Determine elements for news section

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.
@@ -145,77 +145,52 @@ extension Element {
 
 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
-        func markAsIncomplete() {
-            isComplete = false
-        }
+        var isValid = true
+
         let source = "root"
-        self.language = log
-            .required(data.language, name: "language", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.title = log
-            .required(data.title, name: "title", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.language = log.required(data.language, name: "language", source: source, &isValid)
+        self.title = log.required(data.title, name: "title", source: source, &isValid)
         self.subtitle = data.subtitle
         self.description = data.description
         self.linkPreviewTitle = data.linkPreviewTitle ?? data.title ?? ""
-        self.linkPreviewImage = log
-            .linkPreviewThumbnail(customFile: data.linkPreviewImage, for: language, in: folder, source: source)
+        self.linkPreviewImage = data.linkPreviewImage
         let linkPreviewDescription = data.linkPreviewDescription ?? data.description ?? data.subtitle
-        self.linkPreviewDescription = log
-            .required(linkPreviewDescription, name: "linkPreviewDescription", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.moreLinkText = data.moreLinkText ?? Element.LocalizedMetadata.moreLinkDefaultText
-        self.backLinkText = log
-            .required(data.backLinkText, name: "backLinkText", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.linkPreviewDescription = log.required(linkPreviewDescription, name: "linkPreviewDescription", source: source, &isValid)
+        self.moreLinkText = data.moreLinkText
+        self.backLinkText = log.required(data.backLinkText, name: "backLinkText", source: source, &isValid)
         self.parentBackLinkText = "" // Root has no parent
-        self.placeholderTitle = log
-            .required(data.placeholderTitle, name: "placeholderTitle", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.placeholderText = log
-            .required(data.placeholderText, name: "placeholderText", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.placeholderTitle = log.required(data.placeholderTitle, name: "placeholderTitle", source: source, &isValid)
+        self.placeholderText = log.required(data.placeholderText, name: "placeholderText", source: source, &isValid)
         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.relatedContentText = log
-            .required(data.relatedContentText, name: "relatedContentText", source: source) ?? ""
-        self.navigationTextAsNextPage = log
-            .required(data.navigationTextAsNextPage, name: "navigationTextAsNextPage", source: source) ?? ""
-        self.navigationTextAsPreviousPage = log
-            .required(data.navigationTextAsPreviousPage, name: "navigationTextAsPreviousPage", source: source) ?? ""
+        self.externalUrl = log.unused(data.externalUrl, "externalUrl", source: source)
+        self.relatedContentText = log.required(data.relatedContentText, name: "relatedContentText", source: source, &isValid)
+        self.navigationTextAsNextPage = log.required(data.navigationTextAsNextPage, name: "navigationTextAsNextPage", source: source, &isValid)
+        self.navigationTextAsPreviousPage = log.required(data.navigationTextAsPreviousPage, name: "navigationTextAsPreviousPage", source: source, &isValid)
 
-        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
-        func markAsIncomplete() {
-            isComplete = false
-        }
+        var isValid = true
+
         self.language = parent.language
-        self.title = log
-            .required(data.title, name: "title", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.title = log.required(data.title, name: "title", source: source, &isValid)
         self.subtitle = data.subtitle
         self.description = data.description
         self.linkPreviewTitle = data.linkPreviewTitle ?? data.title ?? ""
-        self.linkPreviewImage = log
-            .linkPreviewThumbnail(customFile: data.linkPreviewImage, for: language, in: folder, source: source)
+        self.linkPreviewImage = data.linkPreviewImage
         let linkPreviewDescription = data.linkPreviewDescription ?? data.description ?? data.subtitle
-        self.linkPreviewDescription = log
-            .required(linkPreviewDescription, name: "linkPreviewDescription", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.moreLinkText = log.moreLinkText(data.moreLinkText, parent: parent.moreLinkText, source: source)
+        self.linkPreviewDescription = log.required(linkPreviewDescription, name: "linkPreviewDescription", source: source, &isValid)
+        self.moreLinkText = log.required(data.moreLinkText ?? parent.moreLinkText, name: "moreLinkText", source: source, &isValid)
         self.backLinkText = data.backLinkText ?? data.title ?? ""
         self.parentBackLinkText = parent.backLinkText
         self.placeholderTitle = data.placeholderTitle ?? parent.placeholderTitle
@@ -228,7 +203,7 @@ extension Element.LocalizedMetadata {
         self.navigationTextAsPreviousPage = data.navigationTextAsPreviousPage ?? parent.navigationTextAsPreviousPage
         self.navigationTextAsNextPage = data.navigationTextAsNextPage ?? parent.navigationTextAsNextPage
 
-        guard isComplete else {
+        guard isValid else {
             return nil
         }
     }

Sources/Generator/Content/Element.swift

@@ -126,6 +126,12 @@ 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
+
     /**
      The localized metadata for each language.
      */
@@ -157,122 +163,130 @@ 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.topBarTitle = log
-            .required(metadata.topBarTitle, name: "topBarTitle", source: source) ?? "My Website"
-        self.date = log.unused(metadata.date, "date", source: source)
-        self.endDate = log.unused(metadata.endDate, "endDate", source: source)
-        self.state = log.state(metadata.state, source: source)
+        self.author = log.required(metadata.author, name: "author", source: source, &isValid)
+        self.topBarTitle = log.required(metadata.topBarTitle, name: "topBarTitle", source: source, &isValid)
+        self.date = log.castUnused(metadata.date, "date", source: source)
+        self.endDate = log.castUnused(metadata.endDate, "endDate", source: source)
+        self.state = log.cast(metadata.state, "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.thumbnailPath = metadata.thumbnailPath ?? Element.defaultThumbnailName
-        self.thumbnailStyle = log.unused(metadata.thumbnailStyle, "thumbnailStyle", source: source) ?? .large
-        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.languages = log.required(metadata.languages, name: "languages", source: source)?
+        self.headerType = log.cast(metadata.headerType, "headerType", source: source)
+        self.showMostRecentSection = metadata.showMostRecentSection ?? false
+        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
+        }
+
+        guard isValid else {
             return nil
         }
 
         files.add(page: path, id: id)
-        self.readElements(in: folder, source: nil)
+        self.readElements(in: folder, source: nil, log: log)
     }
 
-    mutating func readElements(in folder: URL, source: String?) {
+    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
         }
 
+        var isValid = true
+
         self.id = metadata.customId ?? folder.lastPathComponent
         self.author = metadata.author ?? parent.author
-        self.topBarTitle = log
-            .unused(metadata.topBarTitle, "topBarTitle", source: source) ?? parent.topBarTitle
-        let date = log.date(from: metadata.date, property: "date", source: source).ifNil {
-            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 {
-            if state != .hidden, parent.useManualSorting {
-                log.add(error: "No 'sortIndex', but parent defines 'useManualSorting' = true", source: source)
-            }
-        }
+        self.topBarTitle = log.unused(metadata.topBarTitle, "topBarTitle", source: source)
+        self.date = metadata.date.unwrapped { log.cast($0, "date", source: source) }
+        self.endDate = metadata.date.unwrapped { log.cast($0, "endDate", source: source) }
+        self.state = log.cast(metadata.state, "state", source: source)
+        self.sortIndex = metadata.sortIndex
         // 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.thumbnailPath = metadata.thumbnailPath ?? Element.defaultThumbnailName
-        self.thumbnailStyle = log.thumbnailStyle(metadata.thumbnailStyle, source: source)
+        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.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)?
-            .compactMap { log.required($0.language, name: "language", source: source) }
+        log.required(metadata.languages, name: "languages", source: source, &isValid)
+            .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
 
+        if self.date == nil, !parent.useManualSorting {
+            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
+        }
+
         files.add(page: path, id: id)
-        self.readElements(in: folder, source: path)
+        self.readElements(in: folder, source: path, log: log)
     }
 }
 
@@ -310,6 +324,17 @@ extension Element {
         }
     }
 
+    func mostRecentElements(_ count: Int) -> [Element] {
+        guard self.containsElements else {
+            return [self]
+        }
+        let all = shownItems
+            .reduce(into: [Element]()) { $0 += $1.mostRecentElements(count) }
+            .filter { $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! }

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?
 

Sources/Generator/Content/GenericMetadata.swift

@@ -125,6 +125,12 @@ 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?
+
     /**
      The localized metadata for each language.
      */
@@ -150,6 +156,7 @@ extension GenericMetadata: Codable {
             .useManualSorting,
             .overviewItemCount,
             .headerType,
+            .showMostRecentSection,
             .languages,
         ]
     }
@@ -169,8 +176,8 @@ extension GenericMetadata {
      - Note: The decoding routine also checks for unknown properties, and writes them to the output.
      - Note: Uses global objects
      */
-    init?(source: String) {
-        guard let data = files.dataOfOptionalFile(atPath: source, source: source) else {
+    init?(source: String, log: MetadataInfoLogger) {
+        guard let data = log.readPotentialMetadata(atPath: source, source: source) else {
             return nil
         }
 
@@ -196,8 +203,7 @@ extension GenericMetadata {
         do {
             self = try decoder.decode(from: data)
         } catch {
-            print("Here \(data)")
-            log.failedToOpen(GenericMetadata.metadataFileName, requiredBy: source, error: error)
+            log.failedToDecodeMetadata(source: source, error: error)
             return nil
         }
     }
@@ -222,6 +228,7 @@ extension GenericMetadata {
             useManualSorting: false,
             overviewItemCount: 6,
             headerType: "left",
+            showMostRecentSection: false,
             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

@@ -39,3 +39,19 @@ extension PageState {
         }
     }
 }
+
+extension PageState: StringProperty {
+
+    init?(_ value: String) {
+        self.init(rawValue: value)
+    }
+
+    static var castFailureReason: String {
+        "Page state must be 'standard', 'draft' or 'hidden'"
+    }
+}
+
+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
@@ -74,3 +79,8 @@ extension String {
         try data(using: .utf8)!.createFolderAndWrite(to: url)
     }
 }
+
+extension String: DefaultValueProvider {
+
+    static var defaultValue: String { "" }
+}

Sources/Generator/Files/Configuration.swift

@@ -56,4 +56,13 @@ struct Configuration: Codable {
     var outputDirectory: URL {
         .init(fileURLWithPath: outputPath)
     }
+
+    func printOverview() {
+        print("         Source folder: \(contentDirectory.path)")
+        print("         Output folder: \(outputDirectory.path)")
+        print("            Page width: \(pageImageWidth)")
+        print("     Minify JavaScript: \(minifyCSSandJS)")
+        print("            Minify CSS: \(minifyCSSandJS)")
+        print(" Create markdown files: \(createMdFilesIfMissing)")
+    }
 }

Sources/Generator/Files/FileSystem.swift

@@ -14,10 +14,14 @@ final class FileSystem {
 
     private let images: ImageGenerator
 
+    private let configuration: Configuration
+
     private var tempFile: URL {
         input.appendingPathComponent(FileSystem.tempFileName)
     }
 
+    let generatorInfoFolder: URL
+
     /**
      All files which should be copied to the output folder
      */
@@ -66,11 +70,12 @@ final class FileSystem {
      */
     private var generatedPages: Set<String> = []
 
-    init(in input: URL, to output: URL) {
+    init(in input: URL, to output: URL, configuration: Configuration) {
         self.input = input
         self.output = output
         self.images = .init(input: input, output: output)
-
+        self.generatorInfoFolder = input.appendingPathComponent("run")
+        self.configuration = configuration
     }
 
     func urlInOutputFolder(_ path: String) -> URL {
@@ -100,18 +105,8 @@ final class FileSystem {
         }
     }
 
-    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 contentOfMdFile(atPath path: String, source: String) -> String? {
+        contentOfOptionalFile(atPath: path, source: source, createEmptyFileIfMissing: configuration.createMdFilesIfMissing)
     }
 
     func contentOfOptionalFile(atPath path: String, source: String, createEmptyFileIfMissing: Bool = false) -> String? {
@@ -138,8 +133,30 @@ final class FileSystem {
     // 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 requireSingleImage(source: String, destination: String, requiredBy path: String, width: Int, desiredHeight: Int? = nil) -> NSSize {
+        images.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? = nil)  -> NSSize {
+        images.requireMultiVersionImage(source: source, destination: destination, requiredBy: path, width: width, desiredHeight: desiredHeight)
+    }
+
+    func requireFullSizeMultiVersionImage(source: String, destination: String, requiredBy path: String) -> NSSize {
+        images.requireMultiVersionImage(source: source, destination: destination, requiredBy: path, width: configuration.pageImageWidth, desiredHeight: nil)
     }
 
     func createImages() {
@@ -252,7 +269,7 @@ final class FileSystem {
     private func minifyJS(at sourceUrl: URL, andWriteTo destinationUrl: URL) -> Bool {
         let command = "uglifyjs \(sourceUrl.path) > \(tempFile.path)"
         do {
-            _ = try safeShell(command)
+            _ = try FileSystem.safeShell(command)
             return copyBinaryFileIfChanged(from: tempFile, to: destinationUrl)
         } catch {
             log.add(error: "Failed to minify \(sourceUrl.path): \(error)", source: source)
@@ -263,7 +280,7 @@ final class FileSystem {
     private func minifyCSS(at sourceUrl: URL, andWriteTo destinationUrl: URL) -> Bool {
         let command = "cleancss \(sourceUrl.path) -o \(tempFile.path)"
         do {
-            _ = try safeShell(command)
+            _ = try FileSystem.safeShell(command)
             return copyBinaryFileIfChanged(from: tempFile, to: destinationUrl)
         } catch {
             log.add(error: "Failed to minify \(sourceUrl.path): \(error)", source: source)
@@ -406,7 +423,7 @@ final class FileSystem {
     // MARK: Running other tasks
 
     @discardableResult
-    func safeShell(_ command: String) throws -> String {
+    static func safeShell(_ command: String) throws -> String {
         let task = Process()
         let pipe = Pipe()
 

Sources/Generator/Files/ImageGenerator.swift

@@ -1,6 +1,7 @@
 import Foundation
 import AppKit
 import CryptoKit
+import Darwin.C
 
 private struct ImageJob {
 
@@ -9,10 +10,18 @@ private struct ImageJob {
     let width: Int
 
     let path: String
+
+    let quality: Float
+
+    let alwaysGenerate: Bool
 }
 
 final class ImageGenerator {
 
+    private let imageOptimSupportedFileExtensions: Set<String> = ["jpg", "png", "svg"]
+
+    private let imageOptimizationBatchSize = 50
+
     /**
      The path to the input folder.
      */
@@ -30,6 +39,13 @@ final class ImageGenerator {
      */
     private var imageJobs: [String : [ImageJob]] = [:]
 
+    /**
+     The images for which to generate multiple versions
+
+     The key is the source file, the value is the path of the requiring page.
+     */
+    private var multiImageJobs: [String : String] = [:]
+
     /**
      The images which could not be found, but are required for the site.
 
@@ -54,6 +70,11 @@ final class ImageGenerator {
      */
     private var generatedImages: Set<String> = []
 
+    /**
+     The images optimized by ImageOptim
+     */
+    private var optimizedImages: Set<String> = []
+
     /**
      A cache to get the size of source images, so that files don't have to be loaded multiple times.
 
@@ -112,7 +133,7 @@ final class ImageGenerator {
         }
     }
 
-    func requireImage(at destination: String, generatedFrom source: String, requiredBy path: String, width: Int, height: Int?) -> NSSize {
+    func requireImage(at destination: String, generatedFrom source: String, requiredBy path: String, quality: Float, width: Int, height: Int?, alwaysGenerate: Bool) -> NSSize {
         requiredImages.insert(destination)
         let height = height.unwrapped(CGFloat.init)
         let sourceUrl = input.appendingPathComponent(source)
@@ -135,28 +156,44 @@ final class ImageGenerator {
             }
         }
 
-        let job = ImageJob(destination: destination, width: width, path: path)
+        let job = ImageJob(
+            destination: destination,
+            width: width,
+            path: path,
+            quality: quality,
+            alwaysGenerate: alwaysGenerate)
+        insert(job: job, source: source)
 
+        return scaledSize
+    }
+
+    private func insert(job: ImageJob, source: String) {
         guard let existingSource = imageJobs[source] else {
             imageJobs[source] = [job]
-            return scaledSize
+            return
         }
 
-        guard let existingJob = existingSource.first(where: { $0.destination == destination}) else {
+        guard let existingJob = existingSource.first(where: { $0.destination == job.destination }) else {
             imageJobs[source] = existingSource + [job]
-            return scaledSize
+            return
         }
 
-        if existingJob.width != width {
-            addWarning("Multiple image widths (\(existingJob.width) and \(width))", destination: destination, path: "\(existingJob.path) and \(path)")
+        if existingJob.width != job.width {
+            addWarning("Multiple image widths (\(existingJob.width) and \(job.width))", destination: job.destination, path: "\(existingJob.path) and \(job.path)")
         }
-        return scaledSize
     }
 
     func createImages() {
+        var count = 0
         for (source, jobs) in imageJobs.sorted(by: { $0.key < $1.key }) {
+            print(String(format: "Creating images: %4d / %d\r", count, imageJobs.count), terminator: "")
+            fflush(stdout)
             create(images: jobs, from: source)
+            count += 1
         }
+        print("                                     \r", terminator: "")
+        createMultiImages()
+        optimizeImages()
         printMissingImages()
         printImageWarnings()
         printGeneratedImages()
@@ -168,7 +205,10 @@ final class ImageGenerator {
             return
         }
         print("\(missingImages.count) missing images:")
-        for (source, path) in missingImages {
+        let sort = missingImages.sorted { (a, b) in
+            a.value < b.value && a.key < b.key
+        }
+        for (source, path) in sort {
             print("  \(source) (required by \(path))")
         }
     }
@@ -207,7 +247,7 @@ final class ImageGenerator {
     }
 
     private func isMissing(_ job: ImageJob) -> Bool {
-        !output.appendingPathComponent(job.destination).exists
+        job.alwaysGenerate || !output.appendingPathComponent(job.destination).exists
     }
 
     private func create(images: [ImageJob], from source: String) {
@@ -233,6 +273,10 @@ final class ImageGenerator {
 
     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()
@@ -272,7 +316,7 @@ final class ImageGenerator {
         NSGraphicsContext.restoreGraphicsState()
 
         // Get NSData, and save it
-        guard let data = rep.representation(using: type, properties: [.compressionFactor: NSNumber(0.7)]) else {
+        guard let data = rep.representation(using: type, properties: [.compressionFactor: NSNumber(value: job.quality)]) else {
             addWarning("Failed to get data", job: job)
             return
         }
@@ -284,4 +328,129 @@ final class ImageGenerator {
         }
         generatedImages.insert(job.destination)
     }
+
+    /**
+     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 @1x version
+        _ = requireScaledMultiImage(source: source, destination: destination, requiredBy: path, width: width, desiredHeight: desiredHeight)
+
+        // Add @2x version
+        return requireScaledMultiImage(
+            source: source,
+            destination: destination.insert("@2x", beforeLast: "."),
+            requiredBy: path,
+            width: width * 2,
+            desiredHeight: desiredHeight.unwrapped { $0 * 2 })
+    }
+
+    @discardableResult
+    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 = !output.appendingPathComponent(avifPath).exists || !output.appendingPathComponent(webpPath).exists
+
+        let size = requireImage(at: destination, generatedFrom: source, requiredBy: path, quality: 1.0, width: width, height: desiredHeight, alwaysGenerate: needsGeneration)
+        multiImageJobs[destination] = path
+        return size
+    }
+
+    private func createMultiImages() {
+        let sort = multiImageJobs.sorted { $0.value < $1.value && $0.key < $1.key }
+        var count = 1
+        for (baseImage, path) in sort {
+            print(String(format: "Creating image versions: %4d / %d\r", count, sort.count), terminator: "")
+            fflush(stdout)
+            createMultiImages(from: baseImage, path: path)
+            count += 1
+        }
+        print("                                     \r", terminator: "")
+    }
+
+    private func createMultiImages(from source: String, path: String) {
+        guard generatedImages.contains(source) else {
+            return
+        }
+
+        let sourceUrl = output.appendingPathComponent(source)
+        let sourcePath = sourceUrl.path
+        guard sourceUrl.exists else {
+            addWarning("No image at path \(sourcePath)", destination: source, path: path)
+            missingImages[source] = path
+            return
+        }
+
+        let avifPath = source.dropAfterLast(".") + ".avif"
+        createAVIF(at: output.appendingPathComponent(avifPath).path, from: sourcePath)
+        generatedImages.insert(avifPath)
+
+        let webpPath = source.dropAfterLast(".") + ".webp"
+        createWEBP(at: output.appendingPathComponent(webpPath).path, from: sourcePath)
+        generatedImages.insert(webpPath)
+
+        compress(at: source)
+    }
+
+    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 {
+            _ = try FileSystem.safeShell(command)
+        } catch {
+            addWarning("Failed to create AVIF image", destination: destination, path: destination)
+        }
+    }
+
+    private func createWEBP(at destination: String, from source: String, quality: Int = 75) {
+        let command = "cwebp \(source) -q \(quality) -o \(destination)"
+        do {
+            _ = try FileSystem.safeShell(command)
+        } catch {
+            addWarning("Failed to create WEBP image", destination: destination, path: destination)
+        }
+    }
+
+    private func compress(at destination: String, quality: Int = 70) {
+        let command = "magick convert \(destination) -quality \(quality)% \(destination)"
+        do {
+            _ = try FileSystem.safeShell(command)
+        } catch {
+            addWarning("Failed to compress image", destination: destination, path: destination)
+        }
+    }
+
+    private func optimizeImages() {
+        let all = generatedImages
+            .filter { imageOptimSupportedFileExtensions.contains($0.lastComponentAfter(".")) }
+            .map { output.appendingPathComponent($0).path }
+        for i in stride(from: 0, to: all.count, by: imageOptimizationBatchSize) {
+            let endIndex = min(i+imageOptimizationBatchSize, all.count)
+            let batch = all[i..<endIndex]
+            print(String(format: "Optimizing images: %4d / %d\r", endIndex, all.count), terminator: "")
+            fflush(stdout)
+            if optimizeImageBatch(batch) {
+                optimizedImages.formUnion(batch)
+            }
+        }
+        print("                                     \r", terminator: "")
+        fflush(stdout)
+        print("\(optimizedImages.count) images optimized")
+    }
+
+    private func optimizeImageBatch(_ batch: ArraySlice<String>) -> Bool {
+        let command = "imageoptim " + batch.joined(separator: " ")
+        do {
+            _ = try FileSystem.safeShell(command)
+            return true
+        } catch {
+            addWarning("Failed to optimize images", destination: "", path: "")
+            return false
+        }
+    }
 }

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

@@ -46,119 +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? {
-        guard let customFile = customFile else {
-            return nil
-        }
-        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
-    }
-
-    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/Generators/OverviewSectionGenerator.swift

@@ -15,6 +15,21 @@ struct OverviewSectionGenerator {
     }
 
     func generate(sections: [Element], in parent: Element, language: String, sectionItemCount: Int) -> String {
+        let content = sectionsContent(sections, in: parent, language: language, sectionItemCount: sectionItemCount)
+        if parent.showMostRecentSection {
+            let news = newsSectionContent(for: parent, language: language, sectionItemCount: sectionItemCount)
+            return news + "\n" + content
+        } else {
+            return content
+        }
+    }
+
+    private func newsSectionContent(for element: Element, language: String, sectionItemCount: Int) -> String {
+        let shownElements = element.mostRecentElements(sectionItemCount)
+        return ""
+    }
+
+    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)

Sources/Generator/Generators/PageContentGenerator.swift

@@ -8,8 +8,11 @@ struct PageContentGenerator {
 
     private let swift = SyntaxHighlighter(format: HTMLOutputFormat())
 
-    init(factory: TemplateFactory) {
+    private let siteRoot: Element
+
+    init(factory: TemplateFactory, siteRoot: Element) {
         self.factory = factory
+        self.siteRoot = siteRoot
     }
 
     func generate(page: Element, language: String, content: String) -> (content: String, includesCode: Bool) {
@@ -120,23 +123,14 @@ struct PageContentGenerator {
     private func handleImage(page: Element, file: String, rightTitle: String?, leftTitle: String?) -> String {
         let imagePath = page.pathRelativeToRootForContainedInputFile(file)
 
-        let size = files.requireImage(
+        let size = files.requireFullSizeMultiVersionImage(
             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)
+            requiredBy: page.path)
 
         let content: [PageImageTemplate.Key : String] = [
-            .image: file,
-            .image2x: file2x,
+            .image: file.dropAfterLast("."),
+            .imageExtension: file.lastComponentAfter("."),
             .width: "\(Int(size.width))",
             .height: "\(Int(size.height))",
             .leftText: leftTitle ?? "",
@@ -261,7 +255,6 @@ struct PageContentGenerator {
             return ""
         }
         var content = [PageLinkTemplate.Key: String]()
-        content[.url] = page.relativePathToOtherSiteElement(file: linkedPage.fullPageUrl(for: language))
         
         content[.title] = linkedPage.title(for: language)
 
@@ -275,13 +268,12 @@ struct PageContentGenerator {
             content[.url] = "href=\"\(relativePageUrl)\""
         }
 
-        content[.image] = relativeImageUrl
+        content[.image] = relativeImageUrl.dropAfterLast(".")
         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)

Sources/Generator/Generators/PageGenerator.swift

@@ -5,8 +5,11 @@ struct PageGenerator {
 
     private let factory: LocalizedSiteTemplate
 
-    init(factory: LocalizedSiteTemplate) {
+    private let contentGenerator: PageContentGenerator
+
+    init(factory: LocalizedSiteTemplate, siteRoot: Element) {
         self.factory = factory
+        self.contentGenerator = PageContentGenerator(factory: factory.factory, siteRoot: siteRoot)
     }
 
     func generate(page: Element, language: String, previousPage: Element?, nextPage: Element?) {
@@ -73,15 +76,11 @@ struct PageGenerator {
     }
 
     private func makeContent(page: Element, metadata: Element.LocalizedMetadata, language: String, path: String) -> (content: String, includesCode: Bool, isEmpty: Bool) {
-        let create = configuration.createMdFilesIfMissing
-        if let raw = files.contentOfOptionalFile(atPath: path, source: page.path, createEmptyFileIfMissing: create)?
-            .trimmed.nonEmpty {
-            let (content, includesCode) = PageContentGenerator(factory: factory.factory)
-                .generate(page: page, language: language, content: raw)
+        if let raw = files.contentOfMdFile(atPath: path, source: page.path)?.trimmed.nonEmpty {
+            let (content, includesCode) = contentGenerator.generate(page: page, language: language, content: raw)
             return (content, includesCode, false)
         } else {
-            let (content, includesCode) = PageContentGenerator(factory: factory.factory)
-                .generate(page: page, language: language, content: metadata.placeholderText)
+            let (content, includesCode) = contentGenerator.generate(page: page, language: language, content: metadata.placeholderText)
             let placeholder = factory.factory.makePlaceholder(title: metadata.placeholderTitle, text: content)
             return (placeholder, includesCode, true)
         }

Sources/Generator/Generators/PageHeadGenerator.swift

@@ -24,7 +24,7 @@ struct PageHeadGenerator {
             let linkPreviewImageName = "thumbnail-link.\(image.lastComponentAfter("."))"
             let sourceImagePath = page.pathRelativeToRootForContainedInputFile(image)
             let destinationImagePath = page.pathRelativeToRootForContainedInputFile(linkPreviewImageName)
-            files.requireImage(
+            files.requireSingleImage(
                 source: sourceImagePath,
                 destination: destinationImagePath,
                 requiredBy: page.path,

Sources/Generator/Generators/SiteGenerator.swift

@@ -26,7 +26,7 @@ struct SiteGenerator {
 
         // Generate sections
         let overviewGenerator = OverviewPageGenerator(factory: template)
-        let pageGenerator = PageGenerator(factory: template)
+        let pageGenerator = PageGenerator(factory: template, siteRoot: site)
         
         var elementsToProcess: [LinkedElement] = [(nil, site, nil)]
         while let (previous, element, next) = elementsToProcess.popLast() {
@@ -51,7 +51,7 @@ struct SiteGenerator {
         element.requiredFiles.forEach(files.require)
         element.externalFiles.forEach(files.exclude)
         element.images.forEach {
-            files.requireImage(
+            files.requireSingleImage(
                 source: $0.sourcePath,
                 destination: $0.destinationPath,
                 requiredBy: element.path,

Sources/Generator/Generators/ThumbnailListGenerator.swift

@@ -14,8 +14,7 @@ struct ThumbnailListGenerator {
     }
 
     private func itemContent(_ item: Element, parent: Element, language: String, style: ThumbnailStyle) -> String {
-        let (thumbnailSourcePath, thumbnailDestPath) = item.thumbnailFilePath(for: language)
-        let relativeImageUrl = parent.relativePathToFileWithPath(thumbnailDestPath)
+
         let metadata = item.localized(for: language)
         var content = [ThumbnailKey : String]()
 
@@ -25,32 +24,26 @@ 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)
+
         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(
+        files.requireMultiVersionImage(
             source: thumbnailSourcePath,
-            destination: thumbnailDestPath,
+            destination: thumbnailDestNoExtension + ".jpg",
             requiredBy: item.path,
             width: style.width,
             desiredHeight: style.height)
 
-        // Create image version for high-resolution screens
-        files.requireImage(
-            source: thumbnailSourcePath,
-            destination: thumbnailDestPath.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/MetadataInfoLogger.swift

@@ -0,0 +1,178 @@
+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(String(format: "Scanning source files: %4d pages found     \r", numberOfMetadataFiles), terminator: "")
+    }
+
+    func printMetadataScanOverview() {
+        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, "invalidProperties")
+        addIfNotZero(unknownProperties, "unknownProperties")
+        addIfNotZero(missingProperties, "missingProperties")
+
+        print(" Number of pages: \(numberOfMetadataFiles)")
+        print("           Notes: " + notes.joined(separator: ", "))
+    }
+
+    func writeResultsToFile(in folder: URL) throws {
+        let url = folder.appendingPathComponent("Metadata issues.txt")
+        var lines: [String] = []
+        if !errors.isEmpty {
+            lines += ["Errors:"] + errors.map { "\($0.source): \($0.message)" }
+        }
+        if !warnings.isEmpty {
+            lines += ["Warnings:"] + warnings.map { "\($0.source): \($0.message)" }
+        }
+        if !unreadableMetadata.isEmpty {
+            lines += ["Unreadable files:"] + unreadableMetadata.map { "\($0.source): \($0.error)" }
+        }
+        if !unusedProperties.isEmpty {
+            lines += ["Unused properties:"] + unusedProperties.map { "\($0.source): \($0.name)" }
+        }
+        if !invalidProperties.isEmpty {
+            lines += ["Invalid properties:"] + invalidProperties.map { "\($0.source): \($0.name) (\($0.reason))" }
+        }
+        if !unknownProperties.isEmpty {
+            lines += ["Unknown properties:"] + unknownProperties.map { "\($0.source): \($0.name)" }
+        }
+        if !missingProperties.isEmpty {
+            lines += ["Missing properties:"] + missingProperties.map { "\($0.source): \($0.name)" }
+        }
+
+        let data = lines.joined(separator: "\n").data(using: .utf8)
+        try data?.createFolderAndWrite(to: url)
+    }
+}

Sources/Generator/Templates/Elements/PageImageTemplate.swift

@@ -4,7 +4,7 @@ struct PageImageTemplate: Template {
 
     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"

Sources/Generator/Templates/Elements/PageLinkTemplate.swift

@@ -5,7 +5,6 @@ struct PageLinkTemplate: Template {
     enum Key: String, CaseIterable {
         case url = "URL"
         case image = "IMAGE"
-        case image2x = "IMAGE_2X"
         case title = "TITLE"
         case path = "PATH"
         case description = "DESCRIPTION"

Sources/Generator/Templates/Elements/ThumbnailTemplate.swift

@@ -8,7 +8,6 @@ protocol ThumbnailTemplate {
 enum ThumbnailKey: String, CaseIterable {
     case url = "URL"
     case image = "IMAGE"
-    case image2x = "IMAGE_2X"
     case title = "TITLE"
     case corner = "CORNER"
 }

Sources/Generator/run.swift

@@ -1,10 +1,8 @@
 import Foundation
 import ArgumentParser
 
-var configuration: Configuration!
 let log = ValidationLog()
 var files: FileSystem!
-var siteRoot: Element!
 
 @main
 struct CHGenerator: ParsableCommand {
@@ -17,17 +15,48 @@ struct CHGenerator: ParsableCommand {
     }
 }
 
-private func generate(configPath: String) throws {
+private func loadSiteData(in folder: URL) throws -> Element? {
+    let log = MetadataInfoLogger(input: folder)
+    print("--- SOURCE FILES -----------------------------------")
+    let root = Element(atRoot: folder, log: log)
+    print("                                                    ")
+    log.printMetadataScanOverview()
+    print("                                                    ")
+    try log.writeResultsToFile(in: files.generatorInfoFolder)
+    return root
+}
+
+private func loadConfiguration(at configPath: String) -> Configuration? {
+    print("--- CONFIGURATION ----------------------------------")
+    print("")
+    print("    Configuration file: \(configPath)")
     let configUrl = URL(fileURLWithPath: configPath)
+    let config: Configuration
+    do {
         let data = try Data(contentsOf: configUrl)
-    configuration = try JSONDecoder().decode(from: data)
+        config = try JSONDecoder().decode(from: data)
+    } catch {
+        print("    Configuration error: \(error)")
+        return nil
+    }
+    config.printOverview()
+    print("                                                    ")
+    return config
+}
+
+private func generate(configPath: String) throws {
+    guard let configuration = loadConfiguration(at: configPath) else {
+        return
+    }
 
     files = .init(
         in: configuration.contentDirectory,
-        to: configuration.outputDirectory)
+        to: configuration.outputDirectory,
+        configuration: configuration)
 
-    siteRoot = Element(atRoot: configuration.contentDirectory)
-    guard siteRoot != nil else {
+
+    // 2. Scan site elements
+    guard let siteRoot = try loadSiteData(in: configuration.contentDirectory) else {
         return
     }
     let siteGenerator = try SiteGenerator()

install.sh

@@ -11,3 +11,6 @@ npm install uglify-js -g
 # Install the clean-css minifier
 # 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