using System.Collections;
using UnityEngine;

namespace Stary.Evo.AudioCore
{
    public class MusicPlayer : AbstractAudio
    {
        private AudioSourcePool audioSourcePool;
        private AudioSource audioSource1;
        private AudioSource audioSource2;
        private AudioSource currentAudioSource;

        public MusicPlayer(AudioSourcePool audioSourcePool)
        {
            this.audioSourcePool = audioSourcePool;
        }

        /// <summary>
        /// 播放背景音乐
        /// </summary>
        /// <param name="audioData">{[clip:音频], [volume:音量], [fadeDuration:自然过渡时间]}</param>
        public override void Play(AudioData audioData)
        {
            audioData = AudioDataInitialize(audioData);
            if (audioSource1 == null)
            {
                audioSource1 = audioSourcePool.GetAudioSource("Music");
                audioSource1.clip = audioData.clip;
                audioSource1.volume = audioData.volume;
                currentAudioSource = audioSource1;
                currentAudioSource.Play();
                CoroutineHelper.StartCoroutine(FadeMusic(audioSource1, audioData.fadeDuration, audioSource2));
            }
            else
            {
                if (audioSource2 == null)
                {
                    audioSource2 = audioSourcePool.GetAudioSource("Music");
                    audioSource2.clip = audioData.clip;
                    audioSource2.volume = audioData.volume;
                    currentAudioSource = audioSource2;
                    currentAudioSource.Play();
                    CoroutineHelper.StartCoroutine(FadeMusic(audioSource2, audioData.fadeDuration, audioSource1));
                }
                else
                {
                    Debug.LogWarning("已同时存在两个背景乐在切换");
                }
            }

        }

        /// <summary>
        /// 关闭背景音乐
        /// </summary>
        /// <param name="audioData">{[fadeDuration:自然过渡时间]}</param>
        public override void Stop(AudioData audioData)
        {
            audioData = AudioDataInitialize(audioData);
            CoroutineHelper.StartCoroutine(FadeOutMusic(currentAudioSource, audioData.fadeDuration));
        }

        /// <summary>
        /// 切换音频
        /// </summary>
        /// <param name="source1">播放的音频</param>
        /// <param name="fadeDuration">变化时间</param>
        /// <param name="source2">停止的音频</param>
        /// <returns></returns>
        private IEnumerator FadeMusic(AudioSource source1, float fadeDuration, AudioSource source2 = null)
        {
            yield return FadeInMusic(source1, fadeDuration);

            if (source2 != null)
            {
                yield return FadeOutMusic(source2, fadeDuration);
            }

        }

        /// <summary>
        /// 关闭音频的协程
        /// </summary>
        /// <param name="source"></param>
        /// <param name="fadeDuration"></param>
        /// <returns></returns>
        private IEnumerator FadeOutMusic(AudioSource source, float fadeDuration)
        {
            float startVolume = source.volume;

            while (source.volume > 0)
            {
                source.volume -= startVolume * Time.deltaTime / fadeDuration;
                yield return null;
            }

            source.Stop();
            audioSourcePool.ReturnAudioSource("Music", source.gameObject);

            if (currentAudioSource == audioSource1)
            {
                audioSource2 = null;
            }
            else if (currentAudioSource == audioSource2)
            {
                audioSource1 = null;
            }
        }

        /// <summary>
        /// 开启音频的协程
        /// </summary>
        /// <param name="source"></param>
        /// <param name="fadeDuration"></param>
        /// <returns></returns>
        private IEnumerator FadeInMusic(AudioSource source, float fadeDuration)
        {
            float targetVolume = source.volume;
            source.volume = 0;

            while (source.volume < targetVolume)
            {
                source.volume += targetVolume * Time.deltaTime / fadeDuration;
                yield return null;
            }
        }
    }
}