MusicPlayer

using System;
using System.IO;
using UnityEngine;

namespace JasonStorey.Music
{
    public class MusicPlayer
    {

        /// <summary>
        /// Pressing Prev in most media players will restart the track if it has been playing a while, but if it is near the start of the track will assume you meant to go back one.
        /// </summary>
        const float PERCENT_PREV_BECOMES_RESTART = 0.1f;


        public void Play()
        {
            if (_source.isPlaying)
            {
                _source.Pause();
                _paused = true;
            }
            else if (_source.clip != null && _paused)
            {
                _source.Play();
                _paused = false;
            }
        }

        public void Play(AudioClip clip)
        {
            if(_source.clip != clip)
            {
                _source.clip = clip;
                OnTrackChanged(_source.clip);
            }
            _source.Play();

        }


        public void Play(Track track)
        {
            CurrentTrack = track;
            Play(track.Clip);
        }

        public void Play(Playlist playlist)
        {
            _currentPlaylist = playlist;
            Play(playlist.Selected);
        }

        public async void Play(string path,AudioType type = AudioType.WAV)
        {
            if (Path.GetExtension(path) == ".mp3")
            {
                Debug.LogWarning($"Cannot stream mp3 files. (Copyright) <color=yellow>{Path.GetFileName(path)}</color> will not play");
                return;
            }
            var clip = await AudioLoader.LoadClipFromPath(path, type);
            Play(clip);
        }

        public void Prev()
        {
            if(PercentThroughCurrentTrack > PERCENT_PREV_BECOMES_RESTART)
                RestartClip();
            else if(_currentPlaylist != null)
            {
                _currentPlaylist.SelectPrev();
                Play(_currentPlaylist);
            }
        }

        public void Next()
        {
            if (_currentPlaylist == null) return;
            _currentPlaylist.SelectNext();
            Play(_currentPlaylist);
        }

        void RestartClip()
        {
            if(_source.isPlaying) _source.Play();
        }


        float PercentThroughCurrentTrack => HasAClip ? _source.clip.length / _source.time : 0;

        public MusicPlayer(AudioSource source) => _source = source;
        readonly AudioSource _source;

        public void UpdateStatus()
        {
            if (_paused) return;
            if (!_source.isPlaying && HasAClip)
            {
                if(_currentPlaylist != null)
                    TryPlayingNextPlaylistTrack();
                else
                {
                    _source.clip = null;
                    OnStopped();
                }
            }
        }

        void TryPlayingNextPlaylistTrack()
        {
            if (_currentPlaylist.AtTheEnd)
            {
                _source.clip = null;
                OnStopped();
                return;
            }
            _currentPlaylist.SelectNext();
            Play(_currentPlaylist);
        }

        public void SeekToPercent(float percent)
        {
            if (!HasAClip) return;
            _source.time = _source.clip.length * percent;
        }

        bool HasAClip => _source.clip != null;
        public Track CurrentTrack { get; private set; }

        protected virtual void OnStopped() => Stopped?.Invoke();

        protected virtual void OnTrackChanged(AudioClip clip)
        {
            if (clip == null) return;
            TrackChanged?.Invoke(clip);
        }

        bool _paused;
        public event Action<AudioClip> TrackChanged;
        public event Action Stopped;
        Playlist _currentPlaylist;
    }
}