import 'dart:async';

import 'package:audio_service/audio_service.dart';
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/services.dart';
import 'package:freezer/api/deezer.dart';
import 'package:freezer/api/definitions.dart';
import 'package:freezer/api/player.dart';
import 'package:freezer/settings.dart';
import 'package:freezer/ui/elements.dart';
import 'package:freezer/translations.i18n.dart';
import 'package:freezer/ui/error.dart';
import 'package:freezer/ui/player_bar.dart';

class LyricsScreen extends StatefulWidget {
  LyricsScreen({Key? key}) : super(key: key);

  @override
  _LyricsScreenState createState() => _LyricsScreenState();
}

class _LyricsScreenState extends State<LyricsScreen> {
  late StreamSubscription _mediaItemSub;
  late StreamSubscription _playbackStateSub;
  int? _currentIndex = -1;
  int? _prevIndex = -1;
  ScrollController _controller = ScrollController();
  final double height = 90;
  Lyrics? lyrics;
  bool _loading = true;
  Object? _error;

  bool _freeScroll = false;
  bool _animatedScroll = false;

  Future _loadForId(String trackId) async {
    //Fetch
    if (_loading == false && lyrics != null) {
      setState(() {
        _freeScroll = false;
        _loading = true;
        lyrics = null;
      });
    }
    try {
      Lyrics l = await deezerAPI.lyrics(trackId);
      setState(() {
        _loading = false;
        lyrics = l;
      });
      _scrollToLyric();
    } catch (e) {
      setState(() {
        _error = e;
      });
    }
  }

  Future<void> _scrollToLyric() async {
    //Lyric height, screen height, appbar height
    double _scrollTo = (height * _currentIndex!) -
        (MediaQuery.of(context).size.height / 2) +
        (height / 2) +
        56;
    if (0 > _scrollTo) return;
    _animatedScroll = true;
    await _controller.animateTo(_scrollTo,
        duration: Duration(milliseconds: 250), curve: Curves.ease);
    _animatedScroll = false;
  }

  @override
  void initState() {
    SchedulerBinding.instance!.addPostFrameCallback((_) {
      //Enable visualizer
      // if (settings.lyricsVisualizer) playerHelper.startVisualizer();
      _playbackStateSub = AudioService.position.listen((position) {
        if (_loading) return;
        _currentIndex =
            lyrics?.lyrics?.lastIndexWhere((l) => l.offset! <= position);
        //Scroll to current lyric
        if (_currentIndex! < 0) return;
        if (_prevIndex == _currentIndex) return;
        //Update current lyric index
        setState(() => null);
        _prevIndex = _currentIndex;
        if (_freeScroll) return;
        _scrollToLyric();
      });
    });
    if (audioHandler.mediaItem.value != null)
      _loadForId(audioHandler.mediaItem.value!.id);

    /// Track change = ~exit~ reload lyrics
    _mediaItemSub = audioHandler.mediaItem.listen((mediaItem) {
      if (mediaItem == null) return;
      if (_controller.hasClients) _controller.jumpTo(0.0);
      _loadForId(mediaItem.id);
    });

    super.initState();
  }

  @override
  void dispose() {
    _mediaItemSub.cancel();
    _playbackStateSub.cancel();
    //Stop visualizer
    // if (settings.lyricsVisualizer) playerHelper.stopVisualizer();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: FreezerAppBar('Lyrics'.i18n,
          systemUiOverlayStyle: 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,
          )),
      body: SafeArea(
        child: Column(
          children: [
            Theme(
              data: settings.themeData!.copyWith(
                  textButtonTheme: TextButtonThemeData(
                      style: ButtonStyle(
                          foregroundColor:
                              MaterialStateProperty.all(Colors.white)))),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.center,
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  if (_freeScroll && !_loading)
                    TextButton(
                        onPressed: () {
                          setState(() => _freeScroll = false);
                          _scrollToLyric();
                        },
                        child: Text(
                          _currentIndex! >= 0
                              ? (lyrics?.lyrics?[_currentIndex!].text ?? '...')
                              : '...',
                          textAlign: TextAlign.center,
                        ),
                        style: ButtonStyle(
                            foregroundColor:
                                MaterialStateProperty.all(Colors.white)))
                ],
              ),
            ),
            Expanded(
              child: Stack(children: [
                //Lyrics
                _error != null
                    ?
                    //Shouldn't really happen, empty lyrics have own text
                    ErrorScreen(message: _error.toString())
                    :
                    // Loading lyrics
                    _loading
                        ? Center(child: CircularProgressIndicator())
                        : NotificationListener(
                            onNotification: (Notification notification) {
                              if (_freeScroll ||
                                  notification is! ScrollStartNotification)
                                return false;
                              if (!_animatedScroll && !_loading)
                                setState(() => _freeScroll = true);
                              return false;
                            },
                            child: ListView.builder(
                              controller: _controller,
                              padding: EdgeInsets.fromLTRB(
                                  0,
                                  0,
                                  0,
                                  settings.lyricsVisualizer! && false
                                      ? 100
                                      : 0),
                              itemCount: lyrics!.lyrics!.length,
                              itemBuilder: (BuildContext context, int i) {
                                return Padding(
                                    padding:
                                        EdgeInsets.symmetric(horizontal: 8.0),
                                    child: Container(
                                        decoration: BoxDecoration(
                                          borderRadius:
                                              BorderRadius.circular(8.0),
                                          color: _currentIndex == i
                                              ? Colors.grey.withOpacity(0.25)
                                              : Colors.transparent,
                                        ),
                                        height: height,
                                        child: InkWell(
                                            borderRadius:
                                                BorderRadius.circular(8.0),
                                            onTap: lyrics!.id != null
                                                ? () => audioHandler.seek(
                                                    lyrics!.lyrics![i].offset!)
                                                : null,
                                            child: Center(
                                              child: Text(
                                                lyrics!.lyrics![i].text!,
                                                textAlign: TextAlign.center,
                                                style: TextStyle(
                                                    fontSize: 26.0,
                                                    fontWeight:
                                                        (_currentIndex == i)
                                                            ? FontWeight.bold
                                                            : FontWeight
                                                                .normal),
                                              ),
                                            ))));
                              },
                            )),

                //Visualizer
                //if (settings.lyricsVisualizer)
                //  Positioned(
                //    bottom: 0,
                //    left: 0,
                //    right: 0,
                //    child: StreamBuilder(
                //        stream: playerHelper.visualizerStream,
                //        builder: (BuildContext context, AsyncSnapshot snapshot) {
                //          List<double> data = snapshot.data ?? [];
                //          double width = MediaQuery.of(context).size.width /
                //              data.length; //- 0.25;
                //          return Row(
                //            crossAxisAlignment: CrossAxisAlignment.end,
                //            children: List.generate(
                //                data.length,
                //                (i) => AnimatedContainer(
                //                      duration: Duration(milliseconds: 130),
                //                      color: settings.primaryColor,
                //                      height: data[i] * 100,
                //                      width: width,
                //                    )),
                //          );
                //        }),
                //  ),
              ]),
            ),
            PlayerBar(shouldHandleClicks: false),
          ],
        ),
      ),
    );
  }
}