using System.Collections.Generic;
using AK.Wwise;
using Sirenix.OdinInspector;
using UnityEngine;
using UnityEngine.SceneManagement;
using Event = AK.Wwise.Event;

namespace SLSUtilities.WwiseAssistance
{
    /// <summary>
    /// 背景音乐管理器。
    /// <para>
    /// 随 <see cref="AudioManager"/> 持久化（DontDestroyOnLoad），跨场景保持唯一实例。
    /// 通过 Wwise Event 播放 / 停止音乐。
    /// 淡入由 Wwise Event 自身的 Fade-In 配置控制，
    /// 淡出由 <c>ExecuteActionOnPlayingID(Stop, transitionDuration)</c> 实现。
    /// </para>
    /// </summary>
    public class BackgroundMusicManager : SerializedMonoBehaviour
    {
        // ──────────────────── 常量 ────────────────────

        private const int DefaultFadeOutMs = 1000;
        private const string LoadingSceneName = "Loading";

        // ──────────────────── 序列化字段 ────────────────────

        [Title("Wwise")]
        [Tooltip("音乐状态名 → Wwise State 映射，播放时自动设置对应 State。")]
        public Dictionary<string, State> baseMusicDictionary;

        [Required]
        [Tooltip("播放 BGM 的 Wwise Event。淡入请在 Wwise Authoring 的该 Event Play 动作上配置 Fade-In。")]
        public Event playMusicEvent;

        // ──────────────────── 运行时状态 ────────────────────

        [Title("Runtime")]
        [ShowInInspector, ReadOnly]
        public bool isOverridden;

        [ShowInInspector, ReadOnly]
        private string lastMusicStateName;

        /// <summary>当前播放的 Wwise Playing ID。</summary>
        private uint currentPlayingID;

        /// <summary>是否在等待下一个场景加载后自动重播。</summary>
        private bool pendingReplay;

        /// <summary> 是否已经开始播放过音乐。用于避免在 Start 前就响应场景加载事件导致的重复播放。</summary>
        private bool _isStarted = false;

        // ──────────────────── 生命周期 ────────────────────

        private void Start()
        {
            if (_isStarted) return;
            _isStarted = true;
            PlayMusic("NormalMusic");
        }

        private void OnEnable() => SceneManager.sceneLoaded += OnSceneLoaded;
        private void OnDisable() => SceneManager.sceneLoaded -= OnSceneLoaded;

        // ──────────────────── 公开 API ────────────────────

        /// <summary>
        /// 播放指定状态的背景音乐。淡入效果由 Wwise Event 自身的 Fade-In 配置控制。
        /// 被覆盖期间仅记录状态名，不实际播放。
        /// </summary>
        public void PlayMusic(string musicStateName)
        {
            lastMusicStateName = musicStateName;

            if (isOverridden) return;

            StopImmediate();

            // 设置 Wwise State 以选择正确的音乐变体
            if (baseMusicDictionary.TryGetValue(musicStateName, out var state))
            {
                state.SetValue();
            }

            currentPlayingID = playMusicEvent.Post(gameObject);

            if (currentPlayingID == AkUnitySoundEngine.AK_INVALID_PLAYING_ID)
            {
                Debug.LogWarning("[BGM] playMusicEvent.Post 返回了无效的 Playing ID。");
            }
        }

        /// <summary>
        /// 立即停止背景音乐（无淡出）。
        /// </summary>
        public void StopMusic() => StopImmediate();

        /// <summary>
        /// 带淡出停止当前音乐，并在下一个非 Loading 场景加载后自动重新播放。
        /// 用于场景切换前调用。
        /// </summary>
        public void TransitionToNextScene(int fadeOutMs = DefaultFadeOutMs)
        {
            pendingReplay = true;
            StopWithFade(fadeOutMs);
        }

        /// <summary>
        /// 设置覆盖标记。被覆盖时 <see cref="PlayMusic"/> 仅记录状态名，不实际播放。
        /// </summary>
        public void SetOverride(bool overridden) => isOverridden = overridden;

        // ──────────────────── 内部实现 ────────────────────

        private void StopImmediate()
        {
            if (currentPlayingID == AkUnitySoundEngine.AK_INVALID_PLAYING_ID) return;

            AkUnitySoundEngine.ExecuteActionOnPlayingID(
                AkActionOnEventType.AkActionOnEventType_Stop,
                currentPlayingID, 0,
                AkCurveInterpolation.AkCurveInterpolation_Linear);
            currentPlayingID = AkUnitySoundEngine.AK_INVALID_PLAYING_ID;
        }

        private void StopWithFade(int fadeOutMs)
        {
            if (currentPlayingID == AkUnitySoundEngine.AK_INVALID_PLAYING_ID) return;

            AkUnitySoundEngine.ExecuteActionOnPlayingID(
                AkActionOnEventType.AkActionOnEventType_Stop,
                currentPlayingID, fadeOutMs,
                AkCurveInterpolation.AkCurveInterpolation_Linear);
            currentPlayingID = AkUnitySoundEngine.AK_INVALID_PLAYING_ID;
        }

        private void OnSceneLoaded(Scene scene, LoadSceneMode mode)
        {
            if (!pendingReplay || scene.name == LoadingSceneName) return;

            pendingReplay = false;
            PlayMusic(string.IsNullOrEmpty(lastMusicStateName) ? "NormalMusic" : lastMusicStateName);
        }
    }
}