import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.util.ArrayList;
import java.util.Random;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class EightPuzzle extends JFrame implements ActionListener {
	private static final String puzzleImage = "img/awesome";
	JButton[] buttons;
	JButton shuffleButton;
	int blank;
	public EightPuzzle() {
	    // Provided initialization--you do not need to modify
	    super("8 Puzzle");
	    ImageIcon[] icons = new ImageIcon[8];
		for (int i = 0; i < 8; i++) {
			String path = puzzleImage + (i/3 + 1) + "" + (i%3 + 1)  + ".png";
			icons[i] = new ImageIcon(new File(path).getAbsolutePath());
		}
        buttons = new JButton[9];
        
        getContentPane().setLayout(new BorderLayout());
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(600, 625);
		
		/*
		 * TODO 1:  Create a JPanel object that uses a grid layout that is 3x3.
		 *          Make the JPanel 600x600 and add it to the center of this
		 *          frame.
		 */

		/*
		 * TODO 2:  Create and add the first 8 JButtons.  You should store the
		 *          JButton objects in the buttons array declared for you.  The
		 *          ith JButton should use the ith ImageIcon as the image in the
		 *          icons array.  You should add "this" as an action listener
		 *          to the each button.
		 */
		for (int i = 0; i < 8; i++) {
		}
		/*
		 * TODO 3:  Create the last JButton.  This one is different, because it
		 *          starts with no icon.  It should also be disabled, since it
		 *          is not a valid move.  It should also add "this" as an
		 *          action listener.
		 */

		blank = 8;
		
		/*
		 * TODO 4:  Create a JButton labelled "Shuffle" and add it to the south
		 *          of the frame.  Be sure to add the appropriate action
		 *          listener.
		 */
	}
	
	/*
	 * TODO 5:  Implement the necessary event handlers in the actionPerformed
	 *          Method.  If one of the tile buttons is clicked, it should call
	 *          tryMove with the index of the button (the index in the buttons
	 *          array).  If the shuffle button is clicked, it should simply call
	 *          the shuffle method, which takes no arguments.
	 */
	public void actionPerformed(ActionEvent e) {
	}

	/* Everything below is complete.  Do not modify. */
	
    private void tryMove(int i) {
        JButton b = buttons[i];
        if (b.getIcon() != null) {
            // north
            if (i-3 >= 0 && buttons[i-3].getIcon() == null) {
                swap(i, i-3);
            }
            // east
            if (i/3 == (i+1)/3 && i+1 < 9 && buttons[i+1].getIcon() == null) {
                swap(i, i+1);
            }
            // south
            if (i+3 < 9 && buttons[i+3].getIcon() == null) {
                swap(i, i+3);
            }
            // west
            if (i/3 == (i-1)/3 && i-1 >= 0 && buttons[i-1].getIcon() == null) {
                swap(i, i-1);
            }
        }
    }
    
    // Swaps two tiles.  Assumes either i or j are blank.
    private void swap(int i, int j) {
        Icon tmp = buttons[i].getIcon();
        buttons[i].setIcon(buttons[j].getIcon());
        buttons[j].setIcon(tmp);
        if (blank == i) {
            blank = j;
            buttons[j].setEnabled(false);
            buttons[i].setEnabled(true);
        }
        else {
            blank = i;
            buttons[j].setEnabled(true);
            buttons[i].setEnabled(false);
        }
    }
    
    private void shuffle() {
        ArrayList<Integer> moves = new ArrayList<Integer>();
        Random r = new Random();
        for (int j = 0; j < 20; j++) {
            if (blank-3 >= 0) {
                moves.add(blank-3);
            }
            // east
            if (blank/3 == (blank+1)/3 && blank+1 < 9) {
                moves.add(blank+1);
            }
            // south
            if (blank+3 < 9) {
                moves.add(blank+3);
            }
            // west
            if (blank/3 == (blank-1)/3 && blank-1 >= 0) {
                moves.add(blank-1);
            }
            swap(blank, moves.get(r.nextInt(moves.size())));
            moves.clear();
        }
    }
    
	public static void main(String[] args) {
		try {
			new EightPuzzle().setVisible(true);
		}
		catch (Exception e) {
			e.printStackTrace();
		}
	}
}