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/***********************************************************************************************************************
 *
 * blueMarine Metadata - open source media workflow
 * Copyright (C) 2007-2011 by Tidalwave s.a.s. (http://www.tidalwave.it)
 *
 ***********************************************************************************************************************
 *
 * Licensed 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.
 *
 ***********************************************************************************************************************
 *
 * WWW: http://bluemarine.tidalwave.it
 * SCM: https://kenai.com/hg/bluemarine~metadata-src
 *
 **********************************************************************************************************************/
package it.tidalwave.metadata.persistence;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import it.tidalwave.metadata.persistence.spi.BeanAccessor;
import it.tidalwave.metadata.persistence.spi.UnknownPropertyException;

/*******************************************************************************
 * 
 * This class describes a single property of a metadata item. 
 * 
 * @author  Fabrizio Giudici
 * @version $Id$
 *
 ******************************************************************************/
public class MetadataProperty extends MetadataComposite
  {
    private final Map> cache = new HashMap>();
    
    /***************************************************************************
     *
     * Creates a new instance given a parent and a name.
     * 
     * @param  parent        the parent
     * @param  propertyName  the name 
     * 
     **************************************************************************/
    public MetadataProperty (@Nonnull final MetadataComposite parent,
                             @Nonnull final String propertyName) 
      {
        super(parent, propertyName);
      }

    /***************************************************************************
     *
     * Returns the property name.
     * 
     * @return   the name of the property
     * 
     **************************************************************************/
    @CheckForNull
    public String getPropertyName() 
      {
        return propertyName;
      }

    /***************************************************************************
     *
     * Returns the property type.
     *
     * @return   the type of the property
     *
     **************************************************************************/
    @Nonnull
    public Class getType()
      throws UnknownPropertyException
      {
        final BeanAccessor beanAccessor = persistenceSpi.findAccessorByClass(getItemClass());
        return (Class)beanAccessor.getDefaultPropertyType(propertyName);
      }

    /***************************************************************************
     *
     * Finds or creates a new PropertyAndValue instance for the given
     * value. This method guarantees that always the same instance is returned 
     * for a given value; this saves time in case the method 
     * {@link PropertyAndValue#getDataObjectCount()} is called multiple times 
     * since it won't be recomputed for multiple instances, and furthermore it 
     * makes it possible for the Persistence Facility to constantly update the 
     * count when new data is added or removed.
     * 
     * @param  value     the value
     * 
     **************************************************************************/
    @Nonnull
    public synchronized PropertyAndValue findOrCreatePropertyAndValue (@CheckForNull final T value)
      {
        // Use a String for the key so you can handle null and 
        // don't worry about value's equals() and hashCode()
        final String key = (value == null) ? "null" : value.toString();     
        PropertyAndValue pav = cache.get(key);
        
        if (pav == null)
          {
            pav = new PropertyAndValue(this, value);
            cache.put(key, pav);
          }
        
        return pav; 
      }
    
    /***************************************************************************
     *
     * Returns the list of all the possible values for this property. This 
     * method dinamically queries the persistent facility and always produces
     * an updated list.
     * 
     * @return   the values for this property
     * 
     **************************************************************************/
    @Nonnull
    public List getValues()
      {
        return persistenceSpi.findValues(this);
      }
    
    /***************************************************************************
     *
     * {@inheritDoc}
     * 
     **************************************************************************/
    @Override
    @Nonnull
    public final String toString()
      {
        return String.format("MetadataProperty[%s]", propertyName);
      }
  }