import 'dart:convert';
import 'dart:io';
import 'dart:async';

import 'package:shelf/shelf.dart';
import 'package:shelf_router/shelf_router.dart';

import 'config/app_config.dart';
import 'util/vips.dart';
import 'domain/repositories/photo_repository.dart';
import 'domain/repositories/album_repository.dart';

final _config = AppConfig();
final vips = Vips(cacheDir: _config.cacheDir);
final albumRepository = AlbumRepository(basePath: _config.dataDir);
final photoRepository = PhotoRepository(_config.dataDir);

Response jsonResponse(dynamic data) {
  return Response.ok(
    jsonEncode(data),
    headers: {'content-type': 'application/json'},
  );
}

/// 路由依赖注入容器
///
/// 允许在测试中使用 mock 或临时目录，而不是全局单例。
class AppRouter {
  final AlbumRepository albumRepository;
  final PhotoRepository photoRepository;
  final Vips vips;

  AppRouter({
    AlbumRepository? albumRepository,
    PhotoRepository? photoRepository,
    Vips? vips,
  }) : albumRepository =
           albumRepository ?? AlbumRepository(basePath: _config.dataDir),
       photoRepository = photoRepository ?? PhotoRepository(_config.dataDir),
       vips = vips ?? Vips(cacheDir: _config.cacheDir);

  /// 创建 API v1 版本的路由
  Router createApiV1Router() {
    final router = Router()
      ..get('/', _rootHandler)
      ..get('/album', (req) => _listAlbumHandler(req, albumRepository))
      ..get('/album/<id>', (req) => _getAlbumHandler(req, albumRepository))
      ..get(
        '/album/<id>/photo',
        (req) => _getPhotosOfAlbumHandler(req, photoRepository),
      )
      ..get('/photo/<id>', (req) => _getPhotoHandler(req, photoRepository))
      ..get(
        '/photo/<id>/file',
        (req) => _getPhotoFileHandler(req, photoRepository),
      )
      ..get(
        '/photo/<id>/preview',
        (req) => _getPhotoPreviewHandler(req, photoRepository, vips),
      )
      ..get('/echo/<message>', _echoHandler);

    return router;
  }

  /// 创建主路由器，将 API v1 挂载到 /api/v1 路径下
  Router createRouter() {
    final router = Router();
    router.mount('/api/v1', createApiV1Router().call);
    return router;
  }
}

/// 创建 API v1 版本的路由（使用全局单例，保持向后兼容）
Router createApiV1Router() {
  return AppRouter().createApiV1Router();
}

/// 创建主路由器，将 API v1 挂载到 /api/v1 路径下（使用全局单例，保持向后兼容）
Router createRouter() {
  return AppRouter().createRouter();
}

Response _rootHandler(Request req) {
  return Response.ok('Hello, World!\n');
}

Response _echoHandler(Request request) {
  final message = request.params['message'];
  return Response.ok('$message\n');
}

Future<Response> _listAlbumHandler(Request req, AlbumRepository repo) async {
  final albums = await repo.getAllAlbums();
  final albumList = albums
      .map(
        (a) => {
          'id': a.id,
          'name': a.name,
          'createdAt': a.createdAt.toIso8601String(),
          'updatedAt': a.updatedAt.toIso8601String(),
        },
      )
      .toList();
  return jsonResponse(albumList);
}

Future<Response> _getAlbumHandler(Request req, AlbumRepository repo) async {
  final idParam = req.params['id'];
  if (idParam == null) {
    return Response.badRequest(body: 'Missing album id');
  }
  final id = int.tryParse(idParam);
  if (id == null) {
    return Response.badRequest(body: 'Invalid album id: $idParam');
  }
  final album = await repo.getAlbumById(id);
  if (album == null) {
    return Response.notFound('Album not found');
  }
  return jsonResponse({'id': album.id, 'name': album.name});
}

Future<Response> _getPhotoHandler(Request req, PhotoRepository repo) async {
  final idParam = req.params['id'];
  if (idParam == null) {
    return Response.badRequest(body: 'Missing photo id');
  }
  final id = int.tryParse(idParam);
  if (id == null) {
    return Response.badRequest(body: 'Invalid photo id: $idParam');
  }

  final photo = await repo.getPhotoById(id);
  if (photo == null) {
    return Response.notFound('Photo not found');
  }
  return jsonResponse(photo);
}

Future<Response> _getPhotoFileHandler(Request req, PhotoRepository repo) async {
  final idParam = req.params['id'];
  if (idParam == null) {
    return Response.badRequest(body: 'Missing photo id');
  }
  final id = int.tryParse(idParam);
  if (id == null) {
    return Response.badRequest(body: 'Invalid photo id: $idParam');
  }

  final photo = await repo.getPhotoById(id);
  if (photo == null) {
    return Response.notFound('Photo not found');
  }

  final filePath = photo.filePath;
  final file = File(filePath);

  if (!await file.exists()) {
    return Response.notFound('File not found');
  }

  // ✅ 修复：使用 StreamController 包装，确保在客户端断开时关闭文件流
  final streamController = StreamController<List<int>>();
  final fileStream = file.openRead();

  // 订阅文件流，并将数据转发到响应流
  final subscription = fileStream.listen(
    streamController.add,
    onError: streamController.addError,
    onDone: streamController.close,
    cancelOnError: true,
  );

  // 当客户端取消订阅时（断开连接），取消文件流订阅并关闭文件
  streamController.onCancel = () {
    subscription.cancel();
    return Future.value();
  };

  return Response.ok(
    streamController.stream,
    headers: {
      'Content-Type': photo.mimeType,
      'Content-Length': photo.fileSize.toString(),
    },
  );
}

Future<Response> _getPhotosOfAlbumHandler(
  Request req,
  PhotoRepository repo,
) async {
  final idParam = req.params['id'];
  if (idParam == null) {
    return Response.badRequest(body: 'Missing album id');
  }
  final albumId = int.tryParse(idParam);
  if (albumId == null) {
    return Response.badRequest(body: 'Invalid album id: $idParam');
  }
  final photos = await repo.getPhotosByAlbumId(albumId);
  return jsonResponse(photos);
}

Future<Response> _getPhotoPreviewHandler(
  Request req,
  PhotoRepository repo,
  Vips vips,
) async {
  final idParam = req.params['id'];
  if (idParam == null) {
    return Response.badRequest(body: 'Missing photo id');
  }
  final id = int.tryParse(idParam);
  if (id == null) {
    return Response.badRequest(body: 'Invalid photo id: $idParam');
  }

  final photo = await repo.getPhotoById(id);
  if (photo == null) {
    return Response.notFound('Photo not found');
  }

  // 从查询参数获取宽度和高度
  final w = int.tryParse(req.url.queryParameters['w'] ?? '');
  final h = int.tryParse(req.url.queryParameters['h'] ?? '');

  final file = await vips.generatePreview(photo.filePath, w: w, h: h);

  if (!await file.exists()) {
    return Response.notFound('File not found');
  }

  // ✅ 修复：使用 StreamController 包装，确保在客户端断开时关闭文件流
  final streamController = StreamController<List<int>>();
  final fileStream = file.openRead();

  // 订阅文件流，并将数据转发到响应流
  final subscription = fileStream.listen(
    streamController.add,
    onError: streamController.addError,
    onDone: streamController.close,
    cancelOnError: true,
  );

  // 当客户端取消订阅时（断开连接），取消文件流订阅并关闭文件
  streamController.onCancel = () {
    subscription.cancel();
    return Future.value();
  };

  return Response.ok(
    streamController.stream,
    headers: {
      'Content-Type': 'image/webp',
      'Content-Length': file.statSync().size.toString(),
    },
  );
}