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

namespace BaseGames.UI.Splash
{
    /// <summary>
    /// 游戏启动 Logo 演出控制器。挂载在 Persistent 场景的 Canvas_Splash 根节点。
    ///
    /// 演出顺序：工作室 Logo 淡入 → 停留 → 淡出 → 游戏标题淡入 → 停留 → 黑幕整体淡出。
    /// 任意按键 / 手柄键可跳过整段演出。
    ///
    /// 与 Core 程序集完全解耦：
    ///   监听 EVT_SplashStartRequest（VoidEventChannelSO）→ 开始演出。
    ///   完成后发布 EVT_SplashComplete（VoidEventChannelSO）→ 通知 BootSequencer 继续。
    /// </summary>
    public class SplashScreenController : MonoBehaviour
    {
        [Header("Canvas Groups")]
        [Tooltip("整个 Splash 画布的根节点 CanvasGroup（用于整体淡出黑幕）")]
        [SerializeField] private CanvasGroup _splashRoot;
        [Tooltip("工作室 Logo CanvasGroup")]
        [SerializeField] private CanvasGroup _studioLogoGroup;
        [Tooltip("游戏标题 Logo CanvasGroup")]
        [SerializeField] private CanvasGroup _gameTitleGroup;

        [Header("时序（秒）")]
        [SerializeField] private float _fadeInDuration   = 0.8f;
        [SerializeField] private float _holdDuration     = 1.5f;
        [SerializeField] private float _fadeOutDuration  = 0.6f;
        [SerializeField] private float _stageGapDuration = 0.3f;

        [Header("Event Channels")]
        [SerializeField] private VoidEventChannelSO _onSplashStartRequest;  // Listen
        [SerializeField] private VoidEventChannelSO _onSplashComplete;       // Raise

        private bool _skipRequested;
        private readonly CompositeDisposable _subs = new();

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

        private void Awake()
        {
            // 初始态：根节点完全不透明（充当开场黑幕），各 Logo 完全透明
            SetAlpha(_splashRoot,       1f, blocksRaycasts: true);
            SetAlpha(_studioLogoGroup,  0f, blocksRaycasts: false);
            SetAlpha(_gameTitleGroup,   0f, blocksRaycasts: false);
        }

        private void OnEnable()  => _onSplashStartRequest?.Subscribe(OnStartRequested).AddTo(_subs);
        private void OnDisable() => _subs.Clear();

        // ── 入口 ─────────────────────────────────────────────────────────────

        private void OnStartRequested() => StartCoroutine(PlayAndNotify());

        private IEnumerator PlayAndNotify()
        {
            yield return StartCoroutine(PlayAsync());
            _onSplashComplete?.Raise();
        }

        // ── 演出主逻辑 ───────────────────────────────────────────────────────

        private IEnumerator PlayAsync()
        {
            _skipRequested = false;

            // Stage 1：工作室 Logo
            if (_studioLogoGroup != null)
            {
                yield return StartCoroutine(FadeGroup(_studioLogoGroup, 0f, 1f, _fadeInDuration));
                yield return StartCoroutine(WaitOrSkip(_holdDuration));
                yield return StartCoroutine(FadeGroup(_studioLogoGroup, 1f, 0f, _fadeOutDuration));
            }

            if (!_skipRequested)
                yield return new WaitForSecondsRealtime(_stageGapDuration);

            // Stage 2：游戏标题
            if (_gameTitleGroup != null)
            {
                yield return StartCoroutine(FadeGroup(_gameTitleGroup, 0f, 1f, _fadeInDuration));
                yield return StartCoroutine(WaitOrSkip(_holdDuration));
                yield return StartCoroutine(FadeGroup(_gameTitleGroup, 1f, 0f, _fadeOutDuration));
            }

            // 黑幕整体淡出（显露主菜单场景）
            yield return StartCoroutine(FadeGroup(_splashRoot, 1f, 0f, _fadeOutDuration));

            if (_splashRoot != null)
                _splashRoot.blocksRaycasts = false;

            gameObject.SetActive(false);
        }

        // ── Unity 输入（任意按键跳过）────────────────────────────────────────

        private void Update()
        {
            if (Input.anyKeyDown)
                _skipRequested = true;
        }

        // ── 内部工具 ─────────────────────────────────────────────────────────

        private IEnumerator FadeGroup(CanvasGroup group, float from, float to, float duration)
        {
            if (group == null) yield break;
            group.alpha = from;
            float elapsed = 0f;
            while (elapsed < duration && !_skipRequested)
            {
                group.alpha = Mathf.Lerp(from, to, elapsed / duration);
                elapsed += Time.unscaledDeltaTime;
                yield return null;
            }
            group.alpha = to;
        }

        private IEnumerator WaitOrSkip(float duration)
        {
            float elapsed = 0f;
            while (elapsed < duration && !_skipRequested)
            {
                elapsed += Time.unscaledDeltaTime;
                yield return null;
            }
        }

        private static void SetAlpha(CanvasGroup group, float alpha, bool blocksRaycasts)
        {
            if (group == null) return;
            group.alpha          = alpha;
            group.blocksRaycasts = blocksRaycasts;
        }
    }
}