using System;
using Microsoft.Xna.Framework;

namespace BouncyCatIsBouncy
{
    struct RadialBB : ICollidable
    {
        public float Radius { get; set; }
        public Vector2 Center { get; set; }

        public RadialBB(float radius) 
            : this()
        {
            Radius = radius;
        }

        public RadialBB(float radius, Vector2 center)
            : this(radius)
        {
            Center = center;
        }


        public CollisionInfo Collides(RadialBB other)
        {
            var difference = Center - other.Center;
            var distSquared = difference.LengthSquared();
            var radiusSum = Radius + other.Radius;

            //If squared distance is less than or equal to the sum of the squared radii, they collide
            if (distSquared <= radiusSum * radiusSum)
            {
                Vector2 normal = Vector2.Normalize(difference);
                float penetration = radiusSum - (float)Math.Sqrt(distSquared);

                return new CollisionInfo(true, normal, penetration);
            }
            return new CollisionInfo();
        }
    }
}