using UnityEngine.Rendering;
namespace Gameplay.Vehicle.TireMark
{

    using UnityEngine;

    public class TireMarkPanel
    {
        public GameObject rootObj;

        public RenderTexture rt;

        // TODO: 这个size可以调整
        private readonly int _textureSize = 2048;

        private Vector3 _centerPos;
        private Vector3 _halfSize;

        public TireMarkPanel(GameObject rootObj)
        {
            this.rootObj = rootObj;
        }

        public void Init()
        {
            // 创建一个空的贴图,RenderTexture
            rt = new RenderTexture(_textureSize, _textureSize, 0, RenderTextureFormat.Default);
            // 设置基础颜色为 透明
            Graphics.SetRenderTarget(rt);
            GL.Clear(true, true, Color.clear);
            Graphics.SetRenderTarget(null);

            var meshRenderer = rootObj.transform.GetChild(0).GetComponent<MeshRenderer>();
            meshRenderer.material.mainTexture = rt;

            // 获取区块大小
            var centerPos = rootObj.transform.position;
            var size = rootObj.transform.localScale;
            var halfSize = size / 2;
            _centerPos = centerPos;
            _halfSize = halfSize;
        }

        public void Dispose()
        {
            Object.Destroy(rt);
            rt = null;
        }

        private readonly Vector2[] _cachePosList = new Vector2[4];
        private readonly Vector3[] _cacheUVList = new Vector3[4];

        public void Draw(TireMarkDrawData drawData,
            CommandBuffer cmd, int debugIndex)
        {
            // 根据drawData的数据，将贴图上的像素点进行修改
            var start = drawData.start;
            var end = drawData.end;
            var width = drawData.width;

            if (drawData.needCalc)
            {
                drawData.needCalc = false;
                if (drawData.isFirst)
                {
                    drawData.isFirst = false;
                    // 获取绘制四边形
                    var c1 = start.pos;
                    var c2 = end.pos;
                    var startLeft = start.rot * new Vector3(width / 2, 0, 0);
                    var p1 = start.pos + startLeft;
                    var p2 = start.pos - startLeft;
                    var endLeft = end.rot * new Vector3(width / 2, 0, 0);
                    var p3 = end.pos + endLeft;
                    var p4 = end.pos - endLeft;
                    // 当c1-p1 与 c2-p3相交时，将p3重置为p1
                    var isIntersect = _IsLineIntersect(c1, p1, c2, p3);
                    if (isIntersect)
                    {
                        p3 = p1;
                    }
                    // 当c1-p2 与 c2-p4相交时，将p4重置为p2
                    isIntersect = _IsLineIntersect(c1, p2, c2, p4);
                    if (isIntersect)
                    {
                        p4 = p2;
                    }

                    drawData.cacheP1 = p1;
                    drawData.cacheP2 = p2;
                    drawData.cacheP3 = p3;
                    drawData.cacheP4 = p4;

                    drawData.cacheC1 = c2;
                }
                else
                {
                    var c1 = drawData.cacheC1;
                    var c2 = end.pos;
                    var p1 = drawData.cacheP1;
                    var p2 = drawData.cacheP2;

                    var endLeft = end.rot * new Vector3(width / 2, 0, 0);
                    var p3 = end.pos + endLeft;
                    var p4 = end.pos - endLeft;

                    // 当c1-p1 与 c2-p3相交时，将p3重置为p1
                    var isIntersect = _IsLineIntersect(c1, p1, c2, p3);
                    if (isIntersect)
                    {
                        p3 = p1;
                    }
                    // 当c1-p2 与 c2-p4相交时，将p4重置为p2
                    isIntersect = _IsLineIntersect(c1, p2, c2, p4);
                    if (isIntersect)
                    {
                        p4 = p2;
                    }

                    drawData.cacheP1 = p1;
                    drawData.cacheP2 = p2;
                    drawData.cacheP3 = p3;
                    drawData.cacheP4 = p4;

                    drawData.cacheC1 = c2;

                }
            }

            // 根据四个点,计算出贴图上的uv坐标
            var pos1 = _GetTexturePos(drawData.cacheP1);
            var pos2 = _GetTexturePos(drawData.cacheP2);
            var pos3 = _GetTexturePos(drawData.cacheP3);
            var pos4 = _GetTexturePos(drawData.cacheP4);

            drawData.cacheP1 = drawData.cacheP3;
            drawData.cacheP2 = drawData.cacheP4;

            // 重排四个uv,确保uv1234是顺时针排列的
            var posList = _cachePosList;
            posList[0] = pos1;
            posList[1] = pos2;
            posList[2] = pos3;
            posList[3] = pos4;
            // _SortUV(posList);

            var isAllOut = true;
            for (int i = 0; i < posList.Length; i++)
            {
                var pos = posList[i];
                if (pos.x is > -1 and < 1 && pos.y is > -1 and < 1)
                {
                    isAllOut = false;
                    break;
                }
            }
            if (isAllOut)
            {
                return;
            }


            var uvList = _cacheUVList;
            var halfUVWidth = drawData.uvWidth / 2f;
            uvList[0] = new Vector3(0.5f - halfUVWidth, drawData.start.uvY % 1f, drawData.start.alpha);
            uvList[1] = new Vector3(0.5f + halfUVWidth, drawData.start.uvY % 1f, drawData.start.alpha);
            uvList[2] = new Vector3(0.5f - halfUVWidth, drawData.end.uvY % 1f, drawData.end.alpha);
            uvList[3] = new Vector3(0.5f + halfUVWidth, drawData.end.uvY % 1f, drawData.end.alpha);

            // TODO: 等待调试
            // var combieStr = "进行绘制 " + debugIndex + ":";
            // combieStr += "pos1:" + pos1 + " ";
            // combieStr += "pos2:" + pos2 + " ";
            // combieStr += "pos3:" + pos3 + " ";
            // combieStr += "pos4:" + pos4 + " ";
            // DebugUtil.LogError(combieStr);

            // 绘制四边形
            DrawQuadrilateral(cmd, rt, posList, uvList, drawData.t2d, drawData.color);
        }

        private readonly Vector3[] _cacheVertices = new Vector3[4];
        private readonly Color[] _cacheUV = new Color[4];
        private readonly Mesh _cacheMesh = new Mesh();
        private readonly int[] _cacheIndices =
        {
            0, 1,
            3, 2
        };
        private static readonly int MainTex = Shader.PropertyToID("_MainTex");
        private static readonly int MainColor = Shader.PropertyToID("_MainColor");

        private void DrawQuadrilateral(CommandBuffer cmd,
            RenderTexture targetTexture,
            Vector2[] screenPosList,
            Vector3[] uvList,
            Texture2D texture2D,
            Color color)
        {
            // 创建 CommandBuffer
            cmd.SetRenderTarget(targetTexture);

            // 设置四边形的顶点和 UV 坐标信息
            Vector3[] vertices = _cacheVertices;
            Color[] uv = _cacheUV;

            // 0 1 2 2 1 3
            vertices[0] = new Vector3(screenPosList[0].x, screenPosList[0].y, 0f);
            vertices[1] = new Vector3(screenPosList[1].x, screenPosList[1].y, 0f);
            vertices[2] = new Vector3(screenPosList[2].x, screenPosList[2].y, 0f);
            vertices[3] = new Vector3(screenPosList[3].x, screenPosList[3].y, 0f);

            uv[0] = new Color(uvList[0].x, uvList[0].y, uvList[0].z);
            uv[1] = new Color(uvList[1].x, uvList[1].y, uvList[1].z);
            uv[2] = new Color(uvList[2].x, uvList[2].y, uvList[2].z);
            uv[3] = new Color(uvList[3].x, uvList[3].y, uvList[3].z);


            // for (int i = 0; i < 4; i++)
            // {
            //     // uv坐标 就是 屏幕坐标
            //     vertices[i] = new Vector3(screenPosList[i].x, -screenPosList[i].y, 0f); // 将 UV 坐标映射到屏幕空间
            // }

            // TEST
            // vertices[0] = new Vector3(-0.094f, 0.289f, 0);
            // vertices[1] = new Vector3(-0.007f, 0.239f, 0);
            // vertices[2] = new Vector3(-0.181f, 0.339f, 0);
            // vertices[3] = new Vector3(-0.186f, 0.330f, 0);

            // 创建 Mesh
            var mesh = _cacheMesh;
            mesh.vertices = vertices;
            mesh.colors = uv;
            mesh.SetIndices(_cacheIndices, MeshTopology.Quads, 0);

            // 设置材质和绘制命令
            var material = TireMarkManager.instance.drawMat;
            material.SetTexture(MainTex, texture2D);
            material.SetColor(MainColor, color);
            cmd.DrawMesh(mesh, Matrix4x4.identity, material);

        }

        private void _SortUV(Vector2[] uvList)
        {
            // 重排四个uv,确保uv1234是顺时针排列的
            Vector2 center = Vector2.zero;
            for (int i = 0; i < uvList.Length; i++)
            {
                center += uvList[i];
            }
            center /= uvList.Length;

            System.Array.Sort(uvList, (a,
                b) =>
            {
                float cross = (a.x - center.x) * (b.y - center.y) - (b.x - center.x) * (a.y - center.y);
                if (cross > 0f)
                {
                    return -1;
                }
                else if (cross < 0f)
                {
                    return 1;
                }
                else
                {
                    return 0;
                }
            });
        }

        private Vector2 _GetTexturePos(Vector3 pos)
        {
            // 根据pos和自身_bounds计算出uv坐标
            var x = (pos.x - _centerPos.x) / _halfSize.x;
            var z = (pos.z - _centerPos.z) / _halfSize.z;
            return new Vector2(x, z);
        }

        private bool _IsLineIntersect(Vector3 p1,
            Vector3 p2,
            Vector3 p3,
            Vector3 p4)
        {
            // 判断两条线段是否相交
            Vector2 A = new Vector2(p1.x, p1.z);
            Vector2 B = new Vector2(p2.x, p2.z);
            Vector2 C = new Vector2(p3.x, p3.z);
            Vector2 D = new Vector2(p4.x, p4.z);

            float denominator = (B.y - A.y) * (D.x - C.x) - (A.x - B.x) * (C.y - D.y);
            if (denominator == 0f)
            {
                return false; // 平行或共线，不相交
            }

            float numerator1 = (A.x - C.x) * (D.y - C.y) - (A.y - C.y) * (D.x - C.x);
            float numerator2 = (A.x - C.x) * (B.y - A.y) - (A.y - C.y) * (B.x - A.x);

            float t1 = numerator1 / denominator;
            float t2 = numerator2 / denominator;

            // 如果 t1 和 t2 在 0~1 之间，则两线段相交
            if (t1 >= 0f && t1 <= 1f && t2 >= 0f && t2 <= 1f)
            {
                return true;
            }

            return false;
        }
    }
}