using System.Collections;
using UnityEngine;
using BaseGames.Core;
using BaseGames.Core.Events;

namespace BaseGames.Audio
{
    /// <summary>BGM 状态机内部状态。</summary>
    public enum MusicState
    {
        Exploration,  // 默认：区域探索 BGM
        Boss,         // Boss 战：Boss 主题 BGM
        Victory,      // Boss 击败后短暂胜利音乐
        None,         // 过场/死亡/主菜单时由 BGMController 直接切换
    }

    /// <summary>
    /// BGM 控制器：订阅世界/Boss/游戏状态事件，指挥 AudioManager 切换 BGM 和快照。
    /// 挂在 Persistent 场景 [AudioManager] 子对象上。
    /// </summary>
    public class BGMController : MonoBehaviour
    {
        [SerializeField] private AudioManager  _audioManager;
        [SerializeField] private AudioConfigSO _config;

        [Header("Event Channels - Subscribe")]
        [SerializeField] private GameStateEventChannelSO _onGameStateChanged;
        [SerializeField] private BoolEventChannelSO      _onBossFightToggled;  // true=开始, false=结束
        [SerializeField] private StringEventChannelSO    _onRegionEntered;

        private MusicState _musicState = MusicState.Exploration;
        private string     _currentRegion = string.Empty;
        private readonly CompositeDisposable _subscriptions = new();

        private void Awake()
        {
            Debug.Assert(_config != null, "[BGMController] _config 未赋值，请在 Inspector 中指定 AudioConfigSO。", this);
        }

        private void OnEnable()
        {
            _onBossFightToggled?.Subscribe(OnBossFightToggled).AddTo(_subscriptions);
            _onRegionEntered?.Subscribe(OnRegionEntered).AddTo(_subscriptions);
            _onGameStateChanged?.Subscribe(HandleStateChanged).AddTo(_subscriptions);
        }

        private void OnDisable()
        {
            _subscriptions.Clear();
        }

        private void OnBossFightToggled(bool started)
        {
            if (started)
            {
                _musicState = MusicState.Boss;
                var clip = _config.GetBossBGM(_currentRegion);
                if (clip == null)
                {
                    Debug.LogWarning($"[BGMController] 区域 '{_currentRegion}' 未配置 Boss BGM，将保持当前音乐。", this);
                }
                else
                {
                    _audioManager.PlayBGM(clip, fadeOutDur: 1f, fadeInDur: 0.5f);
                }
                _audioManager.TransitionToSnapshot("BossFight", 0.5f);
            }
            else
            {
                StartCoroutine(PlayVictoryThenRestore());
            }
        }

        private IEnumerator PlayVictoryThenRestore()
        {
            _musicState = MusicState.Victory;
            _audioManager.PlayBGM(_config.VictoryStingBGM,
                                  fadeOutDur: 0.3f, fadeInDur: 0.1f);
            float dur = _config.VictoryStingDuration;
            yield return new WaitForSecondsRealtime(dur);
            _musicState = MusicState.Exploration;
            OnRegionEntered(_currentRegion);
            _audioManager.TransitionToSnapshot("Default", 1.0f);
        }

        private void OnRegionEntered(string regionId)
        {
            if (regionId == _currentRegion) return;
            _currentRegion = regionId;
            if (_musicState == MusicState.Exploration)
            {
                var clip = _config.GetZoneBGM(regionId);
                if (clip == null)
                {
                    Debug.LogWarning($"[BGMController] 区域 '{regionId}' 未配置 BGM，将保持当前音乐。", this);
                    return;
                }
                _audioManager.PlayBGM(clip, fadeOutDur: 1f, fadeInDur: 1f);
            }
        }

        private void HandleStateChanged(GameStateId state)
        {
            if (state == GameStates.MainMenu)
                _audioManager.PlayBGM(_config.MainMenuBGM,
                                      fadeOutDur: 0.5f, fadeInDur: 1.0f);
            else if (state == GameStates.Paused)
                _audioManager.TransitionToSnapshot("Paused", 0.2f);
            else if (state == GameStates.Dead)
                _audioManager.TransitionToSnapshot("Dead", 1.5f);
            else if (state == GameStates.Gameplay)
                _audioManager.TransitionToSnapshot("Default", 0.3f);
        }
    }
}