Check for unused files in output folder

CHDataManagement/Generator/ImageVersion.swift

@@ -47,7 +47,9 @@ struct ImageVersion {
     }
 
     func wasNowGenerated() {
-        image.generatedImageVersions.insert(versionId)
+        DispatchQueue.main.async {
+            image.generatedImageVersions.insert(versionId)
+        }
     }
 }
 

CHDataManagement/Generator/Page Generators/PageGenerator.swift

@@ -1,3 +1,5 @@
+import Foundation
+
 final class PageGenerator {
 
     private let content: Content
@@ -50,7 +52,8 @@ final class PageGenerator {
                   url: tag.absoluteUrl(in: language))
         }
 
-        let headers = makeHeaders(requiredItems: results.requiredHeaders, results: results)
+        let requiredHeaders = DispatchQueue.main.sync { results.requiredHeaders }
+        let headers = makeHeaders(requiredItems: requiredHeaders, results: results)
         results.require(files: headers.compactMap { $0.requiredFile })
 
         let iconUrl = content.settings.navigation.localized(in: language).rootUrl
@@ -60,6 +63,7 @@ final class PageGenerator {
             url: languageUrl)
 
         let imageUrl = localized.linkPreview.image?.linkPreviewImage(results: results)
+        let icons = DispatchQueue.main.sync { results.requiredIcons }
 
         let pageHeader = PageHeader(
             language: language,
@@ -71,11 +75,13 @@ final class PageGenerator {
             languageButton: languageButton,
             links: content.navigationBar(in: language),
             headers: headers,
-            icons: results.requiredIcons)
+            icons: icons)
+
+        let footers = DispatchQueue.main.sync { results.requiredFooters }
 
         let fullPage = GenericPage(
             header: pageHeader,
-            additionalFooter: results.requiredFooters.sorted().joined()) { content in
+            additionalFooter: footers.sorted().joined()) { content in
                 content += "<article>"
                 if !localized.hideTitle {
                     if !page.hideDate {

CHDataManagement/Generator/Results/GenerationResults.swift

@@ -46,6 +46,12 @@ final class GenerationResults: ObservableObject {
     @Published
     var emptyPages: Set<LocalizedPageId> = []
 
+    @Published
+    var outputFiles: Set<String> = []
+
+    @Published
+    var unusedFilesInOutput: Set<String> = []
+
     /**
      The url redirects to install to prevent broken links.
 
@@ -114,6 +120,8 @@ final class GenerationResults: ObservableObject {
             self.unsavedOutputFiles = []
             self.emptyPages = []
             self.redirects = [:]
+            self.outputFiles = []
+            self.unusedFilesInOutput = []
         }
         for result in cache.values {
             result.reset()
@@ -229,6 +237,15 @@ final class GenerationResults: ObservableObject {
     func redirect(from originalUrl: String, to newUrl: String) {
         update { self.redirects[originalUrl] = newUrl }
     }
+
+    func created(outputFile: String) {
+        update { self.outputFiles.insert(outputFile.withLeadingSlashRemoved) }
+    }
+
+    func determineFiles(unusedIn existingFiles: Set<String>) {
+        let unused = existingFiles.subtracting(outputFiles)
+        update { self.unusedFilesInOutput = unused }
+    }
 }
 
 private extension Dictionary where Value == Set<LocalizedItemId> {