using System.Collections;
using UnityEngine;
using TMPro;

namespace BaseGames.Tutorial
{
    /// <summary>
    /// 教程提示 UI 组件（架构 21_LiquidPuzzleModule §17）。
    /// 负责显示/隐藏提示面板和文字；duration ≤ 0 时不自动消隐。
    /// 使用 CanvasGroup 实现淡入淡出，不依赖 Animator。
    /// </summary>
    [RequireComponent(typeof(CanvasGroup))]
    public class TutorialHintUI : MonoBehaviour
    {
        [SerializeField] private TMP_Text _label;
        [SerializeField] private float    _fadeSpeed = 4f;

        private CanvasGroup _cg;
        private Coroutine   _autoHideCoroutine;
        private Coroutine   _fadeCoroutine;

        private void Awake()
        {
            _cg       = GetComponent<CanvasGroup>();
            _cg.alpha = 0f;
            gameObject.SetActive(false);
        }

        // ── 公共 API ──────────────────────────────────────────────────────
        /// <summary>淡入显示提示文字。duration ≤ 0 时不自动消隐。</summary>
        public void Show(string text, float duration = 0f)
        {
            if (_label != null) _label.text = text;

            // 停止所有进行中的动画/定时
            StopAutoHide();
            StopFade();

            gameObject.SetActive(true);
            _fadeCoroutine = StartCoroutine(FadeTo(1f));

            if (duration > 0f)
                _autoHideCoroutine = StartCoroutine(AutoHideRoutine(duration));
        }

        /// <summary>淡出并隐藏提示面板。</summary>
        public void Hide()
        {
            StopAutoHide();
            StopFade();
            _fadeCoroutine = StartCoroutine(FadeOutAndDeactivate());
        }

        // ── 内部 ──────────────────────────────────────────────────────────
        private void StopAutoHide()
        {
            if (_autoHideCoroutine == null) return;
            StopCoroutine(_autoHideCoroutine);
            _autoHideCoroutine = null;
        }

        private void StopFade()
        {
            if (_fadeCoroutine == null) return;
            StopCoroutine(_fadeCoroutine);
            _fadeCoroutine = null;
        }

        private IEnumerator AutoHideRoutine(float duration)
        {
            yield return new WaitForSecondsRealtime(duration);
            Hide();
            _autoHideCoroutine = null;
        }

        private IEnumerator FadeTo(float target)
        {
            while (!Mathf.Approximately(_cg.alpha, target))
            {
                _cg.alpha = Mathf.MoveTowards(_cg.alpha, target, _fadeSpeed * Time.unscaledDeltaTime);
                yield return null;
            }
            _cg.alpha = target;
        }

        private IEnumerator FadeOutAndDeactivate()
        {
            yield return FadeTo(0f);
            gameObject.SetActive(false);
            _fadeCoroutine = null;
        }
    }
}