comunicmobile/lib/ui/widgets/audio_player_widget.dart

import 'dart:io';

import 'package:audioplayers/audioplayers.dart';
import 'package:comunic/utils/date_utils.dart';
import 'package:flutter/material.dart';

/// Audio player widget
///
/// @author Pierre Hubert

class AudioPlayerWidget extends StatefulWidget {
  final File file;

  const AudioPlayerWidget(this.file);

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

class _AudioPlayerWidgetState extends State<AudioPlayerWidget> {
  AudioPlayer _player;

  Duration _mediaDuration;
  Duration _mediaPosition;

  double get _max => _mediaDuration?.inMilliseconds?.toDouble() ?? 0.0;

  double get _value => _mediaPosition?.inMilliseconds?.toDouble() ?? 0.0;

  bool get _playing =>
      _player != null && _player.state == AudioPlayerState.PLAYING;

  @override
  void dispose() {
    super.dispose();

    if (_player != null) _player.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Material(
      textStyle: TextStyle(color: Colors.white),
      color: Colors.transparent,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Spacer(),
          Icon(Icons.audiotrack, color: Colors.white),
          Spacer(),
          Slider(
            value: _value,
            onChanged: (newValue) =>
                _player.seek(Duration(milliseconds: newValue.toInt())),
            max: _max,
            activeColor: Colors.white,
            min: 0,
          ),
          Spacer(),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Spacer(),
              Text(formatDuration(_mediaPosition ?? Duration())),
              Spacer(),
              _AudioButton(
                  icon: Icons.play_arrow, onTap: _play, visible: !_playing),
              _AudioButton(icon: Icons.pause, onTap: _pause, visible: _playing),
              _AudioButton(icon: Icons.stop, onTap: _stop, visible: _playing),
              Spacer(),
              _playing ? Container() : Text(formatDuration(_mediaDuration ?? Duration())),
              Spacer(),
            ],
          ),
          Spacer(),
        ],
      ),
    );
  }

  void _play() async {
    if (_player == null) {
      _player = AudioPlayer();

      _player.onDurationChanged.listen((newDuration) {
        setState(() => _mediaDuration = newDuration);
      });

      _player.onAudioPositionChanged.listen((newDuration) {
        setState(() => _mediaPosition = newDuration);
      });

      _player.onPlayerStateChanged.listen((event) => setState(() {}));

      _player.onSeekComplete.listen((event) => setState(() {}));
    }

    if (_player.state != AudioPlayerState.PAUSED)
      _player.play(widget.file.absolute.path, isLocal: true);
    else
      _player.resume();
  }

  void _pause() async {
    _player.pause();
  }

  void _stop() {
    _player.stop();
    _player.seek(Duration());
  }
}

class _AudioButton extends StatelessWidget {
  final IconData icon;
  final void Function() onTap;
  final bool visible;

  const _AudioButton({
    Key key,
    @required this.icon,
    @required this.onTap,
    @required this.visible,
  })  : assert(icon != null),
        assert(onTap != null),
        assert(visible != null),
        super(key: key);

  @override
  Widget build(BuildContext context) {
    if (!visible) return Container();

    return IconButton(icon: Icon(icon, color: Colors.white), onPressed: onTap);
  }
}