using System;
using System.Numerics;
using MoonTools.Structs;

namespace MoonTools.Bonk
{
    /// <summary>
    /// A Circle is a shape defined by a radius.
    /// </summary>
    public struct Circle : IShape2D, IEquatable<Circle>
    {
        public int Radius { get; }
        public AABB AABB { get; }

        public Circle(int radius)
        {
            Radius = radius;
            AABB = new AABB(-Radius, -Radius, Radius, Radius);
        }

        public Vector2 Support(Vector2 direction, Transform2D transform)
        {
            return Vector2.Transform(Vector2.Normalize(direction) * Radius, transform.TransformMatrix);
        }

        public AABB TransformedAABB(Transform2D transform2D)
        {
            return AABB.Transformed(AABB, transform2D);
        }

        public override bool Equals(object obj)
        {
            return obj is IShape2D other && Equals(other);
        }

        public bool Equals(IShape2D other)
        {
            return other is Circle circle && Equals(circle);
        }

        public bool Equals(Circle other)
        {
            return Radius == other.Radius;
        }

        public override int GetHashCode()
        {
            return HashCode.Combine(Radius);
        }

        public static bool operator ==(Circle a, Circle b)
        {
            return a.Equals(b);
        }

        public static bool operator !=(Circle a, Circle b)
        {
            return !(a == b);
        }
    }
}