/*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to You 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.apache.commons.codec.net;

 import java.io.ByteArrayOutputStream;

 import java.io.UnsupportedEncodingException;

 import java.util.BitSet;

 import org.apache.commons.codec.BinaryDecoder;

 import org.apache.commons.codec.BinaryEncoder;

 import org.apache.commons.codec.CharEncoding;

 import org.apache.commons.codec.DecoderException;

 import org.apache.commons.codec.EncoderException;

 import org.apache.commons.codec.StringDecoder;

 import org.apache.commons.codec.StringEncoder;

 import org.apache.commons.codec.binary.StringUtils;

 /**

  * Implements the 'www-form-urlencoded' encoding scheme, also misleadingly known as URL encoding.

  * <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>

  * This class is immutable and thread-safe.

  *

  * @see <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>

  *

  * @since 1.2

  * @version $Id: URLCodec.java 1462705 2013-03-30 05:22:40Z ggregory $

  */

 public class URLCodec implements BinaryEncoder, BinaryDecoder, StringEncoder, StringDecoder {

     /**

      * Radix used in encoding and decoding.

      */

     static final int RADIX = 16;

     /**

      * The default charset used for string decoding and encoding.

      *

      * @deprecated TODO: This field will be changed to a private final Charset in 2.0.

      */

     @Deprecated

     protected String charset;

     /**

      * Release 1.5 made this field final.

      */

     protected static final 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() {

         this(CharEncoding.UTF_8);

     }

     /**

      * Constructor which allows for the selection of a default charset.

      *

      * @param charset the default string charset to use.

      */

     public URLCodec(final String charset) {

         super();

         this.charset = charset;

     }

     /**

      * 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, final byte[] bytes) {

         if (bytes == null) {

             return null;

         }

         if (urlsafe == null) {

             urlsafe = WWW_FORM_URL;

         }

         final ByteArrayOutputStream buffer = new ByteArrayOutputStream();

         for (final byte c : bytes) {

             int b = c;

             if (b < 0) {

                 b = 256 + b;

             }

             if (urlsafe.get(b)) {

                 if (b == ' ') {

                     b = '+';

                 }

                 buffer.write(b);

             } else {

                 buffer.write(ESCAPE_CHAR);

                 final char hex1 = Character.toUpperCase(Character.forDigit((b >> 4) & 0xF, RADIX));

                 final char hex2 = Character.toUpperCase(Character.forDigit(b & 0xF, RADIX));

                 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(final byte[] bytes) throws DecoderException {

         if (bytes == null) {

             return null;

         }

         final ByteArrayOutputStream buffer = new ByteArrayOutputStream();

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

             final int b = bytes[i];

             if (b == '+') {

                 buffer.write(' ');

             } else if (b == ESCAPE_CHAR) {

                 try {

                     final int u = Utils.digit16(bytes[++i]);

                     final int l = Utils.digit16(bytes[++i]);

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

                 } catch (final ArrayIndexOutOfBoundsException e) {

                     throw new DecoderException("Invalid URL encoding: ", e);

                 }

             } 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

      */

     @Override

     public byte[] encode(final 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

      */

     @Override

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

         return decodeUrl(bytes);

     }

     /**

      * Encodes a string into its URL safe form using the specified string charset. Unsafe characters are escaped.

      *

      * @param str

      *            string to convert to a URL safe form

      * @param charset

      *            the charset for str

      * @return URL safe string

      * @throws UnsupportedEncodingException

      *             Thrown if charset is not supported

      */

     public String encode(final String str, final String charset) throws UnsupportedEncodingException {

         if (str == null) {

             return null;

         }

         return StringUtils.newStringUsAscii(encode(str.getBytes(charset)));

     }

     /**

      * Encodes a string into its URL safe form using the default string charset. Unsafe characters are escaped.

      *

      * @param str

      *            string to convert to a URL safe form

      * @return URL safe string

      * @throws EncoderException

      *             Thrown if URL encoding is unsuccessful

      *

      * @see #getDefaultCharset()

      */

     @Override

     public String encode(final String str) throws EncoderException {

         if (str == null) {

             return null;

         }

         try {

             return encode(str, getDefaultCharset());

         } catch (final UnsupportedEncodingException e) {

             throw new EncoderException(e.getMessage(), e);

         }

     }

     /**

      * Decodes a URL safe string into its original form using the specified encoding. Escaped characters are converted

      * back to their original representation.

      *

      * @param str

      *            URL safe string to convert into its original form

      * @param charset

      *            the original string charset

      * @return original string

      * @throws DecoderException

      *             Thrown if URL decoding is unsuccessful

      * @throws UnsupportedEncodingException

      *             Thrown if charset is not supported

      */

     public String decode(final String str, final String charset) throws DecoderException, UnsupportedEncodingException {

         if (str == null) {

             return null;

         }

         return new String(decode(StringUtils.getBytesUsAscii(str)), charset);

     }

     /**

      * Decodes a URL safe string into its original form using the default string charset. Escaped characters are

      * converted back to their original representation.

      *

      * @param str

      *            URL safe string to convert into its original form

      * @return original string

      * @throws DecoderException

      *             Thrown if URL decoding is unsuccessful

      * @see #getDefaultCharset()

      */

     @Override

     public String decode(final String str) throws DecoderException {

         if (str == null) {

             return null;

         }

         try {

             return decode(str, getDefaultCharset());

         } catch (final UnsupportedEncodingException e) {

             throw new DecoderException(e.getMessage(), e);

         }

     }

     /**

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

      *

      * @param obj

      *            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

      */

     @Override

     public Object encode(final Object obj) throws EncoderException {

         if (obj == null) {

             return null;

         } else if (obj instanceof byte[]) {

             return encode((byte[])obj);

         } else if (obj instanceof String) {

             return encode((String)obj);

         } else {

             throw new EncoderException("Objects of type " + obj.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 obj

      *            URL safe object to convert into its original form

      * @return original object

      * @throws DecoderException

      *             Thrown if the argument is not a <code>String</code> or <code>byte[]</code>. Thrown if a failure

      *             condition is encountered during the decode process.

      */

     @Override

     public Object decode(final Object obj) throws DecoderException {

         if (obj == null) {

             return null;

         } else if (obj instanceof byte[]) {

             return decode((byte[]) obj);

         } else if (obj instanceof String) {

             return decode((String) obj);

         } else {

             throw new DecoderException("Objects of type " + obj.getClass().getName() + " cannot be URL decoded");

         }

     }

     /**

      * The default charset used for string decoding and encoding.

      *

      * @return the default string charset.

      */

     public String getDefaultCharset() {

         return this.charset;

     }

     /**

      * The <code>String</code> encoding used for decoding and encoding.

      *

      * @return Returns the encoding.

      *

      * @deprecated Use {@link #getDefaultCharset()}, will be removed in 2.0.

      */

     @Deprecated

     public String getEncoding() {

         return this.charset;

     }

 }