// -*- C++ -*-

/**
 *  @file   Codecs.h
 *
 *  $Id$
 *
 *  @author Krishnakumar B <kitty@cs.wustl.edu>
 *
 *  Codecs is a generic wrapper for various encoding and decoding
 *  mechanisms. Currently it includes Base64 content transfer-encoding as
 *  specified by RFC 2045, Multipurpose Internet Mail Extensions (MIME) Part
 *  One: Format of Internet Message Bodies.
 *
 */

#ifndef ACE_CODECS_H
#define ACE_CODECS_H
#include /**/ "ace/pre.h"

#include "ace/Basic_Types.h"
#include "ace/Global_Macros.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

/**
 * @class ACE_Base64
 *
 * @brief Encode/Decode a stream of bytes according to Base64 encoding.
 *
 * This class provides methods to encode or decode a stream of bytes
 * to/from Base64 encoding. It doesn't convert the input stream to a
 * canonical form before encoding.
 *
 */
class ACE_Export ACE_Base64
{
  friend class ace_dewarn_gplusplus;
public:

  //@{

  /**
   * Encodes a stream of bytes to Base64 data
   *
   * @param input Binary data in byte stream.
   * @param input_len Length of the byte stream.
   * @param output_len Length of the encoded Base64 byte stream.
   * @return Encoded Base64 data in byte stream or NULL if input data cannot
   *         be encoded.
   */

  static ACE_Byte* encode (const ACE_Byte* input,
                           const size_t input_len,
                           size_t* output_len);
  /**
   * Decodes a stream of Base64 to bytes data
   *
   * @param input Encoded Base64 data in byte stream.
   * @param output_len Length of the binary byte stream.
   * @return Binary data in byte stream or NULL if input data cannot
   *         be encoded.
   */
  static ACE_Byte* decode (const ACE_Byte* input,
                           size_t* output_len);

  /**
   * Return the length of the encoded input data
   *
   * @param input Encoded Base64 data in byte stream.
   * @return Length of the encoded Base64 data.
   *
   */
  static size_t length (const ACE_Byte* input);

  //@}

private:

  /// Initialize the tables for encoding/decoding.
  static void init();

  // Prevent construction in any form
  ACE_UNIMPLEMENTED_FUNC (ACE_Base64 ())
  ACE_UNIMPLEMENTED_FUNC (ACE_Base64 (const ACE_Base64&))

  /// Symbols which form the Base64 alphabet (Defined as per RFC 2045)
  static const ACE_Byte alphabet_[];

  /// Alphabet used for decoding i.e decoder_[alphabet_[i = 0..63]] = i
  static ACE_Byte decoder_[];

  /// Alphabet used to check valid range of encoded input i.e
  /// member_[alphabet_[0..63]] = 1
  static ACE_Byte member_[];

  /// The padding character used in the encoding
  static const ACE_Byte pad_;

  /// Boolean to denote whether initialization is complete
  static int init_;

  /// Number of columns per line of encoded output (Can have a max value of 76)
  static int max_columns_;

};

#include /**/ "ace/post.h"
#endif /* ACE_CODECS_H */