/*
    * Copyright 2010 James Pether Sörling
    *
    * 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.
   *
   *	$Id$
   *  $HeadURL$
  */
  package com.hack23.cia.service.data.impl;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import javax.persistence.criteria.CriteriaQuery;
  import javax.persistence.criteria.Path;
  import javax.persistence.criteria.Root;
  
  import org.springframework.stereotype.Repository;
  
  import com.hack23.cia.model.external.worldbank.data.impl.Country;
  import com.hack23.cia.model.external.worldbank.data.impl.Indicator;
  import com.hack23.cia.model.external.worldbank.data.impl.WorldBankData;
  import com.hack23.cia.model.external.worldbank.data.impl.WorldBankData_;
  import com.hack23.cia.service.data.api.DataDAO;
  
  /**
   * The Class DataDAOImpl.
   */
  @Repository("DataDAOImpl")
  final class DataDAOImpl extends AbstractGenericDAOImpl<WorldBankData, Long> implements DataDAO {
  
  	/** The Constant EXPECTED_NR_ELEMENTS. */
  	private static final int EXPECTED_NR_ELEMENTS = 2;
  
  	/**
  	 * Instantiates a new data dao impl.
  	 */
  	public DataDAOImpl() {
  		super(WorldBankData.class);
  	}
  
  	@Override
  	public List<String> getIdList() {
  		final CriteriaQuery<Object[]> criteria = getCriteriaBuilder().createQuery(Object[].class);
  		final Root<WorldBankData> personRoot = criteria.from(WorldBankData.class);
  		final Path<Country> countryPath = personRoot.get(WorldBankData_.country);
  		final Path<Indicator> indicatorPath = personRoot.get(WorldBankData_.indicator);
  		criteria.select(getCriteriaBuilder().array(countryPath, indicatorPath));
  		criteria.distinct(true);
  		final List<Object[]> valueArray = getEntityManager().createQuery(criteria).getResultList();
  		final List<String> resultList = new ArrayList<>();
  
  		for (final Object[] objects : valueArray) {
  			if (objects.length == EXPECTED_NR_ELEMENTS) {
  				final StringBuilder stringBuilder = new StringBuilder().append(((Country) objects[0]).getId())
  						.append('.').append(((Indicator) objects[1]).getId());
  				resultList.add(stringBuilder.toString());
  			}
  		}
  		return resultList;
  	}
  
  }