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

public partial class PhysicsManager : Singleton<PhysicsManager>
{

    /// <summary>
    /// circle x,y,radius 
    /// </summary>
    /// <param name="pos1"></param>
    /// <param name="r1"></param>
    /// <param name="pos2"></param>
    /// <param name="r2"></param>
    /// <returns></returns>
    public static bool CircleVsCircle(Vector2 pos1, float r1, Vector2 pos2, float r2)
    {
        return (pos1 - pos2).magnitude <= r1 + r2;
    }

    public static bool CircleVsCircle(Vector3 c1, Vector3 c2)
    {
        return (c1.xy() - c2.xy()).magnitude <= c1.z + c2.z;
    }

    /// <summary>
    /// intersectionÊÇr2¶ÔÓÚr1
    /// </summary>
    /// <param name="b1"></param>
    /// <param name="b2"></param>
    /// <param name="intersection"></param>
    /// <returns></returns>
    public static bool BoxVsBox(Vector4 b1, Vector4 b2, out Vector2 intersection)
    {
        float b1w = b1.z / 2f, b1h = b1.w / 2f, b2w = b2.z / 2f, b2h = b2.w / 2f;
        float distX = b2.x - b1.x;
        float distY = b2.y - b1.y;
        if(Mathf.Abs(distX) < b1w + b2w && Mathf.Abs(distY) < b1h +b2h)
        {
            intersection = new Vector2();
            intersection.x = Mathf.Sign(distX) * (b1w + b2w - Mathf.Abs(distX));
            intersection.y = Mathf.Sign(distY) * (b1h + b2h - Mathf.Abs(distY));
            return true; 
        }
        intersection = Vector2.zero;
        return false;
    }

    public static bool BoxVsCircle(Vector4 box, Vector2 pos, float radius)
    {
        Vector4 boxScaled = box;
        boxScaled.z = box.z + radius * 2;
        boxScaled.w = box.w + radius * 2;
        if (!IsPointInsideBox(boxScaled, pos))
            return false;
        Vector2 v = MathUtils.Abs(pos - box.xy());
        Vector2 u = MathUtils.Max(v - box.zw(), 0);
        return Vector2.Dot(u, u) < radius * radius;
    }

    /// <summary>
    /// box x,y,w,h circle x,y,raduis
    /// </summary>
    /// <param name="box"></param>
    /// <param name="circle"></param>
    /// <returns></returns>
    public static bool BoxVsCircle(Vector4 box, Vector3 circle)
    {
        return BoxVsCircle(box, circle.xy(), circle.z);
    }

    public static bool IsPointInsideBox(Vector4 box, Vector2 point)
    {
        return point.x >= box.x - box.z / 2f
            && point.x <= box.x + box.z / 2f
            && point.y >= box.y - box.w / 2f
            && point.y <= box.y + box.w / 2f;
    }

}