final class Knight: Piece {
	override var unicodeRepresentation: String {
		return color == .Black ? "♞" : "♘"
	}

	override var pseudoLegalPositions: [Square.Position] {
		[
			position + (2, 1),
			position + (2, -1),
			position + (-2, 1),
			position + (-2, -1),
			position + (1, 2),
			position + (1, -2),
			position + (-1, 2),
			position + (-1, -2),
		].filter { $0.index != nil }
	}

	override var legalPositions: [Square.Position] {
		return pseudoLegalPositions.filter { isLegal(on: $0) }
	}

	override func move(to dst: Square.Position) {
	}

	override func isLegal(on pos: Square.Position) -> Bool {
		if let board = board, let s = board[pos] {
			if let p = s.piece {
				if p.color == color { return false }
				if p.kind == .King {
					// TODO: Notify board of check
					delegate?.notify(.kingInCheck(self))
					return false
				}
			}

		}
		return true
	}

	init(with color: Color, on position: Square.Position) {
		super.init(kind: .Knight, on: position, with: color)
	}

}