using UnityEngine;
using UnityEngine.SceneManagement;
using System.Collections;
using TMPro;

public class SceneLoader : MonoBehaviour
{
    // =========================
    //  싱글톤(전역 접근용)
    // =========================
    public static SceneLoader Instance;

    // =========================
    //  로딩 UI 연결
    // =========================
    [Header("로딩 UI 연결")]
    public GameObject loadingCanvas;      // 하이어라키의 'load canvas' 전체(로딩 화면 전체)
    public CanvasGroup backgroundGroup;   // 배경(검정 페이드)용 CanvasGroup
    public TextMeshProUGUI tipText;       // Tip 텍스트(TMP)

    // =========================
    //  로딩 시 나타날 요소들
    // =========================
    [Header("로딩 시 나타날 요소들")]
    public GameObject loadingTextObject;  // "Loading..." 텍스트 오브젝트
    public GameObject tipBarObject;       // TipBar(막대) 오브젝트(부모일 수도 있음)

    [Header("TipBar 실제 배경(선택)")]
    public RectTransform tipBarBackgroundRect;

    // =========================
    //  설정
    // =========================
    [Header("설정")]
    public string[] tips;                  // 랜덤으로 뽑을 팁 문구 배열
    public float fadeDuration = 1.0f;     // 배경 페이드 속도(초)

    // =========================
    //  TipBar 자동 리사이즈 설정
    // =========================
    [Header("TipBar 자동 리사이즈(코드)")]
    [Tooltip("Tip 텍스트 줄바꿈 기준 = 화면 폭의 몇 %를 쓸지")]
    [Range(0.4f, 0.95f)]
    public float wrapWidthScreenRatio = 0.75f;

    [Tooltip("TipBar 안쪽 여백(좌/우 합, 상/하 합)")]
    public Vector2 tipPadding = new Vector2(120f, 60f);

    [Tooltip("TipBar 최소 높이")]
    public float tipBarMinHeight = 70f;

    // =========================
    //  내부 캐시
    // =========================
    private RectTransform _tipBarRect;
    private RectTransform _tipTextRect;
    // private float _tipBarBaseHeight; // 사용하지 않는 변수이므로 삭제하여 경고 해결

    [Header("TipBar 기본 높이(1줄 기준)")]
    public float tipBarBaseHeight = 220f;

    private void Awake()
    {
        if (Instance == null)
        {
            Instance = this;
            DontDestroyOnLoad(gameObject);
        }
        else
        {
            Destroy(gameObject);
            return;
        }

        if (loadingCanvas != null)
            loadingCanvas.SetActive(false);

        if (tipText != null)
            _tipTextRect = tipText.GetComponent<RectTransform>();

        if (tipBarBackgroundRect != null)
            _tipBarRect = tipBarBackgroundRect;
        else if (tipBarObject != null)
            _tipBarRect = tipBarObject.GetComponent<RectTransform>();

        if (tipText != null)
        {
            tipText.enableWordWrapping = true;
            tipText.overflowMode = TextOverflowModes.Overflow;
        }
    }

    public void LoadSceneWithFade(string sceneName)
    {
        StartCoroutine(LoadProcess(sceneName));
    }

    private IEnumerator LoadProcess(string sceneName)
    {
        if (loadingTextObject != null) loadingTextObject.SetActive(false);
        if (tipBarObject != null) tipBarObject.SetActive(false);

        if (loadingCanvas != null) loadingCanvas.SetActive(true);
        if (backgroundGroup != null) backgroundGroup.alpha = 0f;

        // ★ 수정됨: Fade 호출 시 backgroundGroup을 함께 전달
        yield return StartCoroutine(Fade(1f, backgroundGroup));

        if (loadingTextObject != null) loadingTextObject.SetActive(true);
        if (tipBarObject != null) tipBarObject.SetActive(true);

        if (tipText != null)
        {
            if (tips != null && tips.Length > 0)
            {
                int randomIndex = Random.Range(0, tips.Length);
                tipText.text = $"<color=#FFD700>Tip!</color> : {tips[randomIndex]}";
            }
            else
            {
                tipText.text = "";
            }

            ResizeTipBarToFitText();
            yield return null;
            ResizeTipBarToFitText();
        }

        AsyncOperation op = SceneManager.LoadSceneAsync(sceneName);
        op.allowSceneActivation = false;

        float timer = 0f;
        while (timer < 2.0f)
        {
            timer += Time.deltaTime;
            yield return null;
        }

        op.allowSceneActivation = true;

        if (loadingTextObject != null) loadingTextObject.SetActive(false);
        if (tipBarObject != null) tipBarObject.SetActive(false);

        // ★ 수정됨: Fade 호출 시 backgroundGroup을 함께 전달
        yield return StartCoroutine(Fade(0f, backgroundGroup));

        if (loadingCanvas != null) loadingCanvas.SetActive(false);
    }

    // =========================
    //  배경 페이드 함수 (안전 코드 적용)
    // =========================
    private IEnumerator Fade(float targetAlpha, CanvasGroup canvasGroup)
    {
        if (canvasGroup == null)
        {
            Debug.LogWarning("SceneLoader: 페이드할 CanvasGroup이 없습니다!");
            yield break;
        }

        // fadeDuration이 0인 경우 방지
        float duration = Mathf.Max(0.01f, fadeDuration);
        float speed = 1f / duration;

        // null 체크 및 오차 범위 체크 추가
        while (canvasGroup != null && !Mathf.Approximately(canvasGroup.alpha, targetAlpha))
        {
            canvasGroup.alpha = Mathf.MoveTowards(canvasGroup.alpha, targetAlpha, speed * Time.unscaledDeltaTime);
            yield return null;
        }

        if (canvasGroup != null)
        {
            canvasGroup.alpha = targetAlpha;
        }
    }

    private void ResizeTipBarToFitText()
    {
        if (tipText == null || _tipBarRect == null || _tipTextRect == null) return;

        float scale = 1f;
        var canvas = tipText.canvas;
        if (canvas != null) scale = canvas.scaleFactor;

        float safeWrapWidth = (Screen.width * wrapWidthScreenRatio) / Mathf.Max(0.0001f, scale);
        safeWrapWidth = Mathf.Clamp(safeWrapWidth, 600f, 1400f);

        float wrapWidth = Mathf.Max(200f, safeWrapWidth - tipPadding.x);

        _tipTextRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, wrapWidth);

        tipText.enableWordWrapping = true;
        tipText.overflowMode = TextOverflowModes.Overflow;
        tipText.ForceMeshUpdate();

        Vector2 preferred = tipText.GetPreferredValues(tipText.text, wrapWidth, 0f);
        float textHeight = Mathf.Ceil(preferred.y);

        _tipTextRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, textHeight);

        float neededHeight = textHeight + tipPadding.y;
        float barHeight = Mathf.Max(tipBarBaseHeight, neededHeight, tipBarMinHeight);

        _tipBarRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, barHeight);
    }
}