/**
 * 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.intellij.util;


import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Note: this is copy&paste adaptation of the class SpawnProcessKeepAliveChecker.
 * Issue here we cannot reuse the original due to how the IntelliJ plugin is built
 *
 * Created by Andrea Arcuri on 26/11/15.
 */
public class SpawnProcessKeepAliveCheckerIntelliJ {

    private final static ExecutorService executor = Executors.newCachedThreadPool();
    private final static String STILL_ALIVE = "still_alive";
    private final static int DELTA_MS = 5_000;

    private volatile ServerSocket server;
    private volatile Thread serverThread;
    private final AsyncGUINotifier notifier;

    public  SpawnProcessKeepAliveCheckerIntelliJ(AsyncGUINotifier notifier){
        this.notifier = notifier;
    }


    public int startServer() throws IllegalStateException{

        if(server != null || serverThread != null){
            throw  new IllegalStateException("Recorder already running");
        }

        try {
            server = new ServerSocket(0, -1, InetAddress.getLoopbackAddress());
        } catch (IOException e) {
            return -1;
        }

        serverThread = new Thread(){
            @Override public void run(){
                while(! isInterrupted() && server!=null && !server.isClosed()){
                    try {
                        Socket socket = server.accept();
                        socket.setKeepAlive(true);
                        executor.submit(new KeepAliveTask(socket));
                        //notifier.printOnConsole("Registered remote process from "+socket.getRemoteSocketAddress()+"\n");
                    } catch (IOException e) {
                        //fine, expected
                        return;
                    }
                }

            }
        };
        serverThread.start();

        int port = server.getLocalPort();
        //notifier.printOnConsole("Started spawn process manager on port "+ port+"\n");

        return port;
    }

    public void stopServer(){
        //notifier.printOnConsole("Stopping spawn process manager\n");
        try {
            if(server != null) {
                server.close();
                server = null;
            }
        } catch (IOException e) {
            notifier.printOnConsole(e.toString());
        }

        if(serverThread != null) {
            serverThread.interrupt();
            serverThread = null;
        }
    }


    private static class KeepAliveTask implements Runnable{

        private final Socket socket;

        public KeepAliveTask(Socket s){
            socket = s;
        }

        @Override
        public void run() {
            try {
                PrintWriter out = new PrintWriter(socket.getOutputStream());
                while (socket.isConnected()) {
                    out.println(STILL_ALIVE);
                    Thread.sleep(DELTA_MS);
                }
            } catch (Exception e){
                //expected when remote host dies
            }
        }
    }
}