using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using PhxhSDK;
using UnityEngine;
using UnityEditor;
using UnityEngine.Rendering.Universal;
using Object = UnityEngine.Object;

public static class TwoDimensionRenderUtil
{
    private static Camera _camera;
    private static GameObject _gameObject;
    private const float WIDTH = 1920f;
    private const float HEIGHT = 1080f;

    //camera old value
    private static float _oldAspect;
    private static float _oldSize;
    private static Vector3 _oldPosition;
    private static RenderTexture _oldRT;
    private static LayerMask _oldCullingMask;
    private static CameraClearFlags _oldClearFlags;
    private static Color _oldBkgColor;
    private static bool _enablePostProcess;
    private static string _cameraTag;

    //obj old value
    private static int _oldLayer;
    private static Vector3 _oldObjPosition;
    private static Vector3 _oldObjScale;
    private static Transform _oldObjParent;

    //RT old value
    private static RenderTexture _oldActiveRT;
    private static RenderTexture _currRT;

    private static void SaveCameraValue()
    {
        _oldAspect = _camera.aspect;
        _oldSize = _camera.orthographicSize;
        _oldPosition = _camera.transform.position;
        _oldRT = _camera.targetTexture;
        _oldCullingMask = _camera.cullingMask;
        _oldClearFlags = _camera.clearFlags;
        _oldBkgColor = _camera.backgroundColor;
        _enablePostProcess = _camera.GetUniversalAdditionalCameraData().renderPostProcessing;
        _cameraTag = _camera.gameObject.tag;
    }

    private static void RevertCameraValue()
    {
        _camera.aspect = _oldAspect;
        _camera.orthographicSize = _oldSize;
        _camera.transform.position = _oldPosition;
        _camera.targetTexture = _oldRT;
        _camera.cullingMask = _oldCullingMask;
        _camera.clearFlags = _oldClearFlags;
        _camera.backgroundColor = _oldBkgColor;
        _camera.GetUniversalAdditionalCameraData().renderPostProcessing = _enablePostProcess;
        _camera.gameObject.tag = _cameraTag;
    }

    private static void SaveObjValue()
    {
        _oldLayer = _gameObject.layer;
        _oldObjParent = _gameObject.transform.parent;
        _oldObjPosition = _gameObject.transform.position;
        _oldObjScale = _gameObject.transform.lossyScale;
    }

    private static void RevertObject(bool isPrefab)
    {
        if (isPrefab)
        {
            Object.DestroyImmediate(_gameObject);
            return;
        }

        SetGameObjectLayer(_gameObject, _oldLayer);
        _gameObject.transform.position = _oldObjPosition;
        _gameObject.transform.localScale = _oldObjScale;
        _gameObject.transform.parent = _oldObjParent;
    }

    private static void SaveRT()
    {
        _oldActiveRT = RenderTexture.active;
    }

    private static void RevertRT()
    {
        RenderTexture.active = _oldActiveRT;
        RenderTexture.ReleaseTemporary(_currRT);
    }

    [MenuItem("GameObject/RenderToTexture")]
    private static void RenderToTexture()
    {
        var activeGo = Selection.activeGameObject;
        if (activeGo != null)
        {
            Vector3 offset = Vector3.zero;
            Vector3 scale = Vector3.zero;
            Quaternion rotation = Quaternion.identity;
            activeGo.RenderToTexture(Camera.main, "Assets/test.jpg", ref offset, ref scale, ref rotation);
        }
    }

    /// <summary>
    /// 将gameObject渲染到一张贴图上
    /// 注:下面的所有计算都是基于scale值为1的情况，如果要在scale不为1的情况下使用positionOffset和textureScale，则需要自行乘上scale
    /// </summary>
    /// <param name="gameObject"></param>
    /// <param name="camera">需要用来渲染的相机，必须是正交的，且旋转已经设置好了</param>
    /// <param name="path">贴图存放的路径</param>
    /// <param name="positionOffset">三维到二维的偏移量,当三维转二维的时候用三维position加上该值可保证三维和二维刚好重合</param>
    /// <param name="textureScale">转换二维后的缩放值，条件是二维的mesh长宽都为1</param>
    /// <param name="rotation">转换二维后的旋转值</param>
    /// <returns></returns>
    public static Texture2D RenderToTexture(this GameObject gameObject, Camera camera, string path,
        ref Vector3 positionOffset, ref Vector3 textureScale, ref Quaternion rotation)
    {
        if (gameObject == null || camera == null)
        {
            return null;
        }

        if (!camera.orthographic)
        {
            Debug.LogError("current camera is not orthographic");
            return null;
        }

        bool isPrefab = false;
        if (EditorUtility.IsPersistent(gameObject))
        {
            isPrefab = true;
            gameObject = PrefabUtility.InstantiatePrefab(gameObject) as GameObject;
            if (gameObject == null)
            {
                return null;
            }
        }

        var mesh = gameObject.GetComponentInChildren<MeshFilter>().sharedMesh;
        if (mesh == null)
            return null;

        _gameObject = gameObject;
        _camera = camera;
        SaveCameraValue();
        SaveObjValue();
        SaveRT();
        try
        {
            _camera.GetUniversalAdditionalCameraData().renderPostProcessing = false;
            _camera.gameObject.tag = "RenderTwoDimension";
            
            var newLayer = LayerMask.NameToLayer("RenderTool");
            SetGameObjectLayer(gameObject, newLayer);
            gameObject.transform.parent = null;
            gameObject.transform.localScale = Vector3.one;
            gameObject.transform.position = Vector3.zero;
            //设置position y为0不一定物体就刚好位于地面上，需要调整一下
            var msr = gameObject.GetComponentInChildren<MeshRenderer>();
            var meshTrans = msr.transform;
            var yOffset = 0 - msr.bounds.min.y;
            gameObject.transform.position = new Vector3(0, yOffset, 0);

            camera.aspect = WIDTH / HEIGHT;
            var viewPortPoints = GetMeshBorder(mesh, meshTrans,
                camera);
            var left = viewPortPoints[0].x;
            var right = viewPortPoints[1].x;
            var bottom = viewPortPoints[2].y;
            var top = viewPortPoints[3].y;
            camera.transform.position = camera.ViewportToWorldPoint(viewPortPoints[4]);
            camera.cullingMask = 1 << newLayer;
            var rtWidth = Mathf.FloorToInt(WIDTH * (right - left));
            var rtHeight = Mathf.FloorToInt(HEIGHT * (top - bottom));
            var pixelHeightRatio = top - bottom;
            var imageHeight = camera.orthographicSize * pixelHeightRatio * 2;
            var imageWidth = imageHeight * rtWidth / rtHeight;
            textureScale = new Vector3(imageWidth, imageHeight, 1);
            rotation = camera.transform.rotation;
            _currRT = RenderTexture.GetTemporary(rtWidth, rtHeight, 0, RenderTextureFormat.ARGB32);
            camera.aspect = (float)rtWidth / rtHeight;
            camera.orthographicSize *= (top - bottom);
            camera.targetTexture = _currRT;
            camera.clearFlags = CameraClearFlags.Color;
            camera.backgroundColor = Color.clear;
            camera.Render();
            var twoDimensionPositionWS = TwoDimensionToWorldPosition(camera);
            positionOffset = twoDimensionPositionWS - meshTrans.position;
            RenderTexture.active = _currRT;
            Texture2D tex = TextureUtils.Create(gameObject.name, rtWidth, rtHeight);
            tex.ReadPixels(new Rect(0, 0, rtWidth, rtHeight), 0, 0);
            tex.Apply();
            Byte[] bytes = tex.EncodeToJPG();
            FileStream fs = File.Open(path, FileMode.Create);
            BinaryWriter writer = new BinaryWriter(fs);
            writer.Write(bytes);
            writer.Flush();
            writer.Close();
            fs.Close();
            Object.DestroyImmediate(tex);
            AssetDatabase.Refresh();
            var savedTex = AssetDatabase.LoadAssetAtPath<Texture2D>(path);
            if (savedTex != null)
            {
                Debug.Log("保存成功！" + path);
            }

            return savedTex;
        }
        finally
        {
            RevertCameraValue();
            RevertObject(isPrefab);
            RevertRT();
        }
    }

    /// <summary>
    /// 获取mesh在当前相机视角下的边界视口坐标，一定刚好可以包围住mesh
    /// </summary>
    /// <param name="mesh"></param>
    /// <param name="trans"></param>
    /// <param name="cam"></param>
    /// <returns>前四个值是左右下上，最后一个值是中心点</returns>
    private static Vector3[] GetMeshBorder(Mesh mesh, Transform trans, Camera cam)
    {
        Vector3[] result = new Vector3[5];
        float left = float.PositiveInfinity;
        float right = float.NegativeInfinity;
        float top = float.NegativeInfinity;
        float bottom = float.PositiveInfinity;
        Vector3 leftPosSS = Vector3.zero;
        Vector3 rightPosSS = Vector3.zero;
        Vector3 bottomPosSS = Vector3.zero;
        Vector3 topPosSS = Vector3.zero;
        for (int i = 0; i < mesh.vertexCount; i++)
        {
            var vertex = mesh.vertices[i];
            var positionWS = trans.TransformPoint(vertex);
            var positionSS = cam.WorldToViewportPoint(positionWS);
            if (positionSS.x < left)
            {
                left = positionSS.x;
                leftPosSS = positionSS;
            }

            if (positionSS.x > right)
            {
                right = positionSS.x;
                rightPosSS = positionSS;
            }

            if (positionSS.y < bottom)
            {
                bottom = positionSS.y;
                bottomPosSS = positionSS;
            }

            if (positionSS.y > top)
            {
                top = positionSS.y;
                topPosSS = positionSS;
            }
        }

        Vector2 centerSS = new Vector3((left + right) / 2, (top + bottom) / 2, 0);
        result[0] = leftPosSS;
        result[1] = rightPosSS;
        result[2] = bottomPosSS;
        result[3] = topPosSS;
        result[4] = centerSS;

        return result;
    }

    /// <summary>
    /// 将当前相机(必须是正交的)近裁剪面投射到地面上(底部刚好和地面相切，故Z轴不能有旋转)，中心点的世界坐标
    /// 此时的相机已经完成拍摄作业,即已经将镜头对准被拍摄物体且aspect刚好包围被拍摄物
    /// 原理:面片的高度是确定的，等于相机halfSize*cos(x轴旋转)
    /// 假设中心点在相机局部坐标系中的坐标为(0,0,z),获得相机的M矩阵，M矩阵右乘(0,0,z)的y值即为刚刚计算出来的高度值，可建立方程:
    /// height = z*M(1,2)+M(1,3)
    /// 由此可以算出z值，再将(0,0,z)从局部坐标转换到世界坐标即可
    /// </summary>
    /// <param name="camera"></param>
    /// <returns>中心点世界坐标，用该值和被拍摄物件的世界坐标相减可以得到偏移量，用于将物体从三维转二维后坐标依然可以对的上</returns>
    private static Vector3 TwoDimensionToWorldPosition(Camera camera)
    {
        var halfSize = camera.orthographicSize;
        var xAngle = camera.transform.localEulerAngles.x * Mathf.Deg2Rad;
        var height = Mathf.Cos(xAngle) * halfSize;
        var mMatrix = camera.transform.localToWorldMatrix;
        var localZ = (height - mMatrix[1, 3]) / mMatrix[1, 2];
        var localPos = new Vector3(0, 0, localZ);
        var worldPos = camera.transform.TransformPoint(localPos);
        return worldPos;
    }

    // private static Quaternion GetRootGameObjectRotation(Transform rootTrans, Transform currTrans,
    //     Quaternion currQuaternion)
    // {
    //     if (currTrans == rootTrans || currTrans == null)
    //         return currQuaternion;
    //     currQuaternion *= Quaternion.Inverse(currTrans.localRotation);
    //     return GetRootGameObjectRotation(rootTrans, currTrans.parent, currQuaternion);
    // }


    public static void SetGameObjectLayer(GameObject obj, int layer)
    {
        if (obj == null) return;
        obj.layer = layer;
        var trans = obj.transform;
        for (var i = 0; i < trans.childCount; ++i)
        {
            var child = trans.GetChild(i);
            SetGameObjectLayer(child.gameObject, layer);
        }
    }
}