package org.apache.maven.plugin.coreit;
   
   /*
    * 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
   *
   *   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.
   */
  
  import org.apache.maven.plugin.AbstractMojo;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.plugin.MojoFailureException;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Properties;
  
  /**
   * Creates a properties file with the effective values of some user-defined expressions. Unlike Maven's built-in
   * expression syntax for interpolation, these expressions use forward slashes to navigate down the object graph and
   * support access to individual collection/array elements. Furthermore, the result of an expression need not be a scalar
   * value but can also be a collection/array or a bean-like object (from the Maven model). For example, the expression
   * "project/dependencies/0" would extract the first project dependency. In more detail, this example expression could
   * output the following keys to the properties file:
   *
   * <pre>
   * project.dependencies.0.groupId = org.apache.maven
   * project.dependencies.0.artifactId = maven-project
   * project.dependencies.0.type = jar
   * project.dependencies.0.version = 2.0
   * project.dependencies.0.optional = false
   * project.dependencies.0.exclusions = 2
   * project.dependencies.0.exclusions.0.groupId = plexus
   * project.dependencies.0.exclusions.0.artifactId = plexus-utils
   * project.dependencies.0.exclusions.1.groupId = plexus
   * project.dependencies.0.exclusions.1.artifactId = plexus-container-default
   * </pre>
   *
   * Expressions that reference non-existing objects or use invalid collection/array indices silently resolve to
   * <code>null</code>. For collections and arrays, the special index "*" can be used to iterate all elements.
   *
   * @author Benjamin Bentmann
   *
   * @goal eval
   * @phase initialize
   */
  public class EvalMojo
      extends AbstractMojo
  {
  
      /**
       * The project's base directory, used for manual path translation.
       *
       * @parameter default-value="${basedir}"
       * @readonly
       */
      private File basedir;
  
      /**
       * The path to the output file for the properties with the expression values. For each expression given by the
       * parameter {@link #expressions} an similar named properties key will be used to save the expression value. If an
       * expression evaluated to <code>null</code>, there will be no corresponding key in the properties file.
       *
       * @parameter property="expression.outputFile"
       */
      private File outputFile;
  
      /**
       * The set of expressions to evaluate.
       *
       * @parameter
       */
      private String[] expressions;
  
      /**
       * The comma separated set of expressions to evaluate.
       *
       * @parameter property="expression.expressions"
       */
      private String expressionList;
  
      /**
       * The current Maven project against which expressions are evaluated.
       *
       * @parameter default-value="${project}"
      * @readonly
      */
     private Object project;
 
     /**
      * The forked Maven project against which expressions are evaluated.
      *
      * @parameter default-value="${executedProject}"
      * @readonly
      */
     private Object executedProject;
 
     /**
      * The merged user/global settings of the current build against which expressions are evaluated.
      *
      * @parameter default-value="${settings}"
      * @readonly
      */
     private Object settings;
 
     /**
      * The session context of the current build against which expressions are evaluated.
      *
      * @parameter default-value="${session}"
      * @readonly
      */
     private Object session;
 
     /**
      * The local repository of the current build against which expressions are evaluated.
      *
      * @parameter default-value="${localRepository}"
      * @readonly
      */
     private Object localRepository;
 
     /**
      * Runs this mojo.
      *
      * @throws MojoExecutionException If the output file could not be created.
      * @throws MojoFailureException   If the output file has not been set.
      */
     public void execute()
         throws MojoExecutionException, MojoFailureException
     {
         if ( outputFile == null )
         {
             throw new MojoFailureException( "Path name for output file has not been specified" );
         }
 
         /*
          * NOTE: We don't want to test path translation here.
          */
         if ( !outputFile.isAbsolute() )
         {
             outputFile = new File( basedir, outputFile.getPath() ).getAbsoluteFile();
         }
 
         getLog().info( "[MAVEN-CORE-IT-LOG] Creating output file: " + outputFile );
 
         Properties expressionProperties = new Properties();
 
         if ( expressionList != null && expressionList.length() > 0 )
         {
             expressions = expressionList.split( "," );
         }
         if ( expressions != null && expressions.length > 0 )
         {
             Map contexts = new HashMap();
             contexts.put( "project", project );
             contexts.put( "executedProject", executedProject );
             contexts.put( "pom", project );
             contexts.put( "settings", settings );
             contexts.put( "session", session );
             contexts.put( "localRepository", localRepository );
 
             for ( String expression : expressions )
             {
                 Map values = ExpressionUtil.evaluate( expression, contexts );
                 for ( Object key : values.keySet() )
                 {
                     Object value = values.get( key );
                     PropertyUtil.store( expressionProperties, key.toString().replace( '/', '.' ), value );
                 }
             }
         }
 
         try
         {
             PropertyUtil.write( expressionProperties, outputFile );
         }
         catch ( IOException e )
         {
             throw new MojoExecutionException( "Output file could not be created: " + outputFile, e );
         }
 
         getLog().info( "[MAVEN-CORE-IT-LOG] Created output file: " + outputFile );
     }
 
     public void setOutputFile( File outputFile )
     {
         this.outputFile = outputFile;
     }
 }