/**
 * Copyright (C) 2010-2017 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
 */
package org.evosuite.utils;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;

import org.evosuite.Properties;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/*
 * this could should be used by the external process that run the test case
 */
public class ExternalProcessUtilities {
	/** Constant <code>logger</code> */
	protected static final Logger logger = LoggerFactory.getLogger(ExternalProcessUtilities.class);

	protected Socket connection;
	protected ObjectOutputStream out;
	protected ObjectInputStream in;

	/**
	 * <p>
	 * Constructor for ExternalProcessUtilities.
	 * </p>
	 */
	public ExternalProcessUtilities() {
	}

	/**
	 * <p>
	 * connectToMainProcess
	 * </p>
	 * 
	 * @return a boolean.
	 */
	public boolean connectToMainProcess() {

		try {
			connection = new Socket("127.0.0.1", Properties.PROCESS_COMMUNICATION_PORT);
			out = new ObjectOutputStream(connection.getOutputStream());
			in = new ObjectInputStream(connection.getInputStream());
		} catch (Exception e) {
			logger.error("not possible to connect to main process", e);
			return false;
		}

		return true;
	}

	/**
	 * <p>
	 * receiveInstruction
	 * </p>
	 * 
	 * @return a {@link java.lang.Object} object.
	 */
	public Object receiveInstruction() {
		try {
			String message = (String) in.readObject();
			if (message.equals(Messages.NEW_SEARCH))
				return null;
			else if (message.equals(Messages.CONTINUE_SEARCH)) {
				Object population_data = in.readObject();
				return population_data;
			}
		} catch (Exception e) {
			logger.error("error in receiving message", e);
		}

		throw new RuntimeException("no valid message received");
	}

	/**
	 * <p>
	 * askForRestart
	 * </p>
	 * 
	 * @param population_data
	 *            a {@link java.lang.Object} object.
	 */
	public void askForRestart(Object population_data) {
		sendFinalMessage(Messages.NEED_RESTART, population_data);
	}

	/**
	 * <p>
	 * informSearchIsFinished
	 * </p>
	 * 
	 * @param population_data
	 *            a {@link java.lang.Object} object.
	 */
	public void informSearchIsFinished(Object population_data) {
		sendFinalMessage(Messages.FINISHED_COMPUTATION, population_data);
	}

	/**
	 * <p>
	 * sendFinalMessage
	 * </p>
	 * 
	 * @param message
	 *            a {@link java.lang.String} object.
	 * @param population_data
	 *            a {@link java.lang.Object} object.
	 */
	public void sendFinalMessage(String message, Object population_data) {
		try {
			out.writeObject(message);
			out.flush();
			if (Properties.SERIALIZE_RESULT)
				out.writeObject(population_data);
			else
				out.writeObject(null);
			out.flush();
		} catch (Exception e) {
			logger.error("error in sending messages", e);
		}

		//main process will kill this one, but we can exit here just to be sure
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			logger.debug("Thread interrupted while waiting after sending results from client to master",
			             e);
		}
	}
}