code: /**
   * This file is part of Eclipse Steady.
   *
   * Licensed 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.
   *
   * SPDX-License-Identifier: Apache-2.0
   * SPDX-FileCopyrightText: Copyright (c) 2018-2020 SAP SE or an SAP affiliate company and Eclipse Steady contributors
   */
  package org.eclipse.steady.kb.command;
  
  import java.nio.file.Paths;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.ServiceLoader;
  import org.apache.commons.cli.HelpFormatter;
  import org.apache.commons.cli.Options;
  import org.apache.logging.log4j.Logger;
  import org.eclipse.steady.kb.exception.CommandLineParserException;
  import org.eclipse.steady.kb.exception.ValidationException;
  
  /**
   * command executor
   */
  public class CommandExecutor {
  
    private static final String DIRECTORY_OPTION = "d";
    private static final Logger log = org.apache.logging.log4j.LogManager.getLogger();
    private Map<Command.NAME, Command> commands = new HashMap<>();
    private static CommandExecutor commandExecutor;
  
    private CommandExecutor() {
      init();
    }
  
    /**
     * <p>getInstance.</p>
     *
     * @return a {@link org.eclipse.steady.kb.command.CommandExecutor} object
     */
    public static synchronized CommandExecutor getInstance() {
      if (commandExecutor == null) {
        commandExecutor = new CommandExecutor();
      }
      return commandExecutor;
    }
  
    private void init() {
      ServiceLoader<Command> serviceProviders = ServiceLoader.load(Command.class);
      Iterator<Command> iterator = serviceProviders.iterator();
      while (iterator.hasNext()) {
        Command command = iterator.next();
        commands.put(command.getCommandName(), command);
      }
    }
  
    /**
     * command executor
     *
     * @param _args a array of {java.lang.String}
     */
    public void execute(String _args[]) {
      if (_args.length == 0) {
        log.error("No arguments passed");
        return;
      }
  
      Command command = null;
      try {
        command = commands.get(Command.NAME.valueOf(_args[0].toUpperCase()));
      } catch (IllegalArgumentException e) {
        // skip when an unknown command name is passed. Default to import
      }
  
      if (command == null) {
        command = new Import();
      }
  
      Options commandOptions = command.getOptions();
  
      HashMap<String, Object> mapCommandOptionValues;
      try {
        mapCommandOptionValues = CommandParser.parse(_args, commandOptions);
        Object rootDirObj = mapCommandOptionValues.get(DIRECTORY_OPTION);
        if (rootDirObj != null) {
          String rootDir = (String) rootDirObj;
          rootDir = getAbsolutePath(rootDir);
          mapCommandOptionValues.put(DIRECTORY_OPTION, rootDir);
        }
      } catch (CommandLineParserException e) {
        log.error(e.getMessage());
        printHelp(commandOptions);
        return;
      }
  
      try {
        command.validate(mapCommandOptionValues);
      } catch (ValidationException e) {
        log.error(e.getMessage());
        return;
      }
  
      command.run(mapCommandOptionValues);
    }
  
    /**
     * Print command help
     *
     * @param a {@link org.apache.commons.cli.Options}
     */
    private void printHelp(Options commandOptions) {
      // Showing import help
      HelpFormatter formatter = new HelpFormatter();
      formatter.printHelp("java -jar <jar> <options>", new Import().getOptions());
    }
  
    /**
     * get directory absolute path if it is relative
     *
     * @param rootDir
     * @return absolute path
     */
    private String getAbsolutePath(String rootDir) {
      return Paths.get(rootDir).toAbsolutePath().normalize().toString();
    }
  }
  