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

namespace MoonTools.Core.Bonk
{
    /// <summary>
    /// A Minkowski difference between two shapes.
    /// </summary>
    public struct MinkowskiDifference : IEquatable<MinkowskiDifference>
    {
        private IShape2D ShapeA { get; }
        private Transform2D TransformA { get; }
        private IShape2D ShapeB { get; }
        private Transform2D TransformB { get; }

        public MinkowskiDifference(IShape2D shapeA, Transform2D transformA, IShape2D shapeB, Transform2D transformB)
        {
            ShapeA = shapeA;
            TransformA = transformA;
            ShapeB = shapeB;
            TransformB = transformB;
        }

        public Vector2 Support(Vector2 direction)
        {
            return ShapeA.Support(direction, TransformA) - ShapeB.Support(-direction, TransformB);
        }

        public override bool Equals(object other)
        {
            return other is MinkowskiDifference minkowskiDifference && Equals(minkowskiDifference);
        }

        public bool Equals(MinkowskiDifference other)
        {
            return
                ShapeA == other.ShapeA &&
                TransformA == other.TransformA &&
                ShapeB == other.ShapeB &&
                TransformB == other.TransformB;
        }

        public override int GetHashCode()
        {
            return HashCode.Combine(ShapeA, TransformA, ShapeB, TransformB);
        }

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

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