/*
 * Copyright 2011-17 Fraunhofer ISE, energy & meteo Systems GmbH and other contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package org.openmuc.jositransport;

import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;

import javax.net.SocketFactory;

/**
 * This class implements a client Transport Service Access Point (TSAP) over TCP/IP as defined in RFC 1006, ISO 8072,
 * and ISO 8073. It can be used to create TConnections that connect to remote ServerTSAPs.
 * 
 */
public final class ClientTSap {

    private int maxTPDUSizeParam = 16;
    private SocketFactory socketFactory = null;
    private int messageTimeout = 0;
    private int messageFragmentTimeout = 60000;

    public byte[] tSelRemote = null;
    public byte[] tSelLocal = null;

    /**
     * Use this constructor to create a client TSAP that will start connections to remote TSAPs.
     */
    public ClientTSap() {
        socketFactory = SocketFactory.getDefault();
    }

    /**
     * Use this constructor to create a client TSAP that will start connections to remote TSAPs. You could pass an
     * SSLSocketFactory to enable SSL.
     * 
     * @param socketFactory
     *            the socket factory to create the underlying socket
     */
    public ClientTSap(SocketFactory socketFactory) {
        this.socketFactory = socketFactory;
    }

    /**
     * Set the TConnection timeout for waiting for the first byte of a new message. Default is 0 (unlimited)
     * 
     * @param messageTimeout
     *            in milliseconds
     */
    public void setMessageTimeout(int messageTimeout) {
        this.messageTimeout = messageTimeout;
    }

    /**
     * Set the TConnection timeout for receiving data once the beginning of a message has been received. Default is
     * 60000 (60seconds)
     * 
     * @param messageFragmentTimeout
     *            in milliseconds
     */
    public void setMessageFragmentTimeout(int messageFragmentTimeout) {
        this.messageFragmentTimeout = messageFragmentTimeout;
    }

    /**
     * Set the maxTPDUSize. The default maxTPduSize is 65531 (see RFC 1006).
     * 
     * @param maxTPduSizeParam
     *            The maximum length is equal to 2^(maxTPduSizeParam) octets. Note that the actual TSDU size that can be
     *            transfered is equal to TPduSize-3. Default is 65531 octets (see RFC 1006), 7 <= maxTPduSizeParam
     *            <= 16, needs to be set before listening or connecting
     */
    public void setMaxTPDUSizeParam(int maxTPduSizeParam) {
        if (maxTPduSizeParam < 7 || maxTPduSizeParam > 16) {
            throw new IllegalArgumentException("maxTPDUSizeParam is out of bound");
        }
        this.maxTPDUSizeParam = maxTPduSizeParam;
    }

    /**
     * Get the maximum TPDU size parameter to be used by this TSAP
     * 
     * @return the maximum TPDU size parameter
     */
    public int getMaxTPDUSizeParam() {
        return maxTPDUSizeParam;
    }

    /**
     * Calculates and returns the maximum TPDUSize. This is equal to 2^(maxTPDUSizeParam)
     * 
     * @param maxTPDUSizeParam
     *            the size parameter
     * @return the maximum TPDU size
     */
    public static int getMaxTPDUSize(int maxTPDUSizeParam) {
        if (maxTPDUSizeParam < 7 || maxTPDUSizeParam > 16) {
            throw new IllegalArgumentException("maxTPDUSizeParam is out of bound");
        }
        if (maxTPDUSizeParam == 16) {
            return 65531;
        }
        else {
            return (int) Math.pow(2, maxTPDUSizeParam);
        }
    }

    /**
     * Connect to a remote TSAP that is listening at the destination address.
     * 
     * @param address
     *            remote IP
     * @param port
     *            remote port
     * @return the Connection Object
     * @throws IOException
     *             is thrown if connection was unsuccessful.
     */
    public TConnection connectTo(InetAddress address, int port) throws IOException {
        return connectTo(address, port, null, -1);
    }

    /**
     * Connect to a remote TSAP that is listening at the destination address.
     * 
     * @param address
     *            remote IP
     * @param port
     *            remote port
     * @param localAddr
     *            local IP
     * @param localPort
     *            local port
     * @return the Connection Object
     * @throws IOException
     *             is thrown if connection was unsuccessful.
     */
    public TConnection connectTo(InetAddress address, int port, InetAddress localAddr, int localPort)
            throws IOException {
        Socket socket;
        if (localAddr == null) {
            socket = socketFactory.createSocket(address, port);
        }
        else {
            socket = socketFactory.createSocket(address, port, localAddr, localPort);
        }
        TConnection tConnection = new TConnection(socket, maxTPDUSizeParam, messageTimeout, messageFragmentTimeout,
                null);
        tConnection.tSelRemote = tSelRemote;
        tConnection.tSelLocal = tSelLocal;
        tConnection.startConnection();

        return tConnection;
    }

    public void setSocketFactory(SocketFactory socketFactory) {
        this.socketFactory = socketFactory;
    }

}