// Assets/Scripts/World/Liquid/UnderwaterPostProcessingController.cs
using System.Collections;
using BaseGames.Core.Events;
using UnityEngine;
using UnityEngine.Rendering;

namespace BaseGames.World.Liquid
{
    public class UnderwaterPostProcessingController : MonoBehaviour
    {
        [SerializeField] private Volume               _underwaterVolume;    // 水下专属 Volume（WeightMode）
        [SerializeField] private float                _blendInDuration  = 0.3f;
        [SerializeField] private float                _blendOutDuration = 0.3f;
        [SerializeField] private LiquidEventChannelSO _onLiquidEntered;    // EVT_LiquidEntered
        [SerializeField] private LiquidEventChannelSO _onLiquidExited;     // EVT_LiquidExited

        private Coroutine _blendCoroutine;
        private readonly CompositeDisposable _subs = new();

        private void OnEnable()
        {
            _onLiquidEntered?.Subscribe(OnLiquidEntered).AddTo(_subs);
            _onLiquidExited?.Subscribe(OnLiquidExited).AddTo(_subs);
        }

        private void OnDisable() => _subs.Clear();

        private void OnLiquidEntered(LiquidEvent evt)
        {
            if (evt.LiquidType != LiquidType.Water) return;
            BlendVolume(1f, _blendInDuration);
        }

        private void OnLiquidExited(LiquidEvent evt)
        {
            if (evt.LiquidType != LiquidType.Water) return;
            BlendVolume(0f, _blendOutDuration);
        }

        private void BlendVolume(float target, float duration)
        {
            if (_blendCoroutine != null) StopCoroutine(_blendCoroutine);
            _blendCoroutine = StartCoroutine(BlendRoutine(target, duration));
        }

        private IEnumerator BlendRoutine(float target, float duration)
        {
            if (_underwaterVolume == null) yield break;
            float start   = _underwaterVolume.weight;
            float elapsed = 0f;
            while (elapsed < duration)
            {
                elapsed += Time.deltaTime;
                _underwaterVolume.weight = Mathf.Lerp(start, target, elapsed / duration);
                yield return null;
            }
            _underwaterVolume.weight = target;
        }
    }
}