using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SoundManager : MonoBehaviour {

    static SoundManager instance;
    public static SoundManager GetInstance()
    {
        if (!instance)
        {
            GameObject soundManager = new GameObject("SoundManager");
            instance = soundManager.AddComponent(typeof(SoundManager)) as SoundManager;
            instance.Initialize();
        }

        return instance;
    }

    const float MaxVolume_BGM = 1f;
    const float MaxVolume_SFX = 1f;
    static float CurrentVolumeNormalized_BGM = 1f;
    static float CurrentVolumeNormalized_SFX = 1f;
    static bool isMuted = false;

    List<AudioSource> sfxSources;
    AudioSource bgmSource;



    void Initialize()
    {
        // add our bgm sound source
        bgmSource = gameObject.AddComponent(typeof(AudioSource)) as AudioSource;
        bgmSource.loop = true;
        bgmSource.playOnAwake = false;
        bgmSource.volume = GetBGMVolume();
        DontDestroyOnLoad(gameObject);
    }

    // ==================== Volume Getters =====================

    static float GetBGMVolume()
    {
        return isMuted ? 0f : MaxVolume_BGM * CurrentVolumeNormalized_BGM;
    }

    public static float GetSFXVolume()
    {
        return isMuted ? 0f : MaxVolume_SFX * CurrentVolumeNormalized_SFX;
    }

    // ====================== BGM Utils ======================

    void FadeBGMOut(float fadeDuration)
    {
        SoundManager soundMan = GetInstance();
        float delay = 0f;
        float toVolume = 0f;

        if (soundMan.bgmSource.clip == null)
        {
            Debug.LogError("Error: Could not fade BGM out as BGM AudioSource has no currently playing clip.");
        }

        StartCoroutine(FadeBGM(toVolume, delay, fadeDuration));
    }

    void FadeBGMIn(AudioClip bgmClip, float delay, float fadeDuration)
    {
        SoundManager soundMan = GetInstance();
        soundMan.bgmSource.clip = bgmClip;
        soundMan.bgmSource.Play();

        float toVolume = GetBGMVolume();

        StartCoroutine(FadeBGM(toVolume, delay, fadeDuration));
    }

    IEnumerator FadeBGM(float fadeToVolume, float delay, float duration)
    {
        yield return new WaitForSeconds(delay);

        SoundManager soundMan = GetInstance();
        float elapsed = 0f;
        while (duration > 0)
        {
            float t = (elapsed / duration);
            float volume = Mathf.Lerp(0f, fadeToVolume * CurrentVolumeNormalized_BGM, t);
            soundMan.bgmSource.volume = volume;

            elapsed += Time.deltaTime;
            yield return 0;
        }
    }

    // ====================== BGM Functions ======================

    public static void PlayBGM(AudioClip bgmClip, bool fade, float fadeDuration)
    {
        SoundManager soundMan = GetInstance();

        if (fade)
        {
            if (soundMan.bgmSource.isPlaying)
            {
                // fade out, then switch and fade in
                soundMan.FadeBGMOut(fadeDuration / 2);
                soundMan.FadeBGMIn(bgmClip, fadeDuration / 2, fadeDuration / 2);

            }
            else
            {
                // just fade in
                float delay = 0f;
                soundMan.FadeBGMIn(bgmClip, delay, fadeDuration);
            }
        }
        else
        {
            // play immediately
            soundMan.bgmSource.volume = GetBGMVolume();
            soundMan.bgmSource.clip = bgmClip;
            soundMan.bgmSource.Play();
        }
    }

    public static void StopBGM(bool fade, float fadeDuration)
    {
        SoundManager soundMan = GetInstance();
        if (soundMan.bgmSource.isPlaying)
        {
            // fade out, then switch and fade in
            if (fade)
            {
                soundMan.FadeBGMOut(fadeDuration);
            }
            else
            {
                soundMan.bgmSource.Stop();
            }
        }
    }

    // ======================= SFX Utils ====================================

    AudioSource GetSFXSource()
    {
        // set up a new sfx sound source for each new sfx clip
        AudioSource sfxSource = gameObject.AddComponent(typeof(AudioSource)) as AudioSource;
        sfxSource.loop = false;
        sfxSource.playOnAwake = false;
        sfxSource.volume = GetSFXVolume();

        if (sfxSources == null)
        {
            sfxSources = new List<AudioSource>();
        }

        sfxSources.Add(sfxSource);

        return sfxSource;
    }

    IEnumerator RemoveSFXSource(AudioSource sfxSource)
    {
        yield return new WaitForSeconds(sfxSource.clip.length);
        sfxSources.Remove(sfxSource);
        Destroy(sfxSource);
    }

    private void RemoveSFXSourcee(AudioSource sfxSource)
    {
        if (!sfxSource.isPlaying)
        {
            sfxSources.Remove(sfxSource);
            Destroy(sfxSource);
        }
    }

    IEnumerator RemoveSFXSourceFixedLength(AudioSource sfxSource, float length)
    {
        yield return new WaitForSeconds(length);
        sfxSources.Remove(sfxSource);
        Destroy(sfxSource);
    }

    // ====================== SFX Functions =================================

    public static void PlaySFX(AudioClip sfxClip)
    {
        SoundManager soundMan = GetInstance();
        AudioSource source = soundMan.GetSFXSource();
        source.volume = GetSFXVolume();
        source.clip = sfxClip;
        source.Play();

        //soundMan.StartCoroutine(soundMan.RemoveSFXSource(source));
        soundMan.RemoveSFXSourcee(source);
    }

    public static void PlaySFXRandomized(AudioClip sfxClip)
    {
        SoundManager soundMan = GetInstance();
        AudioSource source = soundMan.GetSFXSource();
        source.volume = GetSFXVolume();
        source.clip = sfxClip;
        source.pitch = Random.Range(0.85f, 1.2f);
        source.Play();

        // soundMan.StartCoroutine(soundMan.RemoveSFXSource(source));
        soundMan.RemoveSFXSourcee(source);

    }

    public static void PlaySFXFixedDuration(AudioClip sfxClip, float duration, float volumeMultiplier = 1.0f)
    {
        SoundManager soundMan = GetInstance();
        AudioSource source = soundMan.GetSFXSource();
        source.volume = GetSFXVolume() * volumeMultiplier;
        source.clip = sfxClip;
        source.loop = true;
        source.Play();

        soundMan.StartCoroutine(soundMan.RemoveSFXSourceFixedLength(source, duration));
    }

    // ==================== Volume Control Functions ==========================

    public static void DisableSoundImmediate()
    {
        SoundManager soundMan = GetInstance();
        soundMan.StopAllCoroutines();
        if (soundMan.sfxSources != null)
        {
            foreach (AudioSource source in soundMan.sfxSources)
            {
                source.volume = 0;
            }
        }
        soundMan.bgmSource.volume = 0f;
        isMuted = true;
    }

    public static void EnableSoundImmediate()
    {
        SoundManager soundMan = GetInstance();
        if (soundMan.sfxSources != null)
        {
            foreach (AudioSource source in soundMan.sfxSources)
            {
                source.volume = GetSFXVolume();
            }
        }
        soundMan.bgmSource.volume = GetBGMVolume();
        isMuted = false;
    }

    public static void SetGlobalVolume(float newVolume)
    {
        CurrentVolumeNormalized_BGM = newVolume;
        CurrentVolumeNormalized_SFX = newVolume;
        AdjustSoundImmediate();
    }

    public static void SetSFXVolume(float newVolume)
    {
        CurrentVolumeNormalized_SFX = newVolume;
        AdjustSoundImmediate();
    }

    public static void SetBGMVolume(float newVolume)
    {
        CurrentVolumeNormalized_BGM = newVolume;
        AdjustSoundImmediate();
    }

    public static void AdjustSoundImmediate()
    {
        SoundManager soundMan = GetInstance();
        if (soundMan.sfxSources != null)
        {
            foreach (AudioSource source in soundMan.sfxSources)
            {
                source.volume = GetSFXVolume();
            }
        }
        Debug.Log("BGM Volume: " + GetBGMVolume());
        soundMan.bgmSource.volume = GetBGMVolume();
        Debug.Log("BGM Volume is now: " + GetBGMVolume());
    }
}