package com.corp.prj.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.log4j.Logger;

import ch.ethz.ssh2.Connection;
import ch.ethz.ssh2.SCPClient;
import ch.ethz.ssh2.Session;
import ch.ethz.ssh2.StreamGobbler;

/**
 * Provides static methods for running SSH, scp as well as local commands.
 *
 */
public class CommandRunner {
  private static final Logger logger = Logger.getLogger(CommandRunner.class);

  private CommandRunner() {
  }
  
  /**
   * Get remote file through scp
   * @param host
   * @param username
   * @param password
   * @param remoteFile
   * @param localDir
   * @throws IOException
   */
  public static void scpGet(String host, String username, String password,
      String remoteFile, String localDir) throws IOException {
    if (logger.isDebugEnabled()) {
      logger.debug("spc [" + remoteFile + "] from " + host + " to " + localDir);
    }
    Connection conn = getOpenedConnection(host, username, password);
    SCPClient client = new SCPClient(conn);
    client.get(remoteFile, localDir);
    conn.close();
  }
  
  /**
   * Put local file to remote machine.
   * @param host
   * @param username
   * @param password
   * @param localFile
   * @param remoteDir
   * @throws IOException
   */
  public static void scpPut(String host, String username, String password,
      String localFile, String remoteDir) throws IOException {
    if (logger.isDebugEnabled()) {
      logger.debug("spc [" + localFile + "] to " + host + remoteDir);
    }
    Connection conn = getOpenedConnection(host, username, password);
    SCPClient client = new SCPClient(conn);
    client.put(localFile, remoteDir);
    conn.close();
  }
  
  /**
   * Run SSH command.
   * @param host
   * @param username
   * @param password
   * @param cmd
   * @return exit status
   * @throws IOException
   */
  public static int runSSH(String host, String username, String password,
      String cmd) throws IOException {
    if (logger.isDebugEnabled()) {
      logger.debug("running SSH cmd [" + cmd + "]");
    }

    Connection conn = getOpenedConnection(host, username, password);
    Session sess = conn.openSession();
    sess.execCommand(cmd);

    InputStream stdout = new StreamGobbler(sess.getStdout());
    BufferedReader br = new BufferedReader(new InputStreamReader(stdout));

    while (true) {
      // attention: do not comment this block, or you will hit NullPointerException
      // when you are trying to read exit status
      String line = br.readLine();
      if (line == null)
        break;
      if (logger.isDebugEnabled()) {
        logger.debug(line);
      }
    }

    sess.close();
    conn.close();
    return sess.getExitStatus().intValue();
  }
  
  /**
   * return a opened Connection
   * @param host
   * @param username
   * @param password
   * @return
   * @throws IOException
   */
  private static Connection getOpenedConnection(String host, String username,
      String password) throws IOException {
    if (logger.isDebugEnabled()) {
      logger.debug("connecting to " + host + " with user " + username
          + " and pwd " + password);
    }

    Connection conn = new Connection(host);
    conn.connect(); // make sure the connection is opened
    boolean isAuthenticated = conn.authenticateWithPassword(username,
        password);
    if (isAuthenticated == false)
      throw new IOException("Authentication failed.");
    return conn;
  }
  
  /**
   * Run local command
   * @param cmd
   * @return exit status
   * @throws IOException
   */
  public static int runLocal(String cmd) throws IOException {
    if (logger.isDebugEnabled()) {
      logger.debug("running local cmd [" + cmd + "]");
    }

    Runtime rt = Runtime.getRuntime();
    Process p = rt.exec(cmd);

    InputStream stdout = new StreamGobbler(p.getInputStream());
    BufferedReader br = new BufferedReader(new InputStreamReader(stdout));

    while (true) {
      String line = br.readLine();
      if (line == null)
        break;
      if (logger.isDebugEnabled()) {
        logger.debug(line);
      }

    }
    return p.exitValue();
  }
}