/*
    * Copyright 2006-2011 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.krad.service.impl;
  
  import org.apache.ojb.broker.metadata.ClassDescriptor;
  import org.apache.ojb.broker.metadata.ClassNotPersistenceCapableException;
  import org.apache.ojb.broker.metadata.DescriptorRepository;
  import org.apache.ojb.broker.metadata.FieldDescriptor;
  import org.apache.ojb.broker.metadata.ObjectReferenceDescriptor;
  import org.kuali.rice.core.api.config.property.ConfigContext;
  import org.kuali.rice.core.framework.persistence.jpa.OrmUtils;
  import org.kuali.rice.core.framework.persistence.jpa.metadata.EntityDescriptor;
  import org.kuali.rice.core.framework.persistence.jpa.metadata.MetadataManager;
  import org.kuali.rice.core.framework.persistence.jpa.metadata.ObjectDescriptor;
  import org.kuali.rice.core.framework.persistence.ojb.BaseOjbConfigurer;
  import org.kuali.rice.krad.bo.PersistableBusinessObject;
  import org.kuali.rice.krad.bo.PersistableBusinessObjectExtension;
  import org.kuali.rice.krad.exception.ClassNotPersistableException;
  import org.kuali.rice.krad.util.spring.CacheNoCopy;
  
  import java.util.ArrayList;
  import java.util.List;
  
  public class PersistenceServiceStructureImplBase {
  
  	private DescriptorRepository descriptorRepository;
  
  	/**
  	 * Constructs a PersistenceServiceImpl instance.
  	 */
  	public PersistenceServiceStructureImplBase() {
  		String ojbPropertyFileLocation = ConfigContext.getCurrentContextConfig().getProperty(BaseOjbConfigurer.RICE_OJB_PROPERTIES_PARAM);
          String currentValue = System.getProperty(BaseOjbConfigurer.OJB_PROPERTIES_PROP);
  		try {
  			System.setProperty(BaseOjbConfigurer.OJB_PROPERTIES_PROP, ojbPropertyFileLocation);
  			org.apache.ojb.broker.metadata.MetadataManager metadataManager = org.apache.ojb.broker.metadata.MetadataManager.getInstance();
  			descriptorRepository = metadataManager.getGlobalRepository();
  	    } finally {
  	        if (currentValue == null) {
  	            System.getProperties().remove(BaseOjbConfigurer.OJB_PROPERTIES_PROP);
  	        } else {
  	            System.setProperty(BaseOjbConfigurer.OJB_PROPERTIES_PROP, currentValue);
  	        }
  	    }
  	}
  
  	/**
  	 * @return DescriptorRepository containing everything OJB knows about persistable classes
  	 */
  	protected DescriptorRepository getDescriptorRepository() {
  		return descriptorRepository;
  	}
  
  	/**
  	 *
  	 * This method returns a list of primary key field names.  This method uses the CacheNoCopy caching method.
  	 * "NoCopy" is the faster of the caching annotations, but because it does not make a copy the list that is
  	 * returned must not be modified.  To enforce this the returned list is wrapped in a Collections.unmodifiableList
  	 * method.  This will cause an exception to be thrown if the list is altered.
  	 *
  	 * @param clazz
  	 * @return unmodifiableList of field names.  Any attempt to alter list will result in an UnsupportedOperationException
  	 */
  	@CacheNoCopy
  	public List listPrimaryKeyFieldNames(Class clazz) {
      	// Rice JPA MetadataManager
  		if (isJpaEnabledForKradClass(clazz)) {
  			List fieldNames = new ArrayList();
  	    	EntityDescriptor descriptor = MetadataManager.getEntityDescriptor(clazz);
  	    	for (org.kuali.rice.core.framework.persistence.jpa.metadata.FieldDescriptor field : descriptor.getPrimaryKeys()) {
  	    		fieldNames.add(field.getName());
  	    	}
  	    	return fieldNames;
  		} else {
  	    	// Legacy OJB
  			List fieldNamesLegacy = new ArrayList();
  			ClassDescriptor classDescriptor = getClassDescriptor(clazz);
  			FieldDescriptor keyDescriptors[] = classDescriptor.getPkFields();
  
  			for (int i = 0; i < keyDescriptors.length; ++i) {
  				FieldDescriptor keyDescriptor = keyDescriptors[i];
  				fieldNamesLegacy.add(keyDescriptor.getAttributeName());
  			}
  			return fieldNamesLegacy;
  		}
 	}
 
 	/* Not used anywhere... need to check KFS and batch stuff */
 	/**
 	 * @param classDescriptor
 	 * @return name of the database table associated with given classDescriptor,
 	 *         stripped of its leading schemaName
 	 */
 	/*
 	@CacheNoCopy
 	protected String getTableName(ClassDescriptor classDescriptor) {
 		String schemaName = classDescriptor.getSchema();
 		String fullTableName = classDescriptor.getFullTableName();
 
 		String tableName = null;
 		if (StringUtils.isNotBlank(schemaName)) {
 			tableName = StringUtils.substringAfter(fullTableName, schemaName + ".");
 		}
 		if (StringUtils.isBlank(tableName)) {
 			tableName = fullTableName;
 		}
 
 		return tableName;
 	}
 	*/
 
 	/**
 	 * @param persistableClass
 	 * @return ClassDescriptor for the given Class
 	 * @throws IllegalArgumentException
 	 *             if the given Class is null
 	 * @throws ClassNotPersistableException
 	 *             if the given Class is unknown to OJB
 	 */
 	// Legacy OJB - no need for JPA equivalent
 	protected ClassDescriptor getClassDescriptor(Class persistableClass) {
 		if (persistableClass == null) {
 			throw new IllegalArgumentException("invalid (null) object");
 		}
 
 		ClassDescriptor classDescriptor = null;
 		DescriptorRepository globalRepository = getDescriptorRepository();
 		try {
 			classDescriptor = globalRepository.getDescriptorFor(persistableClass);
 		} catch (ClassNotPersistenceCapableException e) {
 			throw new ClassNotPersistableException("class '" + persistableClass.getName() + "' is not persistable", e);
 		}
 
 		return classDescriptor;
 	}
 	
 	/**
 	 * Determines if JPA is enabled for the KNS and for the given class
 	 * 
 	 * @param clazz the class to check for JPA enabling of
 	 * @return true if JPA is enabled for the class, false otherwise
 	 */
 	public boolean isJpaEnabledForKradClass(Class clazz) {
 		final boolean jpaAnnotated = OrmUtils.isJpaAnnotated(clazz);
 		final boolean jpaEnabled = OrmUtils.isJpaEnabled();
 		final boolean prefixJpaEnabled = OrmUtils.isJpaEnabled("rice.krad");
 		return jpaAnnotated && (jpaEnabled || prefixJpaEnabled);
 	}
 
 	/**
 	 * @see org.kuali.rice.krad.service.PersistenceStructureService#getBusinessObjectAttributeClass(java.lang.Class,
 	 *      java.lang.String)
 	 */
 	@CacheNoCopy
 	public Class<? extends PersistableBusinessObjectExtension> getBusinessObjectAttributeClass(Class<? extends PersistableBusinessObject> clazz, String attributeName) {
 		String baseAttributeName = attributeName;
 		String subAttributeString = null;
 		if (attributeName.contains(".")) {
 			baseAttributeName = attributeName.substring(0, attributeName.indexOf('.'));
 			subAttributeString = attributeName.substring(attributeName.indexOf('.') + 1);
 		}
 
     	// Rice JPA MetadataManager
 		if (isJpaEnabledForKradClass(clazz)) {
 			Class attributeClass = null;
 	    	EntityDescriptor descriptor = MetadataManager.getEntityDescriptor(clazz);
 	    	ObjectDescriptor objectDescriptor = descriptor.getObjectDescriptorByName(baseAttributeName);
 			if (objectDescriptor != null) {
 				attributeClass = objectDescriptor.getTargetEntity();
 			}
 
 			// recurse if necessary
 			if (subAttributeString != null) {
 				attributeClass = getBusinessObjectAttributeClass(attributeClass, subAttributeString);
 			}
 
 			return attributeClass;
 		} else {
 	    	// Legacy OJB
 			Class attributeClassLegacy = null;
 			ClassDescriptor classDescriptor = this.getClassDescriptor(clazz);
 			ObjectReferenceDescriptor refDescriptor = classDescriptor.getObjectReferenceDescriptorByName(baseAttributeName);
 
 			if (refDescriptor != null) {
 				attributeClassLegacy = refDescriptor.getItemClass();
 			}
 
 			// recurse if necessary
 			if (subAttributeString != null) {
 				attributeClassLegacy = getBusinessObjectAttributeClass(attributeClassLegacy, subAttributeString);
 			}
 
 			return attributeClassLegacy;
 		}
 	}
 
 }