/*
 *  Copyright 2004 Clinton Begin
 *
 *  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 com.ibatis.dao.client.template;

import com.ibatis.dao.client.DaoManager;
import com.ibatis.dao.engine.transaction.ojb.OjbBrokerDaoTransaction;
import org.apache.ojb.broker.Identity;
import org.apache.ojb.broker.PersistenceBroker;
import org.apache.ojb.broker.query.Query;
import org.apache.ojb.broker.query.QueryByCriteria;

import java.util.ArrayList;
import java.util.Collection;

/**
 * A DaoTemplate for OJB broker implementations that provides a
 * convenient method to access the broker.
 * <p/>
 * This is the base class for OJB DAOs and provides the CRUD
 * pattern necessary methods plus an additional
 * method to retrieve all instances of a given class.
 */
public abstract class OjbBrokerDaoTemplate
    extends DaoTemplate {

  /**
   * The DaoManager that manages this Dao instance will be passed  in as the parameter to this constructor automatically upon  instantiation.
   *
   * @param daoManager
   */
  public OjbBrokerDaoTemplate(final DaoManager daoManager) {
    super(daoManager);
  }

  /**
   * Puts an instance/value object on the persistentence layer.
   *
   * @param vo the value object.
   */
  public final void create(final Object vo) {

    if (vo == null) {
      throw new IllegalArgumentException("The value object to be created is null.");
    }

    PersistenceBroker broker = getPersistenceBroker();

    broker.store(vo);
  }

  /**
   * Retrieves an instance/value object, according to its primary key,
   *
   * @param vo the value object criteria.
   * @return the value object.
   */
  public final Object retrieveByPk(final Object vo) {

    PersistenceBroker broker = getPersistenceBroker();

    Identity identity = new Identity(vo, broker);

    return broker.getObjectByIdentity(identity);
  }

  /**
   * Updates the instance/value object representation on the persistence layer.
   *
   * @param vo the value object.
   */
  public final void update(final Object vo) {

    if (vo == null) {
      throw new IllegalArgumentException("The value object to be updated is null.");
    }

    PersistenceBroker broker = getPersistenceBroker();

    broker.store(vo);
  }

  /**
   * Removes an instance/value object from the persistence layer.
   *
   * @param vo the value object.
   */
  public final void delete(final Object vo) {

    PersistenceBroker broker = getPersistenceBroker();

    broker.delete(vo);
  }

  /**
   * Retrieves all instances of a given class, from the persistence layer.
   *
   * @param clazz the class of the instances to be fetched.
   * @return all instances of the given class.
   */
  public final Collection retrieveExtent(final Class clazz) {

    PersistenceBroker broker = getPersistenceBroker();

    Query query = new QueryByCriteria(clazz, null);
    Collection collection = new ArrayList();

    collection = broker.getCollectionByQuery(query);

    return collection;
  }

  /**
   * Gets the OJB persistence broker associated with the current
   * DaoTransaction that this Dao is working under.
   *
   * @return A Hibernate Session instance.
   */
  protected final PersistenceBroker getPersistenceBroker() {
    OjbBrokerDaoTransaction trans = (OjbBrokerDaoTransaction) daoManager.getTransaction(this);
    return trans.getBroker();
  }

}