Determine required files from custom HTML

CHDataManagement/Generator/Results/GenerationResults.swift

@@ -49,12 +49,17 @@ final class GenerationResults: ObservableObject {
     @Published
     var emptyPages: Set<LocalizedPageId> = []
 
+    /// The paths to the files in the output folder, without leading slashes
     @Published
     var outputFiles: Set<String> = []
 
     @Published
     var unusedFilesInOutput: Set<String> = []
 
+    /// The paths to files required to be in the output folder, without leading slashes
+    @Published
+    var requiredOutputFiles: Set<String> = []
+
     /**
      The url redirects to install to prevent broken links.
 
@@ -126,6 +131,7 @@ final class GenerationResults: ObservableObject {
             self.redirects = [:]
             self.outputFiles = []
             self.unusedFilesInOutput = []
+            self.requiredOutputFiles = []
         }
         for result in cache.values {
             result.reset()
@@ -257,10 +263,26 @@ final class GenerationResults: ObservableObject {
     }
 
     func determineFiles(unusedIn existingFiles: Set<String>) {
-        let unused = existingFiles.subtracting(outputFiles)
+        // All paths with leading without leading slashes
+        let unused = existingFiles.subtracting(outputFiles).subtracting(requiredOutputFiles)
         update { self.unusedFilesInOutput = unused }
     }
 
+    func determineMissingRequiredFiles(existingFiles: Set<String>) {
+        // All paths with leading without leading slashes
+
+        // Check the files required in the output against the existing files,
+        // and flag missing ones
+        let externalFilePaths = self.externalFiles.map { $0.absoluteUrl.withLeadingSlashRemoved }
+        let fullFiles = existingFiles.union(externalFilePaths)
+        let missing = requiredOutputFiles.filter { path in
+            !fullFiles.contains(path) &&
+            !fullFiles.contains(path + ".html") &&
+            !fullFiles.contains(path + "/1.html")
+        }
+        update { self.requiredOutputFiles = missing }
+    }
+
     func sources(forMissingPage page: String) -> [(page: LocalizedItemId, source: String)] {
         var all = [(page: LocalizedItemId, source: String)]()
         for (id, results) in cache {
@@ -272,6 +294,10 @@ final class GenerationResults: ObservableObject {
         }
         return all
     }
+
+    func requiredOutputFile(_ path: String) {
+        update { self.requiredOutputFiles.insert(path) }
+    }
 }
 
 private extension Dictionary where Value == Set<LocalizedItemId> {