/**
 * UPnP PortMapper - A tool for managing port forwardings via UPnP
 * Copyright (C) 2015 Christoph Pirkl <christoph at users.sourceforge.net>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/**
 *
 */
package org.chris.portmapper.util;

import java.util.HashMap;
import java.util.Map;

public class EncodingUtilities {

    private static Map<Character, String> knownEncodings;

    static {
        knownEncodings = new HashMap<>();
        knownEncodings.put('<', "&lt;");
        knownEncodings.put('>', "&gt;");
        knownEncodings.put('&', "&amp;");
    }

    /**
     * Replace all special characters with their html entities.
     * 
     * @param s
     *            the string in which to replace the special characters.
     * @return the result of the replacement.
     */
    public static String htmlEntityEncode(final String s) {
        final StringBuffer buf = new StringBuffer();

        for (int i = 0; i < s.length(); i++) {
            final char c = s.charAt(i);
            if (c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9') {
                buf.append(c);
            } else {
                if (knownEncodings.containsKey(c)) {
                    buf.append(knownEncodings.get(c));
                } else {
                    buf.append("&#" + (int) c + ";");
                }
            }
        }
        return buf.toString();
    }
}
