using UnityEngine;
using UnityEngine.UI;
using System.Collections.Generic;
using System.IO;

/// <summary>
/// pass
/// </summary>
public class UIToTextureExporter : MonoBehaviour
{
    public RectTransform targetUIRoot;
    public Vector2Int outputResolution = new Vector2Int(1024, 1024);
    public string fileName = "UIRender";
    public string saveFolder = "Exports";

    [ContextMenu("导出 UI 图像")]
    public void ExportUI()
    {
        if (targetUIRoot == null)
        {
            Debug.LogError("请指定 UI 根节点！");
            return;
        }

        // 创建RenderTexture
        RenderTexture rt = new RenderTexture(outputResolution.x, outputResolution.y, 24);
        RenderTexture.active = rt;

        // 清空背景
        GL.Clear(true, true, new Color(0, 0, 0, 0));

        // 创建一个临时Canvas进行渲染
        GameObject tempCanvasGO = new GameObject("TempCanvas", typeof(Canvas));
        Canvas tempCanvas = tempCanvasGO.GetComponent<Canvas>();
        tempCanvas.renderMode = RenderMode.WorldSpace;
        tempCanvas.pixelPerfect = true;

        RectTransform canvasRT = tempCanvas.GetComponent<RectTransform>();
        canvasRT.sizeDelta = outputResolution;

        // 拷贝所有 Graphic 元素
        List<Graphic> graphics = new List<Graphic>();
        targetUIRoot.GetComponentsInChildren(true, graphics);

        foreach (var graphic in graphics)
        {
            if (!graphic.gameObject.activeInHierarchy) continue;

            var clone = Instantiate(graphic, tempCanvas.transform);
            var rect = clone.rectTransform;

            // 保持位置、尺寸
            rect.sizeDelta = graphic.rectTransform.rect.size;
            rect.anchoredPosition = graphic.rectTransform.anchoredPosition;
            rect.localScale = graphic.rectTransform.localScale;
        }

        // 强制渲染一次
        Canvas.ForceUpdateCanvases();

        // 生成截图
        Texture2D result = new Texture2D(outputResolution.x, outputResolution.y, TextureFormat.ARGB32, false);
        result.ReadPixels(new Rect(0, 0, outputResolution.x, outputResolution.y), 0, 0);
        result.Apply();

        // 保存
        string dirPath = Path.Combine(Application.dataPath, saveFolder);
        Directory.CreateDirectory(dirPath);
        string path = Path.Combine(dirPath, fileName + ".png");

        File.WriteAllBytes(path, result.EncodeToPNG());
        Debug.Log($"✅ UI导出成功：{path}");

        // 清理
        DestroyImmediate(result);
        DestroyImmediate(tempCanvasGO);
        RenderTexture.active = null;
        rt.Release();
        DestroyImmediate(rt);
    }
}