import 'dart:io';
import 'package:dio/dio.dart';
import 'package:path/path.dart' as path;
import 'package:worldhopper/models/server.dart';
import 'package:worldhopper/models/stream_link.dart';
import 'package:worldhopper/services/auth_service.dart';
import 'package:worldhopper/services/download_storage_service.dart';

/// Downloads all pages of an OPDS-PS chapter to a local directory
class ImageStreamDownloadService {
  final AuthService _authService;
  final DownloadStorageService _storageService;

  ImageStreamDownloadService({
    AuthService? authService,
    DownloadStorageService? storageService,
  })  : _authService = authService ?? AuthService(),
        _storageService = storageService ?? DownloadStorageService();

  /// Derive file extension from MIME type
  String _extensionForType(String mimeType) {
    final lower = mimeType.toLowerCase();
    if (lower.contains('png')) return '.png';
    if (lower.contains('gif')) return '.gif';
    if (lower.contains('webp')) return '.webp';
    return '.jpg'; // default for image/jpeg and unknown
  }

  /// Download all pages of an image stream chapter
  ///
  /// Returns the chapter directory path on success.
  Future<String> downloadChapter({
    required Server server,
    required StreamLink streamLink,
    required String seriesId,
    required String chapterId,
    void Function(int downloaded, int total)? onProgress,
    CancelToken? cancelToken,
  }) async {
    final dio = _authService.createAuthenticatedClient(server);
    final chapterDir = await _storageService.getChapterDir(seriesId, chapterId);
    final ext = _extensionForType(streamLink.type);
    final totalPages = streamLink.pageCount;

    for (var i = 0; i < totalPages; i++) {
      if (cancelToken?.isCancelled == true) {
        throw DioException(
          requestOptions: RequestOptions(path: ''),
          type: DioExceptionType.cancel,
        );
      }

      final pageUrl = streamLink.getPageUrl(i);
      final filePath = path.join(chapterDir.path, '$i$ext');

      // Skip if already downloaded
      if (await File(filePath).exists()) {
        onProgress?.call(i + 1, totalPages);
        continue;
      }

      await dio.download(
        pageUrl,
        filePath,
        cancelToken: cancelToken,
      );

      onProgress?.call(i + 1, totalPages);
    }

    return chapterDir.path;
  }
}