content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one or more
   *  contributor license agreements.  See the NOTICE file distributed with
   *  this work for additional information regarding copyright ownership.
   *  The ASF licenses this file to You 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
   *
   *      https://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.
   *
   */
  
  package org.apache.tools.ant.util.facade;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Objects;
  import java.util.stream.Stream;
  
  import org.apache.tools.ant.Project;
  import org.apache.tools.ant.types.Path;
  
  /**
   * Helper class for facade implementations - encapsulates treatment of
   * explicit implementation choices, magic properties and
   * implementation specific command line arguments.
   *
   *
   * @since Ant 1.5
   */
  public class FacadeTaskHelper {
  
      /**
       * Command line arguments.
       */
      private List<ImplementationSpecificArgument> args = new ArrayList<>();
  
      /**
       * The explicitly chosen implementation.
       */
      private String userChoice;
  
      /**
       * The magic property to consult.
       */
      private String magicValue;
  
      /**
       * The default value.
       */
      private String defaultValue;
  
      /**
       * User specified path used as classpath when loading the implementation.
       */
      private Path implementationClasspath;
  
      /**
       * @param defaultValue The default value for the implementation.
       * Must not be null.
       */
      public FacadeTaskHelper(String defaultValue) {
          this(defaultValue, null);
      }
  
      /**
       * @param defaultValue The default value for the implementation.
       * Must not be null.
       * @param magicValue the value of a magic property that may hold a user.
       * choice.  May be null.
       */
      public FacadeTaskHelper(String defaultValue, String magicValue) {
          this.defaultValue = defaultValue;
          this.magicValue = magicValue;
      }
  
      /**
       * Used to set the value of the magic property.
       * @param magicValue the value of a magic property that may hold a user.
       */
      public void setMagicValue(String magicValue) {
          this.magicValue = magicValue;
      }
  
      /**
       * Used for explicit user choices.
       * @param userChoice the explicitly chosen implementation.
       */
      public void setImplementation(String userChoice) {
          this.userChoice = userChoice;
      }
  
      /**
       * Retrieves the implementation.
       * @return the implementation.
       */
      public String getImplementation() {
          return userChoice != null ? userChoice
                                    : (magicValue != null ? magicValue
                                                          : defaultValue);
      }
  
      /**
       * Retrieves the explicit user choice.
       * @return the explicit user choice.
       */
      public String getExplicitChoice() {
          return userChoice;
      }
  
      /**
       * Command line argument.
       * @param arg an argument to add.
       */
      public void addImplementationArgument(ImplementationSpecificArgument arg) {
          args.add(arg);
      }
  
      /**
       * Retrieves the command line arguments enabled for the current
       * facade implementation.
       * @return an array of command line arguments.
       */
      public String[] getArgs() {
          String implementation = getImplementation();
          return args.stream().map(arg -> arg.getParts(implementation))
              .filter(Objects::nonNull).flatMap(Stream::of)
              .toArray(String[]::new);
      }
  
      /**
       * Tests whether the implementation has been chosen by the user
       * (either via a magic property or explicitly.
       * @return true if magic or user choice has be set.
       * @since Ant 1.5.2
       */
      public boolean hasBeenSet() {
          return userChoice != null || magicValue != null;
      }
  
      /**
       * The classpath to use when loading the implementation.
       *
       * @param project the current project
       * @return a Path instance that may be appended to
       * @since Ant 1.8.0
       */
      public Path getImplementationClasspath(Project project) {
          if (implementationClasspath == null) {
              implementationClasspath = new Path(project);
          }
          return implementationClasspath;
      }
  }
  