/*
 * Copyright (C) 2022 jimj316
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package moe.nekojimi.chords;

import java.io.IOException;
import java.net.*;
import javax.net.SocketFactory;

/**
 *
 * @author jimj316
 */
public class LocalBindSocketFactory extends SocketFactory
{

    private InetAddress localAddress;

    public InetAddress getLocalAddress()
    {
        return localAddress;
    }

    public void setLocalAddress(InetAddress localAddress)
    {
        this.localAddress = localAddress;
    }

    @Override
    public Socket createSocket() throws IOException
    {
        return new LocalBoundSocket();
//        throw new RuntimeException("Trying to create an empty socket!");
    }

    private InetSocketAddress findFreeSocketAddress()
    {
        return new InetSocketAddress(localAddress, findFreePort(localAddress));
    }

    @Override
    public Socket createSocket(String remoteAddr, int remotePort) throws IOException, UnknownHostException
    {
        return createSocket(remoteAddr, remotePort, localAddress, findFreePort(localAddress));
    }

    @Override
    public Socket createSocket(String remoteAddr, int remotePort, InetAddress x, int localPort) throws IOException, UnknownHostException
    {
        return createSocket(InetAddress.getByName(remoteAddr), remotePort, localAddress, localPort);
    }

    @Override
    public Socket createSocket(InetAddress remoteAddr, int remotePort) throws IOException
    {
        return createSocket(remoteAddr, remotePort, localAddress, findFreePort(localAddress));
    }

    @Override
    public Socket createSocket(InetAddress remoteAddr, int remotePort, InetAddress x, int localPort) throws IOException
    {
        System.out.println("Requested socket; " + localAddress + ":" + localPort + " -> " + remoteAddr + ":" + remotePort);
        Socket socket = new Socket(remoteAddr, remotePort, localAddress, localPort);
        System.out.println("Returned socket; " + socket.getLocalSocketAddress() + ":" + socket.getLocalPort() + " -> " + socket.getRemoteSocketAddress() + ":" + socket.getPort());
        return socket;
    }

    private static int findFreePort(InetAddress localAddr)
    {
        int port = 0;
        // For ServerSocket port number 0 means that the port number is automatically allocated.
        try (ServerSocket socket = new ServerSocket(0, 0, localAddr))
        {
            // Disable timeout and reuse address after closing the socket.
            socket.setReuseAddress(true);
            port = socket.getLocalPort();
        } catch (IOException ignored)
        {
        }
        if (port > 0)
        {
            return port;
        }
        throw new RuntimeException("Could not find a free port");
    }

    private class LocalBoundSocket extends Socket
    {

        @Override
        public void bind(SocketAddress bindpoint) throws IOException
        {
            InetSocketAddress localAddress = findFreeSocketAddress();
            System.err.println("LocalBoundSocket NOT binding to " + bindpoint + ", using " + localAddress + " instead!");
            super.bind(localAddress);
        }
    }

}