/**
 * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
 * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
 * joint initiative of the Federal Chancellery Austria and Graz University of
 * Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */
package at.gv.egiz.pdfas.utils;

import org.apache.commons.lang.StringUtils;

/**
 * Methods in order to create valid delimiter separated data, where the semicolon as used as delimiter, also known as
 * the German version of CSV.
 *
 * @author Datentechnik Innovation GmbH
 * @see <a href="http://tools.ietf.org/html/rfc4180">RFC 4180</a>
 */
public class CsvUtils {

	/**
	 * The delimiter char used instead of COMMA.
	 */
	public static final char DEFAULT_DELIMITER = ';';

	private static final char QUOTE_CHAR = '"';
	private static final char LF_CHAR = '\n';
	private static final char CR_CHAR = '\r';

	private static final char[] SHOULD_BE_QUOTED = { LF_CHAR, CR_CHAR, DEFAULT_DELIMITER, QUOTE_CHAR };
	private static final String CSV_QUOTE = String.valueOf(QUOTE_CHAR);

	/**
	 * Returns an DSV escapted representation of the given object using the default delimiter character (
	 * {@link #DEFAULT_DELIMITER}).
	 *
	 * @param obj
	 *            The object.
	 * @return An escapted representation of the given object.
	 */
	public static String escapeCsvValue(Object obj) {
		// null value should be printed as empty column
		if (obj == null) {
			return "";
		}
		// get String representation of object
		String asString = String.valueOf(obj);
		// do we need to escape anything?
		if (StringUtils.containsNone(asString, SHOULD_BE_QUOTED)) {
			return asString;
		}

		// RFC 4180 (7): If double-quotes are used to enclose fields, then a double-quote
		// appearing inside a field must be escaped by preceding it with
		// another double quote.
		asString = StringUtils.replace(asString, CSV_QUOTE, CSV_QUOTE + CSV_QUOTE);

		// RFC 4180 (6): Fields containing line breaks (CRLF), double quotes, and commas
		// should be enclosed in double-quotes.
		if (StringUtils.containsAny(asString, SHOULD_BE_QUOTED)) {
			return QUOTE_CHAR + asString + QUOTE_CHAR;
		}
		return asString;
	}

}