/*
 * Proposed solution for Concurrent Programming Lab 1, step 7
 */

import java.awt.*;

import javax.swing.JTextField;

class Task7 extends Thread {

    JTextField tf; // Textfield to be used by this task

    public Task7(JTextField t) {
        tf = t;
    }

    void setMyText(final String s) {
        /*
         * Checks if called by GUI thread (= dispatch thread) or not. Although
         * using invokeLater is always sound, calling setText directly is more
         * efficient when called by the GUI thread.
         */
        if (EventQueue.isDispatchThread()) {
            // On GUI thread -- OK to set text directly
            tf.setText(s);
        } else {
            // not on GUI thread -- put update request on event queue
            EventQueue.invokeLater(() -> {
                tf.setText(s);
            });
        }
    }

    public void run() {
        int cols = tf.getColumns();

        boolean useCPU = false; // Set true to consume CPU-cycles

        int basespeed = 5000; // millisecs to do task
        int variation = (useCPU ? 0 : 60); // Speed variation in percent

        long delay = Math.round(((Math.random() - 0.5) * variation / 50 + 1.0) * basespeed / cols);

        String s = "";

        setMyText(s);
        while (s.length() < cols) {

            if (useCPU) {
                for (int j = 0; j < 1000000 * delay; j++) {
                }
            } else {
                try {
                    Thread.sleep(delay);
                } catch (InterruptedException e) {
                    s = s + "|";
                    setMyText(s);
                    break;
                }
            }

            s = s + "#";
            setMyText(s);
        }
    }
}

public class TaskControl_7 {

    static final int N = 10; // Number of Textfields

    static int h = 0; // Number of 'hello'-s

    public static void main(String[] argv) {
        try {

            // Create window with 'N' TextFields: (d.tf[0], ... , d.tf[N-1])
            TaskDisplay d = new TaskDisplay("Task Control 7", N);

            Task7[] task = new Task7[N];

            d.println("Type command (x to exit):");

            // Main command interpretation loop
            W: while (true) {

                char c = d.getKey();
                switch (c) {

                case 'x':
                    break W;

                case 'h':
                    d.println("Hello " + (h++));
                    break;

                case 't':
                    int i = 0;
                    while (i < N) {
                        if (task[i] == null || !task[i].isAlive()) {
                            task[i] = new Task7(d.tf[i]);
                            task[i].start();
                            break;
                        }
                        i++;
                    }
                    if (i == N)
                        d.println("No free text-fields");
                    break;

                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                    int j = ((int) c) - ((int) '0');
                    if (j < N && task[j] != null)
                        task[j].interrupt();
                    break;

                default:
                    d.println("Don't know '" + c + "'");
                }
            }

            d.println("Program terminates");

            for (int i = 0; i < N; i++) {
                if (task[i] != null)
                    task[i].join();
            }

            System.exit(0);

        } catch (Exception e) {
            System.out.println("Exception in Task Control: " + e);
        }
    }
}