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

public class AudioManager : Singleton<AudioManager>
{
    [SerializeField] private AudioSource musicSource;
    [SerializeField] private AudioSource introSource;

    private bool backgroundMusicShouldPlay = true;
    private bool backgroundMusicEnabled = true;
    private bool narrationEnabled = true;
    private bool introIsActive;
    private readonly List<AudioClip> activeIntroClips = new();

    public bool NarrationEnabled => narrationEnabled;
    public AudioClip CurrentIntroClip =>
        introIsActive && introSource != null ? introSource.clip : null;
    public event Action<bool> NarrationEnabledChanged;
    public event Action ActiveIntroChanged;

    protected override void Awake()
    {
        base.Awake();
        musicSource ??= GetComponent<AudioSource>();

        if (introSource != null)
        {
            narrationEnabled = !introSource.mute;
        }
    }

    private void Update()
    {
        if (introIsActive && (introSource == null || !introSource.isPlaying))
        {
            AudioClip previousIntroClip = CurrentIntroClip;

            if (introSource != null)
            {
                activeIntroClips.Remove(introSource.clip);
            }

            introIsActive = false;
            ApplyBackgroundMusicState();
            NotifyActiveIntroChanged(previousIntroClip);
        }
    }

    public void PlayBackgroundMusic()
    {
        backgroundMusicShouldPlay = true;
        ApplyBackgroundMusicState();
    }

    public void PauseBackgroundMusic()
    {
        backgroundMusicShouldPlay = false;
        ApplyBackgroundMusicState();
    }

    public void SetBackgroundMusicEnabled(bool isEnabled)
    {
        backgroundMusicEnabled = isEnabled;
        ApplyBackgroundMusicState();
    }

    public void SetNarrationEnabled(bool isEnabled)
    {
        AudioClip previousIntroClip = CurrentIntroClip;
        narrationEnabled = isEnabled;

        if (introSource != null)
        {
            introSource.mute = false;

            if (!narrationEnabled)
            {
                activeIntroClips.Clear();
                introSource.Stop();
            }
        }

        if (!narrationEnabled)
        {
            introIsActive = false;
            ApplyBackgroundMusicState();
            NotifyActiveIntroChanged(previousIntroClip);
        }

        NarrationEnabledChanged?.Invoke(narrationEnabled);
    }

    public void PlayArtWorkIntro(AudioClip introClip)
    {
        if (!narrationEnabled || introSource == null || introClip == null)
        {
            return;
        }

        if (!activeIntroClips.Contains(introClip))
        {
            activeIntroClips.Add(introClip);
        }

        ApplyActiveIntroState();
    }

    public void PauseArtWorkIntro(AudioClip introClip)
    {
        if (introClip == null)
        {
            return;
        }

        activeIntroClips.Remove(introClip);
        ApplyActiveIntroState();
    }

    private void ApplyActiveIntroState()
    {
        AudioClip previousIntroClip = CurrentIntroClip;
        AudioClip nextIntroClip = activeIntroClips.Count > 0
            ? activeIntroClips[activeIntroClips.Count - 1]
            : null;

        if (introSource == null || nextIntroClip == null)
        {
            if (introSource != null && introSource.isPlaying)
            {
                introSource.Pause();
            }

            introIsActive = false;
            ApplyBackgroundMusicState();
            NotifyActiveIntroChanged(previousIntroClip);
            return;
        }

        if (introSource.clip != nextIntroClip)
        {
            introSource.clip = nextIntroClip;
            introSource.Play();
        }
        else
        {
            introSource.UnPause();

            if (!introSource.isPlaying)
            {
                introSource.Play();
            }
        }

        introIsActive = true;
        ApplyBackgroundMusicState();
        NotifyActiveIntroChanged(previousIntroClip);
    }

    private void NotifyActiveIntroChanged(AudioClip previousIntroClip)
    {
        if (previousIntroClip != CurrentIntroClip)
        {
            ActiveIntroChanged?.Invoke();
        }
    }

    private void ApplyBackgroundMusicState()
    {
        if (musicSource == null)
        {
            return;
        }

        if (!backgroundMusicEnabled || !backgroundMusicShouldPlay || introIsActive)
        {
            if (musicSource.isPlaying)
            {
                musicSource.Pause();
            }

            return;
        }

        if (musicSource.isPlaying)
        {
            return;
        }

        musicSource.UnPause();

        if (!musicSource.isPlaying)
        {
            musicSource.Play();
        }
    }
}