/*
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.ajax4jsf.util.base64;



import java.io.ByteArrayOutputStream;

import java.util.BitSet;



/**

 * <p>Implements the 'www-form-urlencoded' encoding scheme, 

 * also misleadingly known as URL encoding.</p>

 *  

 * <p>For more detailed information please refer to 

 * <a href="http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.1">

 * Chapter 17.13.4 'Form content types'</a> of the 

 * <a href="http://www.w3.org/TR/html4/">HTML 4.01 Specification<a></p>

 * 

 * <p> 

 * This codec is meant to be a replacement for standard Java classes

 * {@link java.net.URLEncoder} and {@link java.net.URLDecoder} 

 * on older Java platforms, as these classes in Java versions below 

 * 1.4 rely on the platform's default charset encoding.

 * </p>

 * 

 * @author Apache Software Foundation

 * @since 1.2

 * @version $Id: URLCodec.java,v 1.1.2.1 2007/01/09 18:59:14 alexsmirnov Exp $

 */

public class URLCodec implements BinaryEncoder, BinaryDecoder {

    

    protected static byte ESCAPE_CHAR = '%';

    /**

     * BitSet of www-form-url safe characters.

     */

    protected static final BitSet WWW_FORM_URL = new BitSet(256);

    

    // Static initializer for www_form_url

    static {

        // alpha characters

        for (int i = 'a'; i <= 'z'; i++) {

            WWW_FORM_URL.set(i);

        }

        for (int i = 'A'; i <= 'Z'; i++) {

            WWW_FORM_URL.set(i);

        }

        // numeric characters

        for (int i = '0'; i <= '9'; i++) {

            WWW_FORM_URL.set(i);

        }

        // special chars

        WWW_FORM_URL.set('-');

        WWW_FORM_URL.set('_');

        WWW_FORM_URL.set('.');

        WWW_FORM_URL.set('*');

        // blank to be replaced with +

        WWW_FORM_URL.set(' ');

    }





    /**

     * Default constructor.

     */

    public URLCodec() {

        super();

    }



    public static final byte[] encodeUrl( byte[] bytes) 

    {

    	return encodeUrl(WWW_FORM_URL, bytes);

    }

    /**

     * Encodes an array of bytes into an array of URL safe 7-bit 

     * characters. Unsafe characters are escaped.

     *

     * @param urlsafe bitset of characters deemed URL safe

     * @param bytes array of bytes to convert to URL safe characters

     * @return array of bytes containing URL safe characters

     */

    public static final byte[] encodeUrl(BitSet urlsafe, byte[] bytes) 

    {

        if (bytes == null) {

            return null;

        }

        if (urlsafe == null) {

            urlsafe = WWW_FORM_URL;

        }

        

        ByteArrayOutputStream buffer = new ByteArrayOutputStream(); 

        for (int i = 0; i < bytes.length; i++) {

            int b = bytes[i];

            if (b < 0) {

                b = 256 + b;

            }

            if (urlsafe.get(b)) {

                if (b == ' ') {

                    b = '+';

                }

                buffer.write(b);

            } else {

                buffer.write('%');

                char hex1 = Character.toUpperCase(

                  Character.forDigit((b >> 4) & 0xF, 16));

                char hex2 = Character.toUpperCase(

                  Character.forDigit(b & 0xF, 16));

                buffer.write(hex1);

                buffer.write(hex2);

            }

        }

        return buffer.toByteArray(); 

    }





    /**

     * Decodes an array of URL safe 7-bit characters into an array of 

     * original bytes. Escaped characters are converted back to their 

     * original representation.

     *

     * @param bytes array of URL safe characters

     * @return array of original bytes 

     * @throws DecoderException Thrown if URL decoding is unsuccessful

     */

    public static final byte[] decodeUrl(byte[] bytes) 

         throws DecoderException

    {

        if (bytes == null) {

            return null;

        }

        ByteArrayOutputStream buffer = new ByteArrayOutputStream(); 

        for (int i = 0; i < bytes.length; i++) {

            int b = bytes[i];

            if (b == '+') {

                buffer.write(' ');

            } else if (b == '%') {

                try {

                    int u = Character.digit((char)bytes[++i], 16);

                    int l = Character.digit((char)bytes[++i], 16);

                    if (u == -1 || l == -1) {

                        throw new DecoderException("Invalid URL encoding");

                    }

                    buffer.write((char)((u << 4) + l));

                } catch(ArrayIndexOutOfBoundsException e) {

                    throw new DecoderException("Invalid URL encoding");

                }

            } else {

                buffer.write(b);

            }

        }

        return buffer.toByteArray(); 

    }





    /**

     * Encodes an array of bytes into an array of URL safe 7-bit 

     * characters. Unsafe characters are escaped.

     *

     * @param bytes array of bytes to convert to URL safe characters

     * @return array of bytes containing URL safe characters

     */

    public byte[] encode(byte[] bytes) {

        return encodeUrl(WWW_FORM_URL, bytes);

    }





    /**

     * Decodes an array of URL safe 7-bit characters into an array of 

     * original bytes. Escaped characters are converted back to their 

     * original representation.

     *

     * @param bytes array of URL safe characters

     * @return array of original bytes 

     * @throws DecoderException Thrown if URL decoding is unsuccessful

     */

    public byte[] decode(byte[] bytes) throws DecoderException {

        return decodeUrl(bytes);

    }





    /**

     * Encodes an object into its URL safe form. Unsafe characters are 

     * escaped.

     *

     * @param pObject string to convert to a URL safe form

     * @return URL safe object

     * @throws EncoderException Thrown if URL encoding is not 

     *                          applicable to objects of this type or

     *                          if encoding is unsuccessful

     */

    public Object encode(Object pObject) throws EncoderException {

        if (pObject == null) {

            return null;

        } else if (pObject instanceof byte[]) {

            return encode((byte[])pObject);

        } else if (pObject instanceof String) {

            return encode((String)pObject);

        } else {

            throw new EncoderException("Objects of type " +

                pObject.getClass().getName() + " cannot be URL encoded"); 

              

        }

    }



    /**

     * Decodes a URL safe object into its original form. Escaped 

     * characters are converted back to their original representation.

     *

     * @param pObject URL safe object to convert into its original form

     * @return original object 

     * @throws DecoderException Thrown if URL decoding is not 

     *                          applicable to objects of this type

     *                          if decoding is unsuccessful

     */

    public Object decode(Object pObject) throws DecoderException {

        if (pObject == null) {

            return null;

        } else if (pObject instanceof byte[]) {

            return decode((byte[])pObject);

        } else if (pObject instanceof String) {

            return decode((String)pObject);

        } else {

            throw new DecoderException("Objects of type " +

                pObject.getClass().getName() + " cannot be URL decoded"); 

              

        }

    }



}

