/*
 *
 * 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.airavata.mft.transport.scp;

import com.jcraft.jsch.*;
import org.apache.airavata.mft.core.api.StreamedReceiver;
import org.apache.airavata.mft.core.streaming.TransportStream;

import java.io.*;

public class SCPReceiver implements StreamedReceiver {

    @Override
    public void receive(TransportStream stream) throws Exception {
        SSHResourceIdentifier sshResourceIdentifier = SCPTransportUtil.getSSHResourceIdentifier(stream.getSourceId());
        Session session = SCPTransportUtil.createSession(sshResourceIdentifier.getUser(), sshResourceIdentifier.getHost(),
                sshResourceIdentifier.getPort(),
                sshResourceIdentifier.getKeyFile(),
                sshResourceIdentifier.getKeyPassphrase());
        transferRemoteToStream(session, sshResourceIdentifier.getRemotePath(), stream);
    }

    private void transferRemoteToStream(Session session, String from, TransportStream stream) throws JSchException, IOException {
        System.out.println("Starting scp receive");
        // exec 'scp -f rfile' remotely
        String command = "scp -f " + from;
        Channel channel = session.openChannel("exec");
        ((ChannelExec) channel).setCommand(command);

        // get I/O streams for remote scp
        OutputStream out = channel.getOutputStream();
        InputStream in = channel.getInputStream();

        channel.connect();

        byte[] buf = new byte[1024];

        // send '\0'
        buf[0] = 0;
        out.write(buf, 0, 1);
        out.flush();

        while (true) {
            int c = checkAck(in);
            if (c != 'C') {
                break;
            }

            // read '0644 '
            in.read(buf, 0, 5);

            long filesize = 0L;
            while (true) {
                if (in.read(buf, 0, 1) < 0) {
                    // error
                    break;
                }
                if (buf[0] == ' ') break;
                filesize = filesize * 10L + (long) (buf[0] - '0');
            }

            String file = null;
            for (int i = 0; ; i++) {
                in.read(buf, i, 1);
                if (buf[i] == (byte) 0x0a) {
                    file = new String(buf, 0, i);
                    break;
                }
            }

            System.out.println("file-size=" + filesize + ", file=" + file);
            // send '\0'
            buf[0] = 0;
            out.write(buf, 0, 1);
            out.flush();

            // read a content of lfile
            int bufSize;
            while (true) {
                if (buf.length < filesize) bufSize = buf.length;
                else bufSize = (int) filesize;
                bufSize = in.read(buf, 0, bufSize);
                if (bufSize < 0) {
                    // error
                    break;
                }
                stream.getOutputStream().write(buf, 0, bufSize);
                stream.getOutputStream().flush();

                filesize -= bufSize;
                if (filesize == 0L) break;
            }

            if (checkAck(in) != 0) {
                System.exit(0);
            }

            // send '\0'
            buf[0] = 0;
            out.write(buf, 0, 1);
            out.flush();
        }

        stream.setStreamCompleted(true);
        channel.disconnect();
        session.disconnect();

        System.out.println("Completed scp receive");

    }

    public int checkAck(InputStream in) throws IOException {
        int b = in.read();
        // b may be 0 for success,
        //          1 for error,
        //          2 for fatal error,
        //         -1
        if (b == 0) return b;
        if (b == -1) return b;

        if (b == 1 || b == 2) {
            StringBuffer sb = new StringBuffer();
            int c;
            do {
                c = in.read();
                sb.append((char) c);
            }
            while (c != '\n');
            if (b == 1) { // error
                System.out.print(sb.toString());
            }
            if (b == 2) { // fatal error
                System.out.print(sb.toString());
            }
        }
        return b;
    }
}