/*

  * 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.nio.charset.Charset;

 import java.util.BitSet;

 import org.apache.commons.codec.BinaryDecoder;

 import org.apache.commons.codec.BinaryEncoder;

 import org.apache.commons.codec.Charsets;

 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;

 /**

  * Codec for the Quoted-Printable section of <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>.

  * <p>

  * The Quoted-Printable encoding is intended to represent data that largely consists of octets that correspond to

  * printable characters in the ASCII character set. It encodes the data in such a way that the resulting octets are

  * unlikely to be modified by mail transport. If the data being encoded are mostly ASCII text, the encoded form of the

  * data remains largely recognizable by humans. A body which is entirely ASCII may also be encoded in Quoted-Printable

  * to ensure the integrity of the data should the message pass through a character- translating, and/or line-wrapping

  * gateway.

  * <p>

  * Note:

  * <p>

  * Rules #3, #4, and #5 of the quoted-printable spec are not implemented yet because the complete quoted-printable spec

  * does not lend itself well into the byte[] oriented codec framework. Complete the codec once the streamable codec

  * framework is ready. The motivation behind providing the codec in a partial form is that it can already come in handy

  * for those applications that do not require quoted-printable line formatting (rules #3, #4, #5), for instance Q codec.

  * <p>

  * This class is immutable and thread-safe.

  *

  * @see <a href="http://www.ietf.org/rfc/rfc1521.txt"> RFC 1521 MIME (Multipurpose Internet Mail Extensions) Part One:

  *          Mechanisms for Specifying and Describing the Format of Internet Message Bodies </a>

  *

  * @since 1.3

  * @version $Id$

  */

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

     /**

      * The default charset used for string decoding and encoding.

      */

     private final Charset charset;

     /**

      * BitSet of printable characters as defined in RFC 1521.

      */

     private static final BitSet PRINTABLE_CHARS = new BitSet(256);

     private static final byte ESCAPE_CHAR = '=';

     private static final byte TAB = 9;

     private static final byte SPACE = 32;

     // Static initializer for printable chars collection

     static {

         // alpha characters

         for (int i = 33; i <= 60; i++) {

             PRINTABLE_CHARS.set(i);

         }

         for (int i = 62; i <= 126; i++) {

             PRINTABLE_CHARS.set(i);

         }

         PRINTABLE_CHARS.set(TAB);

         PRINTABLE_CHARS.set(SPACE);

     }

     /**

      * Default constructor.

      */

     public QuotedPrintableCodec() {

         this(Charsets.UTF_8);

     }

     /**

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

      *

      * @param charset

      *            the default string charset to use.

      * @throws UnsupportedCharsetException

      *             If the named charset is unavailable

      * @since 1.7

      */

     public QuotedPrintableCodec(Charset charset) {

         this.charset = charset;

     }

     /**

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

      *

      * @param charsetName

      *            the default string charset to use.

      * @throws java.nio.charset.UnsupportedCharsetException

      *             If the named charset is unavailable

      * @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable

      */

     public QuotedPrintableCodec(String charsetName) {

         this(Charset.forName(charsetName));

     }

     /**

      * Encodes byte into its quoted-printable representation.

      *

      * @param b

      *            byte to encode

      * @param buffer

      *            the buffer to write to

      */

     private static final void encodeQuotedPrintable(int b, ByteArrayOutputStream buffer) {

         buffer.write(ESCAPE_CHAR);

         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);

     }

     /**

      * Encodes an array of bytes into an array of quoted-printable 7-bit characters. Unsafe characters are escaped.

      * <p>

      * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in

      * RFC 1521 and is suitable for encoding binary data and unformatted text.

      *

      * @param printable

      *            bitset of characters deemed quoted-printable

      * @param bytes

      *            array of bytes to be encoded

      * @return array of bytes containing quoted-printable data

      */

     public static final byte[] encodeQuotedPrintable(BitSet printable, byte[] bytes) {

         if (bytes == null) {

             return null;

         }

         if (printable == null) {

             printable = PRINTABLE_CHARS;

         }

         ByteArrayOutputStream buffer = new ByteArrayOutputStream();

         for (byte c : bytes) {

             int b = c;

             if (b < 0) {

                 b = 256 + b;

             }

             if (printable.get(b)) {

                 buffer.write(b);

             } else {

                 encodeQuotedPrintable(b, buffer);

             }

         }

         return buffer.toByteArray();

     }

     /**

      * Decodes an array quoted-printable characters into an array of original bytes. Escaped characters are converted

      * back to their original representation.

      * <p>

      * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in

      * RFC 1521.

      *

      * @param bytes

      *            array of quoted-printable characters

      * @return array of original bytes

      * @throws DecoderException

      *             Thrown if quoted-printable decoding is unsuccessful

      */

     public static final byte[] decodeQuotedPrintable(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 == ESCAPE_CHAR) {

                 try {

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

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

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

                 } catch (ArrayIndexOutOfBoundsException e) {

                     throw new DecoderException("Invalid quoted-printable encoding", e);

                 }

             } else {

                 buffer.write(b);

             }

         }

         return buffer.toByteArray();

     }

     /**

      * Encodes an array of bytes into an array of quoted-printable 7-bit characters. Unsafe characters are escaped.

      * <p>

      * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in

      * RFC 1521 and is suitable for encoding binary data and unformatted text.

      *

      * @param bytes

      *            array of bytes to be encoded

      * @return array of bytes containing quoted-printable data

      */

     @Override

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

         return encodeQuotedPrintable(PRINTABLE_CHARS, bytes);

     }

     /**

      * Decodes an array of quoted-printable characters into an array of original bytes. Escaped characters are converted

      * back to their original representation.

      * <p>

      * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in

      * RFC 1521.

      *

      * @param bytes

      *            array of quoted-printable characters

      * @return array of original bytes

      * @throws DecoderException

      *             Thrown if quoted-printable decoding is unsuccessful

      */

     @Override

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

         return decodeQuotedPrintable(bytes);

     }

     /**

      * Encodes a string into its quoted-printable form using the default string charset. Unsafe characters are escaped.

      * <p>

      * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in

      * RFC 1521 and is suitable for encoding binary data.

      *

      * @param str

      *            string to convert to quoted-printable form

      * @return quoted-printable string

      * @throws EncoderException

      *             Thrown if quoted-printable encoding is unsuccessful

      *

      * @see #getCharset()

      */

     @Override

     public String encode(String str) throws EncoderException {

         return this.encode(str, getCharset());

     }

     /**

      * Decodes a quoted-printable string into its original form using the specified string charset. Escaped characters

      * are converted back to their original representation.

      *

      * @param str

      *            quoted-printable string to convert into its original form

      * @param charset

      *            the original string charset

      * @return original string

      * @throws DecoderException

      *             Thrown if quoted-printable decoding is unsuccessful

      * @since 1.7

      */

     public String decode(String str, Charset charset) throws DecoderException {

         if (str == null) {

             return null;

         }

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

     }

     /**

      * Decodes a quoted-printable string into its original form using the specified string charset. Escaped characters

      * are converted back to their original representation.

      *

      * @param str

      *            quoted-printable string to convert into its original form

      * @param charset

      *            the original string charset

      * @return original string

      * @throws DecoderException

      *             Thrown if quoted-printable decoding is unsuccessful

      * @throws UnsupportedEncodingException

      *             Thrown if charset is not supported

      */

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

         if (str == null) {

             return null;

         }

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

     }

     /**

      * Decodes a quoted-printable string into its original form using the default string charset. Escaped characters are

      * converted back to their original representation.

      *

      * @param str

      *            quoted-printable string to convert into its original form

      * @return original string

      * @throws DecoderException

      *             Thrown if quoted-printable decoding is unsuccessful. Thrown if charset is not supported.

      * @see #getCharset()

      */

     @Override

     public String decode(String str) throws DecoderException {

         return this.decode(str, this.getCharset());

     }

     /**

      * Encodes an object into its quoted-printable safe form. Unsafe characters are escaped.

      *

      * @param obj

      *            string to convert to a quoted-printable form

      * @return quoted-printable object

      * @throws EncoderException

      *             Thrown if quoted-printable encoding is not applicable to objects of this type or if encoding is

      *             unsuccessful

      */

     @Override

     public Object encode(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 quoted-printable encoded");

         }

     }

     /**

      * Decodes a quoted-printable object into its original form. Escaped characters are converted back to their original

      * representation.

      *

      * @param obj

      *            quoted-printable 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(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 quoted-printable decoded");

         }

     }

     /**

      * Gets the default charset name used for string decoding and encoding.

      *

      * @return the default charset name

      * @since 1.7

      */

     public Charset getCharset() {

         return this.charset;

     }

     /**

      * Gets the default charset name used for string decoding and encoding.

      *

      * @return the default charset name

      */

     public String getDefaultCharset() {

         return this.charset.name();

     }

     /**

      * Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.

      * <p>

      * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in

      * RFC 1521 and is suitable for encoding binary data and unformatted text.

      *

      * @param str

      *            string to convert to quoted-printable form

      * @param charset

      *            the charset for str

      * @return quoted-printable string

      * @since 1.7

      */

     public String encode(String str, Charset charset) {

         if (str == null) {

             return null;

         }

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

     }

     /**

      * Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.

      * <p>

      * This function implements a subset of quoted-printable encoding specification (rule #1 and rule #2) as defined in

      * RFC 1521 and is suitable for encoding binary data and unformatted text.

      *

      * @param str

      *            string to convert to quoted-printable form

      * @param charset

      *            the charset for str

      * @return quoted-printable string

      * @throws UnsupportedEncodingException

      *             Thrown if the charset is not supported

      */

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

         if (str == null) {

             return null;

         }

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

     }

 }