using System.Collections;
using UnityEngine;
using UnityEngine.UI;
using TMPro;
using BaseGames.Core.Events;
using BaseGames.Localization;

namespace BaseGames.UI
{
    /// <summary>
    /// 全屏加载界面：进度条 + 提示文字 + 随机背景图（架构 10_UIModule §7.7）。
    /// </summary>
    public class LoadingScreenManager : MonoBehaviour
    {
        [SerializeField] private GameObject  _loadingRoot;
        [SerializeField] private Image       _progressFill;
        [SerializeField] private TMP_Text    _tipText;
        [SerializeField] private Image[]     _backgroundArts;
        [SerializeField] private string[]    _tipMessages;           // 本地化 key（对应 "UI" 表中的条目，如 "tip_explore"）
        [SerializeField] private float       _minDisplayTime = 0.5f;

        [Header("Event Channels")]
        [SerializeField] private VoidEventChannelSO   _onLoadingStarted;
        [SerializeField] private VoidEventChannelSO   _onLoadingComplete;
        [SerializeField] private FloatEventChannelSO  _onLoadingProgressUpdated;

        private float _shownAt;
        private readonly CompositeDisposable _subs = new();

        private void OnEnable()
        {
            _onLoadingStarted?.Subscribe(Show).AddTo(_subs);
            _onLoadingComplete?.Subscribe(Hide).AddTo(_subs);
            _onLoadingProgressUpdated?.Subscribe(SetProgress).AddTo(_subs);
        }
        private void OnDisable()
        {
            _subs.Clear();
        }

        // ── 公开 API（SceneLoader 可直接调用）────────────────────────────────

        public void Show()
        {
            _shownAt = Time.unscaledTime;
            if (_loadingRoot != null) _loadingRoot.SetActive(true);
            if (_progressFill != null) _progressFill.fillAmount = 0f;

            // 随机背景
            if (_backgroundArts != null && _backgroundArts.Length > 0)
            {
                foreach (var bg in _backgroundArts) if (bg != null) bg.enabled = false;
                _backgroundArts[Random.Range(0, _backgroundArts.Length)].enabled = true;
            }

            // 随机提示（通过 LocalizationManager 解析 key）
            if (_tipText != null && _tipMessages != null && _tipMessages.Length > 0)
                _tipText.text = LocalizationManager.Get(_tipMessages[Random.Range(0, _tipMessages.Length)], LocalizationTable.UI);
        }

        public void Hide() => StartCoroutine(HideAfterMinTime());

        public void SetProgress(float value)
        {
            if (_progressFill != null)
                _progressFill.fillAmount = Mathf.Clamp01(value);
        }

        // ── 内部 ─────────────────────────────────────────────────────────────

        // 缓存等待对象以避免典型路径（剩余时间 == _minDisplayTime）下的重复分配。
        private WaitForSecondsRealtime _cachedFullWait;

        private IEnumerator HideAfterMinTime()
        {
            float elapsed   = Time.unscaledTime - _shownAt;
            float remaining = _minDisplayTime - elapsed;
            if (remaining > 0f)
            {
                // 完整剩余 ≈ 显示时间时复用缓存对象；否则按需新建（罕见路径）。
                if (Mathf.Approximately(remaining, _minDisplayTime))
                {
                    _cachedFullWait ??= new WaitForSecondsRealtime(_minDisplayTime);
                    yield return _cachedFullWait;
                }
                else
                {
                    yield return new WaitForSecondsRealtime(remaining);
                }
            }
            if (_loadingRoot != null) _loadingRoot.SetActive(false);
        }
    }
}