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/*
 * Copyright 2002-2006 the original author or authors.
 *
 * 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.
 */
package org.loom.simpleds;

import javax.persistence.NoResultException;

import org.loom.converter.Converter;
import org.loom.exception.EntityNotFoundException;
import org.loom.i18n.Messages;
import org.loom.interceptor.AbstractPropertyBoundInterceptor;
import org.loom.interceptor.PopulateInterceptor;
import org.loom.interceptor.RetrieveEntityInterceptor;
import org.loom.log.Log;
import org.loom.mapping.Event;
import org.loom.mapping.ParsedAction;
import org.loom.resolution.Resolution;
import org.loom.servlet.params.ServletRequestParameters;
import org.loom.util.PropertyUtils;
import org.simpleds.EntityManager;

import com.google.appengine.api.datastore.Key;

/**
 * Retrieves from the database entities using simpleds instead of JPA
 * 
 * @author icoloma
 */
public class SimpledsRetrieveEntityInterceptor extends AbstractPropertyBoundInterceptor implements RetrieveEntityInterceptor, PopulateInterceptor {

	/** the full path of the ID property, default to the entity PK name */
	private String idPropertyPath;
	
	/** the id property name */
	private String idPropertyName;
	
	/** the property class */
	private Class propertyClass;
	
	private EntityManager entityManager;
	
	private static Log log = Log.getLog(SimpledsRetrieveEntityInterceptor.class);

	public Resolution beforePopulate(ParsedAction action) {
		ServletRequestParameters params = action.getRequest().getRequestParameters();
		Object retrievedEntity = null;
		String idValueAsString = params.getStringParameter(idPropertyPath);
		Event event = action.getEvent();
		if (idValueAsString != null) {
			Messages messages = action.getMessages();
			Converter converter = event.getConverter(idPropertyPath);
			if (converter == null) {
				throw new IllegalArgumentException("No converter was found for " + action.getAction().getClass().getSimpleName() + "." + idPropertyPath+ ". Did you forget to register KeyFactory in your Dependency Injection environment?");
			}
			Key idValueAsObject = (Key) converter.getAsObject(idPropertyPath, idValueAsString, messages, action.getRequest().getMessagesRepository());
			if (messages.get(idPropertyPath) == null) { // conversion ok
				//PropertyBinder propertyBinder = getPropertyBinder();
				if (idValueAsObject != null) {
					try {
						retrievedEntity = entityManager.get(idValueAsObject);
					} catch (NoResultException e) {
						throw new EntityNotFoundException(propertyClass, idValueAsObject, e);
					}
				} else {
					retrievedEntity = null;
				}
				// remove the param so it does not get assigned again on
				// populate time
				params.setAssigned(idPropertyPath);
				log.debug("Assigning value ", getPropertyPath(), " = ", retrievedEntity);
				action.setPropertyAsObject(propertyPath, retrievedEntity);
				// checkVersionNumber(action, retrievedEntity); not yet supported
			}
		}
		return null;
	}

	public void setReadOnly(boolean readOnly) {
		if (readOnly) {
			throw new UnsupportedOperationException("This operation is not supported for simpleds");
		}
	}

	@Override
	public String toString() {
		return "RetrieveEntityInterceptor { property=" + getPropertyPath() + "}";
	}

	public String getIdPropertyPath() {
		return idPropertyPath;
	}

	public void setIdPropertyName(String idPropertyName) {
		throw new UnsupportedOperationException("Only search by PK is supported for simpleds");
	}

	public void setPropertyClass(Class propertyClass) {
		this.propertyClass = propertyClass;
		this.idPropertyName = entityManager.getClassMetadata(propertyClass).getKeyProperty().getName();
		this.idPropertyPath = PropertyUtils.concatPropertyPath(getPropertyPath(), idPropertyName);
	}

	public void setEntityManager(EntityManager entityManager) {
		this.entityManager = entityManager;
	}

}