Fix Autosave "changed by another application " Spam (#2072)

### Description

Fixes an issue where a file save would not correctly update the `CodeFileDocument`'s metadata when saving. This caused scheduled autosave operations to fail with a false positive 'changed by another application' error.

To fix, I'm allowing `NSDocument` to handle the actual file system operation, rather than writing the data like we were before. I've kept the extra logic in the overridden `save` method to fix broken directories. There's no good reason to move the file saving operation out of `NSDocument`, since that subclass likely handles it better than we do with an atomic data write.

I've also moved autosave scheduling out of UI and into the document class.

### Related Issues

* closes #2033

### Checklist

- [x] I read and understood the [contributing guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md) as well as the [code of conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots

N/A

Author: thecoolwinter

CodeEdit/Features/Documents/CodeFileDocument/CodeFileDocument.swift

@@ -94,6 +94,11 @@ final class CodeFileDocument: NSDocument, ObservableObject {
         isDocumentEditedSubject.eraseToAnyPublisher()
     }
 
+    /// A lock that ensures autosave scheduling happens correctly.
+    private var autosaveTimerLock: NSLock = NSLock()
+    /// Timer used to schedule autosave intervals.
+    private var autosaveTimer: Timer?
+
     // MARK: - NSDocument
 
     override static var autosavesInPlace: Bool {
@@ -130,6 +135,8 @@ final class CodeFileDocument: NSDocument, ObservableObject {
         }
     }
 
+    // MARK: - Data
+
     override func data(ofType _: String) throws -> Data {
         guard let sourceEncoding, let data = (content?.string as NSString?)?.data(using: sourceEncoding.nsValue) else {
             Self.logger.error("Failed to encode contents to \(self.sourceEncoding.debugDescription)")
@@ -138,6 +145,8 @@ final class CodeFileDocument: NSDocument, ObservableObject {
         return data
     }
 
+    // MARK: - Read
+
     /// This function is used for decoding files.
     /// It should not throw error as unsupported files can still be opened by QLPreviewView.
     override func read(from data: Data, ofType _: String) throws {
@@ -161,6 +170,8 @@ final class CodeFileDocument: NSDocument, ObservableObject {
         NotificationCenter.default.post(name: Self.didOpenNotification, object: self)
     }
 
+    // MARK: - Autosave
+
     /// Triggered when change occurred
     override func updateChangeCount(_ change: NSDocument.ChangeType) {
         super.updateChangeCount(change)
@@ -183,6 +194,31 @@ final class CodeFileDocument: NSDocument, ObservableObject {
         self.isDocumentEditedSubject.send(self.isDocumentEdited)
     }
 
+    /// If ``hasUnautosavedChanges`` is `true` and an autosave has not already been scheduled, schedules a new autosave.
+    /// If ``hasUnautosavedChanges`` is `false`, cancels any scheduled timers and returns.
+    ///
+    /// All operations are done with the ``autosaveTimerLock`` acquired (including the scheduled autosave) to ensure
+    /// correct timing when scheduling or cancelling timers.
+    override func scheduleAutosaving() {
+        autosaveTimerLock.withLock {
+            if self.hasUnautosavedChanges {
+                guard autosaveTimer == nil else { return }
+                autosaveTimer = Timer.scheduledTimer(withTimeInterval: 2.0, repeats: false) { [weak self] timer in
+                    self?.autosaveTimerLock.withLock {
+                        guard timer.isValid else { return }
+                        self?.autosaveTimer = nil
+                        self?.autosave(withDelegate: nil, didAutosave: nil, contextInfo: nil)
+                    }
+                }
+            } else {
+                autosaveTimer?.invalidate()
+                autosaveTimer = nil
+            }
+        }
+    }
+
+    // MARK: - Close
+
     override func close() {
         super.close()
         NotificationCenter.default.post(name: Self.didCloseNotification, object: fileURL)
@@ -199,7 +235,7 @@ final class CodeFileDocument: NSDocument, ObservableObject {
             let directory = fileURL.deletingLastPathComponent()
             try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true, attributes: nil)
 
-            try data(ofType: fileType ?? "").write(to: fileURL, options: .atomic)
+            super.save(sender)
         } catch {
             presentError(error)
         }

CodeEdit/Features/Editor/Views/CodeFileView.swift

@@ -91,20 +91,6 @@ struct CodeFileView: View {
             }
             .store(in: &cancellables)
 
-        codeFile
-            .contentCoordinator
-            .textUpdatePublisher
-            .debounce(for: 1.0, scheduler: DispatchQueue.main)
-            .sink { _ in
-                // updateChangeCount is automatically managed by autosave(), so no manual call is necessary
-                codeFile.autosave(withImplicitCancellability: false) { error in
-                    if let error {
-                        CodeFileDocument.logger.error("Failed to autosave document, error: \(error)")
-                    }
-                }
-            }
-            .store(in: &cancellables)
-
         codeFile.undoManager = self.undoManager.manager
     }