/*
    * Copyright 2007 Kasper B. Graversen
    * 
    * 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.supercsv.io;
  
  import java.io.IOException;
  import java.io.Writer;
  import java.sql.ResultSet;
  import java.sql.ResultSetMetaData;
  import java.sql.SQLException;
  import java.util.LinkedList;
  import java.util.List;
  
  import org.supercsv.cellprocessor.ift.CellProcessor;
  import org.supercsv.prefs.CsvPreference;
  import org.supercsv.util.Util;
  
  /**
   * CsvResultSetWriter writes a CSV file by mapping each column of the {@code ResultSet} to a column in CSV file using
   * the column names stored in {@code ResultSetMetaData}
   * 
   * @author SingularityFX
   * @since 2.4.0
   */
  public class CsvResultSetWriter extends AbstractCsvWriter implements ICsvResultSetWriter {
  	
  	/**
  	 * Constructs a new {@code CsvResultSetWriter} with the supplied {@code Writer} and CSV preferences. Note that the
  	 * {@code writer} will be wrapped in a {@code BufferedWriter} before accessed.
  	 * 
  	 * @param writer
  	 *            the writer
  	 * @param preference
  	 *            the CSV preferences
  	 * @throws NullPointerException
  	 *             if writer or preference are null
  	 */
  	public CsvResultSetWriter(final Writer writer, final CsvPreference preference) {
  		super(writer, preference);
  	}
  	
  	/**
  	 * {@inheritDoc}
  	 */
  	public void write(final ResultSet resultSet) throws SQLException, IOException {
  		if( resultSet == null ) {
  			throw new NullPointerException("ResultSet cannot be null");
  		}
  		
  		writeHeaders(resultSet); // increments row and line number
  		writeContents(resultSet); // increments row and line number before writing of each row
  	}
  	
  	/**
  	 * {@inheritDoc}
  	 */
  	public void write(ResultSet resultSet, CellProcessor[] writeProcessors) throws SQLException, IOException {
  		if( resultSet == null ) {
  			throw new NullPointerException("ResultSet cannot be null");
  		}
  		if( writeProcessors == null ) {
  			throw new NullPointerException("CellProcessor[] cannot be null");
  		}
  		
  		writeHeaders(resultSet); // increments row and line number
  		writeContents(resultSet, writeProcessors); // increments row and line number before writing of each row
  	}
  	
  	private void writeHeaders(ResultSet resultSet) throws SQLException, IOException {
  		super.incrementRowAndLineNo(); // This will allow the correct row/line numbers to be used in any exceptions
  										// thrown before writing occurs
  		
  		final ResultSetMetaData meta = resultSet.getMetaData();
  		final int numberOfColumns = meta.getColumnCount();
  		final List<Object> headers = new LinkedList<Object>();
  		for( int columnIndex = 1; columnIndex <= numberOfColumns; columnIndex++ ) {
  			headers.add(meta.getColumnName(columnIndex));
  		}
  		super.writeRow(headers);
  	}
  	
  	private void writeContents(ResultSet resultSet) throws SQLException, IOException {
  		final int numberOfColumns = resultSet.getMetaData().getColumnCount();
  		final List<Object> objects = new LinkedList<Object>();
  		while( resultSet.next() ) {
  			super.incrementRowAndLineNo(); // This will allow the correct row/line numbers to be used in any exceptions
 											// thrown before writing occurs
 			objects.clear();
 			for( int columnIndex = 1; columnIndex <= numberOfColumns; columnIndex++ ) {
 				objects.add(resultSet.getObject(columnIndex));
 			}
 			super.writeRow(objects);
 		}
 	}
 	
 	private void writeContents(ResultSet resultSet, CellProcessor[] writeProcessors) throws SQLException, IOException {
 		final int numberOfColumns = resultSet.getMetaData().getColumnCount();
 		final List<Object> objects = new LinkedList<Object>();
 		final List<Object> processedColumns = new LinkedList<Object>();
 		while( resultSet.next() ) {
 			super.incrementRowAndLineNo(); // This will allow the correct row/line numbers to be used in any exceptions
 											// thrown before writing occurs
 			objects.clear();
 			for( int columnIndex = 1; columnIndex <= numberOfColumns; columnIndex++ ) {
 				objects.add(resultSet.getObject(columnIndex));
 			}
 			Util.executeCellProcessors(processedColumns, objects, writeProcessors, getLineNumber(), getRowNumber());
 			super.writeRow(processedColumns);
 		}
 	}
 }