package edu.rice.comp322;

import edu.rice.hj.runtime.actors.Actor;
import edu.rice.hj.runtime.actors.Message;

import static edu.rice.hj.Module0.launchHabaneroApp;

/**
 * Solution to Worksheet 5.
 *
 * @author Shams Imam
 */
public final class Lec29Slide4EchoActor {

    /**
     * Disallow instance creation of utility class.
     */
    private Lec29Slide4EchoActor() {
        super();
    }

    /**
     * <p>main.</p>
     *
     * @param args an array of {@link String} objects.
     */
    public static void main(final String[] args) {
        final String[] messages = new String[]{"Hello", "World", "with", "actors.", StringMessage.END};

        // Actor instances may be safely created outside a global finish
        final EchoActor echoActor = new EchoActor();

        // messages may be sent to the actor, but they won't be processed until
        // the actor is started inside some finish scope
        for (int i = 0; i < 2; i++) {
            final String loopMessage = messages[i];
            System.out.println("Sending: " + loopMessage);
            echoActor.send(new StringMessage(loopMessage));
            busyWait();
        }

        launchHabaneroApp(() -> {
            System.out.println("Starting actor...");
            // Actors can only be started inside a finish scope
            // Actor starts processing messages only after it has been started
            echoActor.start();

            // send more messages to the actor
            for (int i = 2; i < messages.length; i++) {
                final String loopMessage = messages[i];
                System.out.println("Sending: " + loopMessage);
                echoActor.send(new StringMessage(loopMessage));
                busyWait();
            }

            System.out.println("Waiting for actor to terminate");
        });
        System.out.println("Outside the global finish");
    }

    private static void busyWait() {
        // busy wait
        for (int j = 0; j < 100000; j++) {
            Math.random();
        }
    }

    public static final class StringMessage implements Message {

        public static final String END = "__END__";

        /**
         * The wrapped string message
         */
        public final String message;

        /**
         * Constructor.
         *
         * @param pMessage The string to wrap.
         */
        public StringMessage(final String pMessage) {
            this.message = pMessage;
        }
    }

    public static final class EchoActor extends Actor<StringMessage> {

        /**
         * Constructor.
         */
        public EchoActor() {
            super();
        }

        @Override
        protected void process(final StringMessage theMsg) {
            System.out.println("  Processing: " + theMsg.message);
            if (StringMessage.END.equals(theMsg.message)) {
                System.out.println("Terminating actor.");
                exit();
            }
        }
    }


}