Can save the list of expenses

moneymgr_mobile/lib/services/storage/expenses.dart

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+import 'dart:convert';
+import 'dart:io';
+import 'dart:math';
+
+import 'package:freezed_annotation/freezed_annotation.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:path/path.dart' as p;
+import 'package:path_provider/path_provider.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+part 'expenses.freezed.dart';
+part 'expenses.g.dart';
+
+typedef ExpensesList = List<Expense>;
+
+@freezed
+abstract class Expense with _$Expense {
+  const Expense._();
+
+  const factory Expense({
+    /// Internal id used to identify the expense
+    required int id,
+
+    /// Label of the expense
+    required String? label,
+
+    /// The cost shall always be a positive value
+    required double cost,
+
+    /// Time associated with the expense
+    required int time,
+
+    /// Associated file mime type
+    required String mimeType,
+  }) = _Expense;
+
+  factory Expense.fromJson(Map<String, dynamic> json) =>
+      _$ExpenseFromJson(json);
+
+  /// Get associated expense file name
+  String get localFileName {
+    if (mimeType == "application/pdf") return "$id.pdf";
+    if (mimeType == "image/jpeg") return "$id.jpeg";
+    if (mimeType == "image/png") return "$id.png";
+    return id.toString();
+  }
+}
+
+@riverpod
+Future<ExpensesManager> expenses(Ref ref) async => ExpensesManager.instance();
+
+class ExpensesManager {
+  final String storagePath;
+
+  ExpensesManager._({required this.storagePath});
+
+  /// Get an instance of this manager
+  static Future<ExpensesManager> instance() async {
+    final appDir = await getApplicationDocumentsDirectory();
+    final subDir = p.join(appDir.absolute.path, "expenses");
+    final result = await Directory(subDir).create(recursive: true);
+
+    return ExpensesManager._(storagePath: result.absolute.path);
+  }
+
+  /// Get expenses list file path
+  File get expenseFile => File(p.join(storagePath, "list.json"));
+
+  /// Get the files storage path
+  Directory get filesStoragePath => Directory(p.join(storagePath, "exp_files"));
+
+  /// Get the current list of expenses
+  Future<ExpensesList> getList() async {
+    final jsonDec = jsonDecode(await expenseFile.readAsString());
+    return List<Expense>.from(jsonDec.map((m) => Expense.fromJson(m)));
+  }
+
+  /// Save the list of expenses
+  Future<void> saveList(ExpensesList list) async {
+    final jsonDoc = jsonEncode(list.map((t) => t.toJson()));
+    await expenseFile.writeAsString(jsonDoc);
+  }
+
+  /// Add a new expense to the list
+  Future<void> add({
+    required String? label,
+    required double cost,
+    required int time,
+    required List<int> fileContent,
+    required String fileMimeType,
+  }) async {
+    final list = await getList();
+
+    final exp = Expense(
+      id: (list.lastOrNull?.id ?? 0) + Random().nextInt(1000),
+      label: label,
+      cost: cost,
+      time: time,
+      mimeType: fileMimeType,
+    );
+
+    // Create files storage directory if required
+    if (!await filesStoragePath.exists()) {
+      await filesStoragePath.create(recursive: true);
+    }
+
+    // Save associated file
+    final file = File(
+      p.join(filesStoragePath.absolute.path, exp.localFileName),
+    );
+    await file.writeAsBytes(fileContent);
+
+    // Save the list of expenses
+    list.add(exp);
+    await saveList(list);
+  }
+}