// -*- mode: java; c-basic-offset: 2; -*-
// Copyright 2011-2012 MIT, All rights reserved
// Released under the Apache License, Version 2.0
// http://www.apache.org/licenses/LICENSE-2.0

/**
 * Utility class for command execution and I/O redirection.
 *
 * @author andrew.f.mckinney@gmail.com (Andrew F. McKinney)
 */

package com.google.appinventor.blocklyeditor;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;

public final class CommandUtil {

  private static final boolean DEBUG = false;

  public static String executeCommand(String command, boolean waitForResponse) {

    String response = "";
    ProcessBuilder pb = null;

    pb = new ProcessBuilder("bash", "-c", command);
    pb.redirectErrorStream(true);

    if (DEBUG) {
      System.out.println("Command: " + command);
    }

    try {
      Process shell = pb.start();
      if (waitForResponse) {

        // To capture output from the shell
        InputStream shellIn = shell.getInputStream();

        // Wait for the shell to finish and get the return code
        int shellExitStatus = shell.waitFor();

        if (DEBUG) {
          System.out.println("Exit status = " + shellExitStatus);
        }

        response = convertStreamToStr(shellIn);
        shellIn.close();
      }

    } catch (IOException e) {
      System.out.println("Error occured while executing command. Error Description: "
          + e.getMessage());
    } catch (InterruptedException e) {
      System.out.println("Error occured while executing command. Error Description: "
          + e.getMessage());
    }

    return response;
  }

  /*
   * To convert the InputStream to String we use the Reader.read(char[] buffer) method. We iterate
   * until the Reader return -1 which means there's no more data to read. We use the StringWriter
   * class to produce the string.
   */

  public static String convertStreamToStr(InputStream is) throws IOException {

    if (is != null) {
      Writer writer = new StringWriter();

      char[] buffer = new char[1024];
      try {
        Reader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
        int n;
        while ((n = reader.read(buffer)) != -1) {
          writer.write(buffer, 0, n);
        }
      } finally {
        is.close();
      }
      return writer.toString();
    } else {
      return "";
    }
  }

}