/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2017 iText Group NV
 * Authors: Balder Van Camp, Emiel Ackermann, et al.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Affero General Public License for more details.
 * You should have received a copy of the GNU Affero General Public License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA, 02110-1301 USA, or download the license from the following URL:
 * http://itextpdf.com/terms-of-use/
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License,
 * a covered work must retain the producer line in every PDF that is created
 * or manipulated using iText.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the iText software without
 * disclosing the source code of your own applications.
 * These activities include: offering paid services to customers as an ASP,
 * serving PDFs on the fly in a web application, shipping iText with a closed
 * source product.
 *
 * For more information, please contact iText Software Corp. at this
 * address: sales@itextpdf.com
 */
package com.itextpdf.tool.xml.parser.io;

/**
 * Copied from itextpdf.
 *
 */
public class EncodingUtil {
	/**
	 * 
	 * @param decl a string from header or meta tag to detect encoding
	 * @return encoding String
	 */
	public static String getDeclaredEncoding(final String decl) {
		if (decl == null)
			return null;
		int idx = decl.indexOf("encoding");
		if (idx < 0)
			return null;
		int idx1 = decl.indexOf('"', idx);
		int idx2 = decl.indexOf('\'', idx);
		if (idx1 == idx2)
			return null;
		if (idx1 < 0 && idx2 > 0 || idx2 > 0 && idx2 < idx1) {
			int idx3 = decl.indexOf('\'', idx2 + 1);
			if (idx3 < 0)
				return null;
			return decl.substring(idx2 + 1, idx3);
		}
		if (idx2 < 0 && idx1 > 0 || idx1 > 0 && idx1 < idx2) {
			int idx3 = decl.indexOf('"', idx1 + 1);
			if (idx3 < 0)
				return null;
			return decl.substring(idx1 + 1, idx3);
		}
		return null;
	}

}