package ch.ethz.ssh2;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;

/**
 * A very basic <code>SCPClient</code> that can be used to copy files from/to
 * the SSH-2 server. On the server side, the "scp" program must be in the PATH.
 * <p/>
 * This scp client is thread safe - you can download (and upload) different sets
 * of files concurrently without any troubles. The <code>SCPClient</code> is
 * actually mapping every request to a distinct {@link ch.ethz.ssh2.Session}.
 *
 * @author Christian Plattner, plattner@inf.ethz.ch
 * @version $Id: SCPClient.java 85 2014-04-07 14:05:09Z dkocher@sudo.ch $
 */

public class SCPClient {
    Connection conn;

    String charsetName = null;

    /**
     * Set the charset used to convert between Java Unicode Strings and byte encodings
     * used by the server for paths and file names.
     *
     * @param charset the name of the charset to be used or <code>null</code> to use the platform's
     * default encoding.
     * @throws IOException
     * @see #getCharset()
     */
    public void setCharset(String charset) throws IOException {
        if (charset == null) {
            charsetName = charset;
            return;
        }

        try {
            Charset.forName(charset);
        }
        catch (UnsupportedCharsetException e) {
            throw new IOException("This charset is not supported", e);
        }

        charsetName = charset;
    }

    /**
     * The currently used charset for filename encoding/decoding.
     *
     * @return The name of the charset (<code>null</code> if the platform's default charset is being used)
     * @see #setCharset(String)
     */
    public String getCharset() {
        return charsetName;
    }

    public class LenNamePair {
        public long length;
        String filename;
    }

    public SCPClient(Connection conn) {
        if (conn == null)
            throw new IllegalArgumentException("Cannot accept null argument!");

        this.conn = conn;
    }

    protected void readResponse(InputStream is) throws IOException {
        int c = is.read();

        if (c == 0)
            return;

        if (c == -1)
            throw new IOException("Remote scp terminated unexpectedly.");

        if ((c != 1) && (c != 2))
            throw new IOException("Remote scp sent illegal error code.");

        if (c == 2)
            throw new IOException("Remote scp terminated with error.");

        String err = receiveLine(is);
        throw new IOException("Remote scp terminated with error (" + err + ").");
    }

    protected String receiveLine(InputStream is) throws IOException {
        StringBuilder sb = new StringBuilder(30);

        while (true) {
            /* This is a random limit - if your path names are longer, then adjust it */
            if (sb.length() > 8192)
                throw new IOException("Remote scp sent a too long line");

            int c = is.read();

            if (c < 0)
                throw new IOException("Remote scp terminated unexpectedly.");

            if (c == '\n')
                break;

            sb.append((char) c);
        }

        return sb.toString();
    }

    protected LenNamePair parseCLine(String line) throws IOException {
        /* Minimum line: "xxxx y z" ---> 8 chars */
        if (line.length() < 8)
            throw new IOException("Malformed C line sent by remote SCP binary, line too short.");

        if ((line.charAt(4) != ' ') || (line.charAt(5) == ' '))
            throw new IOException("Malformed C line sent by remote SCP binary.");

        int length_name_sep = line.indexOf(' ', 5);

        if (length_name_sep == -1)
            throw new IOException("Malformed C line sent by remote SCP binary.");

        String length_substring = line.substring(5, length_name_sep);
        String name_substring = line.substring(length_name_sep + 1);

        if ((length_substring.length() <= 0) || (name_substring.length() <= 0))
            throw new IOException("Malformed C line sent by remote SCP binary.");

        if ((6 + length_substring.length() + name_substring.length()) != line.length())
            throw new IOException("Malformed C line sent by remote SCP binary.");

        final long len;

        try {
            len = Long.parseLong(length_substring);
        }
        catch (NumberFormatException e) {
            throw new IOException("Malformed C line sent by remote SCP binary, cannot parse file length.");
        }

        if (len < 0)
            throw new IOException("Malformed C line sent by remote SCP binary, illegal file length.");

        LenNamePair lnp = new LenNamePair();
        lnp.length = len;
        lnp.filename = name_substring;
        return lnp;
    }

    /**
     * The session for opened for this SCP transfer must be closed using
     * SCPOutputStream#close
     *
     * @param remoteFile
     * @param length The size of the file to send
     * @param remoteTargetDirectory
     * @param mode
     * @return
     * @throws IOException
     */
    public SCPOutputStream put(final String remoteFile, long length, String remoteTargetDirectory, String mode)
    throws IOException {
        Session sess = null;

        if (null == remoteFile)
            throw new IllegalArgumentException("Null argument.");

        if (null == remoteTargetDirectory)
            remoteTargetDirectory = "";

        if (null == mode)
            mode = "0600";

        if (mode.length() != 4)
            throw new IllegalArgumentException("Invalid mode.");

        for (int i = 0; i < mode.length(); i++)
            if (Character.isDigit(mode.charAt(i)) == false)
                throw new IllegalArgumentException("Invalid mode.");

        remoteTargetDirectory = (remoteTargetDirectory.length() > 0) ? remoteTargetDirectory : ".";
        String cmd = "scp -t -d \"" + remoteTargetDirectory + "\"";
        sess = conn.openSession();
        sess.execCommand(cmd, charsetName);
        return new SCPOutputStream(this, sess, remoteFile, length, mode);
    }

    /**
     * The session for opened for this SCP transfer must be closed using
     * SCPInputStream#close
     *
     * @param remoteFile
     * @return
     * @throws IOException
     */
    public SCPInputStream get(final String remoteFile) throws IOException {
        Session sess = null;

        if (null == remoteFile)
            throw new IllegalArgumentException("Null argument.");

        if (remoteFile.length() == 0)
            throw new IllegalArgumentException("Cannot accept empty filename.");

        String cmd = "scp -f";
        cmd += (" \"" + remoteFile + "\"");
        sess = conn.openSession();
        sess.execCommand(cmd, charsetName);
        return new SCPInputStream(this, sess);
    }
    private void sendBytes(Session sess, byte[] data, String fileName, String mode) throws IOException {
        OutputStream os = sess.getStdin();
        InputStream is = new BufferedInputStream(sess.getStdout(), 512);
        readResponse(is);
        String cline = "C" + mode + " " + data.length + " " + fileName + "\n";
        os.write(cline.getBytes("ISO-8859-1"));
        os.flush();
        readResponse(is);
        os.write(data, 0, data.length);
        os.write(0);
        os.flush();
        readResponse(is);
        os.write("E\n".getBytes("ISO-8859-1"));
        os.flush();
    }

    private void sendFiles(Session sess, String[] files, String[] remoteFiles, String mode) throws IOException {
        byte[] buffer = new byte[8192];
        OutputStream os = new BufferedOutputStream(sess.getStdin(), 40000);
        InputStream is = new BufferedInputStream(sess.getStdout(), 512);
        readResponse(is);

        for (int i = 0; i < files.length; i++) {
            File f = new File(files[i]);
            long remain = f.length();
            String remoteName;

            if ((remoteFiles != null) && (remoteFiles.length > i) && (remoteFiles[i] != null))
                remoteName = remoteFiles[i];
            else
                remoteName = f.getName();

            String cline = "C" + mode + " " + remain + " " + remoteName + "\n";
            os.write(cline.getBytes("ISO-8859-1"));
            os.flush();
            readResponse(is);
            FileInputStream fis = null;

            try {
                fis = new FileInputStream(f);

                while (remain > 0) {
                    int trans;

                    if (remain > buffer.length)
                        trans = buffer.length;
                    else
                        trans = (int) remain;

                    if (fis.read(buffer, 0, trans) != trans)
                        throw new IOException("Cannot read enough from local file " + files[i]);

                    os.write(buffer, 0, trans);
                    remain -= trans;
                }
            }
            finally {
                if (fis != null)
                    fis.close();
            }

            os.write(0);
            os.flush();
            readResponse(is);
        }

        os.write("E\n".getBytes("ISO-8859-1"));
        os.flush();
    }

    private void receiveFiles(Session sess, OutputStream[] targets) throws IOException {
        byte[] buffer = new byte[8192];
        OutputStream os = new BufferedOutputStream(sess.getStdin(), 512);
        InputStream is = new BufferedInputStream(sess.getStdout(), 40000);
        os.write(0x0);
        os.flush();

        for (int i = 0; i < targets.length; i++) {
            LenNamePair lnp = null;

            while (true) {
                int c = is.read();

                if (c < 0)
                    throw new IOException("Remote scp terminated unexpectedly.");

                String line = receiveLine(is);

                if (c == 'T') {
                    /* Ignore modification times */
                    continue;
                }

                if ((c == 1) || (c == 2))
                    throw new IOException("Remote SCP error: " + line);

                if (c == 'C') {
                    lnp = parseCLine(line);
                    break;
                }

                throw new IOException("Remote SCP error: " + ((char) c) + line);
            }

            os.write(0x0);
            os.flush();
            long remain = lnp.length;

            while (remain > 0) {
                int trans;

                if (remain > buffer.length)
                    trans = buffer.length;
                else
                    trans = (int) remain;

                int this_time_received = is.read(buffer, 0, trans);

                if (this_time_received < 0) {
                    throw new IOException("Remote scp terminated connection unexpectedly");
                }

                targets[i].write(buffer, 0, this_time_received);
                remain -= this_time_received;
            }

            readResponse(is);
            os.write(0x0);
            os.flush();
        }
    }

    private void receiveFiles(Session sess, String[] files, String target) throws IOException {
        byte[] buffer = new byte[8192];
        OutputStream os = new BufferedOutputStream(sess.getStdin(), 512);
        InputStream is = new BufferedInputStream(sess.getStdout(), 40000);
        os.write(0x0);
        os.flush();

        for (int i = 0; i < files.length; i++) {
            LenNamePair lnp = null;

            while (true) {
                int c = is.read();

                if (c < 0)
                    throw new IOException("Remote scp terminated unexpectedly.");

                String line = receiveLine(is);

                if (c == 'T') {
                    /* Ignore modification times */
                    continue;
                }

                if ((c == 1) || (c == 2))
                    throw new IOException("Remote SCP error: " + line);

                if (c == 'C') {
                    lnp = parseCLine(line);
                    break;
                }

                throw new IOException("Remote SCP error: " + ((char) c) + line);
            }

            os.write(0x0);
            os.flush();
            File f = new File(target + File.separatorChar + lnp.filename);
            FileOutputStream fop = null;

            try {
                fop = new FileOutputStream(f);
                long remain = lnp.length;

                while (remain > 0) {
                    int trans;

                    if (remain > buffer.length)
                        trans = buffer.length;
                    else
                        trans = (int) remain;

                    int this_time_received = is.read(buffer, 0, trans);

                    if (this_time_received < 0) {
                        throw new IOException("Remote scp terminated connection unexpectedly");
                    }

                    fop.write(buffer, 0, this_time_received);
                    remain -= this_time_received;
                }
            }
            finally {
                if (fop != null)
                    fop.close();
            }

            readResponse(is);
            os.write(0x0);
            os.flush();
        }
    }

    /**
     * Copy a local file to a remote directory, uses mode 0600 when creating the
     * file on the remote side.
     *
     * @param localFile
     *            Path and name of local file.
     * @param remoteTargetDirectory
     *            Remote target directory. Use an empty string to specify the
     *            default directory.
     *
     * @throws IOException
     */
    public void put(String localFile, String remoteTargetDirectory) throws IOException {
        put(new String[] { localFile }, remoteTargetDirectory, "0600");
    }

    /**
     * Copy a set of local files to a remote directory, uses mode 0600 when
     * creating files on the remote side.
     *
     * @param localFiles
     *            Paths and names of local file names.
     * @param remoteTargetDirectory
     *            Remote target directory. Use an empty string to specify the
     *            default directory.
     *
     * @throws IOException
     */

    public void put(String[] localFiles, String remoteTargetDirectory) throws IOException {
        put(localFiles, remoteTargetDirectory, "0600");
    }

    /**
     * Copy a local file to a remote directory, uses the specified mode when
     * creating the file on the remote side.
     *
     * @param localFile
     *            Path and name of local file.
     * @param remoteTargetDirectory
     *            Remote target directory. Use an empty string to specify the
     *            default directory.
     * @param mode
     *            a four digit string (e.g., 0644, see "man chmod", "man open")
     * @throws IOException
     */
    public void put(String localFile, String remoteTargetDirectory, String mode) throws IOException {
        put(new String[] { localFile }, remoteTargetDirectory, mode);
    }

    /**
     * Copy a local file to a remote directory, uses the specified mode and
     * remote filename when creating the file on the remote side.
     *
     * @param localFile
     *            Path and name of local file.
     * @param remoteFileName
     *            The name of the file which will be created in the remote
     *            target directory.
     * @param remoteTargetDirectory
     *            Remote target directory. Use an empty string to specify the
     *            default directory.
     * @param mode
     *            a four digit string (e.g., 0644, see "man chmod", "man open")
     * @throws IOException
     */
    public void put(String localFile, String remoteFileName, String remoteTargetDirectory, String mode)
    throws IOException {
        put(new String[] { localFile }, new String[] { remoteFileName }, remoteTargetDirectory, mode);
    }

    /**
     * Create a remote file and copy the contents of the passed byte array into
     * it. Uses mode 0600 for creating the remote file.
     *
     * @param data
     *            the data to be copied into the remote file.
     * @param remoteFileName
     *            The name of the file which will be created in the remote
     *            target directory.
     * @param remoteTargetDirectory
     *            Remote target directory. Use an empty string to specify the
     *            default directory.
     * @throws IOException
     */

    public void put(byte[] data, String remoteFileName, String remoteTargetDirectory) throws IOException {
        put(data, remoteFileName, remoteTargetDirectory, "0600");
    }

    /**
     * Create a remote file and copy the contents of the passed byte array into
     * it. The method use the specified mode when creating the file on the
     * remote side.
     *
     * @param data
     *            the data to be copied into the remote file.
     * @param remoteFileName
     *            The name of the file which will be created in the remote
     *            target directory.
     * @param remoteTargetDirectory
     *            Remote target directory. Use an empty string to specify the
     *            default directory.
     * @param mode
     *            a four digit string (e.g., 0644, see "man chmod", "man open")
     * @throws IOException
     */
    public void put(byte[] data, String remoteFileName, String remoteTargetDirectory, String mode) throws IOException {
        Session sess = null;

        if ((remoteFileName == null) || (remoteTargetDirectory == null) || (mode == null))
            throw new IllegalArgumentException("Null argument.");

        if (mode.length() != 4)
            throw new IllegalArgumentException("Invalid mode.");

        for (int i = 0; i < mode.length(); i++)
            if (Character.isDigit(mode.charAt(i)) == false)
                throw new IllegalArgumentException("Invalid mode.");

        remoteTargetDirectory = remoteTargetDirectory.trim();
        remoteTargetDirectory = (remoteTargetDirectory.length() > 0) ? remoteTargetDirectory : ".";
        String cmd = "scp -t -d " + remoteTargetDirectory;

        try {
            sess = conn.openSession();
            sess.execCommand(cmd);
            sendBytes(sess, data, remoteFileName, mode);
        }
        catch (IOException e) {
            throw(IOException) new IOException("Error during SCP transfer.").initCause(e);
        }
        finally {
            if (sess != null)
                sess.close();
        }
    }

    /**
     * Copy a set of local files to a remote directory, uses the specified mode
     * when creating the files on the remote side.
     *
     * @param localFiles
     *            Paths and names of the local files.
     * @param remoteTargetDirectory
     *            Remote target directory. Use an empty string to specify the
     *            default directory.
     * @param mode
     *            a four digit string (e.g., 0644, see "man chmod", "man open")
     * @throws IOException
     */
    public void put(String[] localFiles, String remoteTargetDirectory, String mode) throws IOException {
        put(localFiles, null, remoteTargetDirectory, mode);
    }

    public void put(String[] localFiles, String[] remoteFiles, String remoteTargetDirectory, String mode)
    throws IOException {
        Session sess = null;

        /*
         * remoteFiles may be null, indicating that the local filenames shall be
         * used
         */

        if ((localFiles == null) || (remoteTargetDirectory == null) || (mode == null))
            throw new IllegalArgumentException("Null argument.");

        if (mode.length() != 4)
            throw new IllegalArgumentException("Invalid mode.");

        for (int i = 0; i < mode.length(); i++)
            if (Character.isDigit(mode.charAt(i)) == false)
                throw new IllegalArgumentException("Invalid mode.");

        if (localFiles.length == 0)
            return;

        remoteTargetDirectory = remoteTargetDirectory.trim();
        remoteTargetDirectory = (remoteTargetDirectory.length() > 0) ? remoteTargetDirectory : ".";
        String cmd = "scp -t -d " + remoteTargetDirectory;

        for (int i = 0; i < localFiles.length; i++) {
            if (localFiles[i] == null)
                throw new IllegalArgumentException("Cannot accept null filename.");
        }

        try {
            sess = conn.openSession();
            sess.execCommand(cmd);
            sendFiles(sess, localFiles, remoteFiles, mode);
        }
        catch (IOException e) {
            throw(IOException) new IOException("Error during SCP transfer.").initCause(e);
        }
        finally {
            if (sess != null)
                sess.close();
        }
    }

    /**
     * Download a file from the remote server to a local directory.
     *
     * @param remoteFile
     *            Path and name of the remote file.
     * @param localTargetDirectory
     *            Local directory to put the downloaded file.
     *
     * @throws IOException
     */
    public void get(String remoteFile, String localTargetDirectory) throws IOException {
        get(new String[] { remoteFile }, localTargetDirectory);
    }

    /**
     * Download a file from the remote server and pipe its contents into an
     * <code>OutputStream</code>. Please note that, to enable flexible usage
     * of this method, the <code>OutputStream</code> will not be closed nor
     * flushed.
     *
     * @param remoteFile
     *            Path and name of the remote file.
     * @param target
     *            OutputStream where the contents of the file will be sent to.
     * @throws IOException
     */
    public void get(String remoteFile, OutputStream target) throws IOException {
        get(new String[] { remoteFile }, new OutputStream[] { target });
    }

    private void get(String remoteFiles[], OutputStream[] targets) throws IOException {
        Session sess = null;

        if ((remoteFiles == null) || (targets == null))
            throw new IllegalArgumentException("Null argument.");

        if (remoteFiles.length != targets.length)
            throw new IllegalArgumentException("Length of arguments does not match.");

        if (remoteFiles.length == 0)
            return;

        String cmd = "scp -f";

        for (int i = 0; i < remoteFiles.length; i++) {
            if (remoteFiles[i] == null)
                throw new IllegalArgumentException("Cannot accept null filename.");

            String tmp = remoteFiles[i].trim();

            if (tmp.length() == 0)
                throw new IllegalArgumentException("Cannot accept empty filename.");

            cmd += (" " + tmp);
        }

        try {
            sess = conn.openSession();
            sess.execCommand(cmd);
            receiveFiles(sess, targets);
        }
        catch (IOException e) {
            throw(IOException) new IOException("Error during SCP transfer.").initCause(e);
        }
        finally {
            if (sess != null)
                sess.close();
        }
    }

    /**
     * Download a set of files from the remote server to a local directory.
     *
     * @param remoteFiles
     *            Paths and names of the remote files.
     * @param localTargetDirectory
     *            Local directory to put the downloaded files.
     *
     * @throws IOException
     */
    public void get(String remoteFiles[], String localTargetDirectory) throws IOException {
        Session sess = null;

        if ((remoteFiles == null) || (localTargetDirectory == null))
            throw new IllegalArgumentException("Null argument.");

        if (remoteFiles.length == 0)
            return;

        String cmd = "scp -f";

        for (int i = 0; i < remoteFiles.length; i++) {
            if (remoteFiles[i] == null)
                throw new IllegalArgumentException("Cannot accept null filename.");

            String tmp = remoteFiles[i].trim();

            if (tmp.length() == 0)
                throw new IllegalArgumentException("Cannot accept empty filename.");

            cmd += (" " + tmp);
        }

        try {
            sess = conn.openSession();
            sess.execCommand(cmd);
            receiveFiles(sess, remoteFiles, localTargetDirectory);
        }
        catch (IOException e) {
            throw(IOException) new IOException("Error during SCP transfer.").initCause(e);
        }
        finally {
            if (sess != null)
                sess.close();
        }
    }
}