import file code

lib/api/apis/backup_api.dart

@@ -1,31 +1,70 @@
 import 'dart:convert';
 // ignore: avoid_web_libraries_in_flutter
-import 'dart:html' as html;
-
+import 'dart:html';
 
 import 'package:flutter/services.dart';
+import 'package:logger/logger.dart';
 import 'package:wealth_wave/api/db/app_database.dart';
 
 class BackupApi {
   final AppDatabase _db;
 
   BackupApi({final AppDatabase? db}) : _db = db ?? AppDatabase.instance;
 
+  Future<void> importDatabase() async {
+    final file = await _pickFile();
+    if (file == null) {
+      return Future.error('No file selected');
+    }
+
+    final json = await _readJsonFromFile(file);
+
+    if (json == null) {
+      return Future.error('Not a json file');
+    }
+
+    await _db.loadBackup(json);
+  }
+
   Future<void> exportDatabase() async {
     final result = await _db.getBackup();
 
     final jsonString = json.encode(result);
 
-    final blob = html.Blob([Uint8List.fromList(utf8.encode(jsonString))]);
+    final blob = Blob([Uint8List.fromList(utf8.encode(jsonString))]);
 
-    final anchor = html.AnchorElement(href: html.Url.createObjectUrlFromBlob(blob))
+    final anchor = AnchorElement(href: Url.createObjectUrlFromBlob(blob))
       ..target = 'blank'
       ..download = 'wealth_app_data.json';
 
     // Trigger a click event to prompt the user to download the file
-    html.document.body?.append(anchor);
+    document.body?.append(anchor);
     anchor.click();
     // Clean up
-    html.Url.revokeObjectUrl(anchor.href!);
+    Url.revokeObjectUrl(anchor.href!);
+  }
+
+  Future<File?> _pickFile() async {
+    final input = FileUploadInputElement()..accept = 'application/json';
+    input.click();
+
+    await input.onChange.first;
+    return input.files?.isNotEmpty == true ? input.files![0] : null;
+  }
+
+  Future<Map<String, List<Map<String, dynamic>>>?> _readJsonFromFile(
+      File file) async {
+    try {
+      final reader = FileReader();
+      reader.readAsText(file);
+
+      await reader.onLoad.first;
+
+      final jsonString = reader.result as String;
+      return json.decode(jsonString) as Map<String, List<Map<String, dynamic>>>;
+    } catch (e) {
+      Logger().e(e.toString());
+      return null;
+    }
   }
 }

lib/api/db/app_database.dart

@@ -169,6 +169,28 @@ class AppDatabase extends _$AppDatabase {
       'goal_investment_table': goalInvestmentBackup,
     };
   }
+
+  Future<void> loadBackup(
+      Map<String, List<Map<String, dynamic>>> backup) async {
+    await transaction(() async {
+      for (var entry in backup.entries) {
+        var tableName = entry.key;
+        var tableDatas = entry.value;
+
+        for (var tableData in tableDatas) {
+          var columns = tableData.keys.join(', ');
+          var values = tableData.keys.map((key) => '?').join(', ');
+
+          await customInsert(
+            'INSERT INTO $tableName ($columns) VALUES ($values)',
+            variables: tableData.values
+                .map((value) => Variable.withString('$value'))
+                .toList(),
+          );
+        }
+      }
+    });
+  }
 }
 
 DatabaseConnection connectOnWeb() {

lib/presentation/main_presenter.dart

@@ -0,0 +1,28 @@
+import 'package:wealth_wave/api/apis/backup_api.dart';
+import 'package:wealth_wave/core/presenter.dart';
+import 'package:wealth_wave/core/single_event.dart';
+
+class MainPresenter extends Presenter<MainViewState> {
+  final BackupApi _backupApi;
+
+  MainPresenter({final BackupApi? backupApi})
+      : _backupApi = backupApi ?? BackupApi(),
+        super(MainViewState());
+
+  void performImportFile() {
+    _backupApi.importDatabase().then((value) => updateViewState((viewState) {
+          viewState.onImportCompleted = SingleEvent(null);
+        }));
+  }
+
+  void performBackup() {
+    _backupApi.exportDatabase().then((value) => updateViewState((viewState) {
+          viewState.onBackupCompleted = SingleEvent(null);
+        }));
+  }
+}
+
+class MainViewState {
+  SingleEvent<void>? onBackupCompleted;
+  SingleEvent<void>? onImportCompleted;
+}

lib/ui/pages/main_page.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
-import 'package:wealth_wave/api/apis/backup_api.dart';
+import 'package:wealth_wave/core/page_state.dart';
+import 'package:wealth_wave/presentation/main_presenter.dart';
 import 'package:wealth_wave/ui/pages/baskets_page.dart';
 import 'package:wealth_wave/ui/pages/goals_page.dart';
 import 'package:wealth_wave/ui/pages/investments_page.dart';
@@ -13,12 +14,12 @@ class MainPage extends StatefulWidget {
   State<MainPage> createState() => _MainPageState();
 }
 
-class _MainPageState extends State<MainPage> {
+class _MainPageState extends PageState<MainViewState, MainPage, MainPresenter> {
   var _selectedIndex = 0;
   var _isExtended = true;
 
   @override
-  Widget build(BuildContext context) {
+  Widget buildWidget(BuildContext context, MainViewState snapshot) {
     return Scaffold(
         appBar: AppBar(
           backgroundColor: Theme.of(context).colorScheme.inversePrimary,
@@ -27,8 +28,10 @@ class _MainPageState extends State<MainPage> {
             PopupMenuButton<int>(
               onSelected: (value) {
                 if (value == 1) {
-                  BackupApi().exportDatabase();
-                } else if (value == 2) {}
+                  presenter.performBackup();
+                } else if (value == 2) {
+                  presenter.performImportFile();
+                }
               },
               itemBuilder: (context) => [
                 const PopupMenuItem(
@@ -91,6 +94,11 @@ class _MainPageState extends State<MainPage> {
           ),
         ));
   }
+
+  @override
+  MainPresenter initializePresenter() {
+    return MainPresenter();
+  }
 }
 
 class SideNav extends StatelessWidget {