/*
    * 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.lang.reflect.Method;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.supercsv.cellprocessor.ift.CellProcessor;
  import org.supercsv.exception.SuperCsvReflectionException;
  import org.supercsv.prefs.CsvPreference;
  import org.supercsv.util.MethodCache;
  import org.supercsv.util.Util;
  
  /**
   * CsvBeanWriter writes a CSV file by mapping each field on the bean to a column in the CSV file (using the supplied
   * name mapping).
   * 
   * @author Kasper B. Graversen
   * @author James Bassett
   */
  public class CsvBeanWriter extends AbstractCsvWriter implements ICsvBeanWriter {
  	
  	// temporary storage of bean values
  	private final List<Object> beanValues = new ArrayList<Object>();
  	
  	// temporary storage of processed columns to be written
  	private final List<Object> processedColumns = new ArrayList<Object>();
  	
  	// cache of methods for mapping from fields to columns
  	private final MethodCache cache = new MethodCache();
  	
  	/**
  	 * Constructs a new <tt>CsvBeanWriter</tt> with the supplied Writer and CSV preferences. Note that the
  	 * <tt>writer</tt> will be wrapped in a <tt>BufferedWriter</tt> before accessed.
  	 * 
  	 * @param writer
  	 *            the writer
  	 * @param preference
  	 *            the CSV preferences
  	 * @throws NullPointerException
  	 *             if writer or preference are null
  	 */
  	public CsvBeanWriter(final Writer writer, final CsvPreference preference) {
  		super(writer, preference);
  	}
  	
  	/**
  	 * Extracts the bean values, using the supplied name mapping array.
  	 * 
  	 * @param source
  	 *            the bean
  	 * @param nameMapping
  	 *            the name mapping
  	 * @throws NullPointerException
  	 *             if source or nameMapping are null
  	 * @throws SuperCsvReflectionException
  	 *             if there was a reflection exception extracting the bean value
  	 */
  	private void extractBeanValues(final Object source, final String[] nameMapping) {
  		
  		if( source == null ) {
  			throw new NullPointerException("the bean to write should not be null");
  		} else if( nameMapping == null ) {
  			throw new NullPointerException(
  				"the nameMapping array can't be null as it's used to map from fields to columns");
  		}
  		
  		beanValues.clear();
  		
  		for( int i = 0; i < nameMapping.length; i++ ) {
  			
  			final String fieldName = nameMapping[i];
  			
  			if( fieldName == null ) {
  				beanValues.add(null); // assume they always want a blank column
  				
  			} else {
  				Method getMethod = cache.getGetMethod(source, fieldName);
  				try {
  					beanValues.add(getMethod.invoke(source));
  				}
  				catch(final Exception e) {
  					throw new SuperCsvReflectionException(String.format("error extracting bean value for field %s",
 						fieldName), e);
 				}
 			}
 			
 		}
 		
 	}
 	
 	/**
 	 * {@inheritDoc}
 	 */
 	public void write(final Object source, final String... nameMapping) throws IOException {
 		
 		// update the current row/line numbers
 		super.incrementRowAndLineNo();
 		
 		// extract the bean values
 		extractBeanValues(source, nameMapping);
 		
 		// write the list
 		super.writeRow(beanValues);
 	}
 	
 	/**
 	 * {@inheritDoc}
 	 */
 	public void write(final Object source, final String[] nameMapping, final CellProcessor[] processors)
 		throws IOException {
 		
 		// update the current row/line numbers
 		super.incrementRowAndLineNo();
 		
 		// extract the bean values
 		extractBeanValues(source, nameMapping);
 		
 		// execute the processors for each column
 		Util.executeCellProcessors(processedColumns, beanValues, processors, getLineNumber(), getRowNumber());
 		
 		// write the list
 		super.writeRow(processedColumns);
 	}
 }