/*
 * TownHall -- An accurate model or social commentary?
 *
 * TownHall runs as an application and illustrates multiple threads.
 */

import java.lang.*;
import java.util.*;

class SynchronizedQueue extends Vector {

        private int     count;
        private boolean started;
        private boolean waiting;
        private int     writers;

        SynchronizedQueue() {
                count = 0;
                started = false;
        }

        public synchronized void checkIn () {
                started = true;
                count++;
        }

        public synchronized void checkOut () {
                count--;
                notify();
        }

        public synchronized void enqueue(Object elt) {
                super.addElement(elt);
                notify();
        }

        public synchronized boolean anyoneLeft() {
                if (!started) return true;
                if (count > 0) return true;
                else return false;
        }

        public synchronized Object dequeue() {
                Object ret;
                while (anyoneLeft() && (super.elementCount == 0)) {
                        try {
                                wait();
                        } catch (InterruptedException x) { }
                }
                if (super.elementCount > 0) {
                        ret = super.firstElement();
                        super.removeElement(ret);
                } else {
                        ret = null;
                }
                return ret;
        }
}

class Speaker extends Thread {
        int               id;
        int               speech_count;
        SynchronizedQueue my_soapbox;

        static String nouns[] = {
                "dogs", "cats", "elephants", "donkeys", "houses", "monkeys",
                "cars", "bicycles", "computers", "music", "books" };

        static String ends[] = {
                "outlawed", "banned", "imported", "discouraged", "sold", "bought",
                "given away", "made mandatory", "encouraged", "deported", "exported" };


        Speaker(int new_id, int turns, SynchronizedQueue forum) {
                id = new_id;
                speech_count = turns;
                my_soapbox = forum;
        }

        public void run() {
                int i;
                Random r = new Random();
                my_soapbox.checkIn();
                my_soapbox.enqueue("speaker "+ id +" stepping onto soapbox");
                for (i = 0; i < speech_count; i++) {
                        try {
                           sleep((r.nextInt() % 10) * 10);
                        } catch (Exception e) { }
                        my_soapbox.enqueue("speaker "+ id +": " +
                        nouns[Math.abs(r.nextInt())%nouns.length] + " should be " +
                        ends[Math.abs(r.nextInt())%ends.length]);
                }
                my_soapbox.enqueue("speaker "+ id +" stepping off soapbox");
                my_soapbox.checkOut();
        }
}

class MC extends Thread {
        SynchronizedQueue podium;

        MC(SynchronizedQueue new_forum) {
                podium = new_forum;
        }

        public void run() {
                Object utterance;

                System.out.println("MC here: good morning.");

                utterance = podium.dequeue();
                while (utterance != null) {
                        System.out.println(utterance);
                        utterance = podium.dequeue();
                }

                System.out.println("MC here: good night.");
        }
}

class TownHall {
        static SynchronizedQueue podium;
        static int     num_speakers;


        public static void main(String args[]) {
                num_speakers = 5;
                podium = new SynchronizedQueue();

                Speaker[] contenders = new Speaker[num_speakers];
                MC georgeWill = new MC(podium);

                georgeWill.start();

                for(int i = 0; i < num_speakers; i++) {
                        contenders[i] = new Speaker(i, 10, podium);
                        contenders[i].start();
                }
                try {
                        georgeWill.join();
                } catch (InterruptedException x) { }
                System.out.println("Town Hall closing.");
        }
}