import 'dart:async';

import 'package:flutter/material.dart';
import 'package:material_symbols_icons/symbols.dart';
import 'package:provider/provider.dart';

import '../../focus/focusable_action_bar.dart';
import '../../i18n/strings.g.dart';
import '../../media/live_tv_support.dart';
import '../../models/livetv_channel.dart';
import '../../models/livetv_dvr.dart';
import '../../mixins/refreshable.dart';
import '../../mixins/tab_navigation_mixin.dart';
import '../../providers/multi_server_provider.dart';
import '../../providers/settings_provider.dart';
import '../../utils/app_logger.dart';
import '../../utils/desktop_window_padding.dart';
import '../../utils/platform_detector.dart';
import '../../widgets/app_icon.dart';
import '../../widgets/overlay_sheet.dart';
import 'reorder_favorites_sheet.dart';
import 'tabs/guide_tab.dart';
import 'tabs/whats_on_tab.dart';

enum LiveTvTab { guide, whatsOn }

class LiveTvScreen extends StatefulWidget {
  const LiveTvScreen({super.key});

  @override
  State<LiveTvScreen> createState() => _LiveTvScreenState();
}

class _LiveTvScreenState extends State<LiveTvScreen>
    with TickerProviderStateMixin, TabNavigationMixin
    implements FocusableTab {
  final _guideTabFocusNode = FocusNode(debugLabel: 'tab_chip_guide');
  final _whatsOnTabFocusNode = FocusNode(debugLabel: 'tab_chip_whats_on');
  final _guideTabKey = GlobalKey<GuideTabState>();
  final _whatsOnTabKey = GlobalKey<WhatsOnTabState>();

  // App bar action bar
  final _actionBarKey = GlobalKey<FocusableActionBarState>();

  List<LiveTvChannel> _channels = [];
  bool _isLoading = true;
  String? _error;

  // Favorites
  bool _showFavoritesOnly = false;
  Set<String> _favoriteKeys = {};
  List<FavoriteChannel> _favoriteChannels = [];

  /// Source URI per Live TV server/DVR, built from machineIdentifier + EPG provider identifier.
  final Map<String, String> _favoriteSourceByLiveServer = {};
  final Map<String, String> _favoriteSourceByChannel = {};
  final Map<String, String> _favoriteStoreByLiveServer = {};
  final Map<String, String> _favoriteStoreByChannel = {};
  final Map<String, String> _favoriteStoreBySource = {};
  final Map<String, FavoriteChannelPersistenceMode> _favoriteModeByStore = {};

  List<LiveTvChannel> get _filteredChannels {
    if (!_showFavoritesOnly) return _channels;
    if (_favoriteKeys.isEmpty) return const [];
    final channelMap = {for (final c in _channels) _favoriteKeyForChannel(c): c};
    return [
      for (final fav in _favoriteChannels)
        if (channelMap.containsKey(fav.stableKey)) channelMap[fav.stableKey]!,
    ];
  }

  String _liveServerScopeKey(LiveTvServerInfo serverInfo) => '${serverInfo.serverId}\u0000${serverInfo.dvrKey}';

  String _sourceForChannel(LiveTvChannel channel) {
    return channel.favoriteSource ?? _favoriteSourceByChannel[liveTvChannelScopeKey(channel)] ?? '';
  }

  String _favoriteKeyForChannel(LiveTvChannel channel) => favoriteChannelKey(_sourceForChannel(channel), channel.key);

  bool _isFavoriteChannel(LiveTvChannel channel) => _favoriteKeys.contains(_favoriteKeyForChannel(channel));

  void _refreshFavoriteKeys() {
    _favoriteKeys = _favoriteChannels.map((f) => f.stableKey).toSet();
  }

  @override
  List<FocusNode> get tabChipFocusNodes => [_guideTabFocusNode, _whatsOnTabFocusNode];

  @override
  void initState() {
    super.initState();
    suppressAutoFocus = true;
    _showFavoritesOnly = context.read<SettingsProvider>().liveTvDefaultFavorites;
    initTabNavigation();
    _loadChannels();
  }

  @override
  void dispose() {
    _guideTabFocusNode.dispose();
    _whatsOnTabFocusNode.dispose();
    disposeTabNavigation();
    super.dispose();
  }

  @override
  void onTabChanged() {
    if (!tabController.indexIsChanging) {
      super.onTabChanged();
      // Pause/resume timers based on active tab
      switch (LiveTvTab.values[tabController.index]) {
        case LiveTvTab.guide:
          _whatsOnTabKey.currentState?.pauseRefresh();
          _guideTabKey.currentState?.resumeRefresh();
        case LiveTvTab.whatsOn:
          _guideTabKey.currentState?.pauseRefresh();
          _whatsOnTabKey.currentState?.resumeRefresh();
      }
    }
  }

  /// Extracts enabled channel keys from DVR mappings, returning null if no DVR has mapping data.
  Set<String>? _extractEnabledChannelKeys(List<LiveTvDvr> dvrs) {
    final enabledKeys = <String>{};
    bool hasMappings = false;
    for (final dvr in dvrs) {
      if (dvr.channelMappings.isEmpty) continue;
      hasMappings = true;
      for (final m in dvr.channelMappings) {
        if (m.enabled == true && m.channelKey != null) {
          enabledKeys.add(m.channelKey!);
        }
      }
    }
    return hasMappings ? enabledKeys : null;
  }

  Set<String>? _extractEnabledChannelKeysForServerInfo(LiveTvServerInfo serverInfo) {
    final matching = serverInfo.dvrs.where((dvr) => dvr.key == serverInfo.dvrKey).toList();
    return _extractEnabledChannelKeys(matching.isNotEmpty ? matching : serverInfo.dvrs);
  }

  Future<void> _loadChannels() async {
    if (!mounted) return;
    setState(() {
      _isLoading = true;
      _error = null;
    });

    try {
      final multiServer = context.read<MultiServerProvider>();
      final liveTvServers = multiServer.liveTvServers;

      if (liveTvServers.isEmpty) {
        setState(() {
          _isLoading = false;
          _error = t.liveTv.noDvr;
        });
        return;
      }

      final allChannels = <LiveTvChannel>[];
      final seenChannels = <String>{};
      _favoriteSourceByLiveServer.clear();
      _favoriteSourceByChannel.clear();
      _favoriteStoreByLiveServer.clear();
      _favoriteStoreByChannel.clear();
      _favoriteStoreBySource.clear();
      _favoriteModeByStore.clear();

      appLogger.d(
        'Live TV DVRs: ${liveTvServers.map((s) => '${s.serverId}/${s.dvrKey} lineup=${s.lineup}').join(', ')}',
      );

      // Build a set of enabled channel keys per Live TV DVR from cached DVR data.
      final enabledKeysByLiveServer = <String, Set<String>>{};
      for (final serverInfo in liveTvServers) {
        final enabledKeys = _extractEnabledChannelKeysForServerInfo(serverInfo);
        if (enabledKeys != null) {
          enabledKeysByLiveServer[_liveServerScopeKey(serverInfo)] = enabledKeys;
        }
      }

      for (final serverInfo in liveTvServers) {
        try {
          final genericClient = multiServer.getClientForServer(serverInfo.serverId);
          if (genericClient == null) continue;

          final liveTv = genericClient.liveTv;
          final source = await liveTv.buildFavoriteChannelSource(lineup: serverInfo.lineup);
          final storeKey = liveTv.favoriteStoreKey;
          final liveServerKey = _liveServerScopeKey(serverInfo);
          _favoriteSourceByLiveServer[liveServerKey] = source;
          _favoriteStoreByLiveServer[liveServerKey] = storeKey;
          _favoriteStoreBySource[source] = storeKey;
          _favoriteModeByStore[storeKey] = liveTv.favoritePersistenceMode;

          final channels = await genericClient.liveTv.fetchChannels(lineup: serverInfo.lineup);
          // Plex's DVR exposes a separate enabled-channel mapping; Jellyfin
          // already filters to subscribed channels server-side.
          final enabledKeys = enabledKeysByLiveServer[liveServerKey];
          appLogger.d(
            'Channels from ${serverInfo.dvrKey}: ${channels.length} channels (${enabledKeys?.length ?? 'all'} enabled)',
          );
          for (final channel in channels) {
            if (enabledKeys != null && !enabledKeys.contains(channel.key)) continue;
            final scopedChannel = channel.copyWith(
              liveDvrKey: serverInfo.dvrKey,
              favoriteSource: source,
              favoriteStoreKey: storeKey,
            );
            final dedupKey = liveTvChannelScopeKey(scopedChannel);
            if (seenChannels.add(dedupKey)) {
              final scopeKey = liveTvChannelScopeKey(scopedChannel);
              _favoriteSourceByChannel[scopeKey] = source;
              _favoriteStoreByChannel[scopeKey] = storeKey;
              allChannels.add(scopedChannel);
            }
          }
        } catch (e) {
          appLogger.e('Failed to load channels from server ${serverInfo.serverId}', error: e);
        }
      }

      allChannels.sort((a, b) {
        final aNum = double.tryParse(a.number ?? '') ?? 999999;
        final bNum = double.tryParse(b.number ?? '') ?? 999999;
        return aNum.compareTo(bNum);
      });

      if (!mounted) return;

      appLogger.d('Live TV: loaded ${allChannels.length} channels');

      setState(() {
        _channels = allChannels;
        _isLoading = false;
      });

      // Load favorites by backend store: Plex is cloud/account-scoped, Jellyfin per server.
      unawaited(_loadFavorites(multiServer));

      if (allChannels.isNotEmpty && PlatformDetector.shouldUseSideNavigation(context)) {
        WidgetsBinding.instance.addPostFrameCallback((_) {
          if (mounted) _focusCurrentTab();
        });
      }
    } catch (e) {
      appLogger.e('Failed to load Live TV channels', error: e);
      if (mounted) {
        setState(() {
          _isLoading = false;
          _error = e.toString();
        });
      }
    }
  }

  Future<void> _loadFavorites(MultiServerProvider multiServer) async {
    try {
      _favoriteSourceByLiveServer.clear();
      _favoriteStoreBySource.clear();
      _favoriteModeByStore.clear();
      final merged = <FavoriteChannel>[];
      final fetchedStores = <String>{};
      final seenFavorites = <String>{};
      for (final serverInfo in multiServer.liveTvServers) {
        final client = multiServer.getClientForServer(serverInfo.serverId);
        if (client == null) continue;
        final liveTv = client.liveTv;
        final source = await liveTv.buildFavoriteChannelSource(lineup: serverInfo.lineup);
        final storeKey = liveTv.favoriteStoreKey;
        final liveServerKey = _liveServerScopeKey(serverInfo);
        _favoriteSourceByLiveServer[liveServerKey] = source;
        _favoriteStoreByLiveServer[liveServerKey] = storeKey;
        _favoriteStoreBySource[source] = storeKey;
        _favoriteModeByStore[storeKey] = liveTv.favoritePersistenceMode;
        if (!fetchedStores.add(storeKey)) continue;
        final serverFavorites = await liveTv.fetchFavoriteChannels();
        for (final favorite in serverFavorites) {
          _favoriteStoreBySource[favorite.source] = storeKey;
          if (seenFavorites.add(favorite.stableKey)) merged.add(favorite);
        }
      }

      if (!mounted) return;
      setState(() {
        _favoriteChannels = merged;
        _refreshFavoriteKeys();
      });
      appLogger.d('Live TV: loaded ${merged.length} favorite channels');
    } catch (e) {
      appLogger.e('Failed to load favorite channels', error: e);
    }
  }

  void _toggleFavoritesFilter() {
    setState(() {
      _showFavoritesOnly = !_showFavoritesOnly;
    });
  }

  void _toggleFavorite(LiveTvChannel channel) {
    final source = _sourceForChannel(channel);
    final favoriteKey = favoriteChannelKey(source, channel.key);
    final scopeKey = liveTvChannelScopeKey(channel);
    final storeKey = channel.favoriteStoreKey ?? _favoriteStoreByChannel[scopeKey];
    if (storeKey != null) _favoriteStoreBySource[source] = storeKey;

    setState(() {
      if (_favoriteKeys.contains(favoriteKey)) {
        _favoriteChannels = _favoriteChannels.where((f) => f.id != channel.key || f.source != source).toList();
      } else {
        _favoriteChannels = [..._favoriteChannels, FavoriteChannel.fromLiveTvChannel(channel, source)];
      }
      _refreshFavoriteKeys();
    });

    _persistFavorites();
  }

  void _showReorderFavorites() {
    final channelMap = {for (final c in _channels) _favoriteKeyForChannel(c): c};

    OverlaySheetController.showAdaptive(
      context,
      builder: (sheetContext) => ReorderFavoritesSheet(
        favorites: List.from(_favoriteChannels),
        channelMap: channelMap,
        onReorder: (reordered) {
          setState(() {
            _favoriteChannels = reordered;
            _refreshFavoriteKeys();
          });
          _persistFavorites();
        },
        onRemove: (removed) {
          setState(() {
            _favoriteChannels = _favoriteChannels.where((f) => f.stableKey != removed.stableKey).toList();
            _refreshFavoriteKeys();
          });
          _persistFavorites();
        },
      ),
    );
  }

  void _persistFavorites() {
    final multiServer = context.read<MultiServerProvider>();
    final byStore = <String, List<FavoriteChannel>>{};
    for (final f in _favoriteChannels) {
      final storeKey = _favoriteStoreBySource[f.source];
      if (storeKey == null) continue;
      byStore.putIfAbsent(storeKey, () => []).add(f);
    }
    final writtenStores = <String>{};
    for (final serverInfo in multiServer.liveTvServers) {
      final client = multiServer.getClientForServer(serverInfo.serverId);
      if (client == null) continue;
      final liveServerKey = _liveServerScopeKey(serverInfo);
      final storeKey = _favoriteStoreByLiveServer[liveServerKey];
      if (storeKey == null || !writtenStores.add(storeKey)) continue;
      final mode = _favoriteModeByStore[storeKey] ?? client.liveTv.favoritePersistenceMode;
      final source = _favoriteSourceByLiveServer[liveServerKey];
      if (source == null) continue; // not yet resolved — skip; next toggle will catch up
      final channels = switch (mode) {
        FavoriteChannelPersistenceMode.sharedFullList => byStore[storeKey] ?? const <FavoriteChannel>[],
        FavoriteChannelPersistenceMode.serverSlice =>
          (byStore[storeKey] ?? const <FavoriteChannel>[]).where((f) => f.source == source).toList(),
      };
      unawaited(client.liveTv.setFavoriteChannels(channels));
    }
  }

  void _focusCurrentTab() {
    switch (LiveTvTab.values[tabController.index]) {
      case LiveTvTab.guide:
        _guideTabKey.currentState?.focusContent();
      case LiveTvTab.whatsOn:
        _whatsOnTabKey.currentState?.focusFirstHub();
    }
    setState(() {
      suppressAutoFocus = false;
    });
  }

  @override
  void focusActiveTabIfReady() => _focusCurrentTab();

  String _getTabLabel(LiveTvTab tab) {
    return switch (tab) {
      LiveTvTab.guide => t.liveTv.guide,
      LiveTvTab.whatsOn => t.liveTv.whatsOn,
    };
  }

  List<Widget> _buildTabChipItems() {
    return [
      for (int i = 0; i < LiveTvTab.values.length; i++) ...[
        if (i > 0) const SizedBox(width: 8),
        buildTabChip(
          _getTabLabel(LiveTvTab.values[i]),
          i,
          onSelectWhenActive: _focusCurrentTab,
          onNavigateDown: _focusCurrentTab,
          onNavigateRightFromLast: () => _actionBarKey.currentState?.requestFocusOnFirst(),
        ),
      ],
    ];
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final useSideNav = PlatformDetector.shouldUseSideNavigation(context);

    return Scaffold(
      appBar: AppBar(
        title: useSideNav ? Row(children: _buildTabChipItems()) : Text(t.liveTv.title),
        actions: DesktopAppBarHelper.buildAdjustedActions([
          FocusableActionBar(
            key: _actionBarKey,
            onNavigateLeft: () => getTabChipFocusNode(tabCount - 1).requestFocus(),
            onNavigateDown: _focusCurrentTab,
            actions: [
              FocusableAction(
                icon: _showFavoritesOnly ? Symbols.star_rounded : Symbols.star_outline_rounded,
                iconFill: _showFavoritesOnly ? 1.0 : 0.0,
                tooltip: t.liveTv.favorites,
                onPressed: _toggleFavoritesFilter,
              ),
              if (_showFavoritesOnly && _favoriteChannels.length > 1)
                FocusableAction(
                  icon: Symbols.swap_vert_rounded,
                  tooltip: t.liveTv.reorderFavorites,
                  onPressed: _showReorderFavorites,
                ),
              FocusableAction(icon: Symbols.refresh_rounded, tooltip: t.liveTv.reloadGuide, onPressed: _loadChannels),
            ],
          ),
        ]),
      ),
      body: _buildLiveTvBody(theme, useSideNav),
    );
  }

  Widget _buildLiveTvBody(ThemeData theme, bool useSideNav) {
    if (_isLoading) {
      return const Center(child: CircularProgressIndicator());
    }
    if (_error != null) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            AppIcon(Symbols.error_rounded, size: 48, color: theme.colorScheme.error),
            const SizedBox(height: 16),
            Text(_error!, style: theme.textTheme.bodyLarge),
            const SizedBox(height: 16),
            FilledButton.icon(
              onPressed: _loadChannels,
              icon: const AppIcon(Symbols.refresh_rounded),
              label: Text(t.common.retry),
            ),
          ],
        ),
      );
    }
    if (_channels.isEmpty) {
      return Center(child: Text(t.liveTv.noChannels));
    }

    final guideChannels = _filteredChannels;

    return Column(
      children: [
        if (!useSideNav)
          Container(
            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
            alignment: Alignment.centerLeft,
            child: SingleChildScrollView(
              scrollDirection: Axis.horizontal,
              child: Row(children: _buildTabChipItems()),
            ),
          ),
        Expanded(
          child: TabBarView(
            controller: tabController,
            children: [
              GuideTab(
                key: _guideTabKey,
                channels: guideChannels,
                isFavoriteChannel: _isFavoriteChannel,
                onToggleFavorite: _toggleFavorite,
                onNavigateUp: focusTabBar,
                onBack: onTabBarBack,
              ),
              WhatsOnTab(key: _whatsOnTabKey, channels: _channels, onNavigateUp: focusTabBar, onBack: onTabBarBack),
            ],
          ),
        ),
      ],
    );
  }
}