/**
    *    Copyright 2010-2015 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.mybatis.spring.batch;
  
  import static org.springframework.util.Assert.isTrue;
  import static org.springframework.util.Assert.notNull;
  
  import java.util.List;
  
  import org.apache.ibatis.executor.BatchResult;
  import org.apache.ibatis.logging.Log;
  import org.apache.ibatis.logging.LogFactory;
  import org.apache.ibatis.session.ExecutorType;
  import org.apache.ibatis.session.SqlSessionFactory;
  import org.mybatis.spring.SqlSessionTemplate;
  import org.springframework.batch.item.ItemWriter;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.dao.EmptyResultDataAccessException;
  import org.springframework.dao.InvalidDataAccessResourceUsageException;
  
  /**
   * {@code ItemWriter} that uses the batching features from
   * {@code SqlSessionTemplate} to execute a batch of statements for all items
   * provided.<br/>
   *
   * Provided to facilitate the migration from Spring-Batch iBATIS 2 writers to MyBatis 3<br/>
   *
   * The user must provide a MyBatis statement id that points to the SQL statement defined
   * in the MyBatis.<br/>
   *
   * It is expected that {@link #write(List)} is called inside a transaction. If it is not
   * each statement call will be autocommitted and flushStatements will return no results.<br/>
   *
   * The writer is thread safe after its properties are set (normal singleton
   * behavior), so it can be used to write in multiple concurrent transactions.
   *
   * @author Eduardo Macarron
   * 
   * @since 1.1.0
   * @version $Id$
   */
  public class MyBatisBatchItemWriter<T> implements ItemWriter<T>, InitializingBean {
  
    private static final Log LOGGER = LogFactory.getLog(MyBatisBatchItemWriter.class);
  
    private SqlSessionTemplate sqlSessionTemplate;
  
    private String statementId;
  
    private boolean assertUpdates = true;
  
    /**
     * Public setter for the flag that determines whether an assertion is made
     * that all items cause at least one row to be updated.
     *
     * @param assertUpdates the flag to set. Defaults to true;
     */
    public void setAssertUpdates(boolean assertUpdates) {
      this.assertUpdates = assertUpdates;
    }
  
    /**
     * Public setter for {@link SqlSessionFactory} for injection purposes.
     *
     * @param SqlSessionFactory sqlSessionFactory
     */
    public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
      if (sqlSessionTemplate == null) {
        this.sqlSessionTemplate = new SqlSessionTemplate(sqlSessionFactory, ExecutorType.BATCH);
      }
    }
  
    /**
     * Public setter for the {@link SqlSessionTemplate}.
     *
     * @param SqlSessionTemplate the SqlSessionTemplate
     */
    public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
      this.sqlSessionTemplate = sqlSessionTemplate;
    }
  
    /**
     * Public setter for the statement id identifying the statement in the SqlMap
     * configuration file.
     *
     * @param statementId the id for the statement
    */
   public void setStatementId(String statementId) {
     this.statementId = statementId;
   }
 
   /**
    * Check mandatory properties - there must be an SqlSession and a statementId.
    */
   @Override
   public void afterPropertiesSet() {
     notNull(sqlSessionTemplate, "A SqlSessionFactory or a SqlSessionTemplate is required.");
     isTrue(ExecutorType.BATCH == sqlSessionTemplate.getExecutorType(), "SqlSessionTemplate's executor type must be BATCH");
     notNull(statementId, "A statementId is required.");
   }
 
   /**
    * {@inheritDoc}
    */
   @Override
   public void write(final List<? extends T> items) {
 
     if (!items.isEmpty()) {
 
       if (LOGGER.isDebugEnabled()) {
         LOGGER.debug("Executing batch with " + items.size() + " items.");
       }
 
       for (T item : items) {
         sqlSessionTemplate.update(statementId, item);
       }
 
       List<BatchResult> results = sqlSessionTemplate.flushStatements();
 
       if (assertUpdates) {
         if (results.size() != 1) {
           throw new InvalidDataAccessResourceUsageException("Batch execution returned invalid results. " +
               "Expected 1 but number of BatchResult objects returned was " + results.size());
         }
 
         int[] updateCounts = results.get(0).getUpdateCounts();
 
         for (int i = 0; i < updateCounts.length; i++) {
           int value = updateCounts[i];
           if (value == 0) {
             throw new EmptyResultDataAccessException("Item " + i + " of " + updateCounts.length
                 + " did not update any rows: [" + items.get(i) + "]", 1);
           }
         }
       }
     }
   }
 
 }