SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package cc.squirreljme.runtime.gcf;

import java.io.IOException;
import java.util.ServiceLoader;
import javax.microedition.io.ConnectionNotFoundException;

/**
 * This factory is used in the creation of IP based connections thus allowing
 * SquirrelJME access to the internet.
 *
 * @since 2019/05/12
 */
public abstract class IPConnectionFactory
{
    /** The existing connection factory. */
    private static volatile IPConnectionFactory _FACTORY;
    
    /**
     * Resolves the specified IP address.
     *
     * @param __addr The IP address.
     * @return The resolved address.
     * @throws ConnectionNotFoundException If the host was not found.
     * @throws IOException If the address could not resolved.
     * @throws NullPointerException On null arguments.
     * @since 2019/05/12
     */
    public abstract IPAddress resolveAddress(IPAddress __addr)
        throws ConnectionNotFoundException, IOException, NullPointerException;
    
    /**
     * Opens a TCP client connection to the remote address.
     *
     * @param __addr The address to connect to.
     * @return The connection.
     * @throws ConnectionNotFoundException If the connection was not found.
     * @throws IOException On connection issues.
     * @throws NullPointerException On null arguments.
     * @since 2019/05/06
     */
    public abstract TCPClientConnection tcpClientConnect(IPAddress __addr)
        throws ConnectionNotFoundException, IOException, NullPointerException;
    
    /**
     * Returns the factory which manages IP based connections.
     *
     * @return The IP connection factory.
     * @since 2019/05/12
     */
    public static IPConnectionFactory factory()
    {
        // Already created?
        IPConnectionFactory rv = IPConnectionFactory._FACTORY;
        
        // Create factory?
        if (rv == null)
            synchronized (IPConnectionFactory.class)
            {
                // Check for double create
                rv = IPConnectionFactory._FACTORY;
                if (rv != null)
                    return rv;
                
                // Use implementation for this
                /*String ipf = SystemProperties.implementationClass(
                    "cc.squirreljme.runtime.gcf.IPConnectionFactory");
                if (ipf != null)
                    try
                    {
                        rv = (IPConnectionFactory)Class.forName(ipf).
                            newInstance();
                    }
                    catch (ClassNotFoundException|InstantiationException|
                        IllegalAccessException e)
                    {
                        e.printStackTrace();
                    }*/
                
                // Use the first found service
                if (rv == null)
                    for (IPConnectionFactory mb : ServiceLoader.
                        <IPConnectionFactory>load(IPConnectionFactory.class))
                    {
                        rv = mb;
                        break;
                    }
                
                // Fallback to no connection factory (IP not supported)
                if (rv == null)
                    rv = new NullIPConnectionFactory();
                
                // Use it for later and return
                IPConnectionFactory._FACTORY = rv;
            }
        
        return rv;
    }
}