content: /*
   * 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.DecoderException;
  import org.apache.commons.codec.EncoderException;
  import org.apache.commons.codec.CharEncoding;
  import org.apache.commons.codec.StringDecoder;
  import org.apache.commons.codec.StringEncoder;
  import org.apache.commons.codec.binary.StringUtils;
  
  /**
   * <p>
   * Codec for the Quoted-Printable section of <a href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a>.
   * </p>
   * <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>
   * 
   * <p>
   * Note:
   * </p>
   * <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 steamable 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>
   * 
   * @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>
   * 
   * @author Apache Software Foundation
   * @since 1.3
   * @version $Id: QuotedPrintableCodec.java 1080712 2011-03-11 18:26:59Z ggregory $
   */
  public class QuotedPrintableCodec implements BinaryEncoder, BinaryDecoder, StringEncoder, StringDecoder {
      /**
       * The default charset used for string decoding and encoding.
       */
      private final String 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(CharEncoding.UTF_8);
      }
  
      /**
       * Constructor which allows for the selection of a default charset
       * 
       * @param charset
       *                  the default string charset to use.
       */
      public QuotedPrintableCodec(String charset) {
          super();
          this.charset = charset;
      }
  
      /**
       * 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.
       * </p>
       * 
       * @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 (int i = 0; i < bytes.length; i++) {
              int b = bytes[i];
              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.
       * </p>
       * 
       * @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.
       * </p>
       * 
       * @param bytes
       *                  array of bytes to be encoded
       * @return array of bytes containing quoted-printable data
       */
      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.
       * </p>
       * 
       * @param bytes
       *                  array of quoted-printable characters
       * @return array of original bytes
       * @throws DecoderException
       *                  Thrown if quoted-printable decoding is unsuccessful
       */
      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.
       * </p>
       * 
       * @param pString
       *                  string to convert to quoted-printable form
       * @return quoted-printable string
       * 
       * @throws EncoderException
       *                  Thrown if quoted-printable encoding is unsuccessful
       * 
       * @see #getDefaultCharset()
       */
      public String encode(String pString) throws EncoderException {
          if (pString == null) {
              return null;
          }
          try {
              return encode(pString, getDefaultCharset());
          } catch (UnsupportedEncodingException e) {
              throw new EncoderException(e.getMessage(), e);
          }
      }
  
      /**
       * Decodes a quoted-printable string into its original form using the specified string charset. Escaped characters
       * are converted back to their original representation.
       * 
       * @param pString
       *                  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 pString, String charset) throws DecoderException, UnsupportedEncodingException {
          if (pString == null) {
              return null;
          }
          return new String(decode(StringUtils.getBytesUsAscii(pString)), 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 pString
       *                  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 #getDefaultCharset()
       */
      public String decode(String pString) throws DecoderException {
          if (pString == null) {
              return null;
          }
          try {
              return decode(pString, getDefaultCharset());
          } catch (UnsupportedEncodingException e) {
              throw new DecoderException(e.getMessage(), e);
          }
      }
  
      /**
       * Encodes an object into its quoted-printable safe form. Unsafe characters are escaped.
       * 
       * @param pObject
       *                  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
       */
      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 quoted-printable encoded");
          }
      }
  
      /**
       * Decodes a quoted-printable object into its original form. Escaped characters are converted back to their original
       * representation.
       * 
       * @param pObject
       *                  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.
       */
      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 quoted-printable decoded");
          }
      }
  
      /**
       * Returns the default charset used for string decoding and encoding.
       * 
       * @return the default string charset.
       */
      public String getDefaultCharset() {
          return this.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.
       * </p>
       * 
       * @param pString
       *                  string to convert to quoted-printable form
       * @param charset
       *                  the charset for pString
       * @return quoted-printable string
       * 
       * @throws UnsupportedEncodingException
       *                  Thrown if the charset is not supported
       */
      public String encode(String pString, String charset) throws UnsupportedEncodingException {
          if (pString == null) {
              return null;
          }
          return StringUtils.newStringUsAscii(encode(pString.getBytes(charset)));
      }
  }
  