using System;
using System.Collections.Generic;
using System.Numerics;
using MoonTools.Structs;

namespace MoonTools.Bonk
{
    /// <summary>
    /// Axis-aligned bounding box in 3 dimensions.
    /// </summary>
    public struct AABB3D : IEquatable<AABB3D>
    {
        public Vector3 Min { get; private set; }

        public Vector3 Max { get; private set; }

        public float Width { get { return Max.X - Min.X; } }
        public float Height { get { return Max.Y - Min.Y; } }
        public float Depth { get { return Max.Z - Min.Z; } }

        public AABB3D(float minX, float minY, float minZ, float maxX, float maxY, float maxZ)
        {
            Min = new Vector3(minX, minY, minZ);
            Max = new Vector3(maxX, maxY, maxZ);
        }

        public AABB3D(Vector3 min, Vector3 max)
        {
            Min = min;
            Max = max;
        }

        public static bool TestOverlap(AABB3D a, AABB3D b)
        {
            return 
                a.Min.X <= b.Max.X && 
                a.Max.X >= b.Min.X && 
                a.Min.Y <= b.Max.Y && 
                a.Max.Y >= b.Min.Y &&
                a.Min.Z <= b.Max.Z &&
                a.Max.Z >= b.Min.Z;
        }

        public AABB3D Merge(AABB3D other)
        {
            return new AABB3D(
                Vector3.Min(Min, other.Min),
                Vector3.Max(Max, other.Max)
            );
        }

        public IEnumerable<Vector3> AABBCorners()
        {
            yield return Min;
            yield return new Vector3(Min.X, Min.Y, Max.Z);
            yield return new Vector3(Min.X, Max.Y, Min.Z);
            yield return new Vector3(Max.X, Min.Y, Min.Z);
            yield return new Vector3(Min.X, Max.Y, Max.Z);
            yield return new Vector3(Max.X, Min.Y, Max.Z);
            yield return new Vector3(Max.X, Max.Y, Min.Z);
            yield return Max;
        }

        public override bool Equals(object obj)
        {
            return obj is AABB3D d && Equals(d);
        }

        public override int GetHashCode()
        {
            return HashCode.Combine(Min, Max);
        }

        public bool Equals(AABB3D other)
        {
            return Min == other.Min && Max == other.Max;
        }
    }
}