/*

 * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.jndi.toolkit.url;

import java.net.MalformedURLException;

import java.io.UnsupportedEncodingException;

import java.net.URLDecoder;

/**

 * Utilities for dealing with URLs.

 * @author Vincent Ryan

 */

final public class UrlUtil {

    // To prevent creation of this static class

    private UrlUtil() {

    }

    /**

     * Decode a URI string (according to RFC 2396).

     */

    public static final String decode(String s) throws MalformedURLException {

        try {

            return decode(s, "8859_1");

        } catch (UnsupportedEncodingException e) {

            // ISO-Latin-1 should always be available?

            throw new MalformedURLException("ISO-Latin-1 decoder unavailable");

        }

    }

    /**

     * Decode a URI string (according to RFC 2396).

     *

     * Three-character sequences '%xy', where 'xy' is the two-digit

     * hexadecimal representation of the lower 8-bits of a character,

     * are decoded into the character itself.

     *

     * The string is subsequently converted using the specified encoding

     */

    public static final String decode(String s, String enc)

            throws MalformedURLException, UnsupportedEncodingException {

        try {

            return URLDecoder.decode(s, enc);

        } catch (IllegalArgumentException iae) {

            MalformedURLException mue = new MalformedURLException("Invalid URI encoding: " + s);

            mue.initCause(iae);

            throw mue;

        }

    }

    /**

     * Encode a string for inclusion in a URI (according to RFC 2396).

     *

     * Unsafe characters are escaped by encoding them in three-character

     * sequences '%xy', where 'xy' is the two-digit hexadecimal representation

     * of the lower 8-bits of the character.

     *

     * The question mark '?' character is also escaped, as required by RFC 2255.

     *

     * The string is first converted to the specified encoding.

     * For LDAP (2255), the encoding must be UTF-8.

     */

    public static final String encode(String s, String enc)

        throws UnsupportedEncodingException {

        byte[] bytes = s.getBytes(enc);

        int count = bytes.length;

        /*

         * From RFC 2396:

         *

         *     mark = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"

         * reserved = ";" | "/" | ":" | "?" | "@" | "&" | "=" | "+" | "$" | ","

         */

        final String allowed = "=,+;.'-@&/$_()!~*:"; // '?' is omitted

        char[] buf = new char[3 * count];

        int j = 0;

        for (int i = 0; i < count; i++) {

            if ((bytes[i] >= 0x61 && bytes[i] <= 0x7A) || // a..z

                (bytes[i] >= 0x41 && bytes[i] <= 0x5A) || // A..Z

                (bytes[i] >= 0x30 && bytes[i] <= 0x39) || // 0..9

                (allowed.indexOf(bytes[i]) >= 0)) {

                buf[j++] = (char) bytes[i];

            } else {

                buf[j++] = '%';

                buf[j++] = Character.forDigit(0xF & (bytes[i] >>> 4), 16);

                buf[j++] = Character.forDigit(0xF & bytes[i], 16);

            }

        }

        return new String(buf, 0, j);

    }

}