/*
 * 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.cassandra.tools;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.net.InetAddress;
import java.net.MalformedURLException;
import java.net.UnknownHostException;
import java.util.*;

import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import org.apache.commons.cli.*;

import com.datastax.driver.core.AuthProvider;
import com.datastax.driver.core.JdkSSLOptions;
import com.datastax.driver.core.PlainTextAuthProvider;
import com.datastax.driver.core.SSLOptions;
import javax.net.ssl.SSLContext;
import org.apache.cassandra.config.*;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.io.sstable.SSTableLoader;
import org.apache.cassandra.security.SSLFactory;
import org.apache.cassandra.streaming.*;
import org.apache.cassandra.utils.JVMStabilityInspector;
import org.apache.cassandra.utils.NativeSSTableLoaderClient;
import org.apache.cassandra.utils.OutputHandler;

public class BulkLoader
{
    private static final String TOOL_NAME = "sstableloader";
    private static final String VERBOSE_OPTION  = "verbose";
    private static final String HELP_OPTION  = "help";
    private static final String NOPROGRESS_OPTION  = "no-progress";
    private static final String IGNORE_NODES_OPTION  = "ignore";
    private static final String INITIAL_HOST_ADDRESS_OPTION = "nodes";
    private static final String NATIVE_PORT_OPTION = "port";
    private static final String STORAGE_PORT_OPTION = "storage-port";
    private static final String SSL_STORAGE_PORT_OPTION = "ssl-storage-port";
    private static final String USER_OPTION = "username";
    private static final String PASSWD_OPTION = "password";
    private static final String AUTH_PROVIDER_OPTION = "auth-provider";
    private static final String THROTTLE_MBITS = "throttle";
    private static final String INTER_DC_THROTTLE_MBITS = "inter-dc-throttle";

    /* client encryption options */
    private static final String SSL_TRUSTSTORE = "truststore";
    private static final String SSL_TRUSTSTORE_PW = "truststore-password";
    private static final String SSL_KEYSTORE = "keystore";
    private static final String SSL_KEYSTORE_PW = "keystore-password";
    private static final String SSL_PROTOCOL = "ssl-protocol";
    private static final String SSL_ALGORITHM = "ssl-alg";
    private static final String SSL_STORE_TYPE = "store-type";
    private static final String SSL_CIPHER_SUITES = "ssl-ciphers";
    private static final String CONNECTIONS_PER_HOST = "connections-per-host";
    private static final String CONFIG_PATH = "conf-path";

    public static void main(String args[])
    {
        Config.setClientMode(true);
        LoaderOptions options = LoaderOptions.parseArgs(args).validateArguments();
        OutputHandler handler = new OutputHandler.SystemOutput(options.verbose, options.debug);
        SSTableLoader loader = new SSTableLoader(
                options.directory.getAbsoluteFile(),
                new ExternalClient(
                        options.hosts,
                        options.nativePort,
                        options.authProvider,
                        options.storagePort,
                        options.sslStoragePort,
                        options.serverEncOptions,
                        buildSSLOptions(options.clientEncOptions)),
                handler,
                options.connectionsPerHost);
        DatabaseDescriptor.setStreamThroughputOutboundMegabitsPerSec(options.throttle);
        DatabaseDescriptor.setInterDCStreamThroughputOutboundMegabitsPerSec(options.interDcThrottle);
        StreamResultFuture future = null;

        ProgressIndicator indicator = new ProgressIndicator();
        try
        {
            if (options.noProgress)
            {
                future = loader.stream(options.ignores);
            }
            else
            {
                future = loader.stream(options.ignores, indicator);
            }

        }
        catch (Exception e)
        {
            JVMStabilityInspector.inspectThrowable(e);
            System.err.println(e.getMessage());
            if (e.getCause() != null)
                System.err.println(e.getCause());
            e.printStackTrace(System.err);
            System.exit(1);
        }

        try
        {
            future.get();

            if (!options.noProgress)
                indicator.printSummary(options.connectionsPerHost);

            // Give sockets time to gracefully close
            Thread.sleep(1000);
            System.exit(0); // We need that to stop non daemonized threads
        }
        catch (Exception e)
        {
            System.err.println("Streaming to the following hosts failed:");
            System.err.println(loader.getFailedHosts());
            e.printStackTrace(System.err);
            System.exit(1);
        }
    }

    // Return true when everything is at 100%
    static class ProgressIndicator implements StreamEventHandler
    {
        private long start;
        private long lastProgress;
        private long lastTime;

        private int peak = 0;
        private int totalFiles = 0;

        private final Multimap<InetAddress, SessionInfo> sessionsByHost = HashMultimap.create();

        public ProgressIndicator()
        {
            start = lastTime = System.nanoTime();
        }

        public void onSuccess(StreamState finalState)
        {
        }

        public void onFailure(Throwable t)
        {
        }

        public synchronized void handleStreamEvent(StreamEvent event)
        {
            if (event.eventType == StreamEvent.Type.STREAM_PREPARED)
            {
                SessionInfo session = ((StreamEvent.SessionPreparedEvent) event).session;
                sessionsByHost.put(session.peer, session);
            }
            else if (event.eventType == StreamEvent.Type.FILE_PROGRESS || event.eventType == StreamEvent.Type.STREAM_COMPLETE)
            {
                ProgressInfo progressInfo = null;
                if (event.eventType == StreamEvent.Type.FILE_PROGRESS)
                {
                    progressInfo = ((StreamEvent.ProgressEvent) event).progress;
                }

                long time = System.nanoTime();
                long deltaTime = time - lastTime;

                StringBuilder sb = new StringBuilder();
                sb.append("\rprogress: ");

                long totalProgress = 0;
                long totalSize = 0;

                boolean updateTotalFiles = totalFiles == 0;
                // recalculate progress across all sessions in all hosts and display
                for (InetAddress peer : sessionsByHost.keySet())
                {
                    sb.append("[").append(peer).append("]");

                    for (SessionInfo session : sessionsByHost.get(peer))
                    {
                        long size = session.getTotalSizeToSend();
                        long current = 0;
                        int completed = 0;

                        if (progressInfo != null && session.peer.equals(progressInfo.peer) && (session.sessionIndex == progressInfo.sessionIndex))
                        {
                            session.updateProgress(progressInfo);
                        }
                        for (ProgressInfo progress : session.getSendingFiles())
                        {
                            if (progress.isCompleted())
                                completed++;
                            current += progress.currentBytes;
                        }
                        totalProgress += current;

                        totalSize += size;

                        sb.append(session.sessionIndex).append(":");
                        sb.append(completed).append("/").append(session.getTotalFilesToSend());
                        sb.append(" ").append(String.format("%-3d", size == 0 ? 100L : current * 100L / size)).append("% ");

                        if (updateTotalFiles)
                            totalFiles += session.getTotalFilesToSend();
                    }
                }

                lastTime = time;
                long deltaProgress = totalProgress - lastProgress;
                lastProgress = totalProgress;

                sb.append("total: ").append(totalSize == 0 ? 100L : totalProgress * 100L / totalSize).append("% ");
                sb.append(String.format("%-3d", mbPerSec(deltaProgress, deltaTime))).append("MB/s");
                int average = mbPerSec(totalProgress, (time - start));
                if (average > peak)
                    peak = average;
                sb.append("(avg: ").append(average).append(" MB/s)");

                System.out.print(sb.toString());
            }
        }

        private int mbPerSec(long bytes, long timeInNano)
        {
            double bytesPerNano = ((double)bytes) / timeInNano;
            return (int)((bytesPerNano * 1000 * 1000 * 1000) / (1024 * 1024));
        }

        private void printSummary(int connectionsPerHost)
        {
            long end = System.nanoTime();
            long durationMS = ((end - start) / (1000000));
            int average = mbPerSec(lastProgress, (end - start));
            StringBuilder sb = new StringBuilder();
            sb.append("\nSummary statistics: \n");
            sb.append(String.format("   %-30s: %-10d%n", "Connections per host: ", connectionsPerHost));
            sb.append(String.format("   %-30s: %-10d%n", "Total files transferred: ", totalFiles));
            sb.append(String.format("   %-30s: %-10d%n", "Total bytes transferred: ", lastProgress));
            sb.append(String.format("   %-30s: %-10d%n", "Total duration (ms): ", durationMS));
            sb.append(String.format("   %-30s: %-10d%n", "Average transfer rate (MB/s): ", + average));
            sb.append(String.format("   %-30s: %-10d%n", "Peak transfer rate (MB/s): ", + peak));
            System.out.println(sb.toString());
        }
    }

    private static SSLOptions buildSSLOptions(EncryptionOptions.ClientEncryptionOptions clientEncryptionOptions)
    {

        if (!clientEncryptionOptions.enabled)
            return null;

        SSLContext sslContext;
        try
        {
            sslContext = SSLFactory.createSSLContext(clientEncryptionOptions, true);
        }
        catch (IOException e)
        {
            throw new RuntimeException("Could not create SSL Context.", e);
        }

        return JdkSSLOptions.builder()
                            .withSSLContext(sslContext)
                            .withCipherSuites(clientEncryptionOptions.cipher_suites)
                            .build();
    }

    static class ExternalClient extends NativeSSTableLoaderClient
    {
        private final int storagePort;
        private final int sslStoragePort;
        private final EncryptionOptions.ServerEncryptionOptions serverEncOptions;

        public ExternalClient(Set<InetAddress> hosts,
                              int port,
                              AuthProvider authProvider,
                              int storagePort,
                              int sslStoragePort,
                              EncryptionOptions.ServerEncryptionOptions serverEncryptionOptions,
                              SSLOptions sslOptions)
        {
            super(hosts, port, authProvider, sslOptions);
            this.storagePort = storagePort;
            this.sslStoragePort = sslStoragePort;
            this.serverEncOptions = serverEncryptionOptions;
        }

        @Override
        public StreamConnectionFactory getConnectionFactory()
        {
            return new BulkLoadConnectionFactory(storagePort, sslStoragePort, serverEncOptions, false);
        }
    }

    static class LoaderOptions
    {
        public final File directory;

        public boolean debug;
        public boolean verbose;
        public boolean noProgress;
        public int nativePort;
        public String user;
        public String passwd;
        public String authProviderName;
        public AuthProvider authProvider;
        public int throttle = 0;
        public int interDcThrottle = 0;
        public int storagePort;
        public int sslStoragePort;
        public EncryptionOptions.ClientEncryptionOptions clientEncOptions = new EncryptionOptions.ClientEncryptionOptions();
        public int connectionsPerHost = 1;
        public EncryptionOptions.ServerEncryptionOptions serverEncOptions = new EncryptionOptions.ServerEncryptionOptions();

        public final Set<InetAddress> hosts = new HashSet<>();
        public final Set<InetAddress> ignores = new HashSet<>();

        LoaderOptions(File directory)
        {
            this.directory = directory;
        }

        public static LoaderOptions parseArgs(String cmdArgs[])
        {
            CommandLineParser parser = new GnuParser();
            CmdLineOptions options = getCmdLineOptions();
            try
            {
                CommandLine cmd = parser.parse(options, cmdArgs, false);

                if (cmd.hasOption(HELP_OPTION))
                {
                    printUsage(options);
                    System.exit(0);
                }

                String[] args = cmd.getArgs();
                if (args.length == 0)
                {
                    System.err.println("Missing sstable directory argument");
                    printUsage(options);
                    System.exit(1);
                }

                if (args.length > 1)
                {
                    System.err.println("Too many arguments");
                    printUsage(options);
                    System.exit(1);
                }

                String dirname = args[0];
                File dir = new File(dirname);

                if (!dir.exists())
                    errorMsg("Unknown directory: " + dirname, options);

                if (!dir.isDirectory())
                    errorMsg(dirname + " is not a directory", options);

                LoaderOptions opts = new LoaderOptions(dir);

                opts.verbose = cmd.hasOption(VERBOSE_OPTION);
                opts.noProgress = cmd.hasOption(NOPROGRESS_OPTION);

                if (cmd.hasOption(USER_OPTION))
                    opts.user = cmd.getOptionValue(USER_OPTION);

                if (cmd.hasOption(PASSWD_OPTION))
                    opts.passwd = cmd.getOptionValue(PASSWD_OPTION);

                if (cmd.hasOption(AUTH_PROVIDER_OPTION))
                    opts.authProviderName = cmd.getOptionValue(AUTH_PROVIDER_OPTION);

                if (cmd.hasOption(INITIAL_HOST_ADDRESS_OPTION))
                {
                    String[] nodes = cmd.getOptionValue(INITIAL_HOST_ADDRESS_OPTION).split(",");
                    try
                    {
                        for (String node : nodes)
                        {
                            opts.hosts.add(InetAddress.getByName(node.trim()));
                        }
                    }
                    catch (UnknownHostException e)
                    {
                        errorMsg("Unknown host: " + e.getMessage(), options);
                    }

                }
                else
                {
                    System.err.println("Initial hosts must be specified (-d)");
                    printUsage(options);
                    System.exit(1);
                }

                if (cmd.hasOption(IGNORE_NODES_OPTION))
                {
                    String[] nodes = cmd.getOptionValue(IGNORE_NODES_OPTION).split(",");
                    try
                    {
                        for (String node : nodes)
                        {
                            opts.ignores.add(InetAddress.getByName(node.trim()));
                        }
                    }
                    catch (UnknownHostException e)
                    {
                        errorMsg("Unknown host: " + e.getMessage(), options);
                    }
                }

                if (cmd.hasOption(CONNECTIONS_PER_HOST))
                    opts.connectionsPerHost = Integer.parseInt(cmd.getOptionValue(CONNECTIONS_PER_HOST));

                // try to load config file first, so that values can be rewritten with other option values.
                // otherwise use default config.
                Config config;
                if (cmd.hasOption(CONFIG_PATH))
                {
                    File configFile = new File(cmd.getOptionValue(CONFIG_PATH));
                    if (!configFile.exists())
                    {
                        errorMsg("Config file not found", options);
                    }
                    config = new YamlConfigurationLoader().loadConfig(configFile.toURI().toURL());
                }
                else
                {
                    config = new Config();
                    // unthrottle stream by default
                    config.stream_throughput_outbound_megabits_per_sec = 0;
                    config.inter_dc_stream_throughput_outbound_megabits_per_sec = 0;
                }

                if (cmd.hasOption(NATIVE_PORT_OPTION))
                    opts.nativePort = Integer.parseInt(cmd.getOptionValue(NATIVE_PORT_OPTION));
                else
                    opts.nativePort = config.native_transport_port;
                if (cmd.hasOption(STORAGE_PORT_OPTION))
                    opts.storagePort = Integer.parseInt(cmd.getOptionValue(STORAGE_PORT_OPTION));
                else
                    opts.storagePort = config.storage_port;
                if (cmd.hasOption(SSL_STORAGE_PORT_OPTION))
                    opts.sslStoragePort = Integer.parseInt(cmd.getOptionValue(SSL_STORAGE_PORT_OPTION));
                else
                    opts.sslStoragePort = config.ssl_storage_port;
                opts.throttle = config.stream_throughput_outbound_megabits_per_sec;
                opts.interDcThrottle = config.inter_dc_stream_throughput_outbound_megabits_per_sec;
                opts.clientEncOptions = config.client_encryption_options;
                opts.serverEncOptions = config.server_encryption_options;

                if (cmd.hasOption(THROTTLE_MBITS))
                {
                    opts.throttle = Integer.parseInt(cmd.getOptionValue(THROTTLE_MBITS));
                }

                if (cmd.hasOption(INTER_DC_THROTTLE_MBITS))
                {
                    opts.interDcThrottle = Integer.parseInt(cmd.getOptionValue(INTER_DC_THROTTLE_MBITS));
                }

                if (cmd.hasOption(SSL_TRUSTSTORE) || cmd.hasOption(SSL_TRUSTSTORE_PW) ||
                    cmd.hasOption(SSL_KEYSTORE) || cmd.hasOption(SSL_KEYSTORE_PW))
                {
                    opts.clientEncOptions.enabled = true;
                }

                if (cmd.hasOption(SSL_TRUSTSTORE))
                {
                    opts.clientEncOptions.truststore = cmd.getOptionValue(SSL_TRUSTSTORE);
                }

                if (cmd.hasOption(SSL_TRUSTSTORE_PW))
                {
                    opts.clientEncOptions.truststore_password = cmd.getOptionValue(SSL_TRUSTSTORE_PW);
                }

                if (cmd.hasOption(SSL_KEYSTORE))
                {
                    opts.clientEncOptions.keystore = cmd.getOptionValue(SSL_KEYSTORE);
                    // if a keystore was provided, lets assume we'll need to use it
                    opts.clientEncOptions.require_client_auth = true;
                }

                if (cmd.hasOption(SSL_KEYSTORE_PW))
                {
                    opts.clientEncOptions.keystore_password = cmd.getOptionValue(SSL_KEYSTORE_PW);
                }

                if (cmd.hasOption(SSL_PROTOCOL))
                {
                    opts.clientEncOptions.protocol = cmd.getOptionValue(SSL_PROTOCOL);
                }

                if (cmd.hasOption(SSL_ALGORITHM))
                {
                    opts.clientEncOptions.algorithm = cmd.getOptionValue(SSL_ALGORITHM);
                }

                if (cmd.hasOption(SSL_STORE_TYPE))
                {
                    opts.clientEncOptions.store_type = cmd.getOptionValue(SSL_STORE_TYPE);
                }

                if (cmd.hasOption(SSL_CIPHER_SUITES))
                {
                    opts.clientEncOptions.cipher_suites = cmd.getOptionValue(SSL_CIPHER_SUITES).split(",");
                }

                return opts;
            }
            catch (ParseException | ConfigurationException | MalformedURLException e)
            {
                errorMsg(e.getMessage(), options);
                return null;
            }
        }

        public LoaderOptions validateArguments()
        {
            // Both username and password need to be provided
            if ((user != null) != (passwd != null))
                errorMsg("Username and password must both be provided", getCmdLineOptions());

            if (user != null)
            {
                // Support for 3rd party auth providers that support plain text credentials.
                // In this case the auth provider must provide a constructor of the form:
                //
                // public MyAuthProvider(String username, String password)
                if (authProviderName != null)
                {
                    try
                    {
                        Class authProviderClass = Class.forName(authProviderName);
                        Constructor constructor = authProviderClass.getConstructor(String.class, String.class);
                        authProvider = (AuthProvider)constructor.newInstance(user, passwd);
                    }
                    catch (ClassNotFoundException e)
                    {
                        errorMsg("Unknown auth provider: " + e.getMessage(), getCmdLineOptions());
                    }
                    catch (NoSuchMethodException e)
                    {
                        errorMsg("Auth provider does not support plain text credentials: " + e.getMessage(), getCmdLineOptions());
                    }
                    catch (InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e)
                    {
                        errorMsg("Could not create auth provider with plain text credentials: " + e.getMessage(), getCmdLineOptions());
                    }
                }
                else
                {
                    // If a 3rd party auth provider wasn't provided use the driver plain text provider
                    authProvider = new PlainTextAuthProvider(user, passwd);
                }
            }
            // Alternate support for 3rd party auth providers that don't use plain text credentials.
            // In this case the auth provider must provide a nullary constructor of the form:
            //
            // public MyAuthProvider()
            else if (authProviderName != null)
            {
                try
                {
                    authProvider = (AuthProvider)Class.forName(authProviderName).newInstance();
                }
                catch (ClassNotFoundException | InstantiationException | IllegalAccessException e)
                {
                    errorMsg("Unknown auth provider" + e.getMessage(), getCmdLineOptions());
                }
            }

            return this;
        }

        private static void errorMsg(String msg, CmdLineOptions options)
        {
            System.err.println(msg);
            printUsage(options);
            System.exit(1);
        }

        private static CmdLineOptions getCmdLineOptions()
        {
            CmdLineOptions options = new CmdLineOptions();
            options.addOption("v",  VERBOSE_OPTION,      "verbose output");
            options.addOption("h",  HELP_OPTION,         "display this help message");
            options.addOption(null, NOPROGRESS_OPTION,   "don't display progress");
            options.addOption("i",  IGNORE_NODES_OPTION, "NODES", "don't stream to this (comma separated) list of nodes");
            options.addOption("d",  INITIAL_HOST_ADDRESS_OPTION, "initial hosts", "Required. try to connect to these hosts (comma separated) initially for ring information");
            options.addOption("p",  NATIVE_PORT_OPTION, "native transport port", "port used for native connection (default 9042)");
            options.addOption("sp",  STORAGE_PORT_OPTION, "storage port", "port used for internode communication (default 7000)");
            options.addOption("ssp",  SSL_STORAGE_PORT_OPTION, "ssl storage port", "port used for TLS internode communication (default 7001)");
            options.addOption("t",  THROTTLE_MBITS, "throttle", "throttle speed in Mbits (default unlimited)");
            options.addOption("idct",  INTER_DC_THROTTLE_MBITS, "inter-dc-throttle", "inter-datacenter throttle speed in Mbits (default unlimited)");
            options.addOption("u",  USER_OPTION, "username", "username for cassandra authentication");
            options.addOption("pw", PASSWD_OPTION, "password", "password for cassandra authentication");
            options.addOption("ap", AUTH_PROVIDER_OPTION, "auth provider", "custom AuthProvider class name for cassandra authentication");
            options.addOption("cph", CONNECTIONS_PER_HOST, "connectionsPerHost", "number of concurrent connections-per-host.");
            // ssl connection-related options
            options.addOption("ts", SSL_TRUSTSTORE, "TRUSTSTORE", "Client SSL: full path to truststore");
            options.addOption("tspw", SSL_TRUSTSTORE_PW, "TRUSTSTORE-PASSWORD", "Client SSL: password of the truststore");
            options.addOption("ks", SSL_KEYSTORE, "KEYSTORE", "Client SSL: full path to keystore");
            options.addOption("kspw", SSL_KEYSTORE_PW, "KEYSTORE-PASSWORD", "Client SSL: password of the keystore");
            options.addOption("prtcl", SSL_PROTOCOL, "PROTOCOL", "Client SSL: connections protocol to use (default: TLS)");
            options.addOption("alg", SSL_ALGORITHM, "ALGORITHM", "Client SSL: algorithm (default: SunX509)");
            options.addOption("st", SSL_STORE_TYPE, "STORE-TYPE", "Client SSL: type of store");
            options.addOption("ciphers", SSL_CIPHER_SUITES, "CIPHER-SUITES", "Client SSL: comma-separated list of encryption suites to use");
            options.addOption("f", CONFIG_PATH, "path to config file", "cassandra.yaml file path for streaming throughput and client/server SSL.");
            return options;
        }

        public static void printUsage(Options options)
        {
            String usage = String.format("%s [options] <dir_path>", TOOL_NAME);
            String header = System.lineSeparator() +
                            "Bulk load the sstables found in the directory <dir_path> to the configured cluster." +
                            "The parent directories of <dir_path> are used as the target keyspace/table name. " +
                            "So for instance, to load an sstable named Standard1-g-1-Data.db into Keyspace1/Standard1, " +
                            "you will need to have the files Standard1-g-1-Data.db and Standard1-g-1-Index.db into a directory /path/to/Keyspace1/Standard1/.";
            String footer = System.lineSeparator() +
                            "You can provide cassandra.yaml file with -f command line option to set up streaming throughput, client and server encryption options. " +
                            "Only stream_throughput_outbound_megabits_per_sec, inter_dc_stream_throughput_outbound_megabits_per_sec, server_encryption_options and client_encryption_options are read from yaml. " +
                            "You can override options read from cassandra.yaml with corresponding command line options.";
            new HelpFormatter().printHelp(usage, header, options, footer);
        }
    }

    public static class CmdLineOptions extends Options
    {
        /**
         * Add option with argument and argument name
         * @param opt shortcut for option name
         * @param longOpt complete option name
         * @param argName argument name
         * @param description description of the option
         * @return updated Options object
         */
        public Options addOption(String opt, String longOpt, String argName, String description)
        {
            Option option = new Option(opt, longOpt, true, description);
            option.setArgName(argName);

            return addOption(option);
        }

        /**
         * Add option without argument
         * @param opt shortcut for option name
         * @param longOpt complete option name
         * @param description description of the option
         * @return updated Options object
         */
        public Options addOption(String opt, String longOpt, String description)
        {
            return addOption(new Option(opt, longOpt, false, description));
        }
    }
}