import 'dart:async';
import '../media/ids.dart';

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

import '../media/media_item.dart';
import '../media/media_kind.dart';
import '../media/media_playlist.dart';
import '../models/plex/play_queue_response.dart';
import '../providers/multi_server_provider.dart';
import '../providers/playback_state_provider.dart';
import '../utils/video_player_navigation.dart';
import '../i18n/strings.g.dart';
import 'media_list_playback_launcher.dart';
import 'plex_client.dart';

// Re-export the result types so existing imports of this file keep working.
export 'media_list_playback_launcher.dart'
    show PlayQueueResult, PlayQueueSuccess, PlayQueueEmpty, PlayQueueCancelled, PlayQueueError;

/// Plex-specific play queue launcher.
///
/// Centralizes the common pattern of:
/// 1. Creating a play queue via Plex's server-side `/playQueues` resource
/// 2. Setting up [PlaybackStateProvider]
/// 3. Navigating to the video player
/// 4. Handling errors with appropriate feedback
///
/// Implements the backend-neutral [MediaListPlaybackLauncher] entry points
/// on top of that resource.
class PlexPlayQueueLauncher extends MediaListPlaybackLauncher {
  final BuildContext context;
  final PlexClient client;
  final String? serverId;
  final String? serverName;

  /// Narrow test seam for asserting queue publication without building the
  /// full player route dependency tree.
  final PlaybackStateProvider? playbackStateForTesting;
  final Future<void> Function(MediaItem item)? navigateForTesting;

  PlexPlayQueueLauncher({
    required this.context,
    required this.client,
    this.serverId,
    this.serverName,
    this.playbackStateForTesting,
    this.navigateForTesting,
  });

  /// Resolve the right [PlexClient] for [item]'s server and build a launcher.
  /// Falls back to the first available Plex client when [item] doesn't carry
  /// a `serverId`.
  factory PlexPlayQueueLauncher.forContext(BuildContext context, Object item) {
    final String? itemServerId;
    final String? itemServerName;
    if (item is MediaItem) {
      itemServerId = item.serverId;
      itemServerName = item.serverName;
    } else if (item is MediaPlaylist) {
      itemServerId = item.serverId;
      itemServerName = item.serverName;
    } else {
      itemServerId = null;
      itemServerName = null;
    }

    final provider = Provider.of<MultiServerProvider>(context, listen: false);
    PlexClient? plexClient;
    if (itemServerId != null) {
      // Plex-only: server-side `/playQueues` resource has no Jellyfin equivalent.
      plexClient = provider.getPlexClientForServer(ServerId(itemServerId));
    }
    if (plexClient == null) {
      // Fall back to the first online Plex client.
      for (final id in provider.onlineServerIds) {
        final c = provider.getPlexClientForServer(ServerId(id));
        if (c != null) {
          plexClient = c;
          break;
        }
      }
    }
    if (plexClient == null) {
      throw Exception(t.errors.noClientAvailable);
    }
    return PlexPlayQueueLauncher(
      context: context,
      client: plexClient,
      serverId: itemServerId,
      serverName: itemServerName,
    );
  }

  /// Launch playback from a collection or playlist.
  ///
  /// Accepts a [MediaItem] (collection) or [MediaPlaylist]. Typed as [Object]
  /// because Dart has no nominal union type.
  @override
  Future<PlayQueueResult> launchFromCollectionOrPlaylist({
    required Object item,
    required bool shuffle,
    MediaItem? startItem,
    bool showLoadingIndicator = true,
  }) async {
    final facts = MediaListPlaybackLauncher.classifyItem(item);
    if (facts == null) {
      return PlayQueueError(Exception('Item must be either a collection or playlist'));
    }
    final ratingKey = facts.id;
    final itemServerId = facts.serverId ?? serverId;
    final itemServerName = facts.serverName ?? serverName;

    return executeWithLoading(
      context: context,
      showLoading: showLoadingIndicator,
      actionLabel: t.common.shuffle,
      execute: (dismissLoading) async {
        PlayQueueResponse? playQueue;
        final sourceLibraryId = facts.isCollection && item is MediaItem ? item.libraryId : null;
        final sourceLibraryTitle = facts.isCollection && item is MediaItem ? item.libraryTitle : null;
        // Plex's `key` param positions the queue's selected item — passed
        // through when the caller wants playback to start at a specific
        // entry. Ignored on shuffle (the server picks a random head).
        final selectedKey = (!shuffle && startItem != null) ? '/library/metadata/${startItem.id}' : null;

        if (facts.isCollection) {
          final machineId = client.config.machineIdentifier ?? await client.getMachineIdentifier();

          if (machineId == null) {
            throw Exception('Could not get server machine identifier');
          }

          final collectionUri = 'server://$machineId/com.plexapp.plugins.library/library/collections/$ratingKey';
          playQueue = await client.createPlayQueue(
            uri: collectionUri,
            type: 'video',
            shuffle: shuffle ? 1 : 0,
            key: selectedKey,
            librarySectionID: sourceLibraryId,
            librarySectionTitle: sourceLibraryTitle,
          );
        } else {
          // For playlists, use playlistID parameter
          playQueue = await client.createPlayQueue(
            playlistID: int.parse(ratingKey),
            type: 'video',
            shuffle: shuffle ? 1 : 0,
            key: selectedKey,
          );
        }

        playQueue = await _refetchIfEmpty(playQueue, libraryId: sourceLibraryId, libraryTitle: sourceLibraryTitle);

        // Close loading dialog before navigating to the player
        await dismissLoading();

        return _launchFromQueue(
          playQueue: playQueue,
          ratingKey: ratingKey,
          serverId: serverIdOrNull(itemServerId),
          serverName: itemServerName,
          libraryId: sourceLibraryId,
          libraryTitle: sourceLibraryTitle,
          selectedItem: selectedKey != null ? _resolveSelectedMediaItem(playQueue) : null,
        );
      },
    );
  }

  /// Launch shuffled playback for a show or season.
  @override
  Future<PlayQueueResult> launchShuffledShow({required MediaItem metadata, bool showLoadingIndicator = true}) async {
    final kind = metadata.kind;

    if (kind != MediaKind.show && kind != MediaKind.season) {
      return PlayQueueError(Exception('Shuffle play only works for shows and seasons'));
    }

    return executeWithLoading(
      context: context,
      showLoading: showLoadingIndicator,
      actionLabel: t.common.shuffle,
      execute: (dismissLoading) async {
        // Determine the rating key for the play queue
        String showRatingKey;
        if (kind == MediaKind.show) {
          showRatingKey = metadata.id;
        } else {
          // For seasons, we need the show's rating key
          if (metadata.parentId == null) {
            throw Exception('Season is missing parentRatingKey');
          }
          showRatingKey = metadata.parentId!;
        }

        final playQueue = await client.createShowPlayQueue(
          showRatingKey: showRatingKey,
          shuffle: 1,
          librarySectionID: metadata.libraryId,
          librarySectionTitle: metadata.libraryTitle,
        );

        // Close loading dialog before navigating to the player
        await dismissLoading();

        return _launchFromQueue(
          playQueue: playQueue,
          ratingKey: showRatingKey,
          serverId: serverIdOrNull(metadata.serverId ?? serverId),
          serverName: metadata.serverName ?? serverName,
          libraryId: metadata.libraryId,
          libraryTitle: metadata.libraryTitle,
          copyServerInfo: true,
        );
      },
    );
  }

  /// Launch playback from a folder's contents. The `/folder` key and the
  /// owning library are both stamped onto the folder row by the listing
  /// fetch, so the neutral [MediaItem] carries everything Plex needs.
  @override
  Future<PlayQueueResult> launchFromFolder({
    required MediaItem folder,
    required bool shuffle,
    bool showLoadingIndicator = true,
  }) async {
    final folderKey = folder.backendFolderKey;
    if (folderKey == null) {
      return PlayQueueError(Exception('Folder is missing its backend folder key'));
    }
    final libraryId = folder.libraryId;
    final libraryTitle = folder.libraryTitle;

    return executeWithLoading(
      context: context,
      showLoading: showLoadingIndicator,
      actionLabel: shuffle ? t.common.shuffle : t.common.play,
      execute: (dismissLoading) async {
        final folderUri = await client.buildFolderUri(folderKey);

        var playQueue = await client.createPlayQueue(
          uri: folderUri,
          type: 'video',
          shuffle: shuffle ? 1 : 0,
          librarySectionID: libraryId,
          librarySectionTitle: libraryTitle,
        );

        playQueue = await _refetchIfEmpty(playQueue, libraryId: libraryId, libraryTitle: libraryTitle);

        await dismissLoading();

        return _launchFromQueue(
          playQueue: playQueue,
          ratingKey: folderKey,
          serverId: serverIdOrNull(serverId),
          serverName: serverName,
          libraryId: libraryId,
          libraryTitle: libraryTitle,
        );
      },
    );
  }

  /// Creation sometimes returns a queue without its items; re-read it by ID
  /// and keep the refetched copy only when it actually carries items.
  Future<PlayQueueResponse?> _refetchIfEmpty(
    PlayQueueResponse? playQueue, {
    String? libraryId,
    String? libraryTitle,
  }) async {
    if (playQueue == null || (playQueue.items != null && playQueue.items!.isNotEmpty)) {
      return playQueue;
    }
    final fetchedQueue = await client.getPlayQueue(
      playQueue.playQueueID,
      librarySectionID: libraryId,
      librarySectionTitle: libraryTitle,
    );
    if (fetchedQueue != null && fetchedQueue.items != null && fetchedQueue.items!.isNotEmpty) {
      return fetchedQueue;
    }
    return playQueue;
  }

  /// Core method to launch playback from a play queue.
  Future<PlayQueueResult> _launchFromQueue({
    required PlayQueueResponse? playQueue,
    required String ratingKey,
    ServerId? serverId,
    String? serverName,
    String? libraryId,
    String? libraryTitle,
    MediaItem? selectedItem,
    bool copyServerInfo = false,
  }) async {
    if (playQueue == null || playQueue.items == null || playQueue.items!.isEmpty) {
      return const PlayQueueEmpty();
    }

    if (!context.mounted && navigateForTesting == null) {
      return const PlayQueueError('Context not mounted');
    }

    final playbackState = playbackStateForTesting ?? context.read<PlaybackStateProvider>();
    playbackState.setPlayQueueWindowFetcher(
      libraryId == null
          ? (id, {center, window = 50}) => client.getPlayQueue(id, center: center, window: window)
          : (id, {center, window = 50}) => client.getPlayQueue(
              id,
              center: center,
              window: window,
              librarySectionID: libraryId,
              librarySectionTitle: libraryTitle,
            ),
    );
    await playbackState.setPlaybackFromPlayQueue(playQueue, ratingKey);

    if (!context.mounted && navigateForTesting == null) {
      return const PlayQueueError('Context not mounted');
    }

    var itemToPlay = selectedItem ?? playQueue.items!.first;

    if (copyServerInfo && serverId != null) {
      itemToPlay = itemToPlay.copyWith(
        serverId: serverId,
        serverName: serverName ?? itemToPlay.serverName,
        libraryId: itemToPlay.libraryId ?? libraryId,
        libraryTitle: itemToPlay.libraryTitle ?? libraryTitle,
      );
    }

    if (navigateForTesting != null) {
      await navigateForTesting!(itemToPlay);
    } else {
      await navigateToVideoPlayer(context, metadata: itemToPlay);
    }

    return const PlayQueueSuccess();
  }
}

/// Pull the selected item from a play queue. The selected item is identified
/// by `playQueueSelectedItemID`; returns null if the queue has no selection.
MediaItem? _resolveSelectedMediaItem(PlayQueueResponse? playQueue) {
  return playQueue?.selectedItem;
}