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

namespace XFramework.UIExtensions
{
    //UGUI扩展类 可绘制贝塞尔、圆形等图形
    public static class PolygonHelper
    {
        public static void AddUIVertexTriangles(this VertexHelper vh, UIVertex[] verts)
        {
            for (int i = 0; i < verts.Length; i += 3)
            {
                int currentVertCount = vh.currentVertCount;

                for (int index = i; index < i + 3; index++)
                {
                    vh.AddVert(verts[index].position, verts[index].color, verts[index].uv0, verts[index].uv1, verts[index].normal, verts[index].tangent);
                }

                vh.AddTriangle(currentVertCount, currentVertCount + 1, currentVertCount + 2);
            }
        }


        public static void AddUIVertexTriangle(this VertexHelper vh, UIVertex[] verts)
        {
            int currentVertCount = vh.currentVertCount;
            for (int index = 0; index < 3; ++index)
                vh.AddVert(verts[index].position, verts[index].color, verts[index].uv0, verts[index].uv1, verts[index].normal, verts[index].tangent);
            vh.AddTriangle(currentVertCount, currentVertCount + 1, currentVertCount + 2);
        }


        private static void vertex(this List<UIVertex> vertices, float x, float y, Color color)
        {
            UIVertex v = UIVertex.simpleVert;
            v.color = color;
            v.position = new Vector2(x, y);
            v.uv0 = Vector2.zero;
        }



        //画圆形

        public static void circle(this VertexHelper vh, Vector2 pos, float radius, Color color, bool filled = false)
        {
            circle(vh, pos.x, pos.y, radius, Mathf.Max(1, (int)(6 * Mathf.Pow(radius, 1 / 3f))), color, filled);
        }

        public static void circle(this VertexHelper vh, float x, float y, float radius, Color color, bool filled = false)
        {
            circle(vh, x, y, radius, Mathf.Max(1, (int)(6 * Mathf.Pow(radius, 1 / 3f))), color, filled);
        }

        public static void circle(this VertexHelper vh, float x, float y, float radius, int segments, Color color, bool filled = false)
        {
            if (segments > 0)
            {

                float angle = 2 * Mathf.PI / segments;
                float cos = Mathf.Cos(angle);
                float sin = Mathf.Sin(angle);
                float cx = radius, cy = 0;

                List<UIVertex> vs = new List<UIVertex>();

                segments--;
                for (int i = 0; i < segments; i++)
                {
                    vs.vertex(x, y, color);
                    vs.vertex(x + cx, y + cy, color);
                    float temp = cx;
                    cx = cos * cx - sin * cy;
                    cy = sin * temp + cos * cy;
                    vs.vertex(x + cx, y + cy, color);
                }
                vs.vertex(x, y, color);

                vs.vertex(x + cx, y + cy, color);

                cx = radius;
                cy = 0;
                vs.vertex(x + cx, y + cy, color);

                vh.AddUIVertexTriangles(vs.ToArray());
            }
        }


        public static void DrawBeziers(this VertexHelper vh, List<Vector2> points, float segment, float width,List<bool> defaultColor)
        {

            List<BezierUtils> beziers = CreateBeziers(points);

            if (beziers != null)
            {
                for (int i = 0; i < beziers.Count; i++)
                {
                    BezierUtils bezier = beziers[i];
                    DrawBezier(vh, bezier, segment, width);
                }
            }



        }


        public static Vector2 nor(this Vector2 vec)
        {
            float len = vec.magnitude;
            if (len != 0)
            {
                vec.x /= len;
                vec.y /= len;
            }
            return vec;
        }

        public static Vector2 rotate90(this Vector2 vec, int dir)
        {
            float x = vec.x;
            if (dir >= 0)
            {
                vec.x = -vec.y;
                vec.y = x;
            }
            else
            {
                vec.x = vec.y;
                vec.y = -x;
            }
            return vec;
        }

        public static Vector2 cpy(this Vector2 vec)
        {
            return new Vector2(vec.x, vec.y);
        }


        private static void DrawBezier(VertexHelper vh, BezierUtils bezier, float segment, float width)
        {
            List<Vector2> lpos = new List<Vector2>();
            List<Vector2> rpos = new List<Vector2>();
            for (int i = 0; i <= segment; i++)
            {
                Vector2 bezierPos = new Vector2(bezier.beze_x((float)i / (float)segment), bezier.beze_y((float)i / (float)segment));
                Vector2 bezierSpeed = new Vector2(bezier.beze_speed_x((float)i / (float)segment), bezier.beze_speed_y((float)i / (float)segment));
                Vector2 offseta = bezierSpeed.normalized.rotate90(1) * (0.5f * width);
                Vector2 offsetb = bezierSpeed.normalized.rotate90(-1) * (0.5f * width);

                lpos.Add(bezierPos.cpy() + offseta);
                rpos.Add(bezierPos.cpy() + offsetb);
            }

            for (int j = 0; j < segment; j++)
            {
                vh.AddUIVertexQuad(GetQuad(lpos[j], lpos[j + 1], rpos[j + 1], rpos[j]));
            }
        }



        private static UIVertex[] GetQuad(params Vector2[] vertPos)
        {
            UIVertex[] vs = new UIVertex[4];
            Vector2[] uv = new Vector2[4];
            uv[0] = new Vector2(0, 0);
            uv[1] = new Vector2(0, 1);
            uv[2] = new Vector2(1, 0);
            uv[3] = new Vector2(1, 1);
            for (int i = 0; i < 4; i++)
            {
                UIVertex v = UIVertex.simpleVert;
                v.color = Color.blue;
                v.position = vertPos[i];
                v.uv0 = uv[i];
                vs[i] = v;
            }
            return vs;
        }

        private static List<BezierUtils> CreateBeziers(List<Vector2> points)
        {
            float scale = 0.6f;

            List<BezierUtils> beziers = new List<BezierUtils>();

            int originCount = points.Count - 1;


            List<Vector2> midpoints = new List<Vector2>();
            for (int i = 0; i < originCount; i++)
            {
                midpoints.Add(new Vector2(
                  Mathf.Lerp(points[i].x, points[i + 1].x, 0.5f),
                  Mathf.Lerp(points[i].y, points[i + 1].y, 0.5f))
                );
            }

            List<Vector2> ctrlPoints = new List<Vector2>();
            float offsetx;
            float offsety;

            ctrlPoints.Add(new Vector2(
              points[0].x,
              points[0].y
            ));
            for (int i = 0; i < originCount - 1; i++)
            {
                Vector2 orginPoint = points[i + 1];

                offsetx = orginPoint.x - Mathf.Lerp(midpoints[i].x, midpoints[i + 1].x, 0.5f);
                offsety = orginPoint.y - Mathf.Lerp(midpoints[i].y, midpoints[i + 1].y, 0.5f);

                ctrlPoints.Add(new Vector2(
                  midpoints[i].x + offsetx,
                  midpoints[i].y + offsety
                ));
                ctrlPoints.Add(new Vector2(
                  midpoints[i + 1].x + offsetx,
                  midpoints[i + 1].y + offsety
                ));


                ctrlPoints[i * 2 + 1] = Vector2.Lerp(orginPoint, ctrlPoints[i * 2 + 1], scale);
                ctrlPoints[i * 2 + 2] = Vector2.Lerp(orginPoint, ctrlPoints[i * 2 + 2], scale);
            }


            ctrlPoints.Add(new Vector2(
              points[points.Count - 1].x,
              points[points.Count - 1].y
            ));


            for (int i = 0; i < originCount; i++)
            {
                BezierUtils bezier = getBezier(points[i], ctrlPoints[i * 2], ctrlPoints[i * 2 + 1], points[i + 1]);
                beziers.Add(bezier);
            }
            return beziers;
        }


        public static BezierUtils getBezier(Vector2 p0, Vector2 p1, Vector2 p2, Vector2 p3)
        {
            return new BezierUtils(p0.x, p0.y, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y);
        }

    }
}