/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.net.bsd;

import java.io.IOException;

/**
 * RLoginClient is very similar to {@link org.apache.commons.net.bsd.RCommandClient}, from which it is derived, and uses the rcmd() facility implemented in
 * RCommandClient to implement the functionality of the rlogin command that first appeared in 4.2BSD Unix. rlogin is a command used to login to a remote machine
 * from a trusted host, sometimes without issuing a password. The trust relationship is the same as described in the documentation for
 * {@link org.apache.commons.net.bsd.RCommandClient}.
 * <p>
 * As with virtually all of the client classes in org.apache.commons.net, this class derives from SocketClient. But it relies on the connection methods defined
 * in RcommandClient which ensure that the local Socket will originate from an acceptable rshell port. The way to use RLoginClient is to first connect to the
 * server, call the {@link #rlogin rlogin() } method, and then fetch the connection's input and output streams. Interaction with the remote command is
 * controlled entirely through the I/O streams. Once you have finished processing the streams, you should invoke
 * {@link org.apache.commons.net.bsd.RExecClient#disconnect disconnect() } to clean up properly.
 * <p>
 * The standard output and standard error streams of the remote process are transmitted over the same connection, readable from the input stream returned by
 * {@link org.apache.commons.net.bsd.RExecClient#getInputStream getInputStream() }
 * <p>
 * Unlike RExecClient and RCommandClient, it is not possible to tell the rlogind daemon to return the standard error stream over a separate connection.
 * {@link org.apache.commons.net.bsd.RExecClient#getErrorStream getErrorStream() } will always return null. The standard input of the remote process can be
 * written to through the output stream returned by {@link org.apache.commons.net.bsd.RExecClient#getOutputStream getOutputSream() }
 *
 * @see org.apache.commons.net.SocketClient
 * @see RExecClient
 * @see RCommandClient
 */

public class RLoginClient extends RCommandClient {
    /**
     * The default rlogin port. Set to 513 in BSD Unix and according to RFC 1282.
     */
    public static final int DEFAULT_PORT = 513;

    /**
     * The default RLoginClient constructor. Initializes the default port to <code> DEFAULT_PORT </code>.
     */
    public RLoginClient() {
        setDefaultPort(DEFAULT_PORT);
    }

    /**
     * Same as the other rlogin method, but no terminal speed is defined.
     *
     * @param localUsername  the local user
     * @param remoteUsername the remote user
     * @param terminalType   the terminal type
     * @throws IOException on error
     */
    public void rlogin(final String localUsername, final String remoteUsername, final String terminalType) throws IOException {
        rexec(localUsername, remoteUsername, terminalType, false);
    }

    /**
     * Logins into a remote machine through the rlogind daemon on the server to which the RLoginClient is connected. After calling this method, you may interact
     * with the remote login shell through its standard input and output streams. Standard error is sent over the same stream as standard output. You will
     * typically be able to detect the termination of the remote login shell after reaching end of file on its standard output (accessible through
     * {@link #getInputStream getInputStream() }. Disconnecting from the server or closing the process streams before reaching end of file will terminate the
     * remote login shell in most cases.
     * <p>
     * If user authentication fails, the rlogind daemon will request that a password be entered interactively. You will be able to read the prompt from the
     * output stream of the RLoginClient and write the password to the input stream of the RLoginClient.
     *
     * @param localUsername  The user account on the local machine that is trying to login to the remote host.
     * @param remoteUsername The account name on the server that is being logged in to.
     * @param terminalType   The name of the user's terminal (e.g., "vt100", "network", etc.)
     * @param terminalSpeed  The speed of the user's terminal, expressed as a baud rate or bps (e.g., 9600 or 38400)
     * @throws IOException If the rlogin() attempt fails. The exception will contain a message indicating the nature of the failure.
     */
    public void rlogin(final String localUsername, final String remoteUsername, final String terminalType, final int terminalSpeed) throws IOException {
        rexec(localUsername, remoteUsername, terminalType + "/" + terminalSpeed, false);
    }

}
