using System;
using Silk.NET.Maths;

namespace gaemstone.Bloxel;

public readonly struct ChunkPos
	: IEquatable<ChunkPos>
{
	public static readonly ChunkPos ORIGIN = new(0, 0, 0);

	public int X { get; }
	public int Y { get; }
	public int Z { get; }

	public ChunkPos(int x, int y, int z) => (X, Y, Z) = (x, y, z);
	public void Deconstruct(out int x, out int y, out int z) => (x, y, z) = (X, Y, Z);

		public Vector3D<float> GetOrigin() => new(
			X << Chunk.BIT_SHIFT, Y << Chunk.BIT_SHIFT, Z << Chunk.BIT_SHIFT);
		public Vector3D<float> GetCenter() => new(
			(X << Chunk.BIT_SHIFT) + Chunk.LENGTH / 2,
			(Y << Chunk.BIT_SHIFT) + Chunk.LENGTH / 2,
			(Z << Chunk.BIT_SHIFT) + Chunk.LENGTH / 2);


	public ChunkPos Add(int x, int y, int z)
		=> new(X + x, Y + y, Z + z);
	public ChunkPos Add(in ChunkPos other)
		=> new(X + other.X, Y + other.Y, Z + other.Z);
	public ChunkPos Add(BlockFacing facing)
		{ var (x, y, z) = facing; return Add(x, y, z); }
	public ChunkPos Add(Neighbor neighbor)
		{ var (x, y, z) = neighbor; return Add(x, y, z); }

	public ChunkPos Subtract(int x, int y, int z)
		=> new(X - x, Y - y, Z - z);
	public ChunkPos Subtract(in ChunkPos other)
		=> new(X - other.X, Y - other.Y, Z - other.Z);
	public ChunkPos Subtract(BlockFacing facing)
		{ var (x, y, z) = facing; return Subtract(x, y, z); }
	public ChunkPos Subtract(Neighbor neighbor)
		{ var (x, y, z) = neighbor; return Subtract(x, y, z); }


	public bool Equals(ChunkPos other)
		=> (X == other.X) && (Y == other.Y) && (Z == other.Z);
	public override bool Equals(object? obj)
		=> (obj is ChunkPos pos) && Equals(pos);

	public override int GetHashCode() => HashCode.Combine(X, Y, Z);
	public override string ToString() => $"ChunkPos ({X}:{Y}:{Z})";
	public string ToShortString() => $"{X}:{Y}:{Z}";


	public static ChunkPos operator +(ChunkPos left, ChunkPos right) => left.Add(right);
	public static ChunkPos operator -(ChunkPos left, ChunkPos right) => left.Subtract(right);
	public static ChunkPos operator +(ChunkPos left, BlockFacing right) => left.Add(right);
	public static ChunkPos operator -(ChunkPos left, BlockFacing right) => left.Subtract(right);
	public static ChunkPos operator +(ChunkPos left, Neighbor right) => left.Add(right);
	public static ChunkPos operator -(ChunkPos left, Neighbor right) => left.Subtract(right);

	public static bool operator ==(ChunkPos left, ChunkPos right) => left.Equals(right);
	public static bool operator !=(ChunkPos left, ChunkPos right) => !left.Equals(right);
}

public static class ChunkPosExtensions
{
	public static ChunkPos ToChunkPos(this Vector3D<float> pos) => new(
		(int)MathF.Floor(pos.X) >> Chunk.BIT_SHIFT,
		(int)MathF.Floor(pos.Y) >> Chunk.BIT_SHIFT,
		(int)MathF.Floor(pos.Z) >> Chunk.BIT_SHIFT);

	public static ChunkPos ToChunkPos(this BlockPos self) => new(
		self.X >> Chunk.BIT_SHIFT, self.Y >> Chunk.BIT_SHIFT, self.Z >> Chunk.BIT_SHIFT);
	public static BlockPos ToChunkRelative(this BlockPos self) => new(
		self.X & Chunk.BIT_MASK, self.Y & Chunk.BIT_MASK, self.Z & Chunk.BIT_MASK);
	public static BlockPos ToChunkRelative(this BlockPos self, ChunkPos chunk) => new(
		self.X - (chunk.X << Chunk.BIT_SHIFT),
		self.Y - (chunk.Y << Chunk.BIT_SHIFT),
		self.Z - (chunk.Z << Chunk.BIT_SHIFT));
}