first commit

lib/services/storage_service.dart

@@ -0,0 +1,128 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+import 'package:path_provider/path_provider.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import '../models/fuel_entry.dart';
+import '../models/vehicle.dart';
+
+/// Owns the on-disk layout for the app: a `data.json` file holding vehicles
+/// and fuel entries, plus a `receipts/` subfolder holding receipt photos.
+/// The parent directory containing both is user-configurable (see
+/// [setSaveDirectory]) and persisted across launches via SharedPreferences.
+class StorageService {
+  static const _prefsKey = 'save_directory_path';
+  static const _dataFileName = 'fuel_tax_data.json';
+  static const _receiptsFolderName = 'receipts';
+
+  late Directory _saveDirectory;
+
+  Directory get saveDirectory => _saveDirectory;
+
+  Directory get receiptsDirectory =>
+      Directory(p.join(_saveDirectory.path, _receiptsFolderName));
+
+  File get _dataFile => File(p.join(_saveDirectory.path, _dataFileName));
+
+  /// Must be called once before any other method. Loads the previously
+  /// chosen save directory, falling back to the app's own documents
+  /// directory the first time the app runs.
+  Future<void> init() async {
+    final prefs = await SharedPreferences.getInstance();
+    final storedPath = prefs.getString(_prefsKey);
+
+    if (storedPath != null && await Directory(storedPath).exists()) {
+      _saveDirectory = Directory(storedPath);
+    } else {
+      final docsDir = await getApplicationDocumentsDirectory();
+      _saveDirectory = Directory(p.join(docsDir.path, 'FuelTaxTracker'));
+    }
+
+    await _saveDirectory.create(recursive: true);
+    await receiptsDirectory.create(recursive: true);
+  }
+
+  Future<({List<Vehicle> vehicles, List<FuelEntry> entries})> loadData() async {
+    if (!await _dataFile.exists()) {
+      return (vehicles: <Vehicle>[], entries: <FuelEntry>[]);
+    }
+
+    final raw = await _dataFile.readAsString();
+    if (raw.trim().isEmpty) {
+      return (vehicles: <Vehicle>[], entries: <FuelEntry>[]);
+    }
+
+    final json = jsonDecode(raw) as Map<String, dynamic>;
+    final vehicles = (json['vehicles'] as List<dynamic>? ?? [])
+        .map((v) => Vehicle.fromJson(v as Map<String, dynamic>))
+        .toList();
+    final entries = (json['fuelEntries'] as List<dynamic>? ?? [])
+        .map((e) => FuelEntry.fromJson(e as Map<String, dynamic>))
+        .toList();
+
+    return (vehicles: vehicles, entries: entries);
+  }
+
+  Future<void> saveData({
+    required List<Vehicle> vehicles,
+    required List<FuelEntry> entries,
+  }) async {
+    final json = {
+      'vehicles': vehicles.map((v) => v.toJson()).toList(),
+      'fuelEntries': entries.map((e) => e.toJson()).toList(),
+    };
+    await _dataFile.writeAsString(const JsonEncoder.withIndent('  ').convert(json));
+  }
+
+  /// Copies a captured receipt image into the receipts folder and returns
+  /// the path it was stored at.
+  Future<String> storeReceiptImage(File sourceImage, String fuelEntryId) async {
+    final ext = p.extension(sourceImage.path);
+    final destPath = p.join(receiptsDirectory.path, '$fuelEntryId$ext');
+    final copied = await sourceImage.copy(destPath);
+    return copied.path;
+  }
+
+  Future<void> deleteReceiptImage(String? path) async {
+    if (path == null) return;
+    final file = File(path);
+    if (await file.exists()) {
+      await file.delete();
+    }
+  }
+
+  /// Changes where the data file and receipt images live, moving any
+  /// existing data/images from the old location into the new one.
+  Future<void> setSaveDirectory(String newPath) async {
+    final newDir = Directory(newPath);
+    await newDir.create(recursive: true);
+    final newReceiptsDir = Directory(p.join(newPath, _receiptsFolderName));
+    await newReceiptsDir.create(recursive: true);
+
+    final oldDataFile = _dataFile;
+    final oldReceiptsDir = receiptsDirectory;
+
+    if (await oldDataFile.exists() &&
+        p.equals(oldDataFile.path, p.join(newPath, _dataFileName)) == false) {
+      await oldDataFile.copy(p.join(newPath, _dataFileName));
+    }
+
+    if (await oldReceiptsDir.exists()) {
+      await for (final entity in oldReceiptsDir.list()) {
+        if (entity is File) {
+          final destPath = p.join(newReceiptsDir.path, p.basename(entity.path));
+          if (!p.equals(entity.path, destPath)) {
+            await entity.copy(destPath);
+          }
+        }
+      }
+    }
+
+    _saveDirectory = newDir;
+
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setString(_prefsKey, newPath);
+  }
+}