package chapter_14.swing;

import chapter_14.threadPool.ThreadPoolTest;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Map;
import java.util.Random;

/**
 * This program demonstrates that a thread that runs in parallel with the event dispatch thread
 * can cause errors in Swing components.
 * @author jerry-0824
 * @version 1.0.0 2016-12-21 10:52
 */
public class SwingThreadTest {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new SwingThreadFrame();
                frame.setTitle("SwingThreadTest");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}

/**
 * This frame has two buttons to fill a combo box from a separate thread.
 * The "Good" button uses the event queue, the "Bad" button modifies the combo box directly.
 */
class SwingThreadFrame extends JFrame {
    public SwingThreadFrame() {
        final JComboBox<Integer> combo = new JComboBox<>();
        combo.insertItemAt(Integer.MAX_VALUE, 0);
        combo.setPrototypeDisplayValue(combo.getItemAt(0));
        combo.setSelectedIndex(0);

        JPanel panel = new JPanel();

        JButton goodButton = new JButton("Good");
        goodButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                new Thread(new GoodWorkerRunnable(combo)).start();
            }
        });

        panel.add(goodButton);
        JButton badButton = new JButton("Bad");
        badButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                new Thread(new BadWorkerRunnable(combo)).start();
            }
        });
        panel.add(badButton);

        panel.add(combo);
        add(panel);
        pack();
    }
}

/**
 * This runnable modifies a combo box by randomly adding and removing numbers.
 * This can result in errors because the combo methods are not synchronized
 * and both the worker thread and the event dispatch thread access the combo box.
 */
class BadWorkerRunnable implements Runnable {
    private JComboBox<Integer> combo;
    private Random generator;

    public BadWorkerRunnable(JComboBox<Integer> aCombo) {
        combo = aCombo;
        generator = new Random();
    }

    public void run() {
        try {
            while (true) {
                int i= Math.abs(generator.nextInt());

                if (i % 2 == 0) {
                    combo.insertItemAt(i, 0);
                } else if (combo.getItemCount() > 0) {
                    combo.removeItemAt(i % combo.getItemCount());
                }

                Thread.sleep(1);
            }
        } catch (InterruptedException e) {
        }
    }
}


/**
 * This runnable modifies a combo box by randomly adding and removing numbers.
 * In order to ensure that the combo box is not corrupted, the editing operations
 * are forwarded to the event dispatch thread.
 */
class GoodWorkerRunnable implements Runnable {
    private JComboBox<Integer> combo;
    private Random generator;

    public GoodWorkerRunnable(JComboBox<Integer> aCombo) {
        combo = aCombo;
        generator = new Random();
    }

    public void run() {
        try {
            while (true) {
                EventQueue.invokeLater(new Runnable() {
                    @Override
                    public void run() {
                        int i= Math.abs(generator.nextInt());

                        if (i % 2 == 0) {
                            combo.insertItemAt(i, 0);
                        } else if (combo.getItemCount() > 0) {
                            combo.removeItemAt(i % combo.getItemCount());
                        }
                    }
                });

                Thread.sleep(1);
            }
        } catch (InterruptedException e) {
        }
    }
}

