/// Xtream Codes API Service - Mobile Version
///
/// Handles Xtream API communication with batching and caching optimizations
/// for mobile platforms. Designed for performance with TiviMate-level efficiency.
library;

import 'package:dio/dio.dart';
import 'package:flutter/foundation.dart';
import 'dart:async';
import 'dart:io';
import '../models/xtream_models.dart' as model;
import 'package:xtremobile/core/api/dns_resolver.dart';
import 'package:xtremobile/core/models/playlist_config.dart';
import 'xmltv_service.dart';

/// Counting semaphore used to cap concurrent EPG requests.
class _Semaphore {
  _Semaphore(this.maxConcurrent);

  final int maxConcurrent;
  int _current = 0;
  final _waiting = <Completer<void>>[];

  Future<void> acquire() {
    if (_current < maxConcurrent) {
      _current++;
      return Future.value();
    }
    final completer = Completer<void>();
    _waiting.add(completer);
    return completer.future;
  }

  void release() {
    if (_waiting.isNotEmpty) {
      _waiting.removeAt(0).complete();
      return;
    }
    if (_current > 0) _current--;
  }
}

/// EPG cache entry with TTL
class _EpgCacheEntry {
  final Map<String, model.ShortEPG> data;
  final DateTime timestamp;
  static const int ttlSeconds = 3600; // 1 hour TTL

  _EpgCacheEntry(this.data) : timestamp = DateTime.now();

  bool get isExpired =>
      DateTime.now().difference(timestamp).inSeconds > ttlSeconds;
}

/// Default community XMLTV guides, used only when the provider has no EPG of
/// its own. Ordered by preference; the first one that yields programmes wins.
const List<XmltvSource> kDefaultPublicXmltvSources = [
  XmltvSource(
    label: 'EPGShare FR1',
    url: 'https://epgshare01.online/epgshare01/epg_ripper_FR1.xml.gz',
  ),
];

/// Xtream API Service for Mobile
///
/// Optimized for Android with:
/// - Batch EPG loading (N+1 prevention)
/// - Provider-level caching with TTL
/// - XMLTV fallback when the provider serves no EPG
/// - Configurable timeouts and retries
/// - Memory-efficient streaming
class XtreamServiceMobile {
  final String cacheDir;

  /// Replaced with the configured instance in [setPlaylistAsync]; initialised
  /// eagerly so [dispose] is safe even if the service was never configured.
  Dio _dio = Dio();
  String _baseUrl = '';
  String _username = '';
  String _password = '';

  // Batch EPG cache to prevent N+1 queries
  final Map<String, _EpgCacheEntry> _epgBatchCache = {};

  // In-flight batch requests to deduplicate concurrent calls
  final Map<String, Future<Map<String, model.ShortEPG>>> _inFlightBatches = {};

  /// A channel grid asks for EPG one tile at a time, so a screenful fires ~30
  /// simultaneous `player_api.php` calls. Many Xtream panels rate-limit past a
  /// handful of parallel connections and answer with errors, which empties the
  /// EPG of the whole grid. Requests are therefore funnelled in small packets.
  static final _Semaphore _epgGate = _Semaphore(3);

  /// streamId → channel, populated by [getLiveChannels].
  ///
  /// The XMLTV fallback matches on `epg_channel_id` / channel name, neither of
  /// which the per-stream EPG calls carry — this index supplies them without
  /// changing any call site.
  final Map<String, model.Channel> _channelIndex = {};

  late final XmltvService _xmltv = XmltvService(cacheDir);

  /// User-provided XMLTV URL (empty = not configured).
  String _customXmltvUrl = '';

  /// Whether the community guides may be used as the last resort.
  bool _allowPublicXmltv = true;

  /// Set once every XMLTV source has failed, so a channel grid does not retry
  /// a multi-megabyte download for each of its tiles.
  bool _xmltvExhausted = false;

  XtreamServiceMobile(this.cacheDir);

  /// Label of the XMLTV source currently backing the fallback, if any.
  String? get xmltvSourceLabel => _xmltv.loadedSourceLabel;

  /// Configure the XMLTV fallback. Safe to call at any time.
  void setXmltvConfig({String? customUrl, bool? allowPublicFallback}) {
    final normalizedUrl = customUrl?.trim() ?? _customXmltvUrl;
    final changed = normalizedUrl != _customXmltvUrl ||
        (allowPublicFallback ?? _allowPublicXmltv) != _allowPublicXmltv;

    _customXmltvUrl = normalizedUrl;
    _allowPublicXmltv = allowPublicFallback ?? _allowPublicXmltv;

    if (changed) {
      // Sources changed — drop the "nothing works" latch and any indexed guide
      // so the new configuration is actually tried.
      _xmltvExhausted = false;
      _xmltv.clear();
      _epgBatchCache.clear();
    }
  }

  /// Initialize with playlist configuration
  Future<void> setPlaylistAsync(PlaylistConfig config) async {
    _baseUrl = config.dns;
    _username = config.username;
    _password = config.password;

    // Create independent Dio for Xtream API (avoid ApiClient baseUrl issues)
    _dio = Dio(
      BaseOptions(
        connectTimeout: const Duration(seconds: 15),
        receiveTimeout: const Duration(seconds: 30),
        sendTimeout: const Duration(seconds: 15),
      ),
    );

    // Warm the DNS entry for the panel host now, so the first zap does not pay
    // for resolution. Fire-and-forget: playback must never wait on this.
    unawaited(prewarmHost());

    if (kDebugMode) {
      print('✅ [XtreamServiceMobile] Initialized with URL: $_baseUrl');
    }
  }

  /// Resolve and pre-connect to the panel host.
  ///
  /// Opens a bare TCP/TLS socket and closes it immediately: no HTTP request is
  /// issued, so this never consumes one of the provider's connection slots,
  /// while still leaving the DNS entry cached and the route warm.
  Future<void> prewarmHost() async {
    final uri = Uri.tryParse(_baseUrl);
    if (uri == null || uri.host.isEmpty) return;

    try {
      await DnsResolver.resolve(uri.host).timeout(
        const Duration(seconds: 3),
        onTimeout: () => null,
      );
    } catch (_) {
      // DNS pre-resolution is best effort.
    }

    final isSecure = uri.scheme == 'https';
    final port = uri.hasPort ? uri.port : (isSecure ? 443 : 80);

    try {
      final socket = isSecure
          ? await SecureSocket.connect(
              uri.host,
              port,
              timeout: const Duration(milliseconds: 1200),
              onBadCertificate: (_) => true,
            )
          : await Socket.connect(
              uri.host,
              port,
              timeout: const Duration(milliseconds: 1200),
            );
      socket.destroy();
      if (kDebugMode) print('🔥 [Prewarm] ${uri.host}:$port ready');
    } catch (e) {
      if (kDebugMode) print('⚠️ [Prewarm] ${uri.host}:$port failed: $e');
    }
  }

  /// Get live channels for a category (with batch EPG support)
  /// If categoryId is empty, fetches ALL channels from all categories
  Future<List<model.Channel>> getLiveChannels(String categoryId) async {
    try {
      final queryParams = {
        'username': _username,
        'password': _password,
        'action': 'get_live_streams',
      };

      // Only add category_id if specified
      if (categoryId.isNotEmpty) {
        queryParams['category_id'] = categoryId;
      }

      if (kDebugMode) {
        print('🔍 Loading live channels with params: $queryParams');
      }

      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: queryParams,
        options: Options(
          receiveTimeout: const Duration(seconds: 15),
          sendTimeout: const Duration(seconds: 15),
        ),
      );

      if (response.statusCode == 200) {
        if (response.data is List) {
          final channels = (response.data as List)
              .map((e) => model.Channel.fromJson(e))
              .toList();

          // Keep the EPG-matching keys reachable from a bare streamId.
          for (final channel in channels) {
            _channelIndex[channel.streamId] = channel;
          }

          if (kDebugMode) {
            final categories = channels.map((c) => c.categoryName).toSet();
            print(
              '✅ Loaded ${channels.length} channels with ${categories.length} categories: $categories',
            );
          }

          return channels;
        } else if (response.data is Map) {
          if (kDebugMode)
            print('⚠️ API returned a Map instead of List: ${response.data}');
          return [];
        } else {
          if (kDebugMode)
            print(
                '⚠️ API returned unexpected type: ${response.data.runtimeType}');
          return [];
        }
      }

      if (kDebugMode) {
        print(
            '⚠️ Unexpected response status: ${response.statusCode}, body: ${response.data}');
      }
      return [];
    } catch (e) {
      if (kDebugMode) print('❌ Error loading live channels: $e');
      return [];
    }
  }

  /// Get SHORT EPG for a SINGLE channel (legacy, avoid - use getBatchEPG instead)
  Future<model.ShortEPG> getShortEPG(String streamId) async {
    // For backward compatibility, but prefer batch loading
    final batch = await getBatchEPG([streamId]);
    return batch[streamId] ??
        model.ShortEPG(
          id: streamId,
          title: '',
          start: DateTime.now().toIso8601String(),
          end: DateTime.now().add(const Duration(hours: 1)).toIso8601String(),
        );
  }

  /// Get SHORT EPG for MULTIPLE channels in ONE request
  ///
  /// This is the optimized method that prevents N+1 queries.
  /// Instead of 50 requests for 50 channels, this loads all at once.
  /// Results are cached for 1 hour to avoid repeated requests.
  Future<Map<String, model.ShortEPG>> getBatchEPG(
    List<String> streamIds,
  ) async {
    if (streamIds.isEmpty) return {};

    // Create cache key from sorted IDs for consistency
    final cacheKey = streamIds.toSet().toList()..sort();
    final cacheKeyStr = cacheKey.join(',');

    // Check if we have valid cached data
    final cached = _epgBatchCache[cacheKeyStr];
    if (cached != null && !cached.isExpired) {
      if (kDebugMode) {
        print('✅ EPG batch cache hit: ${streamIds.length} channels');
      }
      return cached.data;
    }

    // Check if this batch is already being loaded (deduplication)
    if (_inFlightBatches.containsKey(cacheKeyStr)) {
      if (kDebugMode) print('⏳ Reusing in-flight EPG batch request');
      return _inFlightBatches[cacheKeyStr]!;
    }

    // Load the batch
    final future = _loadEpgBatch(streamIds, cacheKeyStr);
    _inFlightBatches[cacheKeyStr] = future;

    try {
      final result = await future;
      _epgBatchCache[cacheKeyStr] = _EpgCacheEntry(result);
      return result;
    } finally {
      _inFlightBatches.remove(cacheKeyStr);
    }
  }

  /// Internal: Load EPG for a single stream
  /// NOTE: Xtream API get_short_epg only returns results for ONE stream_id at a time.
  /// Response format: {"epg_listings": [...]} where title/description are Base64 encoded.
  Future<Map<String, model.ShortEPG>> _loadEpgBatch(
    List<String> streamIds,
    String cacheKey,
  ) async {
    final result = <String, model.ShortEPG>{};

    // Load EPG for each stream_id individually (API doesn't support true batch)
    for (final streamId in streamIds) {
      await _epgGate.acquire();
      try {
        final response = await _dio
            .get(
              '$_baseUrl/player_api.php',
              queryParameters: {
                'username': _username,
                'password': _password,
                'action': 'get_short_epg',
                'stream_id': streamId,
              },
              options: Options(
                receiveTimeout: const Duration(seconds: 10),
                sendTimeout: const Duration(seconds: 10),
              ),
            )
            .timeout(const Duration(seconds: 10));

        if (response.statusCode == 200 && response.data is Map) {
          final data = response.data as Map;
          final listings = data['epg_listings'];

          if (listings is List && listings.isNotEmpty) {
            // Find the currently airing program
            final now = DateTime.now();
            Map<String, dynamic>? current;

            for (final item in listings) {
              if (item is! Map) continue;
              try {
                final start = DateTime.parse(item['start'].toString());
                final end = DateTime.parse(item['end'].toString());
                if (now.isAfter(start) && now.isBefore(end)) {
                  current = Map<String, dynamic>.from(item);
                  break;
                }
              } catch (_) {}
            }

            // Fallback to first entry if no current program found
            current ??= Map<String, dynamic>.from(listings.first as Map);

            result[streamId] = model.ShortEPG.fromJson({
              ...current,
              'id': streamId,
            });
          }
        }
      } catch (e) {
        if (kDebugMode) print('⚠️ EPG failed for $streamId: $e');
      } finally {
        _epgGate.release();
      }
    }

    // ── Fallback: whatever the provider could not answer for ──────────────
    final missing =
        streamIds.where((id) => !result.containsKey(id)).toList(growable: false);
    if (missing.isNotEmpty) {
      final recovered = await _resolveFromXmltv(missing);
      result.addAll(recovered);
      if (kDebugMode && recovered.isNotEmpty) {
        print(
          '📺 XMLTV fallback recovered ${recovered.length}/${missing.length} '
          'channels via "${_xmltv.loadedSourceLabel}"',
        );
      }
    }

    if (kDebugMode) {
      print('✅ EPG loaded: ${result.length}/${streamIds.length} channels');
    }
    return result;
  }

  /// XMLTV sources to try, in the order requested: the provider's own dump
  /// first (it is often populated even when `get_short_epg` is not), then the
  /// user's URL, then the community guides.
  List<XmltvSource> _xmltvSources() {
    return [
      XmltvSource(
        label: 'Fournisseur (xmltv.php)',
        url: '$_baseUrl/xmltv.php?username=$_username&password=$_password',
      ),
      if (_customXmltvUrl.isNotEmpty)
        XmltvSource(label: 'URL personnalisée', url: _customXmltvUrl),
      if (_allowPublicXmltv) ...kDefaultPublicXmltvSources,
    ];
  }

  /// Resolve missing EPG entries from the XMLTV index, loading it on demand.
  Future<Map<String, model.ShortEPG>> _resolveFromXmltv(
    List<String> streamIds,
  ) async {
    if (_xmltvExhausted) return {};

    // Nothing to match on: the channel list has not been loaded in this
    // session, so neither epg_channel_id nor the name is known.
    final known = streamIds
        .map((id) => _channelIndex[id])
        .whereType<model.Channel>()
        .toList();
    if (known.isEmpty) return {};

    try {
      final loaded = await _xmltv.ensureLoaded(_xmltvSources());
      if (!loaded) {
        _xmltvExhausted = true;
        return {};
      }
    } catch (e) {
      if (kDebugMode) print('⚠️ XMLTV load failed: $e');
      _xmltvExhausted = true;
      return {};
    }

    final resolved = <String, model.ShortEPG>{};
    for (final channel in known) {
      final epg = _xmltv.shortEpgFor(
        streamId: channel.streamId,
        epgChannelId: channel.epgChannelId,
        channelName: channel.name,
      );
      if (epg != null) resolved[channel.streamId] = epg;
    }
    return resolved;
  }

  /// Get live TV categories
  Future<List<model.Category>> getLiveCategories() async {
    try {
      if (kDebugMode) print('🔍 Loading live TV categories with 8s timeout...');

      final response = await _dio
          .get(
            '$_baseUrl/player_api.php',
            queryParameters: {
              'username': _username,
              'password': _password,
              'action': 'get_live_categories',
            },
            options: Options(
              receiveTimeout: const Duration(seconds: 8),
              sendTimeout: const Duration(seconds: 8),
            ),
          )
          .timeout(const Duration(seconds: 8));

      if (response.statusCode == 200) {
        if (response.data is List) {
          final categories = (response.data as List)
              .map((e) => model.Category.fromJson(e))
              .toList();

          if (kDebugMode) {
            print(
                '✅ Loaded ${categories.length} live categories: ${categories.map((c) => c.categoryName).toList()}');
          }

          return categories;
        } else if (response.data is Map) {
          if (kDebugMode)
            print(
                '⚠️ get_live_categories returned a Map (not a list): ${response.data}');
          return [];
        } else {
          if (kDebugMode)
            print(
                '⚠️ get_live_categories returned unexpected type: ${response.data.runtimeType}');
          return [];
        }
      }

      if (kDebugMode) {
        print(
            '⚠️ Failed to load categories (status: ${response.statusCode}, body: ${response.data})');
      }
      return [];
    } on TimeoutException {
      if (kDebugMode) {
        print(
          '⏱️ Timeout loading live categories - will fallback to loading all channels',
        );
      }
      return [];
    } catch (e) {
      if (kDebugMode) print('❌ Error loading live categories: $e');
      return [];
    }
  }

  /// Get VOD categories
  Future<List<model.Category>> getVodCategories() async {
    try {
      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: {
          'username': _username,
          'password': _password,
          'action': 'get_vod_categories',
        },
        options: Options(receiveTimeout: const Duration(seconds: 15)),
      );

      if (response.statusCode == 200 && response.data is List) {
        return (response.data as List)
            .map((e) => model.Category.fromJson(e))
            .toList();
      }
      return [];
    } catch (e) {
      if (kDebugMode) print('❌ Error loading VOD categories: $e');
      return [];
    }
  }

  /// Get movies by category
  /// If categoryId is empty, fetches ALL movies from all categories
  Future<List<model.VodItem>> getMoviesByCategory(String categoryId) async {
    try {
      final queryParams = {
        'username': _username,
        'password': _password,
        'action': 'get_vod_streams',
      };

      // Only add category_id if specified
      if (categoryId.isNotEmpty) {
        queryParams['category_id'] = categoryId;
      }

      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: queryParams,
      );
      if (response.statusCode == 200 && response.data is List) {
        return (response.data as List)
            .map((e) => model.VodItem.fromJson(e))
            .toList();
      }
      return [];
    } catch (e) {
      return [];
    }
  }

  /// Get all movies
  Future<List<model.VodItem>> getMovies() async {
    try {
      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: {
          'username': _username,
          'password': _password,
          'action': 'get_vod_streams',
        },
      );
      if (response.statusCode == 200 && response.data is List) {
        return (response.data as List)
            .map((e) => model.VodItem.fromJson(e))
            .toList();
      }
      return [];
    } catch (e) {
      return [];
    }
  }

  /// Search VOD movies
  Future<List<model.VodItem>> searchMovies(String query) async {
    final all = await getMovies();
    return all
        .where((m) => m.name.toLowerCase().contains(query.toLowerCase()))
        .toList();
  }

  /// Get all series
  Future<List<model.Series>> getSeries() async {
    try {
      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: {
          'username': _username,
          'password': _password,
          'action': 'get_series',
        },
        options: Options(receiveTimeout: const Duration(seconds: 45)),
      );
      if (response.statusCode == 200 && response.data is List) {
        return (response.data as List)
            .map((e) => model.Series.fromJson(e))
            .toList();
      }
      if (kDebugMode) {
        print(
            '⚠️ get_series returned unexpected status or type: ${response.statusCode}');
      }
      return [];
    } catch (e) {
      return [];
    }
  }

  /// Get series paginated / filtered by category
  Future<List<model.Series>> getSeriesPaginated({String? categoryId}) async {
    try {
      final queryParams = {
        'username': _username,
        'password': _password,
        'action': 'get_series',
      };

      if (categoryId != null && categoryId.isNotEmpty) {
        queryParams['category_id'] = categoryId;
      }

      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: queryParams,
        options: Options(receiveTimeout: const Duration(seconds: 30)),
      );

      if (response.statusCode == 200 && response.data is List) {
        return (response.data as List)
            .map((e) => model.Series.fromJson(e))
            .toList();
      }
      return [];
    } catch (e) {
      if (kDebugMode) print('❌ Error loading series by category: $e');
      return [];
    }
  }

  /// Get series categories
  Future<List<model.Category>> getSeriesCategories() async {
    try {
      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: {
          'username': _username,
          'password': _password,
          'action': 'get_series_categories',
        },
        options: Options(receiveTimeout: const Duration(seconds: 15)),
      );

      if (response.statusCode == 200 && response.data is List) {
        return (response.data as List)
            .map((e) => model.Category.fromJson(e))
            .toList();
      }
      return [];
    } catch (e) {
      if (kDebugMode) print('❌ Error loading series categories: $e');
      return [];
    }
  }

  /// Get series info
  Future<model.SeriesInfo?> getSeriesInfo(String seriesId) async {
    try {
      final response = await _dio.get(
        '$_baseUrl/player_api.php',
        queryParameters: {
          'username': _username,
          'password': _password,
          'action': 'get_series_info',
          'series_id': seriesId,
        },
      );

      if (response.statusCode == 200 && response.data is Map) {
        final data = response.data as Map<String, dynamic>;
        final seriesModel = model.Series.fromJson(data['info'] ?? {});

        final episodesMap = <String, List<model.Episode>>{};
        if (data['episodes'] is Map) {
          final seasons = data['episodes'] as Map<String, dynamic>;
          seasons.forEach((seasonNum, episodesList) {
            if (episodesList is List) {
              episodesMap[seasonNum] = episodesList
                  .map((e) => model.Episode.fromJson(e as Map<String, dynamic>))
                  .toList();
            }
          });
        }

        return model.SeriesInfo(
          series: seriesModel,
          episodes: episodesMap,
        );
      }
      return null;
    } catch (e) {
      return null;
    }
  }

  /// Clear cache
  void clearCache() {
    _epgBatchCache.clear();
    _inFlightBatches.clear();
  }

  /// Drop the XMLTV index (keeps its disk cache) and allow a fresh attempt.
  void resetXmltv() {
    _xmltv.clear();
    _xmltvExhausted = false;
    _epgBatchCache.clear();
  }

  /// Get Live Stream URL
  String getLiveStreamUrl(String streamId) {
    return '$_baseUrl/live/$_username/$_password/$streamId.ts';
  }

  /// Get VOD Stream URL
  String getVodStreamUrl(String streamId, String extension) {
    return '$_baseUrl/movie/$_username/$_password/$streamId.$extension';
  }

  /// Get Series Stream URL
  String getSeriesStreamUrl(String streamId, String extension) {
    return '$_baseUrl/series/$_username/$_password/$streamId.$extension';
  }

  /// Search series (local filter on full list)
  Future<List<model.Series>> searchSeries(String query) async {
    try {
      final allSeries = await getSeries();
      if (query.isEmpty) return allSeries;

      final normalizedQuery = query.toLowerCase();
      return allSeries
          .where((s) => s.name.toLowerCase().contains(normalizedQuery))
          .toList();
    } catch (e) {
      if (kDebugMode) print('❌ Error searching series: $e');
      return [];
    }
  }

  /// Dispose service resources
  void dispose() {
    clearCache();
    _channelIndex.clear();
    _xmltv.clear();
    _dio.close(force: true);
  }
}