import 'package:dio/dio.dart';
import 'package:flutter/foundation.dart';
import 'package:worldhopper/models/server.dart';
import 'package:worldhopper/models/stream_link.dart';
import 'package:worldhopper/services/auth_service.dart';
import 'package:worldhopper/services/opds_parser.dart'
    show OPDSParser, ParsedFeed;

/// Service for fetching OPDS feeds over HTTP
class OPDSService {
  final AuthService _authService;
  final OPDSParser _parser;
  final Map<String, Dio> _clients = {};

  OPDSService({
    AuthService? authService,
    OPDSParser? parser,
  })  : _authService = authService ?? AuthService(),
        _parser = parser ?? OPDSParser();

  /// Get or create a Dio client for a server
  Dio _getClient(Server server) {
    if (!_clients.containsKey(server.id)) {
      _clients[server.id] = _authService.createAuthenticatedClient(server);
    }
    return _clients[server.id]!;
  }

  /// Fetch and parse an OPDS feed from a URL
  Future<ParsedFeed> fetchFeed(
    Server server,
    String url, {
    CancelToken? cancelToken,
  }) async {
    try {
      final client = _getClient(server);

      // Log the URL being fetched for debugging
      debugPrint('Fetching OPDS feed: $url');

      final response = await client.get(
        url,
        cancelToken: cancelToken,
        options: Options(
          responseType: ResponseType.plain,
        ),
      );

      if (response.statusCode == 200) {
        final xmlContent = response.data as String;
        return _parser.parseFeed(xmlContent, server: server);
      } else {
        throw ServerException(
          'Failed to fetch feed: HTTP ${response.statusCode}',
          statusCode: response.statusCode,
        );
      }
    } on DioException catch (e) {
      debugPrint(
          'DioException fetching feed from $url: ${e.type}, ${e.message}');
      throw _handleDioException(e);
    } catch (e) {
      debugPrint('Error fetching feed from $url: $e');
      throw ServerException('Error fetching feed: $e');
    }
  }

  /// Fetch the root feed for a server
  Future<ParsedFeed> fetchRootFeed(
    Server server, {
    CancelToken? cancelToken,
  }) async {
    return fetchFeed(server, server.url, cancelToken: cancelToken);
  }

  /// Test connection to a server. Throws on failure with details.
  Future<bool> testConnection(
    Server server, {
    CancelToken? cancelToken,
  }) async {
    await fetchRootFeed(server, cancelToken: cancelToken);
    return true;
  }

  /// Fire a GET request for a PSE page URL so the server registers the page
  /// view (e.g. Kavita tracks reading progress from GET requests).
  ///
  /// Uses [ResponseType.stream] and drains the body immediately so the full
  /// image is never held in memory. Errors are logged but never thrown.
  Future<void> reportPageProgress(
    Server server,
    StreamLink streamLink,
    int page,
  ) async {
    try {
      final client = _getClient(server);
      final url = streamLink.getPageUrl(page);
      final response = await client.get<ResponseBody>(
        url,
        options: Options(responseType: ResponseType.stream),
      );
      // Drain the stream so the connection is released.
      await response.data?.stream.drain<void>();
    } catch (e) {
      debugPrint('reportPageProgress: failed for page $page – $e');
    }
  }

  /// Report the last page as read — convenience wrapper used when a book is
  /// finished.
  Future<void> markAsRead(
    Server server,
    StreamLink streamLink,
  ) async {
    await reportPageProgress(server, streamLink, streamLink.pageCount - 1);
  }

  /// Clear cached clients (useful when server credentials change)
  void clearClients() {
    _clients.clear();
  }

  /// Clear client for a specific server
  void clearClient(String serverId) {
    _clients.remove(serverId);
  }

  /// Handle Dio exceptions and convert to ServerException
  ServerException _handleDioException(DioException e) {
    switch (e.type) {
      case DioExceptionType.connectionTimeout:
      case DioExceptionType.sendTimeout:
      case DioExceptionType.receiveTimeout:
        return ServerException(
          'Connection timeout. Please check your network connection.',
          statusCode: null,
          isNetworkError: true,
        );

      case DioExceptionType.badResponse:
        final statusCode = e.response?.statusCode;
        final body = e.response?.data?.toString() ?? '';
        final bodySnippet =
            body.length > 200 ? '${body.substring(0, 200)}...' : body;
        if (statusCode == 401 || statusCode == 403) {
          return ServerException(
            'Authentication failed (HTTP $statusCode).\n$bodySnippet',
            statusCode: statusCode,
            isAuthError: true,
          );
        } else if (statusCode == 404) {
          return ServerException(
            'Feed not found (404).\n$bodySnippet',
            statusCode: statusCode,
          );
        } else {
          return ServerException(
            'Server error: HTTP $statusCode\n$bodySnippet',
            statusCode: statusCode,
          );
        }

      case DioExceptionType.cancel:
        return ServerException('Request cancelled');

      case DioExceptionType.connectionError:
        return ServerException(
          'Connection error: ${e.message ?? "Could not connect to server"}',
          isNetworkError: true,
        );

      case DioExceptionType.unknown:
        return ServerException(
          'Network error: ${e.message ?? e.error?.toString() ?? "Unknown error"}',
          isNetworkError: true,
        );

      default:
        return ServerException('Error: ${e.message ?? "Unknown error"}');
    }
  }
}

/// Custom exception for OPDS-related errors
class ServerException implements Exception {
  final String message;
  final int? statusCode;
  final bool isNetworkError;
  final bool isAuthError;

  ServerException(
    this.message, {
    this.statusCode,
    this.isNetworkError = false,
    this.isAuthError = false,
  });

  @override
  String toString() => message;
}