factory.html.svgImage(file: file)
-        }
-        let parts = area.components(separatedBy: ",").map { $0.trimmed }
-        guard parts.count == 4,
-              let x = Int(parts[0].trimmed),
-              let y = Int(parts[1].trimmed),
-              let width = Int(parts[2].trimmed),
-              let height = Int(parts[3].trimmed) else {
-            log.add(warning: "Invalid area string for svg image", source: page.path)
-            return factory.html.svgImage(file: file)
-        }
-
-        return factory.html.svgImage(file: file, x: x, y: y, width: width, height: height)
-    }
-
-    private func handleFile(page: Element, file: String, fileExtension: String) -> String {
-        log.add(warning: "Unhandled file \(file) with extension \(fileExtension)", source: page.path)
-        return ""
-    }
-
-    private func handleDownloadButtons(page: Element, content: String) -> String {
-        let buttons = content
-            .components(separatedBy: ";")
-            .compactMap { button -> (file: String, text: String, downloadName: String?)? in
-                let parts = button.components(separatedBy: ",")
-                guard parts.count == 2 || parts.count == 3 else {
-                    log.add(warning: "Invalid button definition", source: page.path)
-                    return nil
-                }
-                let file = parts[0].trimmed
-                let title = parts[1].trimmed
-                let downloadName = parts.count == 3 ? parts[2].trimmed : nil
-
-                // Ensure that file is available
-                let filePath = page.pathRelativeToRootForContainedInputFile(file)
-                files.require(file: filePath)
-
-                return (file, title, downloadName)
-            }
-        return factory.html.downloadButtons(buttons)
-    }
-
-    private func handleExternalButtons(page: Element, content: String) -> String {
-        let buttons = content
-            .components(separatedBy: ";")
-            .compactMap { button -> (url: String, text: String)? in
-                let parts = button.components(separatedBy: ",")
-                guard parts.count == 2 else {
-                    log.add(warning: "Invalid external link definition", source: page.path)
-                    return nil
-                }
-                let url = parts[0].trimmed
-                let title = parts[1].trimmed
-
-                return (url, title)
-            }
-        return factory.html.externalButtons(buttons)
-    }
-
-    private func handleExternalHTML(page: Element, file: String) -> String {
-        let url = page.inputFolder.appendingPathComponent(file)
-        guard url.exists else {
-            log.add(error: "File \(file) not found", source: page.path)
-            return ""
-        }
-        do {
-            return try String(contentsOf: url)
-        } catch {
-            log.add(error: "File \(file) could not be read", source: page.path, error: error)
-            return ""
-        }
-    }
-
-    private func handleSimpleBox(page: Element, content: String) -> String {
-        let parts = content.components(separatedBy: ";")
-        guard parts.count > 1 else {
-            log.add(error: "Invalid box specification", source: page.path)
-            return ""
-        }
-        let title = parts[0]
-        let text = parts.dropFirst().joined(separator: ";")
-        return factory.makePlaceholder(title: title, text: text)
-    }
-
-    private func handlePageLink(page: Element, language: String, pageId: String) -> String {
-        guard let linkedPage = siteRoot.find(pageId) else {
-            log.add(warning: "Page id '\(pageId)' not found", source: page.path)
-            // Remove link since the page can't be found
-            return ""
-        }
-        var content = [PageLinkTemplate.Key: String]()
-        content[.url] = page.relativePathToOtherSiteElement(file: linkedPage.fullPageUrl(for: language))
-        
-        content[.title] = linkedPage.title(for: language)
-
-        let fullThumbnailPath = linkedPage.thumbnailFilePath(for: language)
-        let relativeImageUrl = page.relativePathToOtherSiteElement(file: fullThumbnailPath)
-        let metadata = linkedPage.localized(for: language)
-
-        if linkedPage.state.hasThumbnailLink {
-            let fullPageUrl = linkedPage.fullPageUrl(for: language)
-            let relativePageUrl = page.relativePathToOtherSiteElement(file: fullPageUrl)
-            content[.url] = "href=\"\(relativePageUrl)\""
-        }
-
-        content[.image] = relativeImageUrl
-        if let suffix = metadata.thumbnailSuffix {
-            content[.title] = factory.html.make(title: metadata.title, suffix: suffix)
-        } else {
-            content[.title] = metadata.title
-        }
-        content[.image2x] = relativeImageUrl.insert("@2x", beforeLast: ".")
-
-        let path = linkedPage.makePath(language: language, from: siteRoot)
-        content[.path] = factory.pageLink.makePath(components: path)
-
-        content[.description] = metadata.relatedContentText
-        if let parent = linkedPage.findParent(from: siteRoot), parent.thumbnailStyle == .large {
-            content[.className] = " related-page-link-large"
-        }
-
-        // We assume that the thumbnail images are already required by overview pages.
-        return factory.pageLink.generate(content)
-    }
-}

Sources/Generator/Generators/OverviewPageGenerator.swift

@@ -4,15 +4,17 @@ struct OverviewPageGenerator {
 
     private let factory: LocalizedSiteTemplate
 
-    init(factory: LocalizedSiteTemplate) {
+    private let results: GenerationResultsHandler
+
+    init(factory: LocalizedSiteTemplate, results: GenerationResultsHandler) {
         self.factory = factory
+        self.results = results
     }
 
     func generate(
         section: Element,
         language: String) {
             let path = section.localizedPath(for: language)
-            let url = files.urlInOutputFolder(path)
 
             let metadata = section.localized(for: language)
 
@@ -23,14 +25,12 @@ struct OverviewPageGenerator {
                 sectionUrl: section.sectionUrl(for: language),
                 languageButton: languageButton,
                 page: section)
+            content[.language] = language
             content[.contentClass] = "overview"
             content[.header] = makeHeader(page: section, metadata: metadata, language: language)
             content[.content] = makeContent(section: section, language: language)
-            content[.footer] = section.customFooterContent()
+            content[.footer] = results.getContentOfOptionalFile(at: section.additionalFooterContentPath, source: section.path)
-            guard factory.page.generate(content, to: url) else {
+            factory.page.generate(content, to: path, source: section.path)
-                return
-            }
-            files.generated(page: path)
     }
 
     private func makeContent(section: Element, language: String) -> String {

Sources/Generator/Generators/OverviewSectionGenerator.swift

@@ -2,19 +2,84 @@ import Foundation
 
 struct OverviewSectionGenerator {
 
-    private let multipleSectionsTemplate: OverviewSectionTemplate
+    private let factory: TemplateFactory
-
-    private let singleSectionsTemplate: OverviewSectionCleanTemplate
 
     private let generator: ThumbnailListGenerator
 
-    init(factory: TemplateFactory) {
+    private let siteRoot: Element
-        self.multipleSectionsTemplate = factory.overviewSection
+
-        self.singleSectionsTemplate = factory.overviewSectionClean
+    private let results: GenerationResultsHandler
-        self.generator = ThumbnailListGenerator(factory: factory)
+
+    init(factory: TemplateFactory, siteRoot: Element, results: GenerationResultsHandler) {
+        self.factory = factory
+        self.siteRoot = siteRoot
+        self.results = results
+        self.generator = ThumbnailListGenerator(factory: factory, results: results)
     }
 
     func generate(sections: [Element], in parent: Element, language: String, sectionItemCount: Int) -> String {
+        let content = sectionsContent(sections, in: parent, language: language, sectionItemCount: sectionItemCount)
+        let firstSection = firstSectionContent(for: parent, language: language, sectionItemCount: sectionItemCount)
+        return firstSection + content
+    }
+
+    private func firstSectionContent(for element: Element, language: String, sectionItemCount: Int) -> String {
+        guard element.needsFirstSection else {
+            return ""
+        }
+        let metadata = element.localized(for: language)
+        var result = ""
+        if element.showMostRecentSection {
+            let shownElements = element.mostRecentElements(4).enumerated().map { (number, child) in
+                makeSlideshowItem(child, parent: element, language: language, number: number)
+            }
+            let title = metadata.mostRecentTitle ?? "Recent"
+            result = factory.slideshow.generate([.content: shownElements.joined(separator: "\n"), .title: title])
+        }
+        if !element.featuredPages.isEmpty {
+            let elements = element.featuredPages.compactMap { id -> Element? in
+                guard let linked = siteRoot.find(id) else {
+                    results.warning("Unknown id '\(id)' in 'featuredPages'", source: element.path)
+                    return nil
+                }
+                return linked
+            }.prefix(4).enumerated().map { number, page in
+                makeSlideshowItem(page, parent: element, language: language, number: number)
+            }
+            let title = metadata.featuredTitle ?? "Featured"
+            result += factory.slideshow.generate([.content: elements.joined(separator: "\n"), .title: title])
+        }
+        return factory.slideshows.generate([.content : result])
+    }
+
+    private func makeSlideshowItem(_ item: Element, parent: Element, language: String, number: Int) -> String {
+        let metadata = item.localized(for: language)
+        var content = [SlideshowImageTemplate.Key : String]()
+        content[.number] = "\(number + 1)"
+        content[.altText] = metadata.linkPreviewDescription
+
+        if item.state.hasThumbnailLink {
+            let fullPageUrl = item.fullPageUrl(for: language)
+            let relativePageUrl = parent.relativePathToFileWithPath(fullPageUrl)
+            content[.url] = "href=\"\(relativePageUrl)\""
+        }
+
+        // Image already assumed to be generated
+        let (_, thumbnailDestPath) = item.thumbnailFilePath(for: language)
+        let thumbnailDestNoExtension = thumbnailDestPath.dropAfterLast(".")
+        content[.image] = parent.relativePathToFileWithPath(thumbnailDestNoExtension)
+
+        if let suffix = metadata.thumbnailSuffix {
+            content[.title] = factory.html.make(title: metadata.title, suffix: suffix)
+        } else {
+            content[.title] = metadata.title
+        }
+        let path = item.makePath(language: language, from: siteRoot)
+        content[.subtitle] = factory.pageLink.makePath(components: path)
+        return factory.slideshowImage.generate(content)
+    }
+
+    private func sectionsContent(_ sections: [Element], in parent: Element, language: String, sectionItemCount: Int) -> String {
         sections.map { section in
             let metadata = section.localized(for: language)
             let fullUrl = section.fullPageUrl(for: language)
@@ -30,7 +95,7 @@ struct OverviewSectionGenerator {
                 style: section.thumbnailStyle)
             content[.more] = metadata.moreLinkText
 
-            return multipleSectionsTemplate.generate(content)
+            return factory.overviewSection.generate(content)
         }
         .joined(separator: "\n")
     }
@@ -42,6 +107,6 @@ struct OverviewSectionGenerator {
             parent: section,
             language: language,
             style: section.thumbnailStyle)
-        return singleSectionsTemplate.generate(content)
+        return factory.overviewSectionClean.generate(content)
     }
 }

Sources/Generator/Generators/PageContentGenerator.swift

@@ -0,0 +1,466 @@
+import Foundation
+import Ink
+import Splash
+
+struct PageContentGenerator {
+
+    private let factory: TemplateFactory
+
+    private let siteRoot: Element
+
+    private let results: GenerationResultsHandler
+
+    init(factory: TemplateFactory, siteRoot: Element, results: GenerationResultsHandler) {
+        self.factory = factory
+        self.siteRoot = siteRoot
+        self.results = results
+    }
+
+    func generate(page: Element, language: String, content: String) -> (content: String, headers: RequiredHeaders) {
+        let parser = PageContentParser(
+            factory: factory,
+            siteRoot: siteRoot,
+            results: results,
+            page: page, 
+            language: language)
+        return parser.generatePage(from: content)
+    }
+
+}
+
+final class PageContentParser {
+
+    private let pageLinkMarker = "page:"
+
+    private let largeImageIndicator = "*large*"
+
+    private let factory: TemplateFactory
+
+    private let swift = SyntaxHighlighter(format: HTMLOutputFormat())
+
+    private let siteRoot: Element
+
+    private let results: GenerationResultsHandler
+
+    private let page: Element
+
+    private let language: String
+
+    private var headers = RequiredHeaders()
+
+    private var largeImageCount: Int = 0
+
+    init(factory: TemplateFactory, siteRoot: Element, results: GenerationResultsHandler, page: Element, language: String) {
+        self.factory = factory
+        self.siteRoot = siteRoot
+        self.results = results
+        self.page = page
+        self.language = language
+    }
+
+    func generatePage(from content: String) -> (content: String, headers: RequiredHeaders) {
+        headers = .init()
+
+        let imageModifier = Modifier(target: .images) { html, markdown in
+            self.processMarkdownImage(markdown: markdown, html: html)
+        }
+        let codeModifier = Modifier(target: .codeBlocks) { html, markdown in
+            if markdown.starts(with: "```swift") {
+                let code = markdown.between("```swift", and: "```").trimmed
+                return "<pre><code>" + self.swift.highlight(code) + "</pre></code>"
+            }
+            self.headers.insert(.codeHightlighting)
+            return html
+        }
+        let linkModifier = Modifier(target: .links) { html, markdown in
+            self.handleLink(html: html, markdown: markdown)
+        }
+        let htmlModifier = Modifier(target: .html) { html, markdown in
+            self.handleHTML(html: html, markdown: markdown)
+        }
+        let headlinesModifier = Modifier(target: .headings) { html, markdown in
+            self.handleHeadlines(html: html, markdown: markdown)
+        }
+
+        let parser = MarkdownParser(modifiers: [imageModifier, codeModifier, linkModifier, htmlModifier, headlinesModifier])
+        return (parser.html(from: content), headers)
+
+    }
+
+    private func handleLink(html: String, markdown: Substring) -> String {
+        let file = markdown.between("(", and: ")")
+        if file.hasPrefix(pageLinkMarker) {
+            let textToChange = file.dropAfterFirst("#")
+            let pageId = textToChange.replacingOccurrences(of: pageLinkMarker, with: "")
+            guard let pagePath = results.getPagePath(for: pageId, source: page.path, language: language) else {
+                // Remove link since the page can't be found
+                return markdown.between("[", and: "]")
+            }
+            // Adjust file path to get the page url
+            let url = page.relativePathToOtherSiteElement(file: pagePath)
+            return html.replacingOccurrences(of: textToChange, with: url)
+        }
+
+        if let filePath = page.nonAbsolutePathRelativeToRootForContainedInputFile(file) {
+            // The target of the page link must be present after generation is complete
+            results.expect(file: filePath, source: page.path)
+        }
+        return html
+    }
+
+    private func handleHTML(html: String, markdown: Substring) -> String {
+        // TODO: Check HTML code in markdown for required resources
+        //print("[HTML] Found in page \(page.path):")
+        //print(markdown)
+        // Things to check:
+        // <img src=
+        // <a href=
+        //
+        return html
+    }
+
+    private func handleHeadlines(html: String, markdown: Substring) -> String {
+        let id = markdown
+            .last(after: "#")
+            .trimmed
+            .filter { $0.isNumber || $0.isLetter || $0 == " " }
+            .lowercased()
+            .components(separatedBy: " ")
+            .filter { $0 != "" }
+            .joined(separator: "-")
+        let parts =  html.components(separatedBy: ">")
+        return parts[0] + " id=\"\(id)\">" + parts.dropFirst().joined(separator: ">")
+    }
+
+    private func processMarkdownImage(markdown: Substring, html: String) -> String {
+        // Split the markdown ![alt](file title)
+        // There are several known shorthand commands
+        // For images: ![*large* left_title](file right_title)
+        // For videos: ![option1,option2,...](file)
+        // For svg with custom area: ![x,y,width,height](file.svg)
+        // For downloads: ![download](file1, text1; file2, text2, (download-name); ...)
+        // For a simple box: ![box](title;body)
+        // For 3D models: ![3d](file;Description)
+        // A fancy page link: ![page](page_id)
+        // External pages: ![external](url1, text1; url2, text2, ...)
+        guard let fileAndTitle = markdown.between(first: "](", andLast: ")").removingPercentEncoding else {
+            results.warning("Invalid percent encoding for markdown image", source: page.path)
+            return ""
+        }
+        let alt = markdown.between("[", and: "]").nonEmpty?.removingPercentEncoding
+        if let alt = alt, let command = ShorthandMarkdownKey(rawValue: alt) {
+            return handleShortHandCommand(command, content: fileAndTitle)
+        }
+
+        let file = fileAndTitle.dropAfterFirst(" ")
+        let title = fileAndTitle.contains(" ") ? fileAndTitle.dropBeforeFirst(" ").nonEmpty : nil
+
+        let fileExtension = file.lastComponentAfter(".").lowercased()
+        if let _ = ImageType(fileExtension: fileExtension) {
+            return handleImage(file: file, rightTitle: title, leftTitle: alt, largeImageCount: &largeImageCount)
+        }
+        if let _ = VideoType(rawValue: fileExtension) {
+            return handleVideo(file: file, optionString: alt)
+        }
+        switch fileExtension {
+        case "svg":
+            return handleSvg(file: file, area: alt)
+        case "gif":
+            return handleGif(file: file, altText: alt ?? "gif image")
+        default:
+            return handleFile(file: file, fileExtension: fileExtension)
+        }
+    }
+
+    private func handleShortHandCommand(_ command: ShorthandMarkdownKey, content: String) -> String {
+        switch command {
+        case .downloadButtons:
+            return handleDownloadButtons(content: content)
+        case .externalLink:
+            return handleExternalButtons(content: content)
+        case .includedHtml:
+            return handleExternalHTML(file: content)
+        case .box:
+            return handleSimpleBox(content: content)
+        case .pageLink:
+            return handlePageLink(pageId: content)
+        case .model3d:
+            return handle3dModel(content: content)
+        }
+    }
+
+    private func handleImage(file: String, rightTitle: String?, leftTitle: String?, largeImageCount: inout Int) -> String {
+        let imagePath = page.pathRelativeToRootForContainedInputFile(file)
+        let left: String
+        let createFullScreenVersion: Bool
+        if let leftTitle {
+            createFullScreenVersion = leftTitle.hasPrefix(largeImageIndicator)
+            left = leftTitle.dropBeforeFirst(largeImageIndicator).trimmed
+        } else {
+            left = ""
+            createFullScreenVersion = false
+        }
+        let size = results.requireFullSizeMultiVersionImage(
+            source: imagePath,
+            destination: imagePath,
+            requiredBy: page.path)
+
+        let altText = left.nonEmpty ?? rightTitle ?? "image"
+
+        var content = [PageImageTemplateKey : String]()
+        content[.altText] = altText
+        content[.image] = file.dropAfterLast(".")
+        content[.imageExtension] = file.lastComponentAfter(".")
+        content[.width] = "\(Int(size.width))"
+        content[.height] = "\(Int(size.height))"
+        content[.leftText] = left
+        content[.rightText] = rightTitle ?? ""
+
+        guard createFullScreenVersion else {
+            return factory.image.generate(content)
+        }
+
+        results.requireOriginalSizeImages(
+            source: imagePath,
+            destination: imagePath,
+            requiredBy: page.path)
+
+        largeImageCount += 1
+        content[.number] = "\(largeImageCount)"
+        return factory.largeImage.generate(content)
+    }
+
+    private func handleVideo(file: String, optionString: String?) -> String {
+        let options: [PageVideoTemplate.VideoOption] = optionString.unwrapped { string in
+            string.components(separatedBy: " ").compactMap { optionText -> PageVideoTemplate.VideoOption? in
+                guard let optionText = optionText.trimmed.nonEmpty else {
+                    return nil
+                }
+                guard let option = PageVideoTemplate.VideoOption(rawValue: optionText) else {
+                    results.warning("Unknown video option \(optionText)", source: page.path)
+                    return nil
+                }
+                return option
+            }
+        } ?? []
+
+        let prefix = file.lastComponentAfter("/").dropAfterLast(".")
+
+        // Find all video files starting with the name of the video as a prefix
+        var sources: [PageVideoTemplate.VideoSource] = []
+        do {
+            let folder = results.contentFolder.appendingPathComponent(page.path)
+            let filesInFolder = try FileManager.default.contentsOfDirectory(atPath: folder.path)
+            sources += selectVideoFiles(with: prefix, from: filesInFolder)
+        } catch {
+            results.warning("Failed to check for additional videos", source: page.path)
+        }
+        // Also look in external files
+        sources += selectVideoFiles(with: prefix, from: page.externalFiles)
+            .map { (page.relativePathToFileWithPath($0.url), $0.type) }
+
+        // Require all video files
+        sources.forEach {
+            let path = page.pathRelativeToRootForContainedInputFile($0.url)
+            results.require(file: path, source: page.path)
+        }
+        // Sort, so that order of selection in browser is defined
+        sources.sort { $0.url < $1.url }
+        return factory.video.generate(sources: sources, options: options)
+    }
+
+    private func selectVideoFiles<T>(with prefix: String, from all: T) -> [PageVideoTemplate.VideoSource] where T: Sequence, T.Element == String {
+        all.compactMap {
+                guard $0.lastComponentAfter("/").hasPrefix(prefix) else {
+                    return nil
+                }
+                guard let type = VideoType(rawValue: $0.lastComponentAfter(".").lowercased()) else {
+                    return nil
+                }
+                return (url: $0, type: type)
+            }
+    }
+
+    private func handleGif(file: String, altText: String) -> String {
+        let imagePath = page.pathRelativeToRootForContainedInputFile(file)
+        results.require(file: imagePath, source: page.path)
+
+        guard let size = results.getImageSize(atPath: imagePath, source: page.path) else {
+            return ""
+        }
+        let width = Int(size.width)
+        let height = Int(size.height)
+        return factory.html.image(file: file, width: width, height: height, altText: altText)
+    }
+
+    private func handleSvg(file: String, area: String?) -> String {
+        let imagePath = page.pathRelativeToRootForContainedInputFile(file)
+        results.require(file: imagePath, source: page.path)
+
+        guard let size = results.getImageSize(atPath: imagePath, source: page.path) else {
+            return "" // Missing image warning already produced
+        }
+        let width = Int(size.width)
+        let height = Int(size.height)
+
+        var altText = "image " + file.lastComponentAfter("/")
+        guard let area = area else {
+            return factory.html.image(file: file, width: width, height: height, altText: altText)
+        }
+        let parts = area.components(separatedBy: ",").map { $0.trimmed }
+        switch parts.count {
+        case 1:
+            return factory.html.image(file: file, width: width, height: height, altText: parts[0])
+        case 4:
+            break
+        case 5:
+            altText = parts[4]
+        default:
+            results.warning("Invalid area string for svg image", source: page.path)
+            return factory.html.image(file: file, width: width, height: height, altText: altText)
+        }
+        guard let x = Int(parts[0]),
+              let y = Int(parts[1]),
+              let partWidth = Int(parts[2]),
+              let partHeight = Int(parts[3]) else {
+            results.warning("Invalid area string for svg image", source: page.path)
+            return factory.html.image(file: file, width: width, height: height, altText: altText)
+        }
+        let part = SVGSelection(x, y, partWidth, partHeight)
+        return factory.html.svgImage(file: file, part: part, altText: altText)
+    }
+
+    private func handleFile(file: String, fileExtension: String) -> String {
+        results.warning("Unhandled file \(file) with extension \(fileExtension)", source: page.path)
+        return ""
+    }
+
+    private func handleDownloadButtons(content: String) -> String {
+        let buttons = content
+            .components(separatedBy: ";")
+            .compactMap { button -> (file: String, text: String, downloadName: String?)? in
+                let parts = button.components(separatedBy: ",")
+                guard parts.count == 2 || parts.count == 3 else {
+                    results.warning("Invalid download definition with \(parts)", source: page.path)
+                    return nil
+                }
+                let file = parts[0].trimmed
+                let title = parts[1].trimmed
+                let downloadName = parts.count == 3 ? parts[2].trimmed : nil
+
+                // Ensure that file is available
+                let filePath = page.pathRelativeToRootForContainedInputFile(file)
+                results.require(file: filePath, source: page.path)
+
+                return (file, title, downloadName)
+            }
+        return factory.html.downloadButtons(buttons)
+    }
+
+    private func handleExternalButtons(content: String) -> String {
+        let buttons = content
+            .components(separatedBy: ";")
+            .compactMap { button -> (url: String, text: String)? in
+                let parts = button.components(separatedBy: ",")
+                guard parts.count == 2 else {
+                    results.warning("Invalid external link definition", source: page.path)
+                    return nil
+                }
+                guard let url = parts[0].trimmed.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed) else {
+                    results.warning("Invalid external link \(parts[0].trimmed)", source: page.path)
+                    return nil
+                }
+                let title = parts[1].trimmed
+
+                return (url, title)
+            }
+        return factory.html.externalButtons(buttons)
+    }
+
+    private func handleExternalHTML(file: String) -> String {
+        let path = page.pathRelativeToRootForContainedInputFile(file)
+        return results.getContentOfRequiredFile(at: path, source: page.path) ?? ""
+    }
+
+    private func handleSimpleBox(content: String) -> String {
+        let parts = content.components(separatedBy: ";")
+        guard parts.count > 1 else {
+            results.warning("Invalid box specification", source: page.path)
+            return ""
+        }
+        let title = parts[0]
+        let text = parts.dropFirst().joined(separator: ";")
+        return factory.makePlaceholder(title: title, text: text)
+    }
+
+    private func handlePageLink(pageId: String) -> String {
+        guard let linkedPage = siteRoot.find(pageId) else {
+            // Checking the page path will add it to the missing pages
+            _ = results.getPagePath(for: pageId, source: page.path, language: language)
+            // Remove link since the page can't be found
+            return ""
+        }
+        guard linkedPage.state == .standard else {
+            // Prevent linking to unpublished content
+            return ""
+        }
+        var content = [PageLinkTemplate.Key: String]()
+        
+        content[.title] = linkedPage.title(for: language)
+        content[.altText] = ""
+
+        let fullThumbnailPath = linkedPage.thumbnailFilePath(for: language).destination
+        // Note: Here we assume that the thumbnail was already used elsewhere, so already generated
+        let relativeImageUrl = page.relativePathToOtherSiteElement(file: fullThumbnailPath)
+        let metadata = linkedPage.localized(for: language)
+
+        if linkedPage.state.hasThumbnailLink {
+            let fullPageUrl = linkedPage.fullPageUrl(for: language)
+            let relativePageUrl = page.relativePathToOtherSiteElement(file: fullPageUrl)
+            content[.url] = "href=\"\(relativePageUrl)\""
+        }
+
+        content[.image] = relativeImageUrl.dropAfterLast(".")
+        if let suffix = metadata.thumbnailSuffix {
+            content[.title] = factory.html.make(title: metadata.title, suffix: suffix)
+        } else {
+            content[.title] = metadata.title
+        }
+
+        let path = linkedPage.makePath(language: language, from: siteRoot)
+        content[.path] = factory.pageLink.makePath(components: path)
+
+        content[.description] = metadata.relatedContentText
+        if let parent = linkedPage.findParent(from: siteRoot), parent.thumbnailStyle == .large {
+            content[.className] = " related-page-link-large"
+        }
+
+        // We assume that the thumbnail images are already required by overview pages.
+        return factory.pageLink.generate(content)
+    }
+
+    private func handle3dModel(content: String) -> String {
+        let parts = content.components(separatedBy: ";")
+        guard parts.count > 1 else {
+            results.warning("Invalid 3d model specification", source: page.path)
+            return ""
+        }
+        let file = parts[0]
+        guard file.hasSuffix(".glb") else {
+            results.warning("Invalid 3d model file \(file) (must be .glb)", source: page.path)
+            return ""
+        }
+
+        // Ensure that file is available
+        let filePath = page.pathRelativeToRootForContainedInputFile(file)
+        results.require(file: filePath, source: page.path)
+
+        // Add required file to head
+        headers.insert(.modelViewer)
+
+        let description = parts.dropFirst().joined(separator: ";")
+        return """
+        <model-viewer alt="\(description)" src="\(file)" ar shadow-intensity="1" camera-controls touch-action="pan-y"></model-viewer>
+        """
+    }
+}

Sources/Generator/Generators/PageGenerator.swift

@@ -5,23 +5,31 @@ struct PageGenerator {
 
     private let factory: LocalizedSiteTemplate
 
-    init(factory: LocalizedSiteTemplate) {
+    private let contentGenerator: PageContentGenerator
+
+    private let results: GenerationResultsHandler
+
+    init(factory: LocalizedSiteTemplate, siteRoot: Element, results: GenerationResultsHandler) {
         self.factory = factory
+        self.results = results
+        self.contentGenerator = PageContentGenerator(factory: factory.factory, siteRoot: siteRoot, results: results)
     }
 
     func generate(page: Element, language: String, previousPage: Element?, nextPage: Element?) {
         guard !page.isExternalPage else {
+            results.didCompletePage()
             return
         }
         let path = page.fullPageUrl(for: language)
         let inputContentPath = page.path + "/\(language).md"
         let metadata = page.localized(for: language)
         let nextLanguage = page.nextLanguage(for: language)
-        let (pageContent, pageIncludesCode, pageIsEmpty) = makeContent(
+        let (pageContent, additionalHeaders) = makeContent(
             page: page, metadata: metadata, language: language, path: inputContentPath)
 
         var content = [PageTemplate.Key : String]()
-        content[.head] = factory.pageHead.generate(page: page, language: language, includesCode: pageIncludesCode)
+        content[.language] = language
+        content[.head] = factory.pageHead.generate(page: page, language: language, headers: additionalHeaders)
         let sectionUrl = page.sectionUrl(for: language)
         content[.topBar] = factory.topBar.generate(sectionUrl: sectionUrl, languageButton: nextLanguage, page: page)
         content[.contentClass] = "content"
@@ -32,23 +40,17 @@ struct PageGenerator {
         content[.previousPageUrl] = navLink(from: page, to: previousPage, language: language)
         content[.nextPageLinkText] = nextText(for: nextPage, language: language)
         content[.nextPageUrl] = navLink(from: page, to: nextPage, language: language)
-        content[.footer] = page.customFooterContent()
+        content[.footer] = results.getContentOfOptionalFile(at: page.additionalFooterContentPath, source: page.path)
 
-        if pageIncludesCode {
+        if additionalHeaders.contains(.codeHightlighting) {
             let highlightCode = factory.factory.html.codeHighlightFooter()
             content[.footer] = (content[.footer].unwrapped { $0 + "\n" } ?? "") + highlightCode
         }
 
-        let url = files.urlInOutputFolder(path)
         if page.state == .draft {
-            files.isDraft(path: page.path)
+            results.markPageAsDraft(page: page.path)
-        } else if pageIsEmpty, page.state != .hidden {
-            files.isEmpty(page: path)
         }
-        guard factory.page.generate(content, to: url) else {
+        factory.page.generate(content, to: path, source: page.path)
-            return
-        }
-        files.generated(page: path)
     }
 
     private func navLink(from element: Element, to destination: Element?, language: String) -> String? {
@@ -72,18 +74,14 @@ struct PageGenerator {
         return factory.factory.html.makeNextText(text)
     }
 
-    private func makeContent(page: Element, metadata: Element.LocalizedMetadata, language: String, path: String) -> (content: String, includesCode: Bool, isEmpty: Bool) {
+    private func makeContent(page: Element, metadata: Element.LocalizedMetadata, language: String, path: String) -> (content: String, headers: RequiredHeaders) {
-        let create = configuration.createMdFilesIfMissing
+        if let raw = results.getContentOfMdFile(at: path, source: page.path)?.trimmed.nonEmpty {
-        if let raw = files.contentOfOptionalFile(atPath: path, source: page.path, createEmptyFileIfMissing: create)?
+            let (content, includesCode) = contentGenerator.generate(page: page, language: language, content: raw)
-            .trimmed.nonEmpty {
+            return (content, includesCode)
-            let (content, includesCode) = PageContentGenerator(factory: factory.factory)
-                .generate(page: page, language: language, content: raw)
-            return (content, includesCode, false)
         } else {
-            let (content, includesCode) = PageContentGenerator(factory: factory.factory)
+            let (content, includesCode) = contentGenerator.generate(page: page, language: language, content: metadata.placeholderText)
-                .generate(page: page, language: language, content: metadata.placeholderText)
             let placeholder = factory.factory.makePlaceholder(title: metadata.placeholderTitle, text: content)
-            return (placeholder, includesCode, true)
+            return (placeholder, includesCode)
         }
     }
 

Sources/Generator/Generators/PageHeadGenerator.swift

@@ -2,15 +2,19 @@ import Foundation
 
 struct PageHeadGenerator {
 
+    // TODO: Add to configuration
     static let linkPreviewDesiredImageWidth = 1600
 
     let factory: TemplateFactory
 
-    init(factory: TemplateFactory) {
+    private let results: GenerationResultsHandler
+
+    init(factory: TemplateFactory, results: GenerationResultsHandler) {
         self.factory = factory
+        self.results = results
     }
 
-    func generate(page: Element, language: String, includesCode: Bool = false) -> String {
+    func generate(page: Element, language: String, headers: RequiredHeaders = .init()) -> String {
         let metadata = page.localized(for: language)
 
         var content = [PageHeadTemplate.Key : String]()
@@ -21,28 +25,27 @@ struct PageHeadGenerator {
             // Note: Generate separate destination link for the image,
             // since we don't want a single large image for thumbnails.
             // Warning: Link preview source path must be relative to root
-            let linkPreviewImageName = image.insert("-link", beforeLast: ".")
+            let linkPreviewImageName = "thumbnail-link.\(image.lastComponentAfter("."))"
             let sourceImagePath = page.pathRelativeToRootForContainedInputFile(image)
             let destinationImagePath = page.pathRelativeToRootForContainedInputFile(linkPreviewImageName)
-            files.requireImage(
+            results.requireSingleImage(
                 source: sourceImagePath,
                 destination: destinationImagePath,
                 requiredBy: page.path,
                 width: PageHeadGenerator.linkPreviewDesiredImageWidth)
             content[.image] =  factory.html.linkPreviewImage(file: linkPreviewImageName)
         }
-        content[.customPageContent] = page.customHeadContent()
+        content[.customPageContent] = results.getContentOfOptionalFile(at: page.additionalHeadContentPath, source: page.path)
-        if includesCode {
+
-            let scriptPath = "assets/js/highlight.js"
+        let head = (content[.customPageContent].unwrapped { [$0] } ?? []) + headers
+            .sorted { $0.rawValue < $1.rawValue }
+            .map { option in
+                let scriptPath = "assets/js/\(option.rawValue)"
                 let relative = page.relativePathToOtherSiteElement(file: scriptPath)
-            let includeText = factory.html.scriptInclude(path: relative)
+                return factory.html.scriptInclude(path: relative, asModule: option.asModule)
-            if let head = content[.customPageContent] {
-                content[.customPageContent] = head + "\n" + includeText
-            } else {
-                content[.customPageContent] = includeText
-            }
             }
 
+        content[.customPageContent] = head.joined(separator: "\n")
         return factory.pageHead.generate(content)
     }
 }

Sources/Generator/Generators/ShorthandMarkdownKey.swift

@@ -26,4 +26,9 @@ enum ShorthandMarkdownKey: String {
      A pretty link to another page on the site.
      */
     case pageLink = "page"
+
+    /**
+     A 3D model to display
+     */
+    case model3d = "3d"
 }

Sources/Generator/Generators/SiteGenerator.swift

@@ -6,9 +6,12 @@ struct SiteGenerator {
 
     let templates: TemplateFactory
 
-    init() throws {
+    let results: GenerationResultsHandler
-        let templatesFolder = files.urlInContentFolder("templates")
+
-        self.templates = try TemplateFactory(templateFolder: templatesFolder)
+    init(results: GenerationResultsHandler) throws {
+        self.results = results
+        let templatesFolder = results.contentFolder.appendingPathComponent("templates")
+        self.templates = try TemplateFactory(templateFolder: templatesFolder, results: results)
     }
 
     func generate(site: Element) {
@@ -22,11 +25,12 @@ struct SiteGenerator {
         let template = LocalizedSiteTemplate(
             factory: templates,
             language: language,
-            site: site)
+            site: site,
+            results: results)
 
         // Generate sections
-        let overviewGenerator = OverviewPageGenerator(factory: template)
+        let overviewGenerator = OverviewPageGenerator(factory: template, results: results)
-        let pageGenerator = PageGenerator(factory: template)
+        let pageGenerator = PageGenerator(factory: template, siteRoot: site, results: results)
         
         var elementsToProcess: [LinkedElement] = [(nil, site, nil)]
         while let (previous, element, next) = elementsToProcess.popLast() {
@@ -34,8 +38,7 @@ struct SiteGenerator {
             elementsToProcess.append(contentsOf: element.linkedElements)
 
             processAllFiles(for: element)
-
+            if element.hasVisibleChildren {
-            if !element.elements.isEmpty {
                 overviewGenerator.generate(section: element, language: language)
             } else {
                 pageGenerator.generate(
@@ -48,10 +51,10 @@ struct SiteGenerator {
     }
 
     private func processAllFiles(for element: Element) {
-        element.requiredFiles.forEach(files.require)
+        element.externalFiles.forEach { results.exclude(file: $0, source: element.path) }
-        element.externalFiles.forEach(files.exclude)
+        element.requiredFiles.forEach { results.require(file: $0, source: element.path) }
         element.images.forEach {
-            files.requireImage(
+            results.requireSingleImage(
                 source: $0.sourcePath,
                 destination: $0.destinationPath,
                 requiredBy: element.path,

Sources/Generator/Generators/ThumbnailListGenerator.swift

@@ -4,8 +4,11 @@ struct ThumbnailListGenerator {
 
     private let factory: TemplateFactory
 
-    init(factory: TemplateFactory) {
+    private let results: GenerationResultsHandler
+
+    init(factory: TemplateFactory, results: GenerationResultsHandler) {
         self.factory = factory
+        self.results = results
     }
 
     func generateContent(items: [Element], parent: Element, language: String, style: ThumbnailStyle) -> String {
@@ -14,8 +17,7 @@ struct ThumbnailListGenerator {
     }
 
     private func itemContent(_ item: Element, parent: Element, language: String, style: ThumbnailStyle) -> String {
-        let fullThumbnailPath = item.thumbnailFilePath(for: language)
+
-        let relativeImageUrl = parent.relativePathToFileWithPath(fullThumbnailPath)
         let metadata = item.localized(for: language)
         var content = [ThumbnailKey : String]()
 
@@ -25,32 +27,27 @@ struct ThumbnailListGenerator {
             content[.url] = "href=\"\(relativePageUrl)\""
         }
 
-        content[.image] = relativeImageUrl
+        let (thumbnailSourcePath, thumbnailDestPath) = item.thumbnailFilePath(for: language)
+        let thumbnailDestNoExtension = thumbnailDestPath.dropAfterLast(".")
+        content[.image] = parent.relativePathToFileWithPath(thumbnailDestNoExtension)
+        content[.altText] = metadata.linkPreviewDescription
+
         if style == .large, let suffix = metadata.thumbnailSuffix {
             content[.title] = factory.html.make(title: metadata.title, suffix: suffix)
         } else {
             content[.title] = metadata.title
         }
-        content[.image2x] = relativeImageUrl.insert("@2x", beforeLast: ".")
         content[.corner] = item.cornerText(for: language).unwrapped {
             factory.largeThumbnail.makeCorner(text: $0)
         }
 
-        files.requireImage(
+        results.requireMultiVersionImage(
-            source: fullThumbnailPath,
+            source: thumbnailSourcePath,
-            destination: fullThumbnailPath,
+            destination: thumbnailDestNoExtension + ".jpg",
             requiredBy: item.path,
             width: style.width,
             desiredHeight: style.height)
 
-        // Create image version for high-resolution screens
-        files.requireImage(
-            source: fullThumbnailPath,
-            destination: fullThumbnailPath.insert("@2x", beforeLast: "."),
-            requiredBy: item.path,
-            width: style.width * 2,
-            desiredHeight: style.height * 2)
-
         return factory.thumbnail(style: style).generate(content, shouldIndent: false)
     }
 }

Sources/Generator/Processing/DependencyCheck.swift

@@ -0,0 +1,119 @@
+import Foundation
+
+func checkDependencies() -> Bool {
+    print("--- DEPENDENCIES -----------------------------------")
+    print("                                                    ")
+    defer { print("                                                    ") }
+    var valid = true
+    valid = checkImageOptimAvailability() && valid
+    valid = checkMagickAvailability() && valid
+    valid = checkCwebpAvailability() && valid
+    valid = checkAvifAvailability() && valid
+    valid = checkUglifyJsAvailability() && valid
+    valid = checkCleanCssAvailability() && valid
+    return valid
+}
+
+private func checkImageOptimAvailability() -> Bool {
+    do {
+        let output = try safeShell("imageoptim --version")
+        let version = output.components(separatedBy: ".").compactMap { Int($0.trimmed) }
+        if version.count > 1 {
+            print("            ImageOptim: \(version.map { "\($0)" }.joined(separator: "."))")
+        } else {
+            print("            ImageOptim: Not found, download app from https://imageoptim.com/mac and install using 'npm install imageoptim-cli'")
+            return false
+        }
+    } catch {
+        print("            ImageOptim: Failed to get version (\(error))")
+        return false
+    }
+    return true
+}
+
+private func checkMagickAvailability() -> Bool {
+    do {
+        let output = try safeShell("magick --version")
+        guard let version = output.components(separatedBy: "ImageMagick ").dropFirst().first?
+            .components(separatedBy: " ").first else {
+            print("                Magick: Not found, install using 'brew install imagemagick'")
+            return false
+        }
+        print("                Magick: \(version)")
+    } catch {
+        print("                Magick: Failed to get version (\(error))")
+        return false
+    }
+    return true
+}
+
+private func checkCwebpAvailability() -> Bool {
+    do {
+        let output = try safeShell("cwebp -version")
+        let version = output.components(separatedBy: ".").compactMap { Int($0.trimmed) }
+        if version.count > 1 {
+            print("                 cwebp: \(version.map { "\($0)" }.joined(separator: "."))")
+        } else {
+            print("                 cwebp: Not found, download from https://developers.google.com/speed/webp/download")
+            return false
+        }
+    } catch {
+        print("                 cwebp: Failed to get version (\(error))")
+        return false
+    }
+    return true
+}
+
+private func checkAvifAvailability() -> Bool {
+    do {
+        let output = try safeShell("npx avif --version")
+        let version = output.components(separatedBy: ".").compactMap { Int($0.trimmed) }
+        if version.count > 1 {
+            print("                  avif: \(version.map { "\($0)" }.joined(separator: "."))")
+        } else {
+            print("                  avif: Not found, install using 'npm install avif'")
+            return false
+        }
+    } catch {
+        print("                  avif: Failed to get version (\(error))")
+        return false
+    }
+    return true
+}
+
+
+private func checkUglifyJsAvailability() -> Bool {
+    do {
+        let output = try safeShell("uglifyjs --version")
+        let version = output.dropBeforeFirst("uglify-js").components(separatedBy: ".").compactMap { Int($0.trimmed) }
+        if version.count > 1 {
+            print("             uglify-js: \(version.map { "\($0)" }.joined(separator: "."))")
+        } else {
+            print("'\(output)'")
+            print("             uglify-js: Not found, install using 'npm install uglify-js'")
+            return false
+        }
+    } catch {
+        print("             uglify-js: Failed to get version (\(error))")
+        return false
+    }
+    return true
+}
+
+
+private func checkCleanCssAvailability() -> Bool {
+    do {
+        let output = try safeShell("cleancss --version")
+        let version = output.components(separatedBy: ".").compactMap { Int($0.trimmed) }
+        if version.count > 1 {
+            print("              cleancss: \(version.map { "\($0)" }.joined(separator: "."))")
+        } else {
+            print("              cleancss: Not found, install using 'npm install clean-css-cli'")
+            return false
+        }
+    } catch {
+        print("              cleancss: Failed to get version (\(error))")
+        return false
+    }
+    return true
+}

Sources/Generator/Processing/FileData.swift

@@ -0,0 +1,20 @@
+import Foundation
+
+struct FileData {
+
+    ///The files marked as expected, i.e. they exist after the generation is completed. (`key`: file path, `value`: the file providing the link)
+    var expected: [String : String] = [:]
+
+    /// All files which should be copied to the output folder (`key`: The file path, `value`: The source requiring the file)
+    var toCopy: [String : String] = [:]
+
+    /// The files to minify when copying into output directory. (`key`: the file path relative to the content folder)
+    var toMinify: [String : (source: String, type: MinificationType)] = [:]
+
+    /**
+     The files marked as external in element metadata. (Key: File path, Value: source element)
+
+     Files included here are not generated, since they are assumed to be added separately.
+     */
+    var external: [String : String] = [:]
+}

Sources/Generator/Processing/FileGenerator.swift

@@ -0,0 +1,277 @@
+import Foundation
+
+final class FileGenerator {
+
+    let input: URL
+
+    let outputFolder: URL
+
+    let runFolder: URL
+
+    private let files: FileData
+
+    /// All files copied to the destination.
+    private var copiedFiles: Set<String> = []
+
+    /// Files which could not be read (`key`: file path relative to content)
+    private var unreadableFiles: [String : (source: String, message: String)] = [:]
+
+    /// Files which could not be written (`key`: file path relative to output folder)
+    private var unwritableFiles: [String : (source: String, message: String)] = [:]
+
+    private var failedMinifications: [(file: String, source: String, message: String)] = []
+
+    /// Non-existent files. `key`: file path, `value`: source element
+    private var missingFiles: [String : String] = [:]
+
+    private var minifiedFiles: [String] = []
+
+    private let numberOfFilesToCopy: Int
+
+    private var numberOfCopiedFiles = 0
+
+    private let numberOfFilesToMinify: Int
+
+    private var numberOfMinifiedFiles = 0
+
+    private var numberOfExistingFiles = 0
+
+    private var tempFile: URL {
+        runFolder.appendingPathComponent("temp")
+    }
+
+    init(input: URL, output: URL, runFolder: URL, files: FileData) {
+        self.input = input
+        self.outputFolder = output
+        self.runFolder = runFolder
+        self.files = files
+
+        numberOfFilesToCopy = files.toCopy.count
+        numberOfFilesToMinify = files.toMinify.count
+    }
+
+    func generate() {
+        copy(files: files.toCopy)
+        print("          Copied files: \(copiedFiles.count)/\(numberOfFilesToCopy)       ")
+        minify(files: files.toMinify)
+        print("        Minified files: \(minifiedFiles.count)/\(numberOfFilesToMinify)     ")
+        checkExpected(files: files.expected)
+        print("        Expected files: \(numberOfExistingFiles)/\(files.expected.count)")
+        print("        External files: \(files.external.count)")
+        print("")
+    }
+
+    private func didCopyFile() {
+        numberOfCopiedFiles += 1
+        print("          Copied files: \(numberOfCopiedFiles)/\(numberOfFilesToCopy)   \r", terminator: "")
+        fflush(stdout)
+    }
+
+    private func didMinifyFile() {
+        numberOfMinifiedFiles += 1
+        print("        Minified files: \(numberOfMinifiedFiles)/\(numberOfFilesToMinify)    \r", terminator: "")
+        fflush(stdout)
+    }
+
+    // MARK: File copies
+
+    private func copy(files: [String : String]) {
+        for (file, source) in files {
+            copyFileIfChanged(file: file, source: source)
+        }
+    }
+
+    private func copyFileIfChanged(file: String, source: String) {
+        let cleanPath = cleanRelativeURL(file)
+        let destinationUrl = outputFolder.appendingPathComponent(cleanPath)
+
+        defer { didCopyFile() }
+        guard copyIfChanged(cleanPath, to: destinationUrl, source: source) else {
+            return
+        }
+        copiedFiles.insert(cleanPath)
+    }
+
+    private func copyIfChanged(_ file: String, to destination: URL, source: String) -> Bool {
+        let url = input.appendingPathComponent(file)
+        do {
+            let data = try Data(contentsOf: url)
+            return writeIfChanged(data, file: file, source: source)
+        } catch {
+            markFileAsUnreadable(at: file, requiredBy: source, message: "\(error)")
+            return false
+        }
+    }
+
+    @discardableResult
+    func writeIfChanged(_ data: Data, file: String, source: String) -> Bool {
+        let url = outputFolder.appendingPathComponent(file)
+        // Only write changed files
+        if url.exists, let oldContent = try? Data(contentsOf: url), data == oldContent {
+            return false
+        }
+        do {
+            try data.createFolderAndWrite(to: url)
+            return true
+        } catch {
+            markFileAsUnwritable(at: file, requiredBy: source, message: "Failed to write file: \(error)")
+            return false
+        }
+    }
+
+    // MARK: File minification
+
+    private func minify(files: [String : (source: String, type: MinificationType)]) {
+        for (file, other) in files {
+            minify(file: file, source: other.source, type: other.type)
+        }
+    }
+
+    private func minify(file: String, source: String, type: MinificationType) {
+        let url = input.appendingPathComponent(file)
+        let command: String
+        switch type {
+        case .js:
+            command = "uglifyjs \(url.path) > \(tempFile.path)"
+        case .css:
+            command = "cleancss \(url.path) -o \(tempFile.path)"
+        }
+
+        defer {
+            didMinifyFile()
+            try? tempFile.delete()
+        }
+
+        let output: String
+        do {
+            output = try safeShell(command)
+        } catch {
+            failedMinifications.append((file, source, "Failed to minify with error: \(error)"))
+            return
+        }
+        guard tempFile.exists else {
+            failedMinifications.append((file, source, output))
+            return
+        }
+        let data: Data
+        do {
+            data = try Data(contentsOf: tempFile)
+        } catch {
+            markFileAsUnreadable(at: file, requiredBy: source, message: "\(error)")
+            return
+        }
+        if writeIfChanged(data, file: file, source: source) {
+            minifiedFiles.append(file)
+        }
+    }
+
+
+    private func cleanRelativeURL(_ raw: String) -> String {
+        let raw = raw.dropAfterLast("#") // Clean links to page content
+        guard raw.contains("..") else {
+            return raw
+        }
+        var result: [String] = []
+        for component in raw.components(separatedBy: "/") {
+            if component == ".." {
+                _ = result.popLast()
+            } else {
+                result.append(component)
+            }
+        }
+        return result.joined(separator: "/")
+    }
+
+    private func markFileAsUnreadable(at path: String, requiredBy source: String, message: String) {
+        unreadableFiles[path] = (source, message)
+    }
+
+    private func markFileAsUnwritable(at path: String, requiredBy source: String, message: String) {
+        unwritableFiles[path] = (source, message)
+    }
+
+    // MARK: File expectationts
+
+    private func checkExpected(files: [String: String]) {
+        for (file, source) in files {
+            guard !isExternal(file: file) else {
+                numberOfExistingFiles += 1
+                continue
+            }
+            let cleanPath = cleanRelativeURL(file)
+            let destinationUrl = outputFolder.appendingPathComponent(cleanPath)
+            guard destinationUrl.exists else {
+                markFileAsMissing(at: cleanPath, requiredBy: source)
+                continue
+            }
+            numberOfExistingFiles += 1
+        }
+    }
+
+    private func markFileAsMissing(at path: String, requiredBy source: String) {
+        missingFiles[path] = source
+    }
+
+    /**
+     Check if a file is marked as external.
+
+     Also checks for sub-paths of the file, e.g if the folder `docs` is marked as external,
+     then files like `docs/index.html` are also found to be external.
+     - Note: All paths are either relative to root (no leading slash) or absolute paths of the domain (leading slash)
+     */
+    private func isExternal(file: String) -> Bool {
+        // Deconstruct file path
+        var path = ""
+        for part in file.components(separatedBy: "/") {
+            guard part != "" else {
+                continue
+            }
+            if path == "" {
+                path = part
+            } else {
+                path += "/" + part
+            }
+            if files.external[path] != nil {
+                return true
+            }
+        }
+        return false
+    }
+
+    func writeResults(to file: URL) {
+        guard !unreadableFiles.isEmpty || !unwritableFiles.isEmpty || !failedMinifications.isEmpty || !missingFiles.isEmpty || !copiedFiles.isEmpty || !minifiedFiles.isEmpty || !files.expected.isEmpty || !files.external.isEmpty else {
+            do {
+                if FileManager.default.fileExists(atPath: file.path) {
+                    try FileManager.default.removeItem(at: file)
+                }
+            } catch {
+                print("    Failed to delete file log: \(error)")
+            }
+            return
+        }
+        var lines: [String] = []
+        func add<S>(_ name: String, _ property: S, convert: (S.Element) -> String) where S: Sequence {
+            let elements = property.map { "  " + convert($0) }.sorted()
+            guard !elements.isEmpty else {
+                return
+            }
+            lines.append("\(name):")
+            lines.append(contentsOf: elements)
+        }
+        add("Unreadable files", unreadableFiles) { "\($0.key) (required by \($0.value.source)): \($0.value.message)" }
+        add("Unwritable files", unwritableFiles) { "\($0.key) (required by \($0.value.source)): \($0.value.message)" }
+        add("Failed minifications", failedMinifications) { "\($0.file) (required by \($0.source)): \($0.message)" }
+        add("Missing files", missingFiles) { "\($0.key) (required by \($0.value))" }
+        add("Copied files", copiedFiles) { $0 }
+        add("Minified files", minifiedFiles) { $0 }
+        add("Expected files", files.expected) { "\($0.key) (required by \($0.value))" }
+        add("External files", files.external) { "\($0.key) (required by \($0.value))" }
+
+        let data = lines.joined(separator: "\n").data(using: .utf8)!
+        do {
+            try data.createFolderAndWrite(to: file)
+        } catch {
+            print("    Failed to save file log: \(error)")
+        }
+    }
+}

Sources/Generator/Processing/GenerationResultsHandler.swift

@@ -0,0 +1,492 @@
+import Foundation
+import CryptoKit
+import AppKit
+
+
+enum MinificationType {
+    case js
+    case css
+}
+
+typealias PageMap = [(language: String, pages: [String : String])]
+
+final class GenerationResultsHandler {
+
+    /// The content folder where the input data is stored
+    let contentFolder: URL
+
+    /// The folder where the site is generated
+    let outputFolder: URL
+
+    private let fileUpdates: FileUpdateChecker
+
+    /**
+     All paths to page element folders, indexed by their unique id.
+
+     This relation is used to generate relative links to pages using the ``Element.id`
+     */
+    private let pageMap: PageMap
+
+    private let configuration: Configuration
+
+    private var numberOfProcessedPages = 0
+
+    private let numberOfTotalPages: Int
+
+    init(in input: URL, to output: URL, configuration: Configuration, fileUpdates: FileUpdateChecker, pageMap: PageMap, pageCount: Int) {
+        self.contentFolder = input
+        self.fileUpdates = fileUpdates
+        self.outputFolder = output
+        self.pageMap = pageMap
+        self.configuration = configuration
+        self.numberOfTotalPages = pageCount
+    }
+
+    // MARK: Internal storage
+
+    /// Non-existent files. `key`: file path, `value`: source element
+    private var missingFiles: [String : String] = [:]
+
+    private(set) var files = FileData()
+
+    /// Files which could not be read (`key`: file path relative to content)
+    private var unreadableFiles: [String : (source: String, message: String)] = [:]
+
+    /// Files which could not be written (`key`: file path relative to output folder)
+    private var unwritableFiles: [String : (source: String, message: String)] = [:]
+
+    /// The paths to all files which were changed (relative to output)
+    private var generatedFiles: Set<String> = []
+
+    /// The referenced pages which do not exist (`key`: page id, `value`: source element path)
+    private var missingLinkedPages: [String : String] = [:]
+
+    /// All pages without content which have been created (`key`: page path, `value`: source element path)
+    private var emptyPages: [String : String] = [:]
+
+    /// All pages which have `status` set to ``PageState.draft``
+    private var draftPages: Set<String> = []
+
+    /// Generic warnings for pages
+    private var pageWarnings: [(message: String, source: String)] = []
+
+    /// A cache to get the size of source images, so that files don't have to be loaded multiple times (`key` absolute source path, `value`: image size)
+    private var imageSizeCache: [String : NSSize] = [:]
+
+    private(set) var images = ImageData()
+
+    // MARK: Generic warnings
+
+    private func warning(_ message: String, destination: String, path: String) {
+        let warning = "  \(destination): \(message) required by \(path)"
+        images.warnings.append(warning)
+    }
+
+    func warning(_ message: String, source: String) {
+        pageWarnings.append((message, source))
+    }
+
+    // MARK: Page data
+
+    func getPagePath(for id: String, source: String, language: String) -> String? {
+        guard let pagePath = pageMap.first(where: { $0.language == language})?.pages[id] else {
+            missingLinkedPages[id] = source
+            return nil
+        }
+        return pagePath
+    }
+
+    private func markPageAsEmpty(page: String, source: String) {
+        emptyPages[page] = source
+    }
+
+    func markPageAsDraft(page: String) {
+        draftPages.insert(page)
+    }
+
+    // MARK: File actions
+
+    /**
+     Add a file as required, so that it will be copied to the output directory.
+     Special files may be minified.
+     - Parameter file: The file path, relative to the content directory
+     - Parameter source: The path of the source element requiring the file.
+     */
+    func require(file: String, source: String) {
+        guard !isExternal(file: file) else {
+            return
+        }
+        let url = contentFolder.appendingPathComponent(file)
+        guard url.exists else {
+            markFileAsMissing(at: file, requiredBy: source)
+            return
+        }
+        guard url.isDirectory else {
+            markForCopyOrMinification(file: file, source: source)
+            return
+        }
+        do {
+            try FileManager.default
+                .contentsOfDirectory(atPath: url.path)
+                .forEach {
+                    // Recurse into subfolders
+                    require(file: file + "/" + $0, source: source)
+                }
+        } catch {
+            markFileAsUnreadable(at: file, requiredBy: source, message: "Failed to read folder: \(error)")
+        }
+    }
+
+    private func markFileAsMissing(at path: String, requiredBy source: String) {
+        missingFiles[path] = source
+    }
+
+    private func markFileAsUnreadable(at path: String, requiredBy source: String, message: String) {
+        unreadableFiles[path] = (source, message)
+    }
+
+    private func markFileAsUnwritable(at path: String, requiredBy source: String, message: String) {
+        unwritableFiles[path] = (source, message)
+    }
+
+    private func markFileAsGenerated(file: String) {
+        generatedFiles.insert(file)
+    }
+
+    private func markForCopyOrMinification(file: String, source: String) {
+        let ext = file.lastComponentAfter(".")
+        if configuration.minifyJavaScript, ext == "js" {
+            files.toMinify[file] = (source, .js)
+            return
+        }
+        if configuration.minifyCSS, ext == "css" {
+            files.toMinify[file] = (source, .css)
+            return
+        }
+        files.toCopy[file] = source
+    }
+
+    /**
+     Mark a file as explicitly missing (external).
+
+     This is done for the `externalFiles` entries in metadata,
+     to indicate that these files will be copied to the output folder manually.
+     */
+    func exclude(file: String, source: String) {
+        files.external[file] = source
+    }
+
+    /**
+     Mark a file as expected to be present in the output folder after generation.
+
+     This is done for all links between pages, which only exist after the pages have been generated.
+     */
+    func expect(file: String, source: String) {
+        files.expected[file] = source
+    }
+
+    /**
+     Check if a file is marked as external.
+
+     Also checks for sub-paths of the file, e.g if the folder `docs` is marked as external,
+     then files like `docs/index.html` are also found to be external.
+     - Note: All paths are either relative to root (no leading slash) or absolute paths of the domain (leading slash)
+     */
+    private func isExternal(file: String) -> Bool {
+        // Deconstruct file path
+        var path = ""
+        for part in file.components(separatedBy: "/") {
+            guard part != "" else {
+                continue
+            }
+            if path == "" {
+                path = part
+            } else {
+                path += "/" + part
+            }
+            if files.external[path] != nil {
+                return true
+            }
+        }
+        return false
+    }
+
+    func getContentOfRequiredFile(at path: String, source: String) -> String? {
+        let url = contentFolder.appendingPathComponent(path)
+        guard url.exists else {
+            markFileAsMissing(at: path, requiredBy: source)
+            return nil
+        }
+        return getContentOfFile(at: url, path: path, source: source)
+    }
+
+    /**
+     Get the content of a file which may not exist.
+     */
+    func getContentOfOptionalFile(at path: String, source: String, createEmptyFileIfMissing: Bool = false) -> String? {
+        let url = contentFolder.appendingPathComponent(path)
+        guard url.exists else {
+            if createEmptyFileIfMissing {
+                writeIfChanged(.init(), file: path, source: source)
+            }
+            return nil
+        }
+        return getContentOfFile(at: url, path: path, source: source)
+    }
+
+    func getContentOfMdFile(at path: String, source: String) -> String? {
+        guard let result = getContentOfOptionalFile(at: path, source: source, createEmptyFileIfMissing: configuration.createMdFilesIfMissing) else {
+            markPageAsEmpty(page: path, source: source)
+            return nil
+        }
+        return result
+    }
+
+    private func getContentOfFile(at url: URL, path: String, source: String) -> String? {
+        do {
+            return try String(contentsOf: url)
+        } catch {
+            markFileAsUnreadable(at: path, requiredBy: source, message: "\(error)")
+            return nil
+        }
+    }
+
+    @discardableResult
+    func writeIfChanged(_ data: Data, file: String, source: String) -> Bool {
+        let url = outputFolder.appendingPathComponent(file)
+
+        defer {
+            didCompletePage()
+        }
+        // Only write changed files
+        if url.exists, let oldContent = try? Data(contentsOf: url), data == oldContent {
+            return false
+        }
+        do {
+            try data.createFolderAndWrite(to: url)
+            markFileAsGenerated(file: file)
+            return true
+        } catch {
+            markFileAsUnwritable(at: file, requiredBy: source, message: "Failed to write file: \(error)")
+            return false
+        }
+    }
+
+    // MARK: Images
+
+    /**
+     Request the creation of an image.
+     - Returns: The final size of the image.
+     */
+    @discardableResult
+    func requireSingleImage(source: String, destination: String, requiredBy path: String, width: Int, desiredHeight: Int? = nil) -> NSSize {
+        requireImage(
+            at: destination,
+            generatedFrom: source,
+            requiredBy: path,
+            quality: 0.7,
+            width: width,
+            height: desiredHeight,
+            alwaysGenerate: false)
+    }
+
+    /**
+     Create images of different types.
+
+     This function generates versions for the given image, including png/jpg, avif, and webp. Different pixel density versions (1x and 2x) are also generated.
+     - Parameter destination: The path to the destination file
+     */
+    @discardableResult
+    func requireMultiVersionImage(source: String, destination: String, requiredBy path: String, width: Int, desiredHeight: Int?) -> NSSize {
+        // Add @2x version
+        _ = requireScaledMultiImage(
+            source: source,
+            destination: destination.insert("@2x", beforeLast: "."),
+            requiredBy: path,
+            width: width * 2,
+            desiredHeight: desiredHeight.unwrapped { $0 * 2 })
+
+        // Add @1x version
+        return requireScaledMultiImage(source: source, destination: destination, requiredBy: path, width: width, desiredHeight: desiredHeight)
+    }
+
+    func requireFullSizeMultiVersionImage(source: String, destination: String, requiredBy path: String) -> NSSize {
+        requireMultiVersionImage(source: source, destination: destination, requiredBy: path, width: configuration.pageImageWidth, desiredHeight: nil)
+    }
+
+    func requireOriginalSizeImages(
+        source: String,
+        destination: String,
+        requiredBy path: String) {
+            _ = requireScaledMultiImage(
+                source: source,
+                destination: destination.insert("@full", beforeLast: "."),
+                requiredBy: path,
+                width: configuration.fullScreenImageWidth,
+                desiredHeight: nil)
+        }
+
+    private func requireScaledMultiImage(source: String, destination: String, requiredBy path: String, width: Int, desiredHeight: Int?) -> NSSize {
+        let rawDestinationPath = destination.dropAfterLast(".")
+        let avifPath = rawDestinationPath + ".avif"
+        let webpPath = rawDestinationPath + ".webp"
+        let needsGeneration = !outputFolder.appendingPathComponent(avifPath).exists || !outputFolder.appendingPathComponent(webpPath).exists
+
+        let size = requireImage(at: destination, generatedFrom: source, requiredBy: path, quality: 1.0, width: width, height: desiredHeight, alwaysGenerate: needsGeneration)
+        images.multiJobs[destination] = path
+        return size
+    }
+
+    private func markImageAsMissing(path: String, source: String) {
+        images.missing[path] = source
+    }
+
+    private func requireImage(at destination: String, generatedFrom source: String, requiredBy path: String, quality: Float, width: Int, height: Int?, alwaysGenerate: Bool) -> NSSize {
+        let height = height.unwrapped(CGFloat.init)
+        guard let imageSize = getImageSize(atPath: source, source: path) else {
+            // Image marked as missing here
+            return .zero
+        }
+        let scaledSize = imageSize.scaledDown(to: CGFloat(width))
+
+        // Check desired height, then we can forget about it
+        if let height = height {
+            let expectedHeight = scaledSize.width / CGFloat(width) * height
+            if abs(expectedHeight - scaledSize.height) > 2 {
+                warning("Expected a height of \(expectedHeight) (is \(scaledSize.height))", destination: destination, path: path)
+            }
+        }
+
+        let job = ImageJob(
+            destination: destination,
+            width: width,
+            path: path,
+            quality: quality,
+            alwaysGenerate: alwaysGenerate)
+        insert(job: job, source: source)
+
+        return scaledSize
+    }
+
+    func getImageSize(atPath path: String, source: String) -> NSSize? {
+        if let size = imageSizeCache[path] {
+            return size
+        }
+        let url = contentFolder.appendingPathComponent(path)
+        guard url.exists else {
+            markImageAsMissing(path: path, source: source)
+            return nil
+        }
+        guard let data = getImageData(at: url, path: path, source: source) else {
+            return nil
+        }
+
+        guard let image = NSImage(data: data) else {
+            images.unreadable[path] = source
+            return nil
+        }
+
+        let size = image.size
+        imageSizeCache[path] = size
+        return size
+    }
+
+    private func getImageData(at url: URL, path: String, source: String) -> Data? {
+        do {
+            let data = try Data(contentsOf: url)
+            fileUpdates.didLoad(data, at: path)
+            return data
+        } catch {
+            markFileAsUnreadable(at: path, requiredBy: source, message: "\(error)")
+            return nil
+        }
+    }
+
+    private func insert(job: ImageJob, source: String) {
+        guard let existingSource = images.jobs[source] else {
+            images.jobs[source] = [job]
+            return
+        }
+
+        guard let existingJob = existingSource.first(where: { $0.destination == job.destination }) else {
+            images.jobs[source] = existingSource + [job]
+            return
+        }
+
+        guard existingJob.width != job.width else {
+            return
+        }
+        warning("Existing job with width \(existingJob.width) (from \(existingJob.path)), but width \(job.width)", destination: job.destination, path: existingJob.path)
+    }
+
+    // MARK: Visual output
+
+    func didCompletePage() {
+        numberOfProcessedPages += 1
+        print("       Processed pages: \(numberOfProcessedPages)/\(numberOfTotalPages)    \r", terminator: "")
+        fflush(stdout)
+    }
+
+    func printOverview() {
+        var notes: [String] = []
+        func addIfNotZero(_ count: Int, _ name: String) {
+            guard count > 0 else {
+                return
+            }
+            notes.append("\(count) \(name)")
+        }
+        func addIfNotZero<S>(_ sequence: Array<S>, _ name: String) {
+            addIfNotZero(sequence.count, name)
+        }
+        addIfNotZero(missingFiles.count, "missing files")
+        addIfNotZero(unreadableFiles.count, "unreadable files")
+        addIfNotZero(unwritableFiles.count, "unwritable files")
+        addIfNotZero(missingLinkedPages.count, "missing linked pages")
+        addIfNotZero(pageWarnings.count, "warnings")
+
+        print("         Updated pages: \(generatedFiles.count)/\(numberOfProcessedPages)     ")
+        print("                Drafts: \(draftPages.count)")
+        print("           Empty pages: \(emptyPages.count)")
+        if !notes.isEmpty {
+            print("                 Notes: " + notes.joined(separator: ", "))
+        }
+        print("")
+    }
+
+    func writeResults(to file: URL) {
+        guard !missingFiles.isEmpty || !unreadableFiles.isEmpty || !unwritableFiles.isEmpty || !missingLinkedPages.isEmpty || !pageWarnings.isEmpty || !generatedFiles.isEmpty || !draftPages.isEmpty || !emptyPages.isEmpty else {
+            do {
+                if FileManager.default.fileExists(atPath: file.path) {
+                    try FileManager.default.removeItem(at: file)
+                }
+            } catch {
+                print("    Failed to delete generation log: \(error)")
+            }
+            return
+        }
+        var lines: [String] = []
+        func add<S>(_ name: String, _ property: S, convert: (S.Element) -> String) where S: Sequence {
+            let elements = property.map { "  " + convert($0) }.sorted()
+            guard !elements.isEmpty else {
+                return
+            }
+            lines.append("\(name):")
+            lines.append(contentsOf: elements)
+        }
+        add("Missing files", missingFiles) { "\($0.key) (required by \($0.value))" }
+        add("Unreadable files", unreadableFiles) { "\($0.key) (required by \($0.value.source)): \($0.value.message)" }
+        add("Unwritable files", unwritableFiles) { "\($0.key) (required by \($0.value.source)): \($0.value.message)" }
+        add("Missing linked pages", missingLinkedPages) { "\($0.key) (linked by \($0.value))" }
+        add("Warnings", pageWarnings) { "\($0.source): \($0.message)" }
+        add("Generated files", generatedFiles) { $0 }
+        add("Drafts", draftPages) { $0 }
+        add("Empty pages", emptyPages) { "\($0.key) (from \($0.value))" }
+        let data = lines.joined(separator: "\n").data(using: .utf8)!
+        do {
+            try data.createFolderAndWrite(to: file)
+        } catch {
+            print("    Failed to save generation log: \(error)")
+        }
+    }
+}
+

Sources/Generator/Processing/ImageData.swift

@@ -0,0 +1,19 @@
+import Foundation
+
+struct ImageData {
+
+    /// The images to generate (`key`: the image source path relative to the input folder)
+    var jobs: [String : [ImageJob]] = [:]
+
+    /// The images for which to generate multiple versions (`key`: the source file, `value`: the path of the requiring page)
+    var multiJobs: [String : String] = [:]
+
+    /// All warnings produced for images during generation
+    var warnings: [String] = []
+
+    /// The images which could not be found, but are required for the site (`key`: image path, `value`: source element path)
+    var missing: [String : String] = [:]
+
+    /// Images which could not be read (`key`: file path relative to content, `value`: source element path)
+    var unreadable: [String : String] = [:]
+}

Sources/Generator/Processing/ImageGenerator.swift

@@ -0,0 +1,348 @@
+import Foundation
+import AppKit
+import CryptoKit
+import Darwin.C
+
+final class ImageGenerator {
+
+    private let imageOptimSupportedFileExtensions: Set<String> = ["jpg", "png", "svg"]
+
+    private let imageOptimizationBatchSize = 50
+
+    /**
+     The path to the input folder.
+     */
+    private let input: URL
+
+    /**
+     The path to the output folder
+     */
+    private let output: URL
+
+    private let imageReader: ImageReader
+    
+    /**
+     All warnings produced for images during generation
+     */
+    private var imageWarnings: [String]
+
+    /// The images which could not be found, but are required for the site (`key`: image path, `value`: source element path)
+    private var missingImages: [String : String]
+
+    /// Images which could not be read (`key`: file path relative to content, `value`: source element path)
+    private var unreadableImages: [String : String]
+
+    private var unhandledImages: [String: String] = [:]
+
+    /// All images modified or created during this generator run.
+    private var generatedImages: Set<String> = []
+
+    /// The images optimized by ImageOptim
+    private var optimizedImages: Set<String> = []
+
+    private var failedImages: [(path: String, message: String)] = []
+
+    private var numberOfGeneratedImages = 0
+
+    private let numberOfTotalImages: Int
+
+    private lazy var numberOfImagesToCreate = jobs.reduce(0) { $0 + $1.images.count } + multiJobs.count * 2
+
+    private var numberOfImagesToOptimize = 0
+
+    private var numberOfOptimizedImages = 0
+
+    private let images: ImageData
+
+    private lazy var jobs: [(source: String, images: [ImageJob])] = images.jobs
+        .sorted { $0.key < $1.key }
+        .map { (source: $0.key, images: $0.value) }
+        .filter {
+            // Only load image if required
+            let imageHasChanged = imageReader.imageHasChanged(at: $0.source)
+            return imageHasChanged || $0.images.contains { job in
+                job.alwaysGenerate || !output.appendingPathComponent(job.destination).exists
+            }
+        }
+
+    private lazy var multiJobs: [String : String] = {
+        let imagesToGenerate: Set<String> = jobs.reduce([]) { $0.union($1.images.map { $0.destination }) }
+        return images.multiJobs.filter { imagesToGenerate.contains($0.key) }
+    }()
+
+    init(input: URL, output: URL, reader: ImageReader, images: ImageData) {
+        self.input = input
+        self.output = output
+        self.imageReader = reader
+        self.images = images
+        self.numberOfTotalImages = images.jobs.reduce(0) { $0 + $1.value.count }
+            + images.multiJobs.count * 2
+        self.imageWarnings = images.warnings
+        self.missingImages = images.missing
+        self.unreadableImages = images.unreadable
+    }
+
+    func generateImages() {
+        var notes: [String] = []
+        func addIfNotZero(_ count: Int, _ name: String) {
+            guard count > 0 else {
+                return
+            }
+            notes.append("\(count) \(name)")
+        }
+
+        print("       Changed sources: \(jobs.count)/\(images.jobs.count)")
+        print("          Total images: \(numberOfTotalImages) (\(numberOfTotalImages - imageReader.numberOfFilesAccessed) versions)")
+
+        for (source, jobs) in jobs {
+            create(images: jobs, from: source)
+        }
+        for (baseImage, source) in multiJobs {
+            createMultiImages(from: baseImage, path: source)
+        }
+        print("      Generated images: \(numberOfGeneratedImages)/\(numberOfImagesToCreate)")
+        optimizeImages()
+        print("      Optimized images: \(numberOfOptimizedImages)/\(numberOfImagesToOptimize)")
+
+        addIfNotZero(missingImages.count, "missing images")
+        addIfNotZero(unreadableImages.count, "unreadable images")
+        print("              Warnings: \(imageWarnings.count)")
+        if !notes.isEmpty {
+            print("                 Notes: " + notes.joined(separator: ", "))
+        }
+    }
+
+    private func create(images: [ImageJob], from source: String) {
+        guard let image = imageReader.getImage(atPath: source) else {
+            unreadableImages[source] = images.first!.destination
+            didGenerateImage(count: images.count)
+            return
+        }
+        let jobs = imageReader.imageHasChanged(at: source) ? images : images.filter(isMissing)
+        // Update all images
+        jobs.forEach { job in
+            // Prevent memory overflow due to repeated NSImage operations
+            autoreleasepool {
+                create(job: job, from: image, source: source)
+                didGenerateImage()
+            }
+        }
+    }
+
+    private func isMissing(_ job: ImageJob) -> Bool {
+        job.alwaysGenerate || !output.appendingPathComponent(job.destination).exists
+    }
+
+
+    private func create(job: ImageJob, from image: NSImage, source: String) {
+        let destinationUrl = output.appendingPathComponent(job.destination)
+        create(job: job, from: image, source: source, at: destinationUrl)
+    }
+
+    private func create(job: ImageJob, from image: NSImage, source: String, at destinationUrl: URL) {
+        // Ensure that image file is supported
+        let ext = destinationUrl.pathExtension.lowercased()
+        guard ImageType(fileExtension: ext) != nil else {
+            fatalError()
+        }
+
+        let destinationExtension = destinationUrl.pathExtension.lowercased()
+        guard let type = ImageType(fileExtension: destinationExtension)?.fileType else {
+            unhandledImages[source] = job.destination
+            return
+        }
+
+        let desiredWidth = CGFloat(job.width)
+
+        let sourceRep = image.representations[0]
+        let destinationSize = NSSize(width: sourceRep.pixelsWide, height: sourceRep.pixelsHigh)
+            .scaledDown(to: desiredWidth)
+
+        // create NSBitmapRep manually, if using cgImage, the resulting size is wrong
+        let rep = NSBitmapImageRep(bitmapDataPlanes: nil,
+                                   pixelsWide: Int(destinationSize.width),
+                                   pixelsHigh: Int(destinationSize.height),
+                                   bitsPerSample: 8,
+                                   samplesPerPixel: 4,
+                                   hasAlpha: true,
+                                   isPlanar: false,
+                                   colorSpaceName: NSColorSpaceName.deviceRGB,
+                                   bytesPerRow: Int(destinationSize.width) * 4,
+                                   bitsPerPixel: 32)!
+
+        let ctx = NSGraphicsContext(bitmapImageRep: rep)
+        NSGraphicsContext.saveGraphicsState()
+        NSGraphicsContext.current = ctx
+        image.draw(in: NSMakeRect(0, 0, destinationSize.width, destinationSize.height))
+        ctx?.flushGraphics()
+        NSGraphicsContext.restoreGraphicsState()
+
+        // Get NSData, and save it
+        guard let data = rep.representation(using: type, properties: [.compressionFactor: NSNumber(value: job.quality)]) else {
+            markImageAsFailed(source, error: "Failed to get data")
+            return
+        }
+        do {
+            try data.createFolderAndWrite(to: destinationUrl)
+        } catch {
+            markImageAsFailed(job.destination, error: "Failed to write image (\(error))")
+            return
+        }
+        generatedImages.insert(job.destination)
+    }
+
+    private func markImageAsFailed(_ source: String, error: String) {
+        failedImages.append((source, error))
+    }
+
+    private func createMultiImages(from source: String, path: String) {
+        guard generatedImages.contains(source) else {
+            didGenerateImage(count: 2)
+            return
+        }
+
+        let sourceUrl = output.appendingPathComponent(source)
+        let sourcePath = sourceUrl.path
+        guard sourceUrl.exists else {
+            missingImages[source] = path
+            didGenerateImage(count: 2)
+            return
+        }
+
+        let avifPath = source.dropAfterLast(".") + ".avif"
+        createAVIF(at: output.appendingPathComponent(avifPath).path, from: sourcePath)
+        generatedImages.insert(avifPath)
+        didGenerateImage()
+
+        let webpPath = source.dropAfterLast(".") + ".webp"
+        createWEBP(at: output.appendingPathComponent(webpPath).path, from: sourcePath)
+        generatedImages.insert(webpPath)
+        didGenerateImage()
+
+        compress(at: sourcePath)
+    }
+
+    private func createAVIF(at destination: String, from source: String, quality: Int = 55, effort: Int = 5) {
+        let folder = destination.dropAfterLast("/")
+        let command = "npx avif --input=\(source) --quality=\(quality) --effort=\(effort) --output=\(folder) --overwrite"
+        do {
+            let output = try safeShell(command)
+            if output == "" {
+                return
+            }
+            markImageAsFailed(destination, error: "Failed to create AVIF image: \(output)")
+        } catch {
+            markImageAsFailed(destination, error: "Failed to create AVIF image")
+        }
+    }
+
+    private func createWEBP(at destination: String, from source: String, quality: Int = 75) {
+        let command = "cwebp \(source) -q \(quality) -o \(destination)"
+        do {
+            let output = try safeShell(command)
+            if !output.contains("Error") {
+                return
+            }
+            markImageAsFailed(destination, error: "Failed to create WEBP image: \(output)")
+        } catch {
+            markImageAsFailed(destination, error: "Failed to create WEBP image: \(error)")
+        }
+    }
+
+    private func compress(at destination: String, quality: Int = 70) {
+        let command = "magick convert \(destination) -quality \(quality)% \(destination)"
+        do {
+            let output = try safeShell(command)
+            if output == "" {
+                return
+            }
+            markImageAsFailed(destination, error: "Failed to compress image: \(output)")
+        } catch {
+            markImageAsFailed(destination, error: "Failed to compress image: \(error)")
+        }
+    }
+
+    private func optimizeImages() {
+        let all = generatedImages
+            .filter { imageOptimSupportedFileExtensions.contains($0.lastComponentAfter(".")) }
+            .map { output.appendingPathComponent($0).path }
+        numberOfImagesToOptimize = all.count
+        for i in stride(from: 0, to: numberOfImagesToOptimize, by: imageOptimizationBatchSize) {
+            let endIndex = min(i+imageOptimizationBatchSize, numberOfImagesToOptimize)
+            let batch = all[i..<endIndex]
+            if optimizeImageBatch(batch) {
+                optimizedImages.formUnion(batch)
+            }
+            didOptimizeImage(count: batch.count)
+        }
+    }
+
+    private func optimizeImageBatch(_ batch: ArraySlice<String>) -> Bool {
+        let command = "imageoptim " + batch.joined(separator: " ")
+        do {
+            let output = try safeShell(command)
+            if output.contains("Finished") {
+                return true
+            }
+
+            for image in batch {
+                markImageAsFailed(image, error: "Failed to optimize image: \(output)")
+            }
+            return true
+        } catch {
+            for image in batch {
+                markImageAsFailed(image, error: "Failed to optimize image: \(error)")
+            }
+            return false
+        }
+    }
+
+    // MARK: Output
+
+    private func didGenerateImage(count: Int = 1) {
+        numberOfGeneratedImages += count
+        print("      Generated images: \(numberOfGeneratedImages)/\(numberOfImagesToCreate)    \r", terminator: "")
+        fflush(stdout)
+    }
+
+    private func didOptimizeImage(count: Int) {
+        numberOfOptimizedImages += count
+        print("      Optimized images: \(numberOfOptimizedImages)/\(numberOfImagesToOptimize)    \r", terminator: "")
+        fflush(stdout)
+    }
+
+    func writeResults(to file: URL) {
+        guard !missingImages.isEmpty || !unreadableImages.isEmpty || !failedImages.isEmpty || !unhandledImages.isEmpty || !imageWarnings.isEmpty || !generatedImages.isEmpty || !optimizedImages.isEmpty else {
+            do {
+                if FileManager.default.fileExists(atPath: file.path) {
+                    try FileManager.default.removeItem(at: file)
+                }
+            } catch {
+                print("    Failed to delete image log: \(error)")
+            }
+            return
+        }
+        var lines: [String] = []
+        func add<S>(_ name: String, _ property: S, convert: (S.Element) -> String) where S: Sequence {
+            let elements = property.map { "  " + convert($0) }.sorted()
+            guard !elements.isEmpty else {
+                return
+            }
+            lines.append("\(name):")
+            lines.append(contentsOf: elements)
+        }
+        add("Missing images", missingImages) { "\($0.key) (required by \($0.value))" }
+        add("Unreadable images", unreadableImages) { "\($0.key) (required by \($0.value))" }
+        add("Failed images", failedImages) { "\($0.path): \($0.message)" }
+        add("Unhandled images", unhandledImages) { "\($0.value) (from \($0.key))" }
+        add("Warnings", imageWarnings) { $0 }
+        add("Generated images", generatedImages) { $0 }
+        add("Optimized images", optimizedImages) { $0 }
+        let data = lines.joined(separator: "\n").data(using: .utf8)!
+        do {
+            try data.createFolderAndWrite(to: file)
+        } catch {
+            print("    Failed to save image log: \(error)")
+        }
+    }
+}

Sources/Generator/Processing/MetadataInfoLogger.swift

@@ -0,0 +1,188 @@
+import Foundation
+
+final class MetadataInfoLogger {
+
+    private let input: URL
+
+    private var numberOfMetadataFiles = 0
+
+    private var unusedProperties: [(name: String, source: String)] = []
+
+    private var invalidProperties: [(name: String, source: String, reason: String)] = []
+
+    private var unknownProperties: [(name: String, source: String)] = []
+
+    private var missingProperties: [(name: String, source: String)] = []
+
+    private var unreadableMetadata: [(source: String, error: Error)] = []
+
+    private var warnings: [(source: String, message: String)] = []
+
+    private var errors: [(source: String, message: String)] = []
+
+    init(input: URL) {
+        self.input = input
+    }
+
+    /**
+     Adds an info message if a value is set for an unused property.
+     - Note: Unused properties do not cause an element to be skipped.
+     */
+    @discardableResult
+    func unused<T>(_ value: Optional<T>, _ name: String, source: String) -> T where T: DefaultValueProvider {
+        if let value {
+            unusedProperties.append((name, source))
+            return value
+        }
+        return T.defaultValue
+    }
+
+    /**
+     Cast a string value to another value, and using a default in case of errors.
+     - Note: Invalid string values do not cause an element to be skipped.
+     */
+    func cast<T>(_ value: String, _ name: String, source: String) -> T where T: DefaultValueProvider, T: StringProperty {
+        guard let result = T.init(value) else {
+            invalidProperties.append((name: name, source: source, reason: T.castFailureReason))
+            return T.defaultValue
+        }
+        return result
+    }
+
+    /**
+     Cast a string value to another value, and using a default in case of errors or missing values.
+     - Note: Invalid string values do not cause an element to be skipped.
+     */
+    func cast<T>(_ value: String?, _ name: String, source: String) -> T where T: DefaultValueProvider, T: StringProperty {
+        guard let value else {
+            return T.defaultValue
+        }
+        guard let result = T.init(value) else {
+            invalidProperties.append((name: name, source: source, reason: T.castFailureReason))
+            return T.defaultValue
+        }
+        return result
+    }
+
+    /**
+     Cast the string value of an unused property to another value, and using a default in case of errors.
+     - Note: Invalid string values do not cause an element to be skipped.
+     */
+    func castUnused<R>(_ value: String?, _ name: String, source: String) -> R where R: DefaultValueProvider, R: StringProperty {
+        unused(value.unwrapped { cast($0, name, source: source) }, name, source: source)
+    }
+
+    /**
+     Note an unknown property.
+     - Note: Unknown properties do not cause an element to be skipped.
+     */
+    func unknown(property: String, source: String) {
+        unknownProperties.append((name: property, source: source))
+    }
+
+    /**
+     Ensure that a property is set, and aborting metadata decoding.
+     - Note: Missing required properties cause an element to be skipped.
+     */
+    func required<T>(_ value: T?, name: String, source: String, _ valid: inout Bool) -> T where T: DefaultValueProvider {
+        guard let value = value else {
+            missingProperties.append((name, source))
+            valid = false
+            return T.defaultValue
+        }
+        return value
+    }
+
+    func warning(_ message: String, source: String) {
+        warnings.append((source, message))
+    }
+
+    func error(_ message: String, source: String) {
+        errors.append((source, message))
+    }
+
+    func failedToDecodeMetadata(source: String, error: Error) {
+        unreadableMetadata.append((source, error))
+    }
+
+    func readPotentialMetadata(atPath path: String, source: String) -> Data? {
+        let url = input.appendingPathComponent(path)
+        guard url.exists else {
+            return nil
+        }
+
+        numberOfMetadataFiles += 1
+        printMetadataScanUpdate()
+        do {
+            return try Data(contentsOf: url)
+        } catch {
+            unreadableMetadata.append((source, error))
+            return nil
+        }
+    }
+
+    // MARK: Printing
+
+    private func printMetadataScanUpdate() {
+        print("           Pages found: \(numberOfMetadataFiles)   \r", terminator: "")
+    }
+
+    func printMetadataScanOverview(languages: Int) {
+        var notes = [String]()
+        func addIfNotZero<S>(_ sequence: Array<S>, _ name: String) {
+            guard sequence.count > 0 else {
+                return
+            }
+            notes.append("\(sequence.count) \(name)")
+        }
+        addIfNotZero(warnings, "warnings")
+        addIfNotZero(errors, "errors")
+        addIfNotZero(unreadableMetadata, "unreadable files")
+        addIfNotZero(unusedProperties, "unused properties")
+        addIfNotZero(invalidProperties, "invalid properties")
+        addIfNotZero(unknownProperties, "unknown properties")
+        addIfNotZero(missingProperties, "missing properties")
+
+        print("           Pages found: \(numberOfMetadataFiles)        ")
+        print("             Languages: \(languages)")
+        if !notes.isEmpty {
+            print("                 Notes: " + notes.joined(separator: ", "))
+        }
+    }
+
+    func writeResults(to file: URL) {
+        guard !errors.isEmpty || !warnings.isEmpty || !unreadableMetadata.isEmpty || !unusedProperties.isEmpty || !invalidProperties.isEmpty || !unknownProperties.isEmpty || !missingProperties.isEmpty else {
+            do {
+                if FileManager.default.fileExists(atPath: file.path) {
+                    try FileManager.default.removeItem(at: file)
+                }
+            } catch {
+                print("    Failed to delete metadata log: \(error)")
+            }
+            return
+        }
+        var lines: [String] = []
+        func add<S>(_ name: String, _ property: S, convert: (S.Element) -> String) where S: Sequence {
+            let elements = property.map { "  " + convert($0) }.sorted()
+            guard !elements.isEmpty else {
+                return
+            }
+            lines.append("\(name):")
+            lines.append(contentsOf: elements)
+        }
+        add("Errors", errors) { "\($0.source): \($0.message)" }
+        add("Warnings", warnings) { "\($0.source): \($0.message)" }
+        add("Unreadable files", unreadableMetadata) { "\($0.source): \($0.error)" }
+        add("Unused properties", unusedProperties) { "\($0.source): \($0.name)" }
+        add("Invalid properties", invalidProperties) { "\($0.source): \($0.name) (\($0.reason))" }
+        add("Unknown properties", unknownProperties) { "\($0.source): \($0.name)" }
+        add("Missing properties", missingProperties) { "\($0.source): \($0.name)" }
+
+        let data = lines.joined(separator: "\n").data(using: .utf8)!
+        do {
+            try data.createFolderAndWrite(to: file)
+        } catch {
+            print("    Failed to save metadata log: \(error)")
+        }
+    }
+}

Sources/Generator/Processing/RequiredHeaders.swift

@@ -0,0 +1,15 @@
+import Foundation
+
+enum HeaderFile: String {
+    case codeHightlighting = "highlight.js"
+    case modelViewer = "model-viewer.js"
+
+    var asModule: Bool {
+        switch self {
+        case .codeHightlighting: return false
+        case .modelViewer: return true
+        }
+    }
+}
+
+typealias RequiredHeaders = Set<HeaderFile>

Sources/Generator/Processing/Shell.swift

@@ -0,0 +1,20 @@
+import Foundation
+
+@discardableResult
+func safeShell(_ command: String) throws -> String {
+    let task = Process()
+    let pipe = Pipe()
+
+    task.standardOutput = pipe
+    task.standardError = pipe
+    task.arguments = ["-cl", command]
+    task.executableURL = URL(fileURLWithPath: "/bin/zsh")
+    task.standardInput = nil
+
+    try task.run()
+
+    let data = pipe.fileHandleForReading.readDataToEndOfFile()
+    let output = String(data: data, encoding: .utf8)!
+
+    return output
+}

Sources/Generator/Templates/Elements/BackNavigationTemplate.swift

@@ -10,4 +10,6 @@ struct BackNavigationTemplate: Template {
     static let templateName = "back.html"
 
     let raw: String
+
+    let results: GenerationResultsHandler
 }

Sources/Generator/Templates/Elements/BoxTemplate.swift

@@ -10,4 +10,6 @@ struct BoxTemplate: Template {
     static let templateName = "box.html"
 
     var raw: String
+
+    let results: GenerationResultsHandler
 }

Sources/Generator/Templates/Elements/OverviewSectionCleanTemplate.swift

@@ -9,4 +9,6 @@ struct OverviewSectionCleanTemplate: Template {
     static let templateName = "overview-section-clean.html"
 
     let raw: String
+
+    let results: GenerationResultsHandler
 }

Sources/Generator/Templates/Elements/OverviewSectionTemplate.swift

@@ -12,4 +12,6 @@ struct OverviewSectionTemplate: Template {
     static let templateName = "overview-section.html"
 
     let raw: String
+
+    let results: GenerationResultsHandler
 }

Sources/Generator/Templates/Elements/PageHeadTemplate.swift

@@ -12,5 +12,7 @@ struct PageHeadTemplate: Template {
 
     let raw: String
 
+    let results: GenerationResultsHandler
+
     static let templateName = "head.html"
 }

Sources/Generator/Templates/Elements/PageImageTemplate.swift

@@ -1,18 +1,36 @@
 import Foundation
 
-struct PageImageTemplate: Template {
+enum PageImageTemplateKey: String, CaseIterable {
-
+    case altText = "ALT_TEXT"
-    enum Key: String, CaseIterable {
     case image = "IMAGE"
-        case image2x = "IMAGE_2X"
+    case imageExtension = "IMAGE_EXT"
     case width = "WIDTH"
     case height = "HEIGHT"
     case leftText = "LEFT_TEXT"
     case rightText = "RIGHT_TEXT"
+    case number = "NUMBER"
 }
 
+struct EnlargeableImageTemplate: Template {
+
+    typealias Key = PageImageTemplateKey
+
+    static let templateName = "image-enlargeable.html"
+
+    let raw: String
+
+    let results: GenerationResultsHandler
+
+}
+
+struct PageImageTemplate: Template {
+
+    typealias Key = PageImageTemplateKey
+
     static let templateName = "image.html"
 
     let raw: String
 
+    let results: GenerationResultsHandler
+
 }

Sources/Generator/Templates/Elements/PageLinkTemplate.swift

@@ -3,9 +3,9 @@ import Foundation
 struct PageLinkTemplate: Template {
 
     enum Key: String, CaseIterable {
+        case altText = "ALT_TEXT"
         case url = "URL"
         case image = "IMAGE"
-        case image2x = "IMAGE_2X"
         case title = "TITLE"
         case path = "PATH"
         case description = "DESCRIPTION"
@@ -16,6 +16,8 @@ struct PageLinkTemplate: Template {
 
     let raw: String
 
+    let results: GenerationResultsHandler
+
     func makePath(components: [String]) -> String {
         components.joined(separator: " » ") //  » ")
     }

Sources/Generator/Templates/Elements/PageVideoTemplate.swift

@@ -23,6 +23,8 @@ struct PageVideoTemplate: Template {
 
     let raw: String
 
+    let results: GenerationResultsHandler
+
     func generate<T>(sources: [VideoSource], options: T) -> String where T: Sequence, T.Element == VideoOption {
         let sourcesCode = sources.map(makeSource).joined(separator: "\n")
         let optionCode = options.map { $0.rawValue }.joined(separator: " ")

Sources/Generator/Templates/Elements/SlideshowImageTemplate.swift

@@ -0,0 +1,23 @@
+import Foundation
+
+struct SlideshowImageTemplate: Template {
+
+    enum Key: String, CaseIterable {
+        case altText = "ALT_TEXT"
+        case url = "URL"
+        case image = "IMAGE"
+        case title = "TITLE"
+        case subtitle = "SUBTITLE"
+        case number = "NUMBER"
+    }
+
+    static let templateName = "slideshow-image.html"
+
+    let raw: String
+
+    let results: GenerationResultsHandler
+
+    func makePath(components: [String]) -> String {
+        components.joined(separator: " » ") //  » ")
+    }
+}

Sources/Generator/Templates/Elements/SlideshowTemplate.swift

@@ -0,0 +1,15 @@
+import Foundation
+
+struct SlideshowTemplate: Template {
+
+    enum Key: String, CaseIterable {
+        case title = "TITLE"
+        case content = "CONTENT"
+    }
+
+    static let templateName = "slideshow.html"
+
+    let raw: String
+
+    let results: GenerationResultsHandler
+}

Sources/Generator/Templates/Elements/SlideshowsTemplate.swift

@@ -0,0 +1,14 @@
+import Foundation
+
+struct SlideshowsTemplate: Template {
+
+    enum Key: String, CaseIterable {
+        case content = "CONTENT"
+    }
+
+    static let templateName = "slideshows.html"
+
+    let raw: String
+
+    let results: GenerationResultsHandler
+}

Sources/Generator/Templates/Elements/ThumbnailTemplate.swift

@@ -6,9 +6,9 @@ protocol ThumbnailTemplate {
 }
 
 enum ThumbnailKey: String, CaseIterable {
+    case altText = "ALT_TEXT"
     case url = "URL"
     case image = "IMAGE"
-    case image2x = "IMAGE_2X"
     case title = "TITLE"
     case corner = "CORNER"
 }
@@ -21,6 +21,8 @@ struct LargeThumbnailTemplate: Template, ThumbnailTemplate {
 
     let raw: String
 
+    let results: GenerationResultsHandler
+
     func makeCorner(text: String) -> String {
         "<span class=\"corner\"><span>\(text)</span></span>"
     }
@@ -37,6 +39,8 @@ struct SquareThumbnailTemplate: Template, ThumbnailTemplate {
     static let templateName = "thumbnail-square.html"
 
     let raw: String
+
+    let results: GenerationResultsHandler
 }
 
 struct SmallThumbnailTemplate: Template, ThumbnailTemplate {
@@ -46,5 +50,7 @@ struct SmallThumbnailTemplate: Template, ThumbnailTemplate {
     static let templateName = "thumbnail-small.html"
 
     let raw: String
+
+    let results: GenerationResultsHandler
 }
 

Sources/Generator/Templates/Elements/TopBarTemplate.swift

@@ -12,4 +12,6 @@ struct TopBarTemplate: Template {
     static let templateName = "bar.html"
 
     var raw: String
+
+    let results: GenerationResultsHandler
 }

Sources/Generator/Templates/Filled/LocalizedSiteTemplate.swift

@@ -35,7 +35,7 @@ struct LocalizedSiteTemplate {
         factory.page
     }
 
-    init(factory: TemplateFactory, language: String, site: Element) {
+    init(factory: TemplateFactory, language: String, site: Element, results: GenerationResultsHandler) {
         self.author = site.author
         self.factory = factory
 
@@ -51,7 +51,7 @@ struct LocalizedSiteTemplate {
         self.month = df2
 
         let df3 = DateFormatter()
-        df3.dateFormat = "dd"
+        df3.dateFormat = "d"
         df3.locale = Locale(identifier: language)
         self.day = df3
 
@@ -66,10 +66,8 @@ struct LocalizedSiteTemplate {
             language: language,
             sections: sections,
             topBarWebsiteTitle: site.topBarTitle)
-        self.pageHead = PageHeadGenerator(
+        self.pageHead = PageHeadGenerator(factory: factory, results: results)
-            factory: factory)
+        self.overviewSection = OverviewSectionGenerator(factory: factory, siteRoot: site, results: results)
-        self.overviewSection = OverviewSectionGenerator(
-            factory: factory)
     }
 
     // MARK: Content

Sources/Generator/Templates/Pages/HeaderTemplate.swift

@@ -19,6 +19,8 @@ struct CenteredHeaderTemplate: Template {
 
     let raw: String
 
+    let results: GenerationResultsHandler
+
     static let templateName = "header-center.html"
 }
 
@@ -28,5 +30,7 @@ struct LeftHeaderTemplate: Template {
 
     let raw: String
 
+    let results: GenerationResultsHandler
+
     static let templateName = "header-left.html"
 }

Sources/Generator/Templates/Pages/PageTemplate.swift

@@ -3,6 +3,7 @@ import Foundation
 struct PageTemplate: Template {
 
     enum Key: String, CaseIterable {
+        case language = "LANG"
         case head = "HEAD"
         case topBar = "TOP_BAR"
         case contentClass = "CONTENT_CLASS"
@@ -18,4 +19,6 @@ struct PageTemplate: Template {
     static let templateName = "page.html"
 
     let raw: String
+
+    let results: GenerationResultsHandler
 }

Sources/Generator/Templates/Template.swift

@@ -8,25 +8,33 @@ protocol Template {
     
     var raw: String { get }
 
-    init(raw: String)
+    var results: GenerationResultsHandler { get }
+
+    init(raw: String, results: GenerationResultsHandler)
 
 }
 
 extension Template {
 
-    init(in folder: URL) throws {
+    init(in folder: URL, results: GenerationResultsHandler) throws {
         let url = folder.appendingPathComponent(Self.templateName)
-        try self.init(from: url)
+        try self.init(from: url, results: results)
     }
 
-    init(from url: URL) throws {
+    init(from url: URL, results: GenerationResultsHandler) throws {
+        do {
             let raw = try String(contentsOf: url)
-        self.init(raw: raw)
+            self.init(raw: raw, results: results)
+        } catch {
+            results.warning("Failed to load: \(error)", source: "Template \(url.lastPathComponent)")
+           throw error
+        }
     }
 
-    func generate(_ content: [Key : String], to url: URL) -> Bool {
+    @discardableResult
-        let content = generate(content)
+    func generate(_ content: [Key : String], to file: String, source: String) -> Bool {
-        return files.write(content, to: url)
+        let content = generate(content).data(using: .utf8)!
+        return results.writeIfChanged(content, file: file, source: source)
     }
 
     func generate(_ content: [Key : String], shouldIndent: Bool = false) -> String {

Sources/Generator/Templates/TemplateFactory.swift

@@ -51,31 +51,48 @@ final class TemplateFactory {
 
     let image: PageImageTemplate
 
+    let largeImage: EnlargeableImageTemplate
+
     let video: PageVideoTemplate
 
+    // MARK: Slideshow
+
+    let slideshows: SlideshowsTemplate
+
+    let slideshow: SlideshowTemplate
+
+    let slideshowImage: SlideshowImageTemplate
+
     // MARK: HTML
 
     let html: HTMLElementsGenerator
 
     // MARK: Init
 
-    init(templateFolder: URL) throws {
+    init(templateFolder: URL, results: GenerationResultsHandler) throws {
         self.templateFolder = templateFolder
-        self.backNavigation = try .init(in: templateFolder)
+        func create<T>() throws -> T where T: Template {
-        self.pageHead = try .init(in: templateFolder)
+            try .init(in: templateFolder, results: results)
-        self.topBar = try .init(in: templateFolder)
+        }
-        self.overviewSection = try .init(in: templateFolder)
+        self.backNavigation = try create()
-        self.overviewSectionClean = try .init(in: templateFolder)
+        self.pageHead = try create()
-        self.box = try .init(in: templateFolder)
+        self.topBar = try create()
-        self.pageLink = try .init(in: templateFolder)
+        self.overviewSection = try create()
-        self.largeThumbnail = try .init(in: templateFolder)
+        self.overviewSectionClean = try create()
-        self.squareThumbnail = try .init(in: templateFolder)
+        self.box = try create()
-        self.smallThumbnail = try .init(in: templateFolder)
+        self.pageLink = try create()
-        self.leftHeader = try .init(in: templateFolder)
+        self.largeThumbnail = try create()
-        self.centeredHeader = try .init(in: templateFolder)
+        self.squareThumbnail = try create()
-        self.page = try .init(in: templateFolder)
+        self.smallThumbnail = try create()
-        self.image = try .init(in: templateFolder)
+        self.leftHeader = try create()
-        self.video = try .init(in: templateFolder)
+        self.centeredHeader = try create()
+        self.page = try create()
+        self.image = try create()
+        self.largeImage = try create()
+        self.video = try create()
+        self.slideshow = try create()
+        self.slideshows = try create()
+        self.slideshowImage = try create()
         self.html = .init()
     }
 

Sources/Generator/run.swift

@@ -1,10 +1,6 @@
 import Foundation
 import ArgumentParser
 
-var configuration: Configuration!
-let log = ValidationLog()
-var files: FileSystem!
-var siteRoot: Element!
 
 @main
 struct CHGenerator: ParsableCommand {
@@ -17,28 +13,175 @@ struct CHGenerator: ParsableCommand {
     }
 }
 
-private func generate(configPath: String) throws {
+private func loadConfiguration(at configPath: String) -> Configuration? {
+    print("--- CONFIGURATION ----------------------------------")
+    print("                                                    ")
+    print("    Configuration file: \(configPath)")
     let configUrl = URL(fileURLWithPath: configPath)
+    guard configUrl.exists else {
+        print("                 Error: Configuration file not found")
+        return nil
+    }
+    var config: Configuration
+    do {
         let data = try Data(contentsOf: configUrl)
-    configuration = try JSONDecoder().decode(from: data)
+        config = try JSONDecoder().decode(from: data)
+        config.adjustPathsRelative(to: configUrl.deletingLastPathComponent())
+    } catch {
+        print("   Configuration error: \(error)")
+        return nil
+    }
+    config.printOverview()
+    print("                                                    ")
+    return config
+}
 
-    files = .init(
+private func loadSiteData(in folder: URL, runFolder: URL) throws -> (root: Element, pageMap: PageMap)? {
+    print("--- SOURCE FILES -----------------------------------")
+    print("                                                    ")
+
+    let log = MetadataInfoLogger(input: folder)
+    let root = Element(atRoot: folder, log: log)
+
+    let file = runFolder.appendingPathComponent("metadata.txt")
+    defer {
+        log.writeResults(to: file)
+        print("                                                    ")
+    }
+    guard let root else {
+        log.printMetadataScanOverview(languages: 0)
+        print("                Error: No site root loaded, aborting generation")
+        return nil
+    }
+    let pageMap = root.languages.map { language in
+        (language: language.language,
+         pages: root.getExternalPageMap(language: language.language, log: log))
+    }
+    log.printMetadataScanOverview(languages: root.languages.count)
+    return (root, pageMap)
+}
+
+private func generatePages(from root: Element, configuration: Configuration, fileUpdates: FileUpdateChecker, pageMap: PageMap, runFolder: URL) -> (ImageData, FileData)? {
+    print("--- GENERATION -------------------------------------")
+    print("                                                    ")
+
+    let pageCount = pageMap.reduce(0) { $0 + $1.pages.count }
+    let results = GenerationResultsHandler(
         in: configuration.contentDirectory,
-        to: configuration.outputDirectory)
+        to: configuration.outputDirectory,
+        configuration: configuration,
+        fileUpdates: fileUpdates,
+        pageMap: pageMap,
+        pageCount: pageCount)
 
-    siteRoot = Element(atRoot: configuration.contentDirectory)
+    defer { results.printOverview() }
-    guard siteRoot != nil else {
+
+    let siteGenerator: SiteGenerator
+    do {
+        siteGenerator = try SiteGenerator(results: results)
+    } catch {
+        return nil
+    }
+    siteGenerator.generate(site: root)
+
+    let url = runFolder.appendingPathComponent("pages.txt")
+    results.writeResults(to: url)
+
+    if let error = fileUpdates.writeDetectedFileChanges(to: runFolder) {
+        print("      Hashes not saved: \(error)")
+    }
+    return (results.images, results.files)
+}
+
+private func generateImages(_ images: ImageData, configuration: Configuration, runFolder: URL, fileUpdates: FileUpdateChecker) {
+    print("--- IMAGES -----------------------------------------")
+    print("                                                    ")
+    let reader = ImageReader(in: configuration.contentDirectory, runFolder: runFolder, fileUpdates: fileUpdates)
+    let generator = ImageGenerator(
+        input: configuration.contentDirectory,
+        output: configuration.outputDirectory,
+        reader: reader, images: images)
+    generator.generateImages()
+    print("                                                    ")
+    let file = runFolder.appendingPathComponent("images.txt")
+    generator.writeResults(to: file)
+}
+
+private func copyFiles(files: FileData, configuration: Configuration, runFolder: URL) {
+    print("--- FILES ------------------------------------------")
+    print("                                                    ")
+    let generator = FileGenerator(
+        input: configuration.contentDirectory,
+        output: configuration.outputDirectory,
+        runFolder: runFolder,
+        files: files)
+    generator.generate()
+    let file = runFolder.appendingPathComponent("files.txt")
+    generator.writeResults(to: file)
+}
+
+private func finish(start: Date, complete: Bool) {
+    print("--- SUMMARY ----------------------------------------")
+    print("                                                    ")
+    let duration = Int(-start.timeIntervalSinceNow.rounded())
+    if duration < 3600 {
+        print(String(format: "              Duration: %d:%02d", duration / 60, duration % 60))
+    } else {
+        print(String(format: "              Duration: %d:%02d:%02d", duration / 3600, (duration / 60) % 60, duration % 60))
+    }
+    print("              Complete: \(complete ? "Yes" : "No")")
+    print("                                                    ")
+    print("----------------------------------------------------")
+}
+
+private func generate(configPath: String) throws {
+    let start = Date()
+    var complete = false
+
+    defer {
+        // 6. Print summary
+        finish(start: start, complete: complete)
+    }
+
+    print("                                                    ")
+
+    guard checkDependencies() else {
         return
     }
-    let siteGenerator = try SiteGenerator()
-    siteGenerator.generate(site: siteRoot)
 
-    files.printGeneratedPages()
+    // 1. Load configuration
-    files.printEmptyPages()
+    guard let configuration = loadConfiguration(at: configPath) else {
-    files.printDraftPages()
+        return
-
+    }
-    files.createImages()
+
-    files.copyRequiredFiles()
+    let runFolder = configuration.contentDirectory.appendingPathComponent("run")
-    files.printExternalFiles()
+
-    files.writeDetectedFileChangesToDisk()
+    // 2. Scan site elements
+    guard let (siteRoot, pageMap) = try loadSiteData(in: configuration.contentDirectory, runFolder: runFolder) else {
+        return
+    }
+
+    let fileUpdates = FileUpdateChecker(input: configuration.contentDirectory)
+    switch fileUpdates.loadPreviousRun(from: runFolder)  {
+    case .notLoaded:
+        print("Regarding all files as new (no hashes loaded)")
+    case .loaded:
+        break
+    case .failed(let error):
+        print("Regarding all files as new (\(error))")
+    }
+
+    // 3. Generate pages
+
+    guard let (images, files) = generatePages(from: siteRoot, configuration: configuration, fileUpdates: fileUpdates, pageMap: pageMap, runFolder: runFolder) else {
+        return
+    }
+
+    // 4. Generate images
+    generateImages(images, configuration: configuration, runFolder: runFolder, fileUpdates: fileUpdates)
+
+    // 5. Copy/minify files
+    copyFiles(files: files, configuration: configuration, runFolder: runFolder)
+
+    complete = true
 }

config_example.json

@@ -1,6 +1,8 @@
 {
     "pageImageWidth" : 748,
-    "minifyCSSandJS" : true,
+    "fullScreenImageWidth" : 4000,
+    "minifyJavaScript" : false,
+    "minifyCSS" : false,
     "createMdFilesIfMissing" : false,
     "contentPath" : "/path/to/content/folder",
     "outputPath" : "/path/to/output/folder")

install.sh

@@ -1,13 +1,19 @@
 #!/bin/bash
 # Install the required dependencies for CHGenerator
 
-# Note: The following is only required if `minifyCSSandJS=True`
+# Install magick to resize images
-# is set in the generator configuration
+brew install imagemagick
 
-# Install the Javascript minifier
+# Install avif to create AVIF versions of images
+npm install avif -g
+
+# Install the Javascript minifier (required if `minifyJavaScript = True`)
 # https://github.com/mishoo/UglifyJS
 npm install uglify-js -g
 
-# Install the clean-css minifier
+# Install the clean-css minifier (required if `minifyCSS = True`)
 # https://github.com/clean-css/clean-css-cli
 npm install clean-css-cli -g
+
+# Required to optimize jpg/png/svg
+npm install imageoptim-cli -g