package dev.kske.chess.ui;

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import javax.swing.*;

import dev.kske.chess.board.BoardState;
import dev.kske.chess.board.MoveNode;
import dev.kske.chess.board.Piece.Color;
import dev.kske.chess.event.*;
import dev.kske.chess.game.Game;
import dev.kske.chess.game.NaturalPlayer;

/**
 * The part of this application's {@link MainWindow} that displays {@link Game}s
 * and other components allowing to manipulate them.<br>
 * <br>
 * Project: <strong>Chess</strong><br>
 * File: <strong>GamePane.java</strong><br>
 * Created: <strong>23.08.2019</strong><br>
 *
 * @since Chess v0.4-alpha
 * @author Kai S. K. Engelbart
 */
public class GamePane extends JComponent {

	private static final long serialVersionUID = 4349772338239617477L;

	private JButton btnRestart, btnSwapColors;
	private BoardPane boardPane;
	private Game game;
	private Color activeColor;
	private JPanel moveSelectionPanel;
	private JButton btnFirst, btnPrevious, btnNext, btnLast;

	/**
	 * Creates an instance of {@link GamePane}.
	 */
	public GamePane() {
		activeColor = Color.WHITE;

		GridBagLayout gridBagLayout = new GridBagLayout();
		gridBagLayout.columnWidths = new int[] {
			450, 1, 0
		};
		gridBagLayout.rowHeights = new int[] {
			33, 267, 1, 0
		};
		gridBagLayout.columnWeights = new double[] {
			0.0, 1.0, 1.0
		};
		gridBagLayout.rowWeights = new double[] {
			1.0, 1.0, 1.0, Double.MIN_VALUE
		};
		setLayout(gridBagLayout);

		JPanel toolPanel = new JPanel();
		btnRestart = new JButton("Restart");
		btnRestart.addActionListener(evt -> {
			if (game != null) {
				game.reset();
				game.start();
			}
		});

		btnSwapColors = new JButton("Play as black");
		btnSwapColors.addActionListener(evt -> {
			game.swapColors();
			btnSwapColors
				.setText("Play as " + activeColor.toString().toLowerCase());
			activeColor = activeColor.opposite();
		});

		toolPanel.add(btnRestart);
		toolPanel.add(btnSwapColors);

		GridBagConstraints gbc_toolPanel = new GridBagConstraints();
		gbc_toolPanel.anchor = GridBagConstraints.NORTH;
		gbc_toolPanel.fill = GridBagConstraints.HORIZONTAL;
		gbc_toolPanel.gridx = 0;
		gbc_toolPanel.gridy = 0;
		gbc_toolPanel.gridwidth = 2;
		add(toolPanel, gbc_toolPanel);

		moveSelectionPanel = new JPanel();
		GridBagConstraints gbc_moveSelectionPanel = new GridBagConstraints();
		gbc_moveSelectionPanel.fill = GridBagConstraints.BOTH;
		gbc_moveSelectionPanel.gridx = 2;
		gbc_moveSelectionPanel.gridy = 0;
		add(moveSelectionPanel, gbc_moveSelectionPanel);

		btnFirst = new JButton("First");
		btnFirst.setEnabled(false);
		moveSelectionPanel.add(btnFirst);

		btnPrevious = new JButton("Previous");
		btnPrevious.addActionListener(evt -> {
			if (game != null) {
				game.getBoard().selectPreviousNode();
				getBoardPane().getOverlayComponent().clearArrow();
				repaint();
			}
		});
		moveSelectionPanel.add(btnPrevious);

		btnNext = new JButton("Next");
		btnNext.addActionListener(evt -> {
			if (game != null) {
				int numVariations
					= game.getBoard().getLog().getLast().getVariations().size();
				int index;
				if (numVariations == 1)
					index = 1;
				else
					index
						= Integer.parseInt(
							JOptionPane
								.showInputDialog("Enter the variation index.")
						);
				game.getBoard().selectNextNode(index);
				getBoardPane().getOverlayComponent().clearArrow();
				repaint();
			}
		});
		moveSelectionPanel.add(btnNext);

		btnLast = new JButton("Last");
		btnLast.setEnabled(false);
		moveSelectionPanel.add(btnLast);

		boardPane = new BoardPane();
		GridBagConstraints gbc_boardPane = new GridBagConstraints();
		gbc_boardPane.fill = GridBagConstraints.BOTH;
		gbc_boardPane.gridx = 0;
		gbc_boardPane.gridy = 1;
		add(boardPane, gbc_boardPane);

		JPanel numberPanel = new JPanel(new GridLayout(8, 1));
		GridBagConstraints gbc_numberPanel = new GridBagConstraints();
		gbc_numberPanel.anchor = GridBagConstraints.WEST;
		gbc_numberPanel.fill = GridBagConstraints.VERTICAL;
		gbc_numberPanel.gridx = 1;
		gbc_numberPanel.gridy = 1;
		add(numberPanel, gbc_numberPanel);

		JPanel letterPanel = new JPanel(new GridLayout(1, 8));
		GridBagConstraints gbc_letterPanel = new GridBagConstraints();
		gbc_letterPanel.anchor = GridBagConstraints.NORTH;
		gbc_letterPanel.fill = GridBagConstraints.HORIZONTAL;
		gbc_letterPanel.gridx = 0;
		gbc_letterPanel.gridy = 2;
		add(letterPanel, gbc_letterPanel);

		// Initialize board coordinates
		for (int i = 0; i < 8; i++) {
			numberPanel.add(new JLabel(String.valueOf(8 - i)));
			JLabel letterLabel = new JLabel(String.valueOf((char) (65 + i)));
			letterLabel.setHorizontalAlignment(SwingConstants.CENTER);
			letterPanel.add(letterLabel);
		}
		JScrollPane scrollPane = new JScrollPane();
		GridBagConstraints gbc_scrollPane = new GridBagConstraints();
		gbc_scrollPane.fill = GridBagConstraints.BOTH;
		gbc_scrollPane.gridx = 2;
		gbc_scrollPane.gridy = 1;
		add(scrollPane, gbc_scrollPane);

		JList<MoveNode> pgnList = new JList<>();
		pgnList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
		pgnList.setLayoutOrientation(JList.HORIZONTAL_WRAP);
		pgnList.setVisibleRowCount(0);
		pgnList.setCellRenderer(new MoveNodeRenderer());
		scrollPane.setViewportView(pgnList);

		// Listen to moves and game (re-)starts and update the move list or
		// disable the
		// color switching buttons if necessary
		EventBus.getInstance().register(new Subscriber() {

			@Override
			public void handle(Event<?> event) {
				if (
					event instanceof MoveEvent && (((MoveEvent) event)
						.getBoardState() == BoardState.CHECKMATE
						|| ((MoveEvent) event)
							.getBoardState() == BoardState.STALEMATE)
				)
					btnSwapColors.setEnabled(false);
				else
					if (event instanceof GameStartEvent)
						btnSwapColors.setEnabled(
							game.getPlayers().get(Color.WHITE) instanceof NaturalPlayer ^ game.getPlayers().get(Color.BLACK) instanceof NaturalPlayer
						);

				if (game.getBoard().getLog() == null)
					return;

				DefaultListModel<MoveNode> model = new DefaultListModel<>();
				game.getBoard().getLog().forEach(model::addElement);
				pgnList.setModel(model);
			}

			@Override
			public Set<Class<?>> supports() {
				return new HashSet<>(
					Arrays.asList(MoveEvent.class, GameStartEvent.class)
				);
			}
		});
	}

	/**
	 * @return The {@link BoardPane} instance associated with this game pane
	 */
	public BoardPane getBoardPane() { return boardPane; }

	/**
	 * @return The {@link Game} instance associated with this game pane
	 */
	public Game getGame() { return game; }

	/**
	 * Assigns a new {@link Game} instance to this game pane. If exactly one of
	 * the
	 * players is natural, color swapping functionality is enabled.
	 *
	 * @param game The {@link Game} to assign to this game pane.
	 */
	public void setGame(Game game) {
		if (this.game != null)
			this.game.stop();
		this.game = game;
	}
}