using System.Numerics;

namespace Shogi.Domain
{
	public class MoveSet
	{

		public static readonly MoveSet King = new(new List<Move>(8)
		{
			new Move(Direction.Up),
			new Move(Direction.Left),
			new Move(Direction.Right),
			new Move(Direction.Down),
			new Move(Direction.UpLeft),
			new Move(Direction.UpRight),
			new Move(Direction.DownLeft),
			new Move(Direction.DownRight)
		});

		public static readonly MoveSet Bishop = new(new List<Move>(4)
		{
			new Move(Direction.UpLeft, Distance.MultiStep),
			new Move(Direction.UpRight, Distance.MultiStep),
			new Move(Direction.DownLeft, Distance.MultiStep),
			new Move(Direction.DownRight, Distance.MultiStep)
		});

		public static readonly MoveSet PromotedBishop = new(new List<Move>(8)
		{
			new Move(Direction.Up),
			new Move(Direction.Left),
			new Move(Direction.Right),
			new Move(Direction.Down),
			new Move(Direction.UpLeft, Distance.MultiStep),
			new Move(Direction.UpRight, Distance.MultiStep),
			new Move(Direction.DownLeft, Distance.MultiStep),
			new Move(Direction.DownRight, Distance.MultiStep)
		});

		public static readonly MoveSet GoldGeneral = new(new List<Move>(6)
		{
			new Move(Direction.Up),
			new Move(Direction.UpLeft),
			new Move(Direction.UpRight),
			new Move(Direction.Left),
			new Move(Direction.Right),
			new Move(Direction.Down)
		});

		public static readonly MoveSet Knight = new(new List<Move>(2)
		{
			new Move(Direction.KnightLeft),
			new Move(Direction.KnightRight)
		});

		public static readonly MoveSet Lance = new(new List<Move>(1)
		{
			new Move(Direction.Up, Distance.MultiStep),
		});

		public static readonly MoveSet Pawn = new(new List<Move>(1)
		{
			new Move(Direction.Up)
		});

		public static readonly MoveSet Rook = new(new List<Move>(4)
		{
			new Move(Direction.Up, Distance.MultiStep),
			new Move(Direction.Left, Distance.MultiStep),
			new Move(Direction.Right, Distance.MultiStep),
			new Move(Direction.Down, Distance.MultiStep)
		});

		public static readonly MoveSet PromotedRook = new(new List<Move>(8)
		{
			new Move(Direction.Up, Distance.MultiStep),
			new Move(Direction.Left, Distance.MultiStep),
			new Move(Direction.Right, Distance.MultiStep),
			new Move(Direction.Down, Distance.MultiStep),
			new Move(Direction.UpLeft),
			new Move(Direction.UpRight),
			new Move(Direction.DownLeft),
			new Move(Direction.DownRight)
		});

		public static readonly MoveSet SilverGeneral = new(new List<Move>(4)
		{
			new Move(Direction.Up),
			new Move(Direction.UpLeft),
			new Move(Direction.UpRight),
			new Move(Direction.DownLeft),
			new Move(Direction.DownRight)
		});

		private readonly ICollection<Move> moves;
		private readonly ICollection<Move> upsidedownMoves;

		private MoveSet(ICollection<Move> moves)
		{
			this.moves = moves;
			upsidedownMoves = moves.Select(m => new Move(Vector2.Negate(m.Direction), m.Distance)).ToList();
		}

		public ICollection<Move> GetMoves(bool isUpsideDown) => isUpsideDown ? upsidedownMoves : moves;
	}
}