/*
 * 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 examples.ftp;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.SocketException;
import java.net.UnknownHostException;
import org.apache.commons.net.tftp.TFTP;
import org.apache.commons.net.tftp.TFTPClient;

/***
 * This is an example of a simple Java tftp client.
 * Notice how all of the code is really just argument processing and
 * error handling.
 * <p>
 * Usage: tftp [options] hostname localfile remotefile
 * hostname   - The name of the remote host
 * localfile  - The name of the local file to send or the name to use for
 *              the received file
 * remotefile - The name of the remote file to receive or the name for
 *              the remote server to use to name the local file being sent.
 * options: (The default is to assume -r -b)
 *        -s Send a local file
 *        -r Receive a remote file
 *        -a Use ASCII transfer mode
 *        -b Use binary transfer mode
 ***/
public final class TFTPExample
{
    static final String USAGE =
        "Usage: tftp [options] hostname localfile remotefile\n\n" +
        "hostname   - The name of the remote host\n" +
        "localfile  - The name of the local file to send or the name to use for\n" +
        "\tthe received file\n" +
        "remotefile - The name of the remote file to receive or the name for\n" +
        "\tthe remote server to use to name the local file being sent.\n\n" +
        "options: (The default is to assume -r -b)\n" +
        "\t-s Send a local file\n" +
        "\t-r Receive a remote file\n" +
        "\t-a Use ASCII transfer mode\n" +
        "\t-b Use binary transfer mode\n";

    public static void main(String[] args)
    {
        boolean receiveFile = true, closed;
        int transferMode = TFTP.BINARY_MODE, argc;
        String arg, hostname, localFilename, remoteFilename;
        TFTPClient tftp;

        // Parse options
        for (argc = 0; argc < args.length; argc++)
        {
            arg = args[argc];
            if (arg.startsWith("-"))
            {
                if (arg.equals("-r")) {
                    receiveFile = true;
                } else if (arg.equals("-s")) {
                    receiveFile = false;
                } else if (arg.equals("-a")) {
                    transferMode = TFTP.ASCII_MODE;
                } else if (arg.equals("-b")) {
                    transferMode = TFTP.BINARY_MODE;
                } else {
                    System.err.println("Error: unrecognized option.");
                    System.err.print(USAGE);
                    System.exit(1);
                }
            } else {
                break;
            }
        }

        // Make sure there are enough arguments
        if (args.length - argc != 3)
        {
            System.err.println("Error: invalid number of arguments.");
            System.err.print(USAGE);
            System.exit(1);
        }

        // Get host and file arguments
        hostname = args[argc];
        localFilename = args[argc + 1];
        remoteFilename = args[argc + 2];

        // Create our TFTP instance to handle the file transfer.
        tftp = new TFTPClient();

        // We want to timeout if a response takes longer than 60 seconds
        tftp.setDefaultTimeout(60000);

        // Open local socket
        try
        {
            tftp.open();
        }
        catch (SocketException e)
        {
            System.err.println("Error: could not open local UDP socket.");
            System.err.println(e.getMessage());
            System.exit(1);
        }

        // We haven't closed the local file yet.
        closed = false;

        // If we're receiving a file, receive, otherwise send.
        if (receiveFile)
        {
            FileOutputStream output = null;
            File file;

            file = new File(localFilename);

            // If file exists, don't overwrite it.
            if (file.exists())
            {
                System.err.println("Error: " + localFilename + " already exists.");
                System.exit(1);
            }

            // Try to open local file for writing
            try
            {
                output = new FileOutputStream(file);
            }
            catch (IOException e)
            {
                tftp.close();
                System.err.println("Error: could not open local file for writing.");
                System.err.println(e.getMessage());
                System.exit(1);
            }

            // Try to receive remote file via TFTP
            try
            {
                tftp.receiveFile(remoteFilename, transferMode, output, hostname);
            }
            catch (UnknownHostException e)
            {
                System.err.println("Error: could not resolve hostname.");
                System.err.println(e.getMessage());
                System.exit(1);
            }
            catch (IOException e)
            {
                System.err.println(
                    "Error: I/O exception occurred while receiving file.");
                System.err.println(e.getMessage());
                System.exit(1);
            }
            finally
            {
                // Close local socket and output file
                tftp.close();
                try
                {
                    if (output != null) {
                        output.close();
                    }
                    closed = true;
                }
                catch (IOException e)
                {
                    closed = false;
                    System.err.println("Error: error closing file.");
                    System.err.println(e.getMessage());
                }
            }

            if (!closed) {
                System.exit(1);
            }

        } else {
            // We're sending a file
            FileInputStream input = null;

            // Try to open local file for reading
            try
            {
                input = new FileInputStream(localFilename);
            }
            catch (IOException e)
            {
                tftp.close();
                System.err.println("Error: could not open local file for reading.");
                System.err.println(e.getMessage());
                System.exit(1);
            }

            // Try to send local file via TFTP
            try
            {
                tftp.sendFile(remoteFilename, transferMode, input, hostname);
            }
            catch (UnknownHostException e)
            {
                System.err.println("Error: could not resolve hostname.");
                System.err.println(e.getMessage());
                System.exit(1);
            }
            catch (IOException e)
            {
                System.err.println(
                    "Error: I/O exception occurred while sending file.");
                System.err.println(e.getMessage());
                System.exit(1);
            }
            finally
            {
                // Close local socket and input file
                tftp.close();
                try
                {
                    if (input != null) {
                        input.close();
                    }
                    closed = true;
                }
                catch (IOException e)
                {
                    closed = false;
                    System.err.println("Error: error closing file.");
                    System.err.println(e.getMessage());
                }
            }

            if (!closed) {
                System.exit(1);
            }

        }

    }

}


