import 'dart:async';
import 'dart:math';
import 'package:audio_service/audio_service.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:freezer/api/definitions.dart';
import 'package:freezer/api/player.dart';
import 'package:freezer/translations.i18n.dart';
import 'package:freezer/ui/menu.dart';
import 'package:freezer/ui/tiles.dart';

class QueueScreen extends StatelessWidget {
  const QueueScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text('Queue'.i18n),
          systemOverlayStyle: SystemUiOverlayStyle(
            statusBarColor: Colors.transparent,
            statusBarIconBrightness: Brightness.light,
            statusBarBrightness: Brightness.light,
            systemNavigationBarColor: Theme.of(context).scaffoldBackgroundColor,
            systemNavigationBarDividerColor: Color(
                Theme.of(context).scaffoldBackgroundColor.value - 0x00111111),
            systemNavigationBarIconBrightness: Brightness.light,
          ),
          // actions: <Widget>[
          //   IconButton(
          //     icon: Icon(
          //       Icons.shuffle,
          //       semanticLabel: "Shuffle".i18n,
          //     ),
          //     onPressed: () async {
          //       await playerHelper.toggleShuffle();
          //       setState(() {});
          //     },
          //   )
          // ],
        ),
        body: const SafeArea(child: QueueListWidget(shouldPopOnTap: true)));
  }
}

class QueueListWidget extends StatefulWidget {
  final bool shouldPopOnTap;
  const QueueListWidget({super.key, this.shouldPopOnTap = false});

  @override
  State<QueueListWidget> createState() => _QueueListWidgetState();
}

class _QueueListWidgetState extends State<QueueListWidget> {
  static const itemExtent = 68.0; // height of each TrackTile
  final _scrollController = ScrollController();
  late StreamSubscription _queueSub;
  static const _dismissibleBackground = DecoratedBox(
      decoration: BoxDecoration(color: Colors.red),
      child: Align(
          alignment: Alignment.centerLeft,
          child: Padding(
              padding: EdgeInsets.symmetric(horizontal: 24.0),
              child: Icon(Icons.delete))));
  static const _dismissibleSecondaryBackground = DecoratedBox(
      decoration: BoxDecoration(color: Colors.red),
      child: Align(
          alignment: Alignment.centerRight,
          child: Padding(
              padding: EdgeInsets.symmetric(horizontal: 24.0),
              child: Icon(Icons.delete))));

  bool _isReordering = false;

  /// Basically a simple list that keeps itself synchronized with [AudioHandler.queue],
  /// so that the [ReorderableListView] is updated instanly (as it should be)
  List<MediaItem> _queueCache = [];

  @override
  void initState() {
    _queueCache = List.from(audioHandler.queue.value); // avoid shadow-copying
    _queueSub = audioHandler.queue.listen((newQueue) {
      print('got new queue!');
      // if (listEquals(_queueCache, newQueue)) {
      //   print('avoiding rebuilding queue since they are the same');
      //   return;
      // }
      _queueCache = List.from(newQueue);

      setState(() {});
    });
    WidgetsBinding.instance.addPostFrameCallback((_) {
      // calculate position of current item
      double position = min(playerHelper.queueIndex * itemExtent,
          _scrollController.position.maxScrollExtent);

      _scrollController.jumpTo(position);
    });
    super.initState();
  }

  @override
  void dispose() {
    _queueSub.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ReorderableListView.builder(
      buildDefaultDragHandles: false,
      scrollController: _scrollController,
      // specify the itemExtent normally and remove it when reordering because of an issue with [SliverFixedExtentList]
      // https://github.com/flutter/flutter/issues/84901
      itemExtent: _isReordering ? null : itemExtent,
      onReorderStart: (_) => setState(() => _isReordering = true),
      onReorderEnd: (_) => setState(() => _isReordering = true),
      onReorder: (oldIndex, newIndex) {
        setState(() => _queueCache.reorder(oldIndex, newIndex));
        if (oldIndex == playerHelper.queueIndex) {
          audioHandler.customAction('setIndex', {'index': newIndex});
        }
        playerHelper.reorder(oldIndex, newIndex);
      },
      itemCount: _queueCache.length,
      itemBuilder: (BuildContext context, int index) {
        final mediaItem = _queueCache[index];
        final int itemId = mediaItem.extras!['id'] ?? 0;
        return Dismissible(
          key: ValueKey(mediaItem.id.hashCode | itemId),
          background: _dismissibleBackground,
          secondaryBackground: _dismissibleSecondaryBackground,
          onDismissed: (_) {
            audioHandler.removeQueueItemAt(index).then((value) {
              if (index == playerHelper.queueIndex) {
                audioHandler.skipToNext();
              }
            });
            setState(() => _queueCache.removeAt(index));
          },
          confirmDismiss: (_) {
            final completer = Completer<bool>();
            ScaffoldMessenger.of(context).clearSnackBars();
            ScaffoldMessenger.of(context)
                .showSnackBar(SnackBar(
                    behavior: SnackBarBehavior.floating,
                    content: Text('Song deleted from queue'.i18n),
                    action: SnackBarAction(
                        label: 'UNDO'.i18n,
                        onPressed: () => completer.complete(false))))
                .closed
                .then((value) {
              if (value == SnackBarClosedReason.action) return;
              completer.complete(true);
            });
            return completer.future;
          },
          child: SizedBox(
            height: itemExtent,
            child: TrackTile.fromMediaItem(
              mediaItem,
              trailing: ReorderableDragStartListener(
                  index: index, child: const Icon(Icons.drag_handle)),
              onTap: () {
                audioHandler.skipToQueueItem(index).then((value) {
                  if (widget.shouldPopOnTap) {
                    Navigator.of(context).pop();
                  }
                });
              },
              onSecondary: (_) => MenuSheet(context)
                  .defaultTrackMenu(Track.fromMediaItem(mediaItem)),
              checkTrackOffline: false,
            ),
          ),
        );
      },
    );
  }
}