final class Knight: Piece {
	weak var board: Board?
	var kind: Kind = .Knight

	var unicodeRepresentation: String {
		return color == .Black ? "♞" : "♘"
	}
	var color: Color

	var position: Square.Position

	var pseudoLegalPositions: [Square.Position] {
		let directions: [Square.Position] = [
			.init(rank: position.rank + 2, file: position.file + 1),
			.init(rank: position.rank + 2, file: position.file - 1),
			.init(rank: position.rank - 2, file: position.file + 1),
			.init(rank: position.rank - 2, file: position.file - 1),
			.init(rank: position.rank + 1, file: position.file + 2),
			.init(rank: position.rank + 1, file: position.file - 2),
			.init(rank: position.rank - 1, file: position.file + 2),
			.init(rank: position.rank - 1, file: position.file - 2)
		]
		return directions.filter { $0.index != nil }
	}

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

	func move(to dst: Square.Position) -> Bool {
		return false
	}

	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
					return false
				}
			}

		}
		return true
	}

	init(color: Color, on position: Square.Position) {
		self.color = color
		self.position = position
	}

}