/*
    * $Id: EnvironmentScopeExtractor.java 1294456 2012-02-28 04:44:55Z nlebas $
    *
    * 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.
   */
  package org.apache.tiles.request.freemarker.extractor;
  
  import java.util.Collections;
  import java.util.Enumeration;
  
  import org.apache.tiles.request.attribute.AttributeExtractor;
  import org.apache.tiles.request.freemarker.FreemarkerRequestException;
  
  import freemarker.core.Environment;
  import freemarker.template.TemplateModel;
  import freemarker.template.TemplateModelException;
  import freemarker.template.utility.DeepUnwrap;
  
  /**
   * Extract attributes from {@link Environment} objects as a scope.
   *
   * @version $Rev: 1294456 $ $Date: 2012-02-28 15:44:55 +1100 (Tue, 28 Feb 2012) $
   */
  public class EnvironmentScopeExtractor implements AttributeExtractor {
  
      /**
       * The environment.
       */
      private Environment request;
  
      /**
       * Constructor.
       *
       * @param request The environment.
       */
      public EnvironmentScopeExtractor(Environment request) {
          this.request = request;
      }
  
      @Override
      public void removeValue(String name) {
          request.setVariable(name, null);
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public Enumeration<String> getKeys() {
          try {
              return Collections.<String> enumeration(request.getKnownVariableNames());
          } catch (TemplateModelException e) {
              throw new FreemarkerRequestException("Cannot iterate variable names correctly", e);
          }
      }
  
      @Override
      public Object getValue(String key) {
          try {
              TemplateModel variable = request.getVariable(key);
              if (variable != null) {
                  return DeepUnwrap.unwrap(variable);
              }
              return null;
          } catch (TemplateModelException e) {
              throw new FreemarkerRequestException("Cannot get attribute with name '" + key + "'", e);
          }
      }
  
      @Override
      public void setValue(String key, Object value) {
          try {
              TemplateModel model = request.getObjectWrapper().wrap(value);
              request.setVariable(key, model);
          } catch (TemplateModelException e) {
              throw new FreemarkerRequestException("Error when wrapping an object setting the '" + key + "' attribute", e);
          }
      }
  }