/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.yarn;

import com.google.common.base.Preconditions;

import java.util.Vector;

import javax.annotation.concurrent.NotThreadSafe;

/**
 * This class is used to build a string representing a shell command by adding arguments.
 *
 * TODO(binfan): to share this class into util.
 */
@NotThreadSafe
public class CommandBuilder {
  private String mBase;
  private Vector<String> mArgs = new Vector<String>(10);

  /**
   * @param base the base string to use for constructing the command, e.g. for echo "hello world"
   *        this would be "echo"
   */
  public CommandBuilder(String base) {
    mBase = Preconditions.checkNotNull(base);
  }

  /**
   * Adds the string value of the given argument to the command.
   *
   * @param arg the argument to add
   * @return the {@link CommandBuilder} with the argument added
   */
  public CommandBuilder addArg(Object arg) {
    mArgs.add(String.valueOf(arg));
    return this;
  }

  /**
   * Adds the string value of the given option argument to the command.
   *
   * For example, to add "-name myFile" to construct the command "find . -name myFile", opt should
   * be "-name" and arg should be "myFile".
   *
   * @param opt the option flag
   * @param arg the argument
   * @return the {@link CommandBuilder} with the argument added
   */
  public CommandBuilder addArg(String opt, Object arg) {
    mArgs.add(opt + " " + String.valueOf(arg));
    return this;
  }

  // Get final command
  @Override
  public String toString() {
    StringBuilder builder = new StringBuilder(mBase + " ");
    for (String str : mArgs) {
      builder.append(str).append(" ");
    }
    return builder.toString();
  }
}