chess/src/main/java/dev/kske/chess/board/MoveNode.java

package dev.kske.chess.board;

import java.util.*;

import dev.kske.chess.board.Piece.Color;

/**
 * Project: <strong>Chess</strong><br>
 * File: <strong>MoveNode.java</strong><br>
 * Created: <strong>02.10.2019</strong><br>
 *
 * @since Chess v0.5-alpha
 * @author Kai S. K. Engelbart
 */
public class MoveNode {

	/**
	 * The index of the white kingside casting in a casting rights array.
	 */
	public static final int WHITE_KINGSIDE = 0;

	/**
	 * The index of the white queenside castling in a castling rights array.
	 */
	public static final int WHITE_QUEENSIDE = 1;

	/**
	 * The index of the white kingside casting in a casting rights array.
	 */
	public static final int BLACK_KINGSIDE = 2;

	/**
	 * The index of the white queenside castling in a castling rights array.
	 */
	public static final int BLACK_QUEENSIDE = 3;

	/**
	 * The move on the board associated with this move node.
	 */
	public final Move move;

	/**
	 * The piece captured by the move.
	 */
	public final Piece capturedPiece;

	/**
	 * The castling rights present during the move.
	 */
	public final boolean[] castlingRights;

	/**
	 * The en passant target position or {@code null} if the move is not an en
	 * passant move.
	 */
	public final Position enPassant;

	/**
	 * The color active during the move.
	 */
	public final Color activeColor;

	/**
	 * The number of moves performed since the beginning of the game.
	 */
	public final int fullmoveCounter;

	/**
	 * The halfmoves performed since the last capture move or pawn move.
	 */
	public final int halfmoveClock;

	private MoveNode parent;
	private List<MoveNode> variations;

	/**
	 * Creates a new {@link MoveNode}.
	 *
	 * @param move            the logged {@link Move}
	 * @param capturedPiece   the {@link Piece} captures by the logged
	 *                        {@link Move}
	 * @param castlingRights  the castling rights present during the move
	 * @param enPassant       the en passant {@link Position} valid after the
	 *                        logged
	 *                        {@link Move}, or {@code null} if there is none
	 * @param activeColor     the {@link Color} active after the logged
	 *                        {@link Move}
	 * @param fullmoveCounter the number of moves made until the current move
	 * @param halfmoveClock   the number of halfmoves since the last capture
	 *                        move or
	 *                        pawn move
	 */
	public MoveNode(
		Move move, Piece capturedPiece, boolean castlingRights[],
		Position enPassant, Color activeColor, int fullmoveCounter,
		int halfmoveClock
	) {
		this.move = move;
		this.capturedPiece = capturedPiece;
		this.castlingRights = castlingRights;
		this.enPassant = enPassant;
		this.activeColor = activeColor;
		this.fullmoveCounter = fullmoveCounter;
		this.halfmoveClock = halfmoveClock;
	}

	/**
	 * Creates a (deep) copy of another {@link MoveNode}.
	 *
	 * @param other          The {@link MoveNode} to copy
	 * @param copyVariations When this is set to {@code true} a deep copy is
	 *                       created, which
	 *                       considers subsequent variations
	 */
	public MoveNode(MoveNode other, boolean copyVariations) {
		this(
			other.move,
			other.capturedPiece,
			other.castlingRights.clone(),
			other.enPassant,
			other.activeColor,
			other.fullmoveCounter,
			other.halfmoveClock
		);
		if (copyVariations && other.variations != null) {
			if (variations == null)
				variations = new ArrayList<>();
			for (MoveNode variation : other.variations) {
				MoveNode copy = new MoveNode(variation, true);
				copy.parent = this;
				variations.add(copy);
			}
		}
	}

	/**
	 * Adds another {@link MoveNode} as a child node.
	 *
	 * @param variation The {@link MoveNode} to append to this {@link MoveNode}
	 */
	public void addVariation(MoveNode variation) {
		if (variations == null)
			variations = new ArrayList<>();
		if (!variations.contains(variation)) {
			variations.add(variation);
			variation.parent = this;
		}
	}

	/**
	 * @return A list of all variations associated with this {@link MoveNode}
	 */
	public List<MoveNode> getVariations() { return variations; }

	/**
	 * @return {@code true} if this move node has any variations
	 */
	public boolean hasVariations() {
		return variations != null && variations.size() > 0;
	}

	/**
	 * @return the parent node of this move node
	 */
	public MoveNode getParent() { return parent; }

	/**
	 * Sets the parent node of this move node
	 *
	 * @param parent the parent node to set
	 */
	public void setParent(MoveNode parent) { this.parent = parent; }

	/**
	 * @return {@code true} if this move node has a parent
	 */
	public boolean hasParent() {
		return parent != null;
	}

	@Override
	public String toString() {
		return String.format(
			"MoveNode[move=%s,capturedPiece=%s,castlingRights=%s,enPassant=%s,activeColor=%s,fullmoveCounter=%d,halfmoveClock=%d]",
			move,
			capturedPiece,
			Arrays.toString(castlingRights),
			enPassant,
			activeColor,
			fullmoveCounter,
			halfmoveClock
		);
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + Arrays.hashCode(castlingRights);
		result = prime * result + Objects.hash(
			activeColor,
			capturedPiece,
			enPassant,
			fullmoveCounter,
			halfmoveClock,
			move
		);
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		MoveNode other = (MoveNode) obj;
		return activeColor == other.activeColor
			&& Objects.equals(capturedPiece, other.capturedPiece)
			&& Arrays.equals(castlingRights, other.castlingRights) && Objects.equals(enPassant, other.enPassant)
			&& fullmoveCounter == other.fullmoveCounter
			&& halfmoveClock == other.halfmoveClock
			&& Objects.equals(move, other.move);
	}
}