/* 
 * GUI for Concurrent Programmering Lab 1 (Swing version)
 */

import java.awt.*;
import java.awt.event.*;
import java.lang.reflect.InvocationTargetException;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.ScrollPaneConstants;

// Auxiliary class to buffer key events.
// You are not supposed to understand this yet!

class KeyBuffer extends KeyAdapter {

    static int K = 1000;
    int in, out, no = 0;

    char[] buf = new char[K];

    synchronized public void keyPressed(KeyEvent e) {
        char c = e.getKeyChar();
        e.consume();
        if (c != KeyEvent.CHAR_UNDEFINED && no < K) {
            buf[in++] = c;
            in = in % K;
            no++;
            notify();
        }
    }

    synchronized public char Get() {
        while (no == 0)
            try {
                wait();
            } catch (Exception e) {
            }
        char c = buf[out++];
        out = out % K;
        no--;
        return c;
    }

}

// Class that provides a GUI for the lab

public class TaskDisplay extends JFrame {

    public JTextField[] tf;
    JTextArea txt;
    JScrollPane pane;

    static final int width = 40;
    static final int minhistory = 1000;

    private KeyBuffer kb;

    private void initGUI(int n) {
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        // Create 'n' TextFields

        if (n > 0)
            tf = new JTextField[n];

        setFont(new Font("Monospaced", Font.BOLD, 12));

        setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        c.gridx = 0;
        c.gridy = GridBagConstraints.RELATIVE;
        c.insets = new Insets(5, 5, 5, 5);

        for (int i = 0; i < tf.length; i++) {
            c.gridx = 0;
            Label l = new Label("Task " + i);
            add(l, c);
            c.gridx = 1;
            tf[i] = new JTextField(width);
            tf[i].setEditable(false);
            tf[i].setForeground(Color.blue);
            tf[i].setBackground(Color.white);

            add(tf[i], c);
        }

        // txt = new JTextArea("",8,width,TextArea.SCROLLBARS_VERTICAL_ONLY);
        txt = new JTextArea("", 8, width);
        txt.addKeyListener(kb);
        txt.setEditable(false);
        txt.setBackground(Color.white);
        pane = new JScrollPane(txt);
        pane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

        c.gridx = 0;
        c.gridwidth = 2;
        c.fill = GridBagConstraints.HORIZONTAL;
        add(pane, c);

        pack();
        setVisible(true);
        txt.requestFocus();
    }

    public TaskDisplay(String name, final int n) throws InvocationTargetException, InterruptedException {

        super(name);

        kb = new KeyBuffer();

        // Initialization of Swing components should be done by the GUI thread
        EventQueue.invokeAndWait(new Runnable() {
            public void run() {
                initGUI(n);
            }
        });
    }

    // Assumed not to be called by GUI thread (but ok if it is)
    public void println(String s) {
        EventQueue.invokeLater(() -> {
            int last = txt.getDocument().getLength();
            txt.setCaretPosition(last); // set caret at end
            if (last > 2 * minhistory)
                txt.replaceRange("", 0, last - minhistory);
            txt.append(s + "\n");
        });
    }

    // Wrapper for key buffer Get-operation (which is thread-safe)
    public char getKey() {
        return kb.Get();
    }

}