/*
    * $Id: ReadOnlyVariableResolverFactory.java 1049688 2010-12-15 20:15:41Z apetrelli $
    *
    * 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.mvel;
  
  import java.util.HashMap;
  
  import org.apache.tiles.context.TilesRequestContextHolder;
  import org.mvel2.UnresolveablePropertyException;
  import org.mvel2.integration.VariableResolver;
  import org.mvel2.integration.impl.BaseVariableResolverFactory;
  
  /**
   * A base variable resolver factory that is read-only.
   *
   * @version $Rev: 1049688 $ $Date: 2010-12-16 07:15:41 +1100 (Thu, 16 Dec 2010) $
   */
  public abstract class ReadOnlyVariableResolverFactory extends
          BaseVariableResolverFactory {
  
      /**
       * The Tiles request holder.
       */
      protected TilesRequestContextHolder requestHolder;
  
      /**
       * Constructor.
       *
       * @param requestHolder The Tiles request holder.
       * @since 3..0
       */
      public ReadOnlyVariableResolverFactory(TilesRequestContextHolder requestHolder) {
          this.requestHolder = requestHolder;
          variableResolvers = new HashMap<String, VariableResolver>();
      }
  
      /** {@inheritDoc} */
      public VariableResolver createVariable(String name, Object value) {
          if (nextFactory != null) {
              return nextFactory.createVariable(name, value);
          }
          throw new UnsupportedOperationException("This variable resolver factory is read only");
      }
  
      /** {@inheritDoc} */
      public VariableResolver createVariable(String name, Object value,
              Class<?> type) {
          variableResolvers = new HashMap<String, VariableResolver>();
          if (nextFactory != null) {
              return nextFactory.createVariable(name, value, type);
          }
          throw new UnsupportedOperationException("This variable resolver factory is read only");
      }
  
      /** {@inheritDoc} */
      public boolean isResolveable(String name) {
          return isTarget(name) || isNextResolveable(name);
      }
  
      /** {@inheritDoc} */
      @Override
      public VariableResolver getVariableResolver(String name) {
          if (isResolveable(name)) {
              if (variableResolvers != null && variableResolvers.containsKey(name)) {
                  return variableResolvers.get(name);
              } else if (isTarget(name)) {
                  VariableResolver variableResolver = createVariableResolver(name);
                  variableResolvers.put(name, variableResolver);
                  return variableResolver;
              } else if (nextFactory != null) {
                  return nextFactory.getVariableResolver(name);
              }
          }
  
          throw new UnresolveablePropertyException("unable to resolve variable '" + name + "'");
      }
  
      /**
       * Creates a variable resolver.
       *
       * @param name The name of the property.
       * @return The variable resolver.
      * @since 3.0.0
      */
     public abstract VariableResolver createVariableResolver(String name);
 
     /**
      * Base variable resolver.
      *
      * @version $Rev: 1049688 $ $Date: 2010-12-16 07:15:41 +1100 (Thu, 16 Dec 2010) $
      * @since 3.0.0
      */
     public abstract static class ReadOnlyVariableResolver implements VariableResolver {
 
         /**
          * The name of the property.
          */
         protected String name;
 
         /**
          * Constructor.
          *
          * @param name The name of the property.
          * @since 2.2.0
          */
         public ReadOnlyVariableResolver(String name) {
             this.name = name;
         }
 
         /** {@inheritDoc} */
         public int getFlags() {
             return 0;
         }
 
         /** {@inheritDoc} */
         public String getName() {
             return name;
         }
 
         /** {@inheritDoc} */
         public void setStaticType(@SuppressWarnings("rawtypes") Class type) {
             // Does nothing for the moment.
         }
 
         /** {@inheritDoc} */
         public void setValue(Object value) {
             throw new UnsupportedOperationException("This resolver is read-only");
         }
     }
 }