import 'dart:io';

import 'package:flutter_test/flutter_test.dart';
import 'package:fuel_tax_tracker/services/cloud/cloud_storage_provider.dart';
import 'package:fuel_tax_tracker/services/cloud_sync_service.dart';
import 'package:fuel_tax_tracker/services/database_service.dart';
import 'package:fuel_tax_tracker/services/db_schema.dart';
import 'package:path/path.dart' as p;
import 'package:path_provider_platform_interface/path_provider_platform_interface.dart';
import 'package:plugin_platform_interface/plugin_platform_interface.dart';
import 'package:sqflite_common_ffi/sqflite_ffi.dart';

/// Confirms [CloudSyncService]'s orchestration (lock → check remote →
/// upload → release) works against *any* [CloudStorageProvider], using a
/// fake one — coverage for the provider-agnostic logic itself, independent
/// of which real backend (Google Drive, Dropbox, OneDrive) it's wired to.
void main() {
  late Directory tempDir;
  late DatabaseService databaseService;

  setUpAll(() {
    sqfliteFfiInit();
    databaseFactory = databaseFactoryFfi;
  });

  setUp(() async {
    tempDir = await Directory.systemTemp.createTemp('cloud_sync_service_test_');
    PathProviderPlatform.instance = _FakePathProviderPlatform(tempDir.path);
    databaseService = DatabaseService();
    await databaseService.init();
  });

  tearDown(() async {
    await databaseService.rawDb.close();
    await tempDir.delete(recursive: true);
  });

  test('syncNow acquires a lock, uploads the data file, and releases the lock', () async {
    final session = _FakeSession();
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
    syncService.configure('app-folder-id');

    final result = await syncService.syncNow();

    expect(result.ranSync, isTrue);
    expect(session.createdLockNames, hasLength(1));
    expect(session.createdLockNames.first, startsWith('tester@example.com-'));
    expect(session.uploadedFileNames, contains(dataFileName));
    expect(session.deletedFileIds, ['lock-id'], reason: 'the lock must be released afterward');
  });

  test('syncNow uploads a pending receipt into Receipts/<vin>/<yyyy.mm>', () async {
    final session = _FakeSession();
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
    syncService.configure('app-folder-id');

    final db = databaseService.rawDb;
    await db.insert('vehicles', {
      'id': 'vehicle-1',
      'vin': '1FMPU18L1TLB51349',
      'nickname': null,
      'updated_at': 0,
      'deleted_at': null,
      'dirty': 0,
    });
    final receiptFile = File(p.join(tempDir.path, 'receipt.jpg'))..writeAsBytesSync([1, 2, 3]);
    await db.insert('fuel_entries', {
      'id': 'entry-1',
      'vehicle_id': 'vehicle-1',
      // Mid-month/mid-year so DateTime.fromMillisecondsSinceEpoch's local
      // interpretation can't drift into a different month depending on the
      // machine's timezone (unlike epoch 0, which can land in Dec 1969).
      'date': DateTime(2026, 3, 15).millisecondsSinceEpoch,
      'gallons': 10.0,
      'price_per_gallon': 3.5,
      'total_cost': 35.0,
      'receipt_image_path': receiptFile.path,
      'receipt_drive_file_id': null,
      'updated_at': 0,
      'deleted_at': null,
      'dirty': 1,
    });

    final result = await syncService.syncNow(keepLocalReceiptCopies: true);

    expect(result.ranSync, isTrue);
    expect(session.uploadedFileFolders['entry-1.jpg'],
        'app-folder-id/$receiptsFolderName/1FMPU18L1TLB51349/2026.03');
  });

  test('selectAppFolder creates/finds the app folder under the picked parent', () async {
    final session = _FakeSession();
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);

    final folderId = await syncService.selectAppFolder('parent-id');

    expect(folderId, 'parent-id/$appFolderName');
    expect(session.findOrCreateFolderCalls, ['parent-id/$appFolderName']);
  });

  test('selectAppFolder uses the picked folder directly if it is already the app folder',
      () async {
    final session = _FakeSession();
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);

    final folderId =
        await syncService.selectAppFolder('parent-id/$appFolderName', currentFolderName: appFolderName);

    expect(folderId, 'parent-id/$appFolderName');
    expect(session.findOrCreateFolderCalls, isEmpty,
        reason: 'should not nest another app folder inside a folder already named that');
  });

  test(
      'selectAppFolder moves an already-configured app folder to a new parent instead of '
      'creating a fresh one there', () async {
    final session = _FakeSession();
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
    // Establishes an app folder under the first parent — e.g. the root
    // default a fresh connection assumes (see AppState.connectProvider) —
    // before the user picks somewhere else.
    await syncService.selectAppFolder('root');
    expect(syncService.isConfigured, isTrue);

    final newFolderId = await syncService.selectAppFolder('new-parent-id');

    expect(session.moveFolderCalls, ['root/$appFolderName->new-parent-id']);
    expect(newFolderId, 'new-parent-id/moved');
    expect(session.findOrCreateFolderCalls, ['root/$appFolderName'],
        reason: 'only the very first (root) selection created a folder; the second moved it');
  });

  test(
      'selectAppFolder adopts a same-named folder already at the destination instead of '
      'moving onto/alongside it', () async {
    final session = _FakeSession()
      ..foldersByParent['new-parent-id'] = [CloudFolder(id: 'shared-folder-id', name: appFolderName)];
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
    await syncService.selectAppFolder('root');

    final folderId = await syncService.selectAppFolder('new-parent-id');

    expect(folderId, 'shared-folder-id');
    expect(session.moveFolderCalls, isEmpty, reason: 'adopted the existing one, did not move onto it');
  });

  test('syncNow is a no-op when not configured with a folder yet', () async {
    final session = _FakeSession();
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);

    final result = await syncService.syncNow();

    expect(result.ranSync, isFalse);
    expect(session.createdLockNames, isEmpty);
  });

  group('beforeUpload hook', () {
    test('is awaited after pulling/merging remote changes but before anything is uploaded',
        () async {
      final calls = <String>[];
      // A real copy of the (correctly schema'd, currently empty) local
      // database — CloudSyncService ATTACHes and merges against whatever
      // downloadFileBytes returns, so it has to be an actual valid SQLite
      // database, not arbitrary bytes.
      final remoteDbBytes = await File(databaseService.databasePath).readAsBytes();
      final session = _FakeSession();
      session.existingDataFile = CloudFileInfo(id: 'remote-db-id', versionTag: 'remote-v1');
      session.remoteDbBytes = remoteDbBytes;
      session.onDownload = () => calls.add('download');
      session.onUpload = (name) => calls.add('upload:$name');
      final provider = _FakeProvider(session);
      final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
      syncService.configure('app-folder-id');

      final result = await syncService.syncNow(
        beforeUpload: () async {
          calls.add('beforeUpload');
          return true;
        },
      );

      expect(result.ranSync, isTrue);
      expect(result.adGateBlocked, isFalse);
      expect(calls.first, 'download', reason: 'pull/merge happens first');
      expect(calls[1], 'beforeUpload');
      // Everything after beforeUpload is an upload (the data-file push,
      // possibly preceded by pending receipt uploads — none pending here).
      expect(calls.skip(2), everyElement(startsWith('upload:')));
      expect(calls, contains('upload:$dataFileName'));
    });

    test('is awaited even when there is nothing to pull (no existing remote data file yet)',
        () async {
      final calls = <String>[];
      final session = _FakeSession()..onUpload = (name) => calls.add('upload:$name');
      final provider = _FakeProvider(session);
      final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
      syncService.configure('app-folder-id');

      await syncService.syncNow(
        beforeUpload: () async {
          calls.add('beforeUpload');
          return true;
        },
      );

      expect(calls.first, 'beforeUpload');
      expect(calls, contains('upload:$dataFileName'));
    });

    test('a false return blocks the upload but keeps whatever was already pulled/merged',
        () async {
      final calls = <String>[];
      final remoteDbBytes = await File(databaseService.databasePath).readAsBytes();
      final session = _FakeSession();
      session.existingDataFile = CloudFileInfo(id: 'remote-db-id', versionTag: 'remote-v1');
      session.remoteDbBytes = remoteDbBytes;
      session.onDownload = () => calls.add('download');
      session.onUpload = (name) => calls.add('upload:$name');
      final provider = _FakeProvider(session);
      final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
      syncService.configure('app-folder-id');

      final result = await syncService.syncNow(beforeUpload: () async => false);

      expect(result.ranSync, isFalse);
      expect(result.adGateBlocked, isTrue);
      expect(calls, ['download'], reason: 'pull/merge still ran; nothing was uploaded');
      expect(session.deletedFileIds, ['lock-id'],
          reason: 'the lock must still be released when the gate blocks the upload');
    });

    test('omitting it changes nothing — every other syncNow call site keeps working', () async {
      final session = _FakeSession();
      final provider = _FakeProvider(session);
      final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
      syncService.configure('app-folder-id');

      final result = await syncService.syncNow();

      expect(result.ranSync, isTrue);
    });
  });

  test(
      'pull/merge does not throw against a remote snapshot from before the '
      'ad_free_entitlement table existed', () async {
    // Simulates a real user's pre-existing cloud folder: a DB file uploaded
    // by an older app version, with only the schema that existed then (no
    // ad_free_entitlement table) — CloudSyncService must skip merging that
    // table rather than throw "no such table: remote_db.ad_free_entitlement".
    final oldSchemaDbPath = p.join(tempDir.path, 'old_schema_remote.db');
    final oldSchemaDb = await databaseFactory.openDatabase(oldSchemaDbPath);
    await oldSchemaDb.execute(createVehiclesTableSql);
    await oldSchemaDb.execute(createFuelEntriesTableSql);
    await oldSchemaDb.execute(createFuelEntriesIndexSql);
    await oldSchemaDb.close();

    final session = _FakeSession();
    session.existingDataFile = CloudFileInfo(id: 'remote-db-id', versionTag: 'remote-v1');
    session.remoteDbBytes = await File(oldSchemaDbPath).readAsBytes();
    final provider = _FakeProvider(session);
    final syncService = CloudSyncService(provider: provider, databaseService: databaseService);
    syncService.configure('app-folder-id');

    final result = await syncService.syncNow();

    expect(result.ranSync, isTrue);
  });
}

class _FakePathProviderPlatform extends PathProviderPlatform with MockPlatformInterfaceMixin {
  final String tempPath;
  _FakePathProviderPlatform(this.tempPath);

  @override
  Future<String?> getApplicationDocumentsPath() async => tempPath;

  @override
  Future<String?> getTemporaryPath() async => tempPath;
}

class _FakeSession implements CloudStorageSession {
  final List<String> createdLockNames = [];
  final List<String> deletedFileIds = [];
  final List<String> uploadedFileNames = [];
  final Map<String, String> uploadedFileFolders = {};
  final List<String> findOrCreateFolderCalls = [];
  CloudFileInfo? existingDataFile;
  void Function()? onDownload;
  void Function(String name)? onUpload;

  /// Bytes [downloadFileBytes] returns — needs to be a real, attachable
  /// SQLite database (with the vehicles/fuel_entries schema) for
  /// [CloudSyncService]'s ATTACH-based merge to succeed against it, not
  /// just arbitrary bytes. Tests that exercise the pull/merge path set this
  /// to a copy of their own [DatabaseService]'s (already correctly
  /// schema'd) database file.
  List<int> remoteDbBytes = const [];

  @override
  bool get supportsSharedWithMe => false;

  /// Folders [listFolders] returns, keyed by the `parentId` they'd be
  /// listed under — empty (nothing at any destination) unless a test sets
  /// this up, e.g. to simulate a same-named app folder someone else
  /// already created at the destination.
  final Map<String, List<CloudFolder>> foldersByParent = {};

  @override
  Future<List<CloudFolder>> listFolders({String? parentId, bool sharedWithMe = false}) async =>
      foldersByParent[parentId] ?? [];

  @override
  Future<String> findOrCreateFolder({required String parentId, required String name}) async {
    findOrCreateFolderCalls.add('$parentId/$name');
    return '$parentId/$name';
  }

  final List<String> moveFolderCalls = [];

  @override
  Future<String> moveFolder({required String folderId, required String newParentId}) async {
    moveFolderCalls.add('$folderId->$newParentId');
    return '$newParentId/moved';
  }

  @override
  Future<CloudFileInfo?> findFile({required String folderId, required String name}) async {
    return name == dataFileName ? existingDataFile : null;
  }

  @override
  Future<List<int>> downloadFileBytes(String fileId) async {
    onDownload?.call();
    return remoteDbBytes;
  }

  @override
  Future<CloudFileInfo> uploadFile({
    required String folderId,
    required String name,
    String? existingFileId,
    required File localFile,
    required String contentType,
  }) async {
    uploadedFileNames.add(name);
    uploadedFileFolders[name] = folderId;
    onUpload?.call(name);
    return CloudFileInfo(id: 'uploaded-$name', versionTag: 'v1');
  }

  @override
  Future<void> deleteFile(String fileId) async => deletedFileIds.add(fileId);

  @override
  Future<String> createLockFile({required String folderId, required String name}) async {
    createdLockNames.add(name);
    return 'lock-id';
  }

  @override
  Future<List<CloudLockFile>> listLockFiles(String folderId) async => [];

  @override
  void close() {}
}

class _FakeProvider implements CloudStorageProvider {
  final _FakeSession session;
  _FakeProvider(this.session);

  @override
  CloudProviderId get id => CloudProviderId.googleDrive;

  @override
  String get displayName => 'Fake Provider';

  @override
  bool get isSignedIn => true;

  @override
  String? get accountLabel => 'tester@example.com';

  @override
  Future<bool> attemptSilentSignIn() async => true;

  @override
  Future<String> signIn() async => accountLabel!;

  @override
  Future<void> signOut() async {}

  @override
  CloudStorageSession beginSession() => session;
}