/*
    * Copyright 2006-2009 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.springframework.batch.item.database;
  
  import java.sql.Connection;
  import java.sql.PreparedStatement;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  
  
  import org.springframework.jdbc.core.PreparedStatementSetter;
  import org.springframework.jdbc.core.RowMapper;
  import org.springframework.jdbc.support.JdbcUtils;
  import org.springframework.util.Assert;
  import org.springframework.util.ClassUtils;
  
  /**
   * <p>
   * Simple item reader implementation that opens a JDBC cursor and continually retrieves the
   * next row in the ResultSet. 
   * </p>
   * 
   * <p>
   * The statement used to open the cursor is created with the 'READ_ONLY' option since a non read-only 
   * cursor may unnecessarily lock tables or rows. It is also opened with 'TYPE_FORWARD_ONLY' option. 
   * By default the cursor will be opened using a separate connection which means that it will not participate 
   * in any transactions created as part of the step processing.
   * </p>
   *  
   * <p>
   * Each call to {@link #read()} will call the provided RowMapper, passing in the
   * ResultSet. 
   * </p>
   * 
   * @author Lucas Ward
   * @author Peter Zozom
   * @author Robert Kasanicky
   * @author Thomas Risberg
   */
  public class JdbcCursorItemReader<T> extends AbstractCursorItemReader<T> {
  
  	PreparedStatement preparedStatement;
  
  	PreparedStatementSetter preparedStatementSetter;
  
  	String sql;
  
  	RowMapper rowMapper;
  
  	public JdbcCursorItemReader() {
  		super();
  		setName(ClassUtils.getShortName(JdbcCursorItemReader.class));
  	}
  
  	/**
  	 * Set the RowMapper to be used for all calls to read().
  	 * 
  	 * @param rowMapper
  	 */
  	public void setRowMapper(RowMapper rowMapper) {
  		this.rowMapper = rowMapper;
  	}
  
  	/**
  	 * Set the SQL statement to be used when creating the cursor. This statement
  	 * should be a complete and valid SQL statement, as it will be run directly
  	 * without any modification.
  	 * 
  	 * @param sql
  	 */
  	public void setSql(String sql) {
  		this.sql = sql;
  	}
  
  	/**
  	 * Set the PreparedStatementSetter to use if any parameter values that need
  	 * to be set in the supplied query.
  	 * 
  	 * @param preparedStatementSetter
  	 */
  	public void setPreparedStatementSetter(PreparedStatementSetter preparedStatementSetter) {
  		this.preparedStatementSetter = preparedStatementSetter;
  	}
  
  	/**
 	 * Assert that mandatory properties are set.
 	 * 
 	 * @throws IllegalArgumentException if either data source or sql properties
 	 * not set.
 	 */
 	public void afterPropertiesSet() throws Exception {
 		super.afterPropertiesSet();
 		Assert.notNull(sql, "The SQL query must be provided");
 		Assert.notNull(rowMapper, "RowMapper must be provided");
 	}
 
 
 	protected void openCursor(Connection con) {	
 		try {
 			if (isUseSharedExtendedConnection()) {
 				preparedStatement = con.prepareStatement(sql, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY,
 						ResultSet.HOLD_CURSORS_OVER_COMMIT);
 			}
 			else {
 				preparedStatement = con.prepareStatement(sql, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
 			}
 			applyStatementSettings(preparedStatement);
 			if (this.preparedStatementSetter != null) {
 				preparedStatementSetter.setValues(preparedStatement);
 			}
 			this.rs = preparedStatement.executeQuery();
 			handleWarnings(preparedStatement);
 		}
 		catch (SQLException se) {
 			close();
 			throw getExceptionTranslator().translate("Executing query", getSql(), se);
 		}
 	
 	}
 
 
 	@SuppressWarnings("unchecked")
 	protected T readCursor(ResultSet rs, int currentRow) throws SQLException {
 		return (T) rowMapper.mapRow(rs, currentRow);
 	}
 	
 	/**
 	 * Close the cursor and database connection.
 	 */
 	protected void cleanupOnClose() throws Exception {
 		JdbcUtils.closeStatement(this.preparedStatement);
 	}
 
 	@Override
 	public String getSql() {
 		return this.sql;
 	}
 }