/* ======================================================================
The Bodington System Software License, Version 1.0
 
Copyright (c) 2001 The University of Leeds.  All rights reserved.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
 
1.  Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
 
2.  Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
 
3.  The end-user documentation included with the redistribution, if any,
must include the following acknowledgement:  "This product includes
software developed by the University of Leeds
(http://www.bodington.org/)."  Alternately, this acknowledgement may
appear in the software itself, if and wherever such third-party
acknowledgements normally appear.
 
4.  The names "Bodington", "Nathan Bodington", "Bodington System",
"Bodington Open Source Project", and "The University of Leeds" must not be
used to endorse or promote products derived from this software without
prior written permission. For written permission, please contact
d.gardner@leeds.ac.uk.
 
5.  The name "Bodington" may not appear in the name of products derived
from this software without prior written permission of the University of
Leeds.
 
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO,  TITLE,  THE IMPLIED WARRANTIES
OF QUALITY  AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
EVENT SHALL THE UNIVERSITY OF LEEDS OR ITS CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
=========================================================
 
This software was originally created by the University of Leeds and may contain voluntary
contributions from others.  For more information on the Bodington Open Source Project, please
see http://bodington.org/
 
====================================================================== */
package org.bodington.util;

import java.io.IOException;
import java.io.Writer;
import java.util.regex.Pattern;

/**
 * A CSV file writer. This escapes all the passed content so it can be written
 * safely to a CSV file.
 * Implementation created as we can't reuse an existing GPL CSV project.
 * Guidance from:
 * http://www.creativyst.com/Doc/Articles/CSV/CSV01.htm
 * @author buckett
 */
public class CSVWriter
{
    // Starts of ends with a blank, or contains a double quote, comma or newline
    private static final Pattern shouldQuote = Pattern.compile("(^\\p{Blank})|\"|,|\\n|\\r|(\\p{Blank}$)");
    private static final Pattern doubleQuote = Pattern.compile("\""); 
    private static final String separator = ",";
    
    private Writer out;
    private boolean firstColumn = true;
    private String lineEnding = "\n";

    
    /**
     * Create the writer wrapping up an existing writer.
     * @param out The output to send the CSV file to.
     */
    public CSVWriter (Writer out)
    {
        this.out = out;
    }

    /**
     * Write a single data value to the CSV file.
     * @param data The data to write to the CSV file
     */
    public void write(String data) throws IOException
    {
        if (firstColumn)
            firstColumn = false;
        else
            out.write(separator);
        out.write(formatData(data));
    }
    
    /**
     * Terminates the current CSV row.
     */
    public void writeln() throws IOException
    {
        out.write(lineEnding);
        firstColumn = true;
    }
    
    /**
     * Outputs a complete CSV row.
     * @param columns The data to write out to row. 
     */
    public void writeln(String[] columns) throws IOException
    {
        for (int column = 0; column < columns.length; column++)
            write(columns[column]);
        writeln();
    }
    
    
    private String formatData(String data)
    {
        if (shouldQuote.matcher(data).find())
        {
            data = "\""+ doubleQuote.matcher(data).replaceAll("\"\"")+ "\"";
        }
        return data;
    }

}