package org.apache.maven.resolver.internal.ant.types;
   
   /*
    * 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.model.Model;
  import org.apache.tools.ant.Project;
  import org.codehaus.plexus.interpolation.reflection.ReflectionValueExtractor;
  
  /**
   */
  class ModelValueExtractor
  {
  
      private static final String PREFIX_PROPERTIES = "properties.";
  
      private final String prefix;
  
      private final Project project;
  
      private final Model model;
  
      ModelValueExtractor( String prefix, Model model, Project project )
      {
          if ( model == null )
          {
              throw new IllegalArgumentException( "reference to Maven POM has not been specified" );
          }
          if ( project == null )
          {
              throw new IllegalArgumentException( "reference to Ant project has not been specified" );
          }
          if ( prefix == null || prefix.length() <= 0 )
          {
              prefix = "pom.";
          }
          else if ( !prefix.endsWith( "." ) )
          {
              prefix += '.';
          }
          this.prefix = prefix;
          this.model = model;
          this.project = project;
      }
  
      public Project getProject()
      {
          return project;
      }
  
      public boolean isApplicable( String expression )
      {
          return expression.startsWith( prefix );
      }
  
      public Object getValue( String expression )
      {
          if ( expression.startsWith( prefix ) )
          {
              String expr = expression.substring( prefix.length() );
              try
              {
                  if ( expr.startsWith( PREFIX_PROPERTIES ) )
                  {
                      String key = expr.substring( PREFIX_PROPERTIES.length() );
                      return model.getProperties().getProperty( key );
                  }
  
                  return ReflectionValueExtractor.evaluate( expr, model, false );
              }
              catch ( Exception e )
              {
                  project.log( "Could not retrieve '" + expression + "' from POM: " + e.getMessage(), e, Project.MSG_WARN );
                  return null;
              }
          }
          else
          {
              return null;
          }
      }
  
  }