feat: persist timetable and validate confirmed imports

2026-10-12 23:18:51 +08:00
parent ae8e347e49
commit 808af007a2
13 changed files with 852 additions and 0 deletions
@@ -0,0 +1,49 @@
+import 'dart:io';
+import 'dart:convert';
+
+import 'snapshot_store.dart';
+import '../domain/app_snapshot.dart';
+
+class FileSnapshotStore extends SnapshotStore {
+  FileSnapshotStore(this.directory);
+  final Directory directory;
+  File get _file => File('${directory.path}/hepan_snapshot.json');
+  File get _backup => File('${directory.path}/hepan_snapshot.bak');
+  Future<AppSnapshot> _read(File file) async {
+    final value = jsonDecode(await file.readAsString());
+    if (value is! Map<String, dynamic>) throw const FormatException('保存文件损坏');
+    return AppSnapshot.fromJson(value);
+  }
+
+  @override
+  Future<AppSnapshot?> load() async =>
+      await _file.exists() ? await _read(_file) : null;
+  @override
+  Future<void> save(AppSnapshot snapshot) async {
+    await directory.create(recursive: true);
+    final text = jsonEncode(snapshot.toJson());
+    // Validate before touching the last successfully saved version.
+    AppSnapshot.fromJson(jsonDecode(text) as Map<String, dynamic>);
+    if (await _file.exists()) {
+      try {
+        await _read(_file);
+        await _file.copy(_backup.path);
+      } on FormatException {
+        /* Keep an existing valid backup. */
+      }
+    }
+    final temporary = File('${_file.path}.tmp');
+    await temporary.writeAsString(text, flush: true);
+    await temporary.rename(_file.path);
+  }
+
+  @override
+  Future<AppSnapshot> restoreBackup() async {
+    if (!await _backup.exists()) throw StateError('没有可恢复的备份');
+    final previous = await _read(_backup);
+    final temporary = File('${_file.path}.tmp');
+    await temporary.writeAsString(jsonEncode(previous.toJson()), flush: true);
+    await temporary.rename(_file.path);
+    return previous;
+  }
+}