Save automatically, improve mocks

CHDataManagement/Model/Content+Save.swift

@@ -2,7 +2,47 @@ import Foundation
 
 extension Content {
 
-    func saveToDisk() -> Bool {
+    func needsSave() {
+        setModificationTimestamp()
+
+        if saveState == .isSaved {
+            update(saveState: saveState)
+        }
+        // Wait a few seconds for a save, to allow additional changes
+        // Reduces the number of saves
+        DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(5)) {
+            self.saveIfNeeded()
+        }
+    }
+
+    func saveIfNeeded() {
+        guard saveState != .isSaved else {
+            return
+        }
+        if Date.now.timeIntervalSince(lastModification) < 5 {
+            // Additional modification made
+            // Wait for next scheduled invocation of saveIfNeeded()
+            // if the overall unsaved time is not too long
+            if Date.now.timeIntervalSince(lastSave) < 30 {
+                //print("Waiting while modifying")
+                return
+            }
+            print("Saving after 30 seconds of modifications")
+        }
+        saveUnconditionally()
+    }
+
+    func saveUnconditionally() {
+        guard saveToDisk() else {
+            update(saveState: .failedToSave)
+            // TODO: Try to save again
+            return
+        }
+        update(saveState: .isSaved)
+        setLastSaveTimestamp()
+    }
+
+    private func saveToDisk() -> Bool {
         guard didLoadContent else { return false }
         guard storage.contentScope != nil else {
             print("Storage not initialized, not saving content")
@@ -10,12 +50,28 @@ extension Content {
         }
 
         var failedSaves = 0
-        failedSaves += pages.count { !storage.save(pageMetadata: $0.data, for: $0.id) }
-        failedSaves += posts.count { !storage.save(post: $0.data, for: $0.id) }
-        failedSaves += tags.count { !storage.save(tagMetadata: $0.data, for: $0.id) }
-        failedSaves.increment(!storage.save(settings: settings.data(tagOverview: tagOverview)))
-        failedSaves += files.count { !storage.save(fileInfo: $0.data, for: $0.id) }
+        var saves = 0
+        let pageSaves = saveChanged(pages)
+        failedSaves += pageSaves.unsaved
+        saves += pageSaves.saved
 
+        let postSaves = saveChanged(posts)
+        failedSaves += postSaves.unsaved
+        saves += postSaves.saved
+
+        let tagSaves = saveChanged(tags)
+        failedSaves += tagSaves.unsaved
+        saves += tagSaves.saved
+
+        failedSaves.increment(!storage.save(settings: settings.data(tagOverview: tagOverview)))
+
+        let fileSaves = saveChanged(files)
+        failedSaves += fileSaves.unsaved
+        saves += fileSaves.saved
+
+        if saves > 0 {
+            print("Saved \(saves) changed items")
+        }
         if failedSaves > 0 {
             print("Save partially failed with \(failedSaves) errors")
             return false
@@ -39,4 +95,22 @@ extension Content {
         }
         return success
     }
+
+    private func saveChanged<S>(_ items: S) -> (saved: Int, unsaved: Int, unchanged: Int) where S: Sequence, S.Element: StorageItem {
+        var failed = 0
+        var saved = 0
+        var unchanged = 0
+        for item in items {
+            guard let wasSaved = item.saveIfNeeded() else {
+                unchanged += 1
+                continue
+            }
+            if wasSaved {
+                saved += 1
+            } else {
+                failed += 1
+            }
+        }
+        return (saved, failed, unchanged)
+    }
 }