package dev.kske.chess.board;

import java.util.ArrayList;
import java.util.List;

/**
 * Project: <strong>Chess</strong><br>
 * File: <strong>King.java</strong><br>
 * Created: <strong>01.07.2019</strong><br>
 *
 * @since Chess v0.1-alpha
 * @author Kai S. K. Engelbart
 */
public class King extends Piece {

	/**
	 * Creates king {@link Piece}.
	 *
	 * @param color the color of this king
	 * @param board the board on which this king will be placed
	 */
	public King(Color color, Board board) {
		super(color, board);
	}

	@Override
	public boolean isValidMove(Move move) {
		return move.getxDist() == 2 && move.getyDist() == 0
			&& (move.getDest().x == 6 && canCastleKingside()
				|| move.getDest().x == 2 && canCastleQueenside())
			|| move.getxDist() <= 1 && move.getyDist() <= 1
				&& checkDestination(move);
	}

	@Override
	protected List<Move> getPseudolegalMoves(Position pos) {
		List<Move> moves = new ArrayList<>();
		for (int i = Math.max(0, pos.x - 1); i < Math.min(8, pos.x + 2); i++)
			for (
				int j = Math.max(0, pos.y - 1);
				j < Math.min(8, pos.y + 2);
				j++
			)
				if (i != pos.x || j != pos.y) {
					Move move = new Move(pos, new Position(i, j));
					if (
						board.getDest(move) == null
							|| board.getDest(move).getColor() != getColor()
					)
						moves.add(move);
				}

		// Castling
		if (canCastleKingside())
			moves.add(new Castling(pos, new Position(6, pos.y)));
		if (canCastleQueenside())
			moves.add(new Castling(pos, new Position(2, pos.y)));

		return moves;
	}

	private boolean canCastleKingside() {
		if (
			board.getLog().getCastlingRights()[getColor() == Color.WHITE
				? MoveNode.WHITE_KINGSIDE
				: MoveNode.BLACK_KINGSIDE]
		) {
			int y = getColor() == Color.WHITE ? 7 : 0;
			Position kingPos = new Position(4, y);
			Position jumpPos = new Position(5, y);
			Position kingDest = new Position(6, y);
			Position rookPos = new Position(7, y);
			return canCastle(kingPos, kingDest, rookPos, jumpPos);
		}
		return false;
	}

	private boolean canCastleQueenside() {
		if (
			board.getLog().getCastlingRights()[getColor() == Color.WHITE
				? MoveNode.WHITE_QUEENSIDE
				: MoveNode.BLACK_QUEENSIDE]
		) {
			int y = getColor() == Color.WHITE ? 7 : 0;
			Position kingPos = new Position(4, y);
			Position jumpPos = new Position(3, y);
			Position freeDest = new Position(1, y);
			Position rookPos = new Position(0, y);
			return canCastle(kingPos, freeDest, rookPos, jumpPos);
		}
		return false;
	}

	private boolean canCastle(
		Position kingPos, Position freeDest, Position rookPos, Position jumpPos
	) {
		Piece rook = board.get(rookPos);
		return rook != null && rook instanceof Rook && isFreePath(
			new Move(kingPos, freeDest)
		) && !board.isAttacked(kingPos, getColor().opposite())
			&& !board.isAttacked(jumpPos, getColor().opposite());
	}

	@Override
	public int getValue() { return 0; }
}