Improve asset handling

CHDataManagement/Model/Content+Generation.swift

@@ -1,5 +1,54 @@
+import Foundation
+
 extension Content {
 
+    func generatePage(_ page: Page) -> Bool {
+        guard startGenerating() else { return false }
+        defer { endGenerating() }
+
+        for language in ContentLanguage.allCases {
+            guard generateInternal(page, in: language) else {
+                return false
+            }
+        }
+        return true
+    }
+
+    func generatePage(_ page: Page, in language: ContentLanguage) -> Bool {
+        guard startGenerating() else { return false }
+        defer { endGenerating() }
+        return generateInternal(page, in: language)
+    }
+
+    private func startGenerating() -> Bool {
+        guard !isGeneratingWebsite else {
+            return false
+        }
+        // TODO: Fix bug where multiple generating operations can be started
+        // due to dispatch of locking property on main queue
+        DispatchQueue.main.async {
+            self.isGeneratingWebsite = true
+        }
+        return true
+    }
+
+    private func endGenerating() {
+        DispatchQueue.main.async {
+            self.isGeneratingWebsite = false
+        }
+    }
+
+    private func generateInternal(_ page: Page, in language: ContentLanguage) -> Bool {
+        let generator = LocalizedWebsiteGenerator(
+            content: self,
+            language: language)
+        if !generator.generate(page: page) {
+            print("Generation failed")
+            return false
+        }
+        return true
+    }
+
     private func makeCleanAbsolutePath(_ path: String) -> String {
         ("/" + path).replacingOccurrences(of: "//", with: "/")
     }
@@ -36,10 +85,20 @@ extension Content {
         tags.first { $0.id == tagId }
     }
 
+    // MARK: Generation input
+
     func navigationBar(in language: ContentLanguage) -> [NavigationBar.Link] {
         settings.navigationItems.map {
             .init(text: $0.title(in: language),
                   url: $0.absoluteUrl(in: language))
         }
     }
+
+    var defaultPageHeaders: Set<HeaderElement> {
+        var result: Set<HeaderElement> = [.charset, .viewport]
+        if let defaultCss = settings.posts.defaultCssFile {
+            result.insert(.css(file: defaultCss, order: HeaderElement.defaultCssFileOrder))
+        }
+        return result
+    }
 }