import 'package:dio/dio.dart';
import 'package:flutter/foundation.dart';
import 'package:worldhopper/models/server.dart';
import 'package:worldhopper/services/dio_factory.dart';

/// Cached authentication data for a Kavita server.
class KavitaAuth {
  final String token;
  final String apiKey;
  final DateTime expiry;

  const KavitaAuth({
    required this.token,
    required this.apiKey,
    required this.expiry,
  });

  bool get isExpired => DateTime.now().isAfter(expiry);
}

/// Paginated result from Kavita API.
class KavitaPaginatedResult {
  final List<Map<String, dynamic>> items;
  final int totalItems;

  const KavitaPaginatedResult({
    required this.items,
    required this.totalItems,
  });
}

/// HTTP client for the Kavita REST API.
///
/// Handles JWT authentication with caching, and provides typed methods
/// for each Kavita endpoint used by the app.
class KavitaApiClient {
  final Dio _dio;

  /// In-memory auth cache: serverId → KavitaAuth.
  final Map<String, KavitaAuth> _authCache = {};

  /// Auth cache lifetime (29 days; Kavita tokens last 30).
  static const _authTtl = Duration(days: 29);

  KavitaApiClient({Dio? dio}) : _dio = dio ?? createDio();

  // ---------------------------------------------------------------------------
  // Authentication
  // ---------------------------------------------------------------------------

  /// Get or refresh authentication for a server. Returns JWT + apiKey.
  Future<KavitaAuth> getAuth(Server server) async {
    final cached = _authCache[server.id];
    if (cached != null && !cached.isExpired) {
      return cached;
    }

    if (server.username == null || server.password == null) {
      throw KavitaApiException('No credentials configured for server');
    }

    debugPrint('KavitaApi: logging in to ${server.url}');

    final Response response;
    try {
      response = await _dio.post(
        '${server.url}/api/Account/login',
        data: {
          'username': server.username,
          'password': server.password,
        },
      );
    } on DioException catch (e) {
      final body = e.response?.data?.toString() ?? '';
      final status = e.response?.statusCode;
      throw KavitaApiException(
        'Login failed: HTTP $status\n$body',
        statusCode: status,
      );
    }

    final data = response.data as Map<String, dynamic>;
    final token = data['token'] as String?;
    final apiKey = data['apiKey'] as String?;

    if (token == null || apiKey == null) {
      throw KavitaApiException(
          'Login response missing token or apiKey\n${response.data}');
    }

    final auth = KavitaAuth(
      token: token,
      apiKey: apiKey,
      expiry: DateTime.now().add(_authTtl),
    );
    _authCache[server.id] = auth;
    return auth;
  }

  /// Clear cached auth for a server.
  void clearAuth(String serverId) {
    _authCache.remove(serverId);
  }

  // ---------------------------------------------------------------------------
  // Library
  // ---------------------------------------------------------------------------

  /// GET /api/Library/libraries — list all libraries.
  Future<List<Map<String, dynamic>>> getLibraries(Server server) async {
    final auth = await getAuth(server);
    final response = await _dio.get(
      '${server.url}/api/Library/libraries',
      options: _authOptions(auth),
    );
    return (response.data as List).cast<Map<String, dynamic>>();
  }

  // ---------------------------------------------------------------------------
  // Series
  // ---------------------------------------------------------------------------

  /// POST /api/Series/v2 — list series filtered by library, paginated.
  Future<KavitaPaginatedResult> getSeries(
    Server server, {
    required int libraryId,
    int page = 1,
    int pageSize = 20,
  }) async {
    final auth = await getAuth(server);
    final response = await _dio.post(
      '${server.url}/api/Series/v2',
      queryParameters: {
        'PageNumber': page,
        'PageSize': pageSize,
      },
      data: {
        'statements': [
          {
            'field': 19, // FilterField.Libraries
            'comparison': 0, // FilterComparison.Equal
            'value': '$libraryId',
          },
        ],
        'combination': 0, // And
        'sortOptions': {
          'sortField': 1, // SortName
          'isAscending': true,
        },
        'limitTo': 0,
      },
      options: _authOptions(auth),
    );

    final items = (response.data as List).cast<Map<String, dynamic>>();
    // Kavita returns total count in pagination headers
    final totalStr = response.headers.value('pagination');
    int totalItems = items.length;
    if (totalStr != null) {
      try {
        // Pagination header is JSON: {"currentPage":1,"itemsPerPage":20,"totalItems":42,"totalPages":3}
        // Parse totalItems from it
        final paginationMatch =
            RegExp(r'"totalItems"\s*:\s*(\d+)').firstMatch(totalStr);
        if (paginationMatch != null) {
          totalItems = int.parse(paginationMatch.group(1)!);
        }
      } catch (_) {
        // Ignore parsing errors
      }
    }

    return KavitaPaginatedResult(items: items, totalItems: totalItems);
  }

  /// GET /api/Series/series-detail — get volumes and chapters for a series.
  Future<Map<String, dynamic>> getSeriesDetail(
    Server server, {
    required int seriesId,
  }) async {
    final auth = await getAuth(server);
    final response = await _dio.get(
      '${server.url}/api/Series/series-detail',
      queryParameters: {'seriesId': seriesId},
      options: _authOptions(auth),
    );
    return response.data as Map<String, dynamic>;
  }

  /// GET /api/Series/{seriesId} — get series metadata.
  Future<Map<String, dynamic>> getSeriesInfo(
    Server server, {
    required int seriesId,
  }) async {
    final auth = await getAuth(server);
    final response = await _dio.get(
      '${server.url}/api/Series/$seriesId',
      options: _authOptions(auth),
    );
    return response.data as Map<String, dynamic>;
  }

  // ---------------------------------------------------------------------------
  // Reading
  // ---------------------------------------------------------------------------

  /// GET /api/Reader/chapter-info — get page count and metadata for a chapter.
  Future<Map<String, dynamic>> getChapterInfo(
    Server server, {
    required int chapterId,
  }) async {
    final auth = await getAuth(server);
    final response = await _dio.get(
      '${server.url}/api/Reader/chapter-info',
      queryParameters: {'chapterId': chapterId},
      options: _authOptions(auth),
    );
    return response.data as Map<String, dynamic>;
  }

  /// GET /api/Reader/get-progress — get reading progress for a chapter.
  Future<Map<String, dynamic>?> getProgress(
    Server server, {
    required int chapterId,
  }) async {
    final auth = await getAuth(server);
    try {
      final response = await _dio.get(
        '${server.url}/api/Reader/get-progress',
        queryParameters: {'chapterId': chapterId},
        options: _authOptions(auth),
      );
      return response.data as Map<String, dynamic>?;
    } on DioException catch (e) {
      if (e.response?.statusCode == 404) return null;
      rethrow;
    }
  }

  /// POST /api/Reader/progress — save reading progress.
  Future<void> saveProgress(
    Server server, {
    required int chapterId,
    required int volumeId,
    required int seriesId,
    required int libraryId,
    required int pageNum,
    String? bookScrollId,
  }) async {
    final auth = await getAuth(server);
    await _dio.post(
      '${server.url}/api/Reader/progress',
      data: {
        'chapterId': chapterId,
        'volumeId': volumeId,
        'seriesId': seriesId,
        'libraryId': libraryId,
        'pageNum': pageNum,
        if (bookScrollId != null) 'bookScrollId': bookScrollId,
      },
      options: _authOptions(auth),
    );
  }

  /// POST /api/Reader/mark-volume-read
  Future<void> markVolumeRead(
    Server server, {
    required int seriesId,
    required int volumeId,
  }) async {
    final auth = await getAuth(server);
    await _dio.post(
      '${server.url}/api/Reader/mark-volume-read',
      data: {
        'seriesId': seriesId,
        'volumeId': volumeId,
      },
      options: _authOptions(auth),
    );
  }

  /// POST /api/Reader/mark-volume-unread
  Future<void> markVolumeUnread(
    Server server, {
    required int seriesId,
    required int volumeId,
  }) async {
    final auth = await getAuth(server);
    await _dio.post(
      '${server.url}/api/Reader/mark-volume-unread',
      data: {
        'seriesId': seriesId,
        'volumeId': volumeId,
      },
      options: _authOptions(auth),
    );
  }

  // ---------------------------------------------------------------------------
  // Image URLs (constructed, not fetched — apiKey in query param)
  // ---------------------------------------------------------------------------

  /// Build a series cover URL.
  String seriesCoverUrl(String baseUrl, String apiKey, int seriesId) =>
      '$baseUrl/api/Image/series-cover?seriesId=$seriesId&apiKey=$apiKey';

  /// Build a volume cover URL.
  String volumeCoverUrl(String baseUrl, String apiKey, int volumeId) =>
      '$baseUrl/api/Image/volume-cover?volumeId=$volumeId&apiKey=$apiKey';

  /// Build a chapter cover URL.
  String chapterCoverUrl(String baseUrl, String apiKey, int chapterId) =>
      '$baseUrl/api/Image/chapter-cover?chapterId=$chapterId&apiKey=$apiKey';

  /// Build a page image URL template (with {pageNumber} placeholder).
  String pageImageUrlTemplate(String baseUrl, String apiKey, int chapterId) =>
      '$baseUrl/api/Reader/image?chapterId=$chapterId&page={pageNumber}&apiKey=$apiKey';

  // ---------------------------------------------------------------------------
  // Downloads
  // ---------------------------------------------------------------------------

  /// Download a chapter file. Returns the downloaded file.
  Future<void> downloadChapter(
    Server server, {
    required int chapterId,
    required String savePath,
    void Function(int received, int total)? onProgress,
    CancelToken? cancelToken,
  }) async {
    final auth = await getAuth(server);
    await _dio.download(
      '${server.url}/api/Download/chapter',
      savePath,
      queryParameters: {'chapterId': chapterId},
      options: Options(headers: {'Authorization': 'Bearer ${auth.token}'}),
      onReceiveProgress: onProgress,
      cancelToken: cancelToken,
    );
  }

  // ---------------------------------------------------------------------------
  // Helpers
  // ---------------------------------------------------------------------------

  Options _authOptions(KavitaAuth auth) =>
      Options(headers: {'Authorization': 'Bearer ${auth.token}'});
}

/// Exception for Kavita API errors.
class KavitaApiException implements Exception {
  final String message;
  final int? statusCode;

  KavitaApiException(this.message, {this.statusCode});

  @override
  String toString() => 'KavitaApiException: $message';
}