chess/src/main/java/dev/kske/chess/game/NaturalPlayer.java

package dev.kske.chess.game;

import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.List;
import java.util.stream.Collectors;

import javax.swing.JComboBox;
import javax.swing.JOptionPane;

import dev.kske.chess.board.Move;
import dev.kske.chess.board.Piece;
import dev.kske.chess.board.Piece.Color;
import dev.kske.chess.board.Position;
import dev.kske.chess.ui.OverlayComponent;

/**
 * Enables the user to make moves in a {@link Game} by clicking on a
 * {@link Piece} and then selecting one of the highlighted positions as the move
 * destination.<br>
 * <br>
 * Project: <strong>Chess</strong><br>
 * File: <strong>NaturalPlayer.java</strong><br>
 * Created: <strong>06.07.2019</strong><br>
 *
 * @since Chess v0.1-alpha
 * @author Kai S. K. Engelbart
 */
public class NaturalPlayer extends Player implements MouseListener {

	private final OverlayComponent overlayComponent;

	private boolean moveRequested;
	private Piece selectedPiece;
	private List<Move> possibleMoves;

	/**
	 * Creates an instance of {@link NaturalPlayer}.
	 *
	 * @param game             the game in which this player will be used
	 * @param color            the piece color this player will control
	 * @param overlayComponent the overlay component that will be used to
	 *                         display
	 *                         possible moves to the user
	 */
	public NaturalPlayer(
		Game game, Color color, OverlayComponent overlayComponent
	) {
		super(game, color);
		this.overlayComponent = overlayComponent;
		name = "Player";
		moveRequested = false;

		overlayComponent.addMouseListener(this);
	}

	@Override
	public void requestMove() {
		moveRequested = true;
	}

	@Override
	public void cancelMove() {
		moveRequested = false;
	}

	@Override
	public void disconnect() {
		overlayComponent.removeMouseListener(this);
	}

	@Override
	public void mousePressed(MouseEvent evt) {
		if (!moveRequested)
			return;
		if (selectedPiece == null) {

			// Get selected Piece
			final Position pos = new Position(
				evt.getPoint().x / overlayComponent.getTileSize(),
				evt.getPoint().y / overlayComponent.getTileSize()
			);
			selectedPiece = board.get(pos);

			// Check if a piece was selected
			if (selectedPiece != null)
				// Discard selection if the piece has the wrong color
				if (selectedPiece.getColor() == color.opposite())
					selectedPiece = null;
				else {

					// Generate all moves possible with the selected piece and
					// display their
					// destinations
					possibleMoves = selectedPiece.getMoves(pos);
					overlayComponent.displayDots(
						possibleMoves.stream().map(Move::getDest).collect(Collectors.toList())
					);
				}
		} else {
			Position dest = new Position(
				evt.getPoint().x / overlayComponent.getTileSize(),
				evt.getPoint().y / overlayComponent.getTileSize()
			);

			// Get all moves leading to the specified destination
			List<Move> selectedMoves = possibleMoves.stream()
				.filter(m -> m.getDest().equals(dest))
				.collect(Collectors.toList());
			if (!selectedMoves.isEmpty()) {
				Move move;

				// Process pawn promotion if necessary
				if (selectedMoves.size() > 1) {

					// Let the user select a promotion piece
					JComboBox<Move> comboBox
						= new JComboBox<>(selectedMoves.toArray(new Move[0]));
					JOptionPane.showMessageDialog(
						overlayComponent,
						comboBox,
						"Select a promotion",
						JOptionPane.QUESTION_MESSAGE
					);

					move = selectedMoves.get(comboBox.getSelectedIndex());
				} else
					move = selectedMoves.get(0);
				// Tell the game to execute the move
				moveRequested = false;
				game.onMove(NaturalPlayer.this, move);
			}
			// Discard the selection
			overlayComponent.clearDots();
			selectedPiece = null;
			possibleMoves = null;
		}
	}

	@Override
	public void mouseClicked(MouseEvent e) {}

	@Override
	public void mouseReleased(MouseEvent e) {}

	@Override
	public void mouseEntered(MouseEvent e) {}

	@Override
	public void mouseExited(MouseEvent e) {}
}