using UnityEngine;
using UnityEditor;
using System.Collections.Generic;
using System;

public class BillboardGenerator : EditorWindow
{
    private string targetTag = "BillboardTarget";
    private string savePath = "Assets/{0}/BillboardTextures/";

    private string sceneName = "MinimalistBedroom";
    private int textureSize = 512;

    private string combainedPath;

    [MenuItem("Tools/Billboard Generator")]
    static void Init()
    {
        BillboardGenerator window = (BillboardGenerator)EditorWindow.GetWindow(typeof(BillboardGenerator));
        window.Show();
    }

    void OnGUI()
    {
        GUILayout.Label("Billboard Generator Settings", EditorStyles.boldLabel);
        targetTag = EditorGUILayout.TextField("Target Tag", targetTag);
        textureSize = EditorGUILayout.IntField("Texture Size", textureSize);
        sceneName = EditorGUILayout.TextField("Scene Name", sceneName);
        savePath = EditorGUILayout.TextField("Save Path", savePath);

        combainedPath = string.Format(savePath, sceneName);

        if (GUILayout.Button("Generate Billboards"))
        {
            GenerateBillboards();
        }
    }

    void GenerateBillboards()
    {
        // 确保保存路径存在
        if (!System.IO.Directory.Exists(combainedPath))
        {
            System.IO.Directory.CreateDirectory(combainedPath);
        }

        // 在方法开始时添加 tag
        SerializedObject tagManager = new SerializedObject(AssetDatabase.LoadAllAssetsAtPath("ProjectSettings/TagManager.asset")[0]);
        SerializedProperty tagsProp = tagManager.FindProperty("tags");

        // 检查 tag 是否已存在
        bool found = false;
        for (int i = 0; i < tagsProp.arraySize; i++)
        {
            SerializedProperty t = tagsProp.GetArrayElementAtIndex(i);
            if (t.stringValue.Equals("Billboard")) { found = true; break; }
        }

        // 如果 tag 不存在，添加它
        if (!found)
        {
            tagsProp.InsertArrayElementAtIndex(tagsProp.arraySize);
            SerializedProperty newTag = tagsProp.GetArrayElementAtIndex(tagsProp.arraySize - 1);
            newTag.stringValue = "Billboard";
            tagManager.ApplyModifiedProperties();
        }

        // 获取所有标记的物体
        GameObject[] taggedObjects = GameObject.FindGameObjectsWithTag(targetTag);

        foreach (GameObject obj in taggedObjects)
        {
            // 创建临时相机
            GameObject tempCameraObj = new GameObject("TempCamera");
            Camera tempCamera = tempCameraObj.AddComponent<Camera>();
            tempCamera.clearFlags = CameraClearFlags.SolidColor;
            tempCamera.backgroundColor = new Color(0, 0, 0, 0); // 透明背景

            // 获取目标对象及其子对象的所有Renderer组件
            Renderer[] renderers = obj.GetComponentsInChildren<Renderer>();
            if (renderers.Length == 0)
            {
                Debug.LogWarning($"No Renderer found in {obj.name} or its children.");
                continue; // 跳过此对象，或者根据需要处理
            }

            // 初始化包围盒为第一个Renderer的bounds
            Bounds bounds = renderers[0].bounds;
            // 合并所有Renderer的bounds
            for (int i = 1; i < renderers.Length; i++)
            {
                bounds.Encapsulate(renderers[i].bounds);
            }

            // 设置相机位置和朝向
            float distance = bounds.extents.magnitude * 2.0f; // 根据需要调整倍率
            Vector3 direction = obj.transform.forward; // 模型的正面方向
            Vector3 cameraPosition = bounds.center - direction * distance;
            tempCamera.transform.position = cameraPosition;
            tempCamera.transform.LookAt(bounds.center);

            // 设置相机视野
            tempCamera.orthographic = true;
            tempCamera.orthographicSize = bounds.extents.magnitude;

            // 创建RenderTexture，支持Alpha通道
            RenderTexture rt = new RenderTexture(textureSize, textureSize, 24, RenderTextureFormat.ARGB32);
            rt.antiAliasing = 1; // 禁用MSAA
            tempCamera.targetTexture = rt;

            // 渲染到纹理
            tempCamera.Render();

            // 创建Texture2D并读取RenderTexture
            RenderTexture.active = rt;
            Texture2D texture = new Texture2D(textureSize, textureSize, TextureFormat.RGBA32, false);
            texture.ReadPixels(new Rect(0, 0, textureSize, textureSize), 0, 0);
            texture.Apply();
            RenderTexture.active = null; // 重置

            // 保存贴图
            string texturePath = combainedPath + obj.name + "_billboard.png";
            byte[] bytes = texture.EncodeToPNG();
            System.IO.File.WriteAllBytes(texturePath, bytes);
            AssetDatabase.ImportAsset(texturePath); // 确保资源已导入

            // 设置贴图的导入设置，支持透明度
            TextureImporter importer = AssetImporter.GetAtPath(texturePath) as TextureImporter;
            if (importer != null)
            {
                importer.textureType = TextureImporterType.Default;
                importer.alphaIsTransparency = true;
                importer.mipmapEnabled = false;
                importer.SaveAndReimport();
            }

            // 创建材质
            string materialPath = combainedPath + obj.name + "_billboard.mat";
            Material billboardMaterial = new Material(Shader.Find("Unlit/Transparent"));
            AssetDatabase.CreateAsset(billboardMaterial, materialPath);
            billboardMaterial.mainTexture = AssetDatabase.LoadAssetAtPath<Texture2D>(texturePath);

            // 创建Billboard预制体
            GameObject billboard = GameObject.CreatePrimitive(PrimitiveType.Quad);
            billboard.name = obj.name + "_Billboard";
            billboard.transform.position = obj.transform.position;
            billboard.transform.localRotation = Quaternion.identity; // 重置旋转
            billboard.transform.localScale = obj.transform.localScale;
            billboard.GetComponent<MeshRenderer>().material = billboardMaterial;

            // 添加Billboard脚本
            billboard.AddComponent<BillboardBehavior>();

            // 创建预制体
            string prefabPath = combainedPath + obj.name + "_billboard.prefab";
            PrefabUtility.SaveAsPrefabAsset(billboard, prefabPath);

            // 清理临时对象
            DestroyImmediate(tempCameraObj);
            DestroyImmediate(billboard);

            // 在场景中隐藏原物体
            obj.SetActive(false);

            // 加载并实例化Billboard预制体到场景中
            GameObject billboardPrefab = AssetDatabase.LoadAssetAtPath<GameObject>(prefabPath);
            if (billboardPrefab != null)
            {
                GameObject billboardInstance = PrefabUtility.InstantiatePrefab(billboardPrefab) as GameObject;
                billboardInstance.transform.position = obj.transform.position;
                billboardInstance.transform.localRotation = Quaternion.identity; // 重置旋转
                billboardInstance.transform.localScale = obj.transform.localScale;

                // 将billboard放在原物体的父级下
                billboardInstance.transform.SetParent(obj.transform.parent);
                billboardInstance.tag = "Billboard";
            }
            else
            {
                Debug.LogError($"Failed to load billboard prefab at path: {prefabPath}");
            }
        }

        Debug.Log("Billboard generation completed!");
    }
}

// Billboard行为脚本
public class BillboardBehavior : MonoBehaviour
{
    private Camera mainCamera;

    void Start()
    {
        mainCamera = Camera.main;
    }

    void Update()
    {
        transform.LookAt(mainCamera.transform.position);
        transform.rotation = Quaternion.Euler(0, transform.rotation.eulerAngles.y, 0);
    }
}