/*
 * 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.cli.fs.command;

import alluxio.AlluxioURI;
import alluxio.annotation.PublicApi;
import alluxio.cli.CommandUtils;
import alluxio.client.file.FileSystemContext;
import alluxio.exception.AlluxioException;
import alluxio.exception.status.InvalidArgumentException;
import alluxio.grpc.SetAttributePOptions;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;

import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.annotation.concurrent.ThreadSafe;

/**
 * Changes the owner of a file or directory specified by args.
 */
@ThreadSafe
@PublicApi
public final class ChownCommand extends AbstractFileSystemCommand {

  private static final Option RECURSIVE_OPTION =
      Option.builder("R").longOpt("recursive")
          .required(false)
          .hasArg(false)
          .desc("change owner recursively")
          .build();

  private String mGroup;
  private String mOwner;

  /**
   * Creates a new instance of {@link ChownCommand}.
   *
   * @param fsContext an Alluxio file system handle
   */
  public ChownCommand(FileSystemContext fsContext) {
    super(fsContext);
  }

  @Override
  protected void runPlainPath(AlluxioURI path, CommandLine cl)
      throws AlluxioException, IOException {
    if (mGroup == null) {
      chown(path, mOwner, cl.hasOption(RECURSIVE_OPTION.getOpt()));
    } else {
      chown(path, mOwner, mGroup, cl.hasOption(RECURSIVE_OPTION.getOpt()));
    }
  }

  @Override
  public String getCommandName() {
    return "chown";
  }

  @Override
  public void validateArgs(CommandLine cl) throws InvalidArgumentException {
    CommandUtils.checkNumOfArgsEquals(this, cl, 2);
  }

  @Override
  public Options getOptions() {
    return new Options().addOption(RECURSIVE_OPTION);
  }

  /**
   * See https://paulgorman.org/technical/presentations/linux_username_conventions.pdf
   * in which the author refers to IEEE Std 1003.1-2001 regarding the standards for
   * valid POSIX usernames.
   */
  private static final Pattern USER_GROUP_PATTERN =
      Pattern.compile("(?<user>[\\w][\\w-.]*\\$?)(:(?<group>[\\w][\\w-.]*\\$?))?");

  /**
   * Changes the owner for the path specified in args.
   *
   * @param path The {@link AlluxioURI} path as the input of the command
   * @param owner The owner to be updated to the file or directory
   * @param recursive Whether change the owner recursively
   */
  private void chown(AlluxioURI path, String owner, boolean recursive)
      throws AlluxioException, IOException {
    SetAttributePOptions options =
        SetAttributePOptions.newBuilder().setOwner(owner).setRecursive(recursive).build();
    mFileSystem.setAttribute(path, options);
    System.out.println("Changed owner of " + path + " to " + owner);
  }

  /**
   * Changes the owner and group for the path specified in args.
   *
   * @param path the {@link AlluxioURI} path to update
   * @param owner the new owner
   * @param group the new group
   * @param recursive whether to change the owner and group recursively
   */
  private void chown(AlluxioURI path, String owner, String group, boolean recursive)
      throws AlluxioException, IOException {
    SetAttributePOptions options = SetAttributePOptions.newBuilder().setOwner(owner).setGroup(group)
        .setRecursive(recursive).build();
    mFileSystem.setAttribute(path, options);
    System.out.println("Changed owner:group of " + path + " to " + owner + ":" + group + ".");
  }

  @Override
  public int run(CommandLine cl) throws AlluxioException, IOException {
    String[] args = cl.getArgs();
    AlluxioURI path = new AlluxioURI(args[1]);
    Matcher matchUserGroup = USER_GROUP_PATTERN.matcher(args[0]);
    if (matchUserGroup.matches()) {
      mOwner = matchUserGroup.group("user");
      mGroup = matchUserGroup.group("group");
      runWildCardCmd(path, cl);
      return 0;
    }
    System.out.println("Failed to parse " + args[0] + " as user or user:group");
    return -1;
  }

  @Override
  public String getUsage() {
    return "chown [-R/--recursive] <owner>[:<group>] <path>";
  }

  @Override
  public String getDescription() {
    return "Changes the owner of a file or directory specified by args."
        + " Specify -R/--recursive to change the owner recursively.";
  }
}
