using o0.Geometry2D.Float;
using System;
using UnityEngine;

namespace ZIM.Unity
{
    public static partial class ZIMMath
    {
        // 向量与x轴的夹角，返回0-360度
        public static float DegreeToXAxis(this Vector v)
        {
            //var a = v.x > 0 ? Math.Atan(v.y / v.x) * 180 / Math.PI : 180 + Math.Atan(v.y / v.x) * 180 / Math.PI;
            var a = Math.Atan2(v.y, v.x) * 180 / Math.PI;
            if (a < 0)
                a += 360;
            return (float)a;
        }

        // Projects a vector onto another vector.
        public static Vector2 Project(this Vector2 vector, Vector2 onNormal)
        {
            float dotProduct = Vector2.Dot(vector, onNormal);
            float magnitudeSquared = onNormal.sqrMagnitude;
            if (magnitudeSquared < Mathf.Epsilon)
                return Vector2.zero;
            return (dotProduct / magnitudeSquared) * onNormal;
        }

        public static float LengthManhattan(this Vector2 v) => Math.Abs(v.x) + Math.Abs(v.y);
        public static double LengthManhattan(Vector2 v1, Vector2 v2) => (v1 - v2).LengthManhattan();

        // 可以用于判断点位V于直线AB哪一侧
        // return的值 等于0: 点在线上，大于0: 三角形ABV是逆时针，小于0: 三角形ABV是顺时针 （注：Line的构造函数会修改AB的顺序）
        public static float LineCrossWithPoint(this Line l, Vector v)
        {
            var ld = l.B - l.A;
            var vd = v - l.A;
            return ld.x * vd.y - ld.y * vd.x;
        }
    }
}