Backup.

lib/view_model/backup_view_model.dart

@@ -0,0 +1,68 @@
+import 'package:cake_wallet/core/backup.dart';
+import 'package:cake_wallet/core/execution_state.dart';
+import 'package:cake_wallet/entities/secret_store_key.dart';
+import 'package:cake_wallet/store/secret_store.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+import 'package:mobx/mobx.dart';
+
+part 'backup_view_model.g.dart';
+
+class BackupExportFile {
+  BackupExportFile(this.content, {@required this.name});
+
+  final String name;
+  final List<int> content;
+}
+
+class BackupViewModel = BackupViewModelBase with _$BackupViewModel;
+
+abstract class BackupViewModelBase with Store {
+  BackupViewModelBase(this.secureStorage, this.secretStore, this.backupService)
+      : isBackupPasswordVisible = false {
+    state = InitialExecutionState();
+    final key = generateStoreKeyFor(key: SecretStoreKey.backupPassword);
+    secretStore.values.observe((change) {
+      if (change.key == key) {
+        backupPassword = secretStore.read(key);
+      }
+    }, fireImmediately: true);
+  }
+
+  final FlutterSecureStorage secureStorage;
+  final SecretStore secretStore;
+  final BackupService backupService;
+
+  @observable
+  ExecutionState state;
+
+  @observable
+  bool isBackupPasswordVisible;
+
+  @observable
+  String backupPassword;
+
+  @action
+  Future<void> init() async {
+    final key = generateStoreKeyFor(key: SecretStoreKey.backupPassword);
+    backupPassword = await secureStorage.read(key: key);
+  }
+
+  @action
+  Future<BackupExportFile> exportBackup() async {
+    try {
+      state = IsExecutingState();
+      final backupContent = await backupService.exportBackup('', nonce: '');
+      state = ExecutedSuccessfullyState();
+
+      return BackupExportFile(backupContent.toList(),
+          name: 'backup_${DateTime.now().toString()}.zip');
+    } catch (e) {
+      print(e.toString());
+      state = FailureState(e.toString());
+    }
+  }
+
+  @action
+  void showMasterPassword() => isBackupPasswordVisible = true;
+}