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

public class MultiImageBlender : MonoBehaviour
{
    [Header("Base Settings")] public RectTransform container;
    public Shader blendShader;
    public string fileName = "MultiBlendResult";
    public string saveFolder = "Exports";

    [Header("Advanced Settings")] [Tooltip("Render order: from bottom to top (child index)")]
    public bool useHierarchyOrder = true;

    public Vector2Int outputResolution = new Vector2Int(1024, 1024);

    private List<Image> targetImages = new List<Image>();
    private RenderTexture compositeRT;

    [ContextMenu("Execute Blend Export")]
    public void ExecuteBlendExport()
    {
        // 初始化目标列表
        CollectImages();

        // 创建渲染目标
        CreateRenderTexture();

        // 初始化画布
        ClearRenderTexture(compositeRT, Color.clear);

        // 混合所有图片
        foreach (Image img in targetImages)
        {
            if (!img.gameObject.activeInHierarchy) continue;

            if (img.sprite == null)
            {
                continue;
            }

            // 准备纹理数据
            Texture2D coloredTex = ProcessImageTexture(img);
            Vector2 offset = CalculatePositionOffset(img.rectTransform);

            // 执行混合
            BlendLayer(coloredTex, img.color, offset);

            DestroyImmediate(coloredTex);
        }

        // 保存结果
        SaveResult();

        // 清理资源
        ReleaseResources();
    }

    void CollectImages()
    {
        targetImages.Clear();

        if (useHierarchyOrder)
        {
            // 按层级顺序收集（从底到顶）
            foreach (Transform child in container)
            {
                CollectRecursive(child);
            }
        }
        else
        {
            // 使用无序模式
            Image[] images = container.GetComponentsInChildren<Image>();
            targetImages.AddRange(images);
        }

        void CollectRecursive(Transform parent)
        {
            Image img = parent.GetComponent<Image>();
            if (img != null) targetImages.Add(img);

            foreach (Transform child in parent)
            {
                CollectRecursive(child);
            }
        }
    }

    Texture2D ProcessImageTexture(Image image)
    {
        // 获取原始纹理
        Texture2D sourceTex = image.sprite.texture;

        // 应用颜色
        Color[] pixels = sourceTex.GetPixels();
        for (int i = 0; i < pixels.Length; i++)
        {
            pixels[i] = pixels[i] * image.color;
        }

        // 创建新纹理
        Texture2D coloredTex = new Texture2D(
            sourceTex.width,
            sourceTex.height,
            sourceTex.format,
            false
        );

        coloredTex.SetPixels(pixels);
        coloredTex.Apply();

        return coloredTex;
    }

    Vector2 CalculatePositionOffset(RectTransform rt)
    {
        // 将局部坐标转换为容器空间坐标
        Vector2 anchoredPos = rt.anchoredPosition;

        // 计算标准化偏移（相对于输出分辨率）
        return new Vector2(
            anchoredPos.x / outputResolution.x,
            anchoredPos.y / outputResolution.y
        );
    }

    void CreateRenderTexture()
    {
        if (compositeRT != null)
            compositeRT.Release();

        compositeRT = new RenderTexture(
            outputResolution.x,
            outputResolution.y,
            24,
            RenderTextureFormat.ARGB32
        );
    }

    void ClearRenderTexture(RenderTexture rt, Color clearColor)
    {
        RenderTexture.active = rt;
        GL.Clear(true, true, clearColor);
        RenderTexture.active = null;
    }

    void BlendLayer(Texture2D sourceTex, Color blendColor, Vector2 offset)
    {
        Material blendMat = new Material(blendShader);
        blendMat.SetTexture("_MainTex", sourceTex);
        blendMat.SetColor("_BlendColor", blendColor);
        blendMat.SetVector("_BlendOffset", offset);

        // 临时RT用于混合
        RenderTexture tempRT = RenderTexture.GetTemporary(
            compositeRT.width,
            compositeRT.height,
            0,
            compositeRT.format
        );

        // 复制当前状态
        Graphics.Blit(compositeRT, tempRT);

        // 执行混合
        Graphics.Blit(tempRT, compositeRT, blendMat);

        // 清理临时RT
        RenderTexture.ReleaseTemporary(tempRT);
        DestroyImmediate(blendMat);
    }

    void SaveResult()
    {
        Texture2D outputTex = new Texture2D(
            compositeRT.width,
            compositeRT.height,
            TextureFormat.ARGB32,
            false
        );

        RenderTexture.active = compositeRT;
        outputTex.ReadPixels(new Rect(0, 0, compositeRT.width, compositeRT.height), 0, 0);
        outputTex.Apply();

        // 保存文件
        string dirPath = Path.Combine(Application.dataPath, saveFolder);
        Directory.CreateDirectory(dirPath);

        string filePath = Path.Combine(dirPath, fileName + ".png");
        File.WriteAllBytes(filePath, outputTex.EncodeToPNG());

        Debug.Log($"导出成功：{filePath}");
        DestroyImmediate(outputTex);
    }

    void ReleaseResources()
    {
        if (compositeRT != null)
        {
            compositeRT.Release();
            DestroyImmediate(compositeRT);
        }

        Resources.UnloadUnusedAssets();
    }

    void OnDestroy()
    {
        ReleaseResources();
    }
}