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

namespace BaseGames.UI
{
    /// <summary>
    /// 单条通知弹窗（架构 10_UIModule §11）。
    /// 由 ToastManager 控制显示和自动隐藏。
    /// </summary>
    [RequireComponent(typeof(CanvasGroup))]
    public class ToastNotification : MonoBehaviour
    {
        [SerializeField] private TMP_Text  _titleText;
        [SerializeField] private TMP_Text  _bodyText;
        [SerializeField] private Image     _icon;
        [SerializeField] private float     _displayDuration = 3f;
        [SerializeField] private float     _fadeDuration    = 0.25f;

        private CanvasGroup _cg;
        private Coroutine   _hideCoroutine;
        private WaitForSecondsRealtime _waitDisplay;  // 缓存：避免每次 Show 堆分配

        /// <summary>淡入 + 保持 + 淡出的总时长（供 ToastManager 队列计时用）。</summary>
        public float TotalTime => _displayDuration + _fadeDuration * 2f;

        private void Awake()
        {
            _cg = GetComponent<CanvasGroup>();
            _cg.alpha = 0f;
            _waitDisplay = new WaitForSecondsRealtime(_displayDuration);
        }

        public void Show(string title, string body, Sprite icon = null)
        {
            if (_titleText != null) _titleText.text = title;
            if (_bodyText  != null) _bodyText.text  = body;
            if (_icon      != null)
            {
                _icon.sprite  = icon;
                _icon.enabled = icon != null;
            }

            gameObject.SetActive(true);
            if (_hideCoroutine != null) StopCoroutine(_hideCoroutine);
            _hideCoroutine = StartCoroutine(AutoHide());
        }

        private IEnumerator AutoHide()
        {
            // 淡入
            yield return StartCoroutine(FadeTo(1f));
            // 保持（复用缓存的 WaitForSecondsRealtime）
            yield return _waitDisplay;
            // 淡出
            yield return StartCoroutine(FadeTo(0f));
            gameObject.SetActive(false);
        }

        private IEnumerator FadeTo(float target)
        {
            float start   = _cg.alpha;
            float elapsed = 0f;
            while (elapsed < _fadeDuration)
            {
                _cg.alpha = Mathf.Lerp(start, target, elapsed / _fadeDuration);
                elapsed  += Time.unscaledDeltaTime;
                yield return null;
            }
            _cg.alpha = target;
        }
    }

    // ─────────────────────────────────────────────────────────────────────────
    /// <summary>
    /// 通知队列管理器（架构 10_UIModule §11 ToastManager）。
    /// 同时只显示一条 Toast；队列不为空时前一条结束后立即显示下一条。
    /// 订阅 EVT_AchievementUnlocked / EVT_AbilityUnlocked 事件频道。
    /// </summary>
    public class ToastManager : MonoBehaviour
    {
        [SerializeField] private ToastNotification _toast;

        [Header("Event Channels")]
        [SerializeField] private StringEventChannelSO _onAchievementUnlocked; // EVT_AchievementUnlocked
        [SerializeField] private StringEventChannelSO _onAbilityUnlocked;     // EVT_AbilityUnlocked

        private readonly Queue<(string title, string body, Sprite icon)> _queue = new();
        private readonly CompositeDisposable _subs = new();
        private bool _showing;
        private WaitForSecondsRealtime _queueWait;  // 缓存：避免 ProcessQueue 每条堆分配

        private void Awake()
        {
            // _toast.TotalTime 基于 Inspector 常量，只需 Awake 时初始化一次
            if (_toast != null)
                _queueWait = new WaitForSecondsRealtime(_toast.TotalTime + 0.1f);
        }

        private void OnEnable()
        {
            _onAchievementUnlocked?.Subscribe(OnAchievement).AddTo(_subs);
            _onAbilityUnlocked?.Subscribe(OnAbility).AddTo(_subs);
        }
        private void OnDisable()
        {
            _subs.Clear();
        }

        private void OnAchievement(string id)
            => Enqueue(LocalizationManager.Get("TOAST_ACHIEVEMENT_TITLE", LocalizationTable.UI), id, null);

        private void OnAbility(string abilityId)
            => Enqueue(LocalizationManager.Get("TOAST_ABILITY_TITLE", LocalizationTable.UI), abilityId, null);

        public void Enqueue(string title, string body, Sprite icon = null)
        {
            _queue.Enqueue((title, body, icon));
            if (!_showing) StartCoroutine(ProcessQueue());
        }

        private IEnumerator ProcessQueue()
        {
            _showing = true;
            while (_queue.Count > 0)
            {
                var (title, body, icon) = _queue.Dequeue();
                // _toast 为 null 时直接终止队列（不能显示，也无需等待）
                if (_toast == null) break;
                _toast.Show(title, body, icon);
                // 使用缓存的等待对象，_toast 为 null 时已在上方 break
                if (_queueWait == null)
                    _queueWait = new WaitForSecondsRealtime(_toast.TotalTime + 0.1f);
                yield return _queueWait;
            }
            _showing = false;
        }
    }
}