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

public class MANAGER_Music : MonoBehaviour
{
    public static MANAGER_Music Instance;

    [Header("Main Settings")]
    [Range(0f, 1f)]
    [SerializeField] private float maxVolume = 0.5f;
    [SerializeField] private float fadeDuration = 1.5f;
    
    [Tooltip("Настрой кривую: 0,0 -> 1,1. Плавный выход в начале и конце сделает переход естественнее.")]
    [SerializeField] private AnimationCurve fadeCurve = AnimationCurve.Linear(0, 0, 1, 1);

    private AudioSource sourceA;
    private AudioSource sourceB;
    private AudioSource activeSource;
    private Coroutine fadeCoroutine;

    [Header("Mixer Settings")]
    [SerializeField] private AudioMixerGroup musicGroup; 

    private Dictionary<AudioClip, float> savedPlaybackTimes = new Dictionary<AudioClip, float>();

    void Awake()
    {
        if (Instance == null)
        {
            Instance = this;
            SetupSources(); 
        }
        else 
        { 
            Destroy(gameObject); 
        }
    }

    
    private void SetupSources()
    {
        sourceA = gameObject.AddComponent<AudioSource>();
        sourceB = gameObject.AddComponent<AudioSource>();
        
        if (musicGroup != null) 
        {
            sourceA.outputAudioMixerGroup = musicGroup;
            sourceB.outputAudioMixerGroup = musicGroup;
        }

        sourceA.loop = sourceB.loop = true;
        sourceA.playOnAwake = sourceB.playOnAwake = false;
        
        activeSource = sourceA;
        activeSource.volume = 0; 
    }

    public void SwitchMusic(AudioClip newClip)
    {
        if (activeSource.clip == newClip) return;

        AudioSource nextSource = (activeSource == sourceA) ? sourceB : sourceA;
        
        if (fadeCoroutine != null) StopCoroutine(fadeCoroutine);
        fadeCoroutine = StartCoroutine(FadeSequence(nextSource, newClip));
    }

    private IEnumerator FadeSequence(AudioSource nextSource, AudioClip newClip)
    {
        float t = 0;
        float startVol = activeSource.volume;

        if (newClip != null)
        {
            nextSource.clip = newClip;
            
            if (savedPlaybackTimes.TryGetValue(newClip, out float savedTime))
            {
                nextSource.time = savedTime; 
            }
            else
            {
                nextSource.time = 0f; 
            }
            
            nextSource.Play();
        }

        while (t < fadeDuration)
        {
            t += Time.deltaTime;
            float progress = t / fadeDuration;
            float curveValue = fadeCurve.Evaluate(progress);

            activeSource.volume = Mathf.Lerp(startVol, 0, curveValue);
            
            if (newClip != null)
                nextSource.volume = Mathf.Lerp(0, maxVolume, curveValue);

            yield return null;
        }

        if (activeSource.clip != null)
        {
            savedPlaybackTimes[activeSource.clip] = activeSource.time;
        }

        activeSource.Stop();
        activeSource.volume = 0;
        
        activeSource = nextSource;
        activeSource.volume = maxVolume;
        fadeCoroutine = null;
    }

    public void SetVolume(float volume)
    {
        maxVolume = Mathf.Clamp01(volume);
        if (activeSource != null) activeSource.volume = maxVolume;
    }
}