Generate list of redirects

CHDataManagement/Generator/Results/GenerationResults.swift

@@ -46,6 +46,15 @@ final class GenerationResults: ObservableObject {
     @Published
     var emptyPages: Set<LocalizedPageId> = []
 
+    /**
+     The url redirects to install to prevent broken links.
+
+     The key is the original url, and the value the new url of the content, relative to the output folder.
+     The dictionary is used to create a map of redirects for Nginx.
+     */
+    @Published
+    var redirects: [String : String] = [:]
+
     /// The cache of previously used GenerationResults
     private var cache: [ItemId : PageGenerationResults] = [:]
 
@@ -114,6 +123,8 @@ final class GenerationResults: ObservableObject {
         update { self.warnings = warnings }
         let unsavedOutputFiles = cache.values.map { $0.unsavedOutputFiles.keys }.union()
         update { self.unsavedOutputFiles = unsavedOutputFiles }
+        let redirects = cache.values.compactMap { $0.redirect }.reduce(into: [:]) { $0[$1.originalUrl] = $1.newUrl }
+        update { self.redirects = redirects }
     }
 
     private func update(_ operation: @escaping () -> Void) {
@@ -185,7 +196,11 @@ final class GenerationResults: ObservableObject {
     }
 
     func empty(_ page: LocalizedPageId) {
-        update {self.emptyPages.insert(page) }
+        update { self.emptyPages.insert(page) }
+    }
+
+    func redirect(from originalUrl: String, to newUrl: String) {
+        update { self.redirects[originalUrl] = newUrl }
     }
 }
 

CHDataManagement/Generator/Results/PageGenerationResults.swift

@@ -77,6 +77,8 @@ final class PageGenerationResults: ObservableObject {
 
     private(set) var pageIsEmpty: Bool
 
+    private(set) var redirect: (originalUrl: String, newUrl: String)?
+
     init(itemId: ItemId, delegate: GenerationResults) {
         self.itemId = itemId
         self.delegate = delegate
@@ -100,6 +102,7 @@ final class PageGenerationResults: ObservableObject {
         warnings = []
         unsavedOutputFiles = [:]
         pageIsEmpty = false
+        redirect = nil
     }
 
     func reset() {
@@ -123,6 +126,7 @@ final class PageGenerationResults: ObservableObject {
         warnings = []
         unsavedOutputFiles = [:]
         pageIsEmpty = false
+        redirect = nil
     }
 
     // MARK: Adding entries
@@ -251,5 +255,10 @@ final class PageGenerationResults: ObservableObject {
         pageIsEmpty = true
         delegate.empty(.init(language: itemId.language, pageId: page.id))
     }
+
+    func redirect(from originalUrl: String, to newUrl: String) {
+        redirect = (originalUrl, newUrl)
+        delegate.redirect(from: originalUrl, to: newUrl)
+    }
 }
 

CHDataManagement/Model/Content+Generation.swift

@@ -13,6 +13,7 @@ extension Content {
             self.generateRequiredImages()
             self.results.recalculate()
             self.generateListOfExternalFiles()
+            self.generateListOfUrlMappings()
             self.status("Generation completed")
         }
     }
@@ -240,6 +241,10 @@ extension Content {
                 tag: tag)
             let generator = PostListPageGenerator(source: source)
             generator.createPages(for: posts)
+
+            if let originalUrl = tag.localized(in: language).originalUrl {
+                results.redirect(from: originalUrl, to: tag.absoluteUrl(in: language))
+            }
         }
     }
 
@@ -274,11 +279,16 @@ extension Content {
             return
         }
 
-        let path = page.absoluteUrl(in: language) + ".html"
-        guard storage.write(content, to: path) else {
+        let pageUrl = page.absoluteUrl(in: language)
+        let filePath = pageUrl + ".html"
+        guard storage.write(content, to: filePath) else {
             print("Failed to save page \(page.id)")
             return
         }
+
+        if let originalUrl = page.localized(in: language).originalUrl {
+            results.redirect(from: originalUrl, to: pageUrl)
+        }
     }
 
     // MARK: Additional infos
@@ -303,4 +313,27 @@ extension Content {
 
         storage.write(content, to: externalFileListName)
     }
+
+    private var redirectsListFileName: String { "redirects.txt" }
+
+    private func generateListOfUrlMappings() {
+        let redirects = results.redirects.map { "\($0.key) \($0.value);" }
+        guard !redirects.isEmpty else {
+            if storage.hasFileInOutputFolder(redirectsListFileName) {
+                storage.deleteInOutputFolder(redirectsListFileName)
+            }
+            return
+        }
+
+        let list = redirects.sorted().joined(separator: "\n    ")
+
+        let content =
+            """
+            map $request_uri $redirect_uri {
+                \(list)
+            }
+            """
+
+        storage.write(content, to: redirectsListFileName)
+    }
 }