//
// aegis - project change supervisor
// Copyright (C) 2014 Peter Miller
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or (at
// your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/>.
//

#ifndef LIBAEGIS_OUTPUT_FILTER_BASE85_H
#define LIBAEGIS_OUTPUT_FILTER_BASE85_H

#include <libaegis/output/filter.h>

/**
  * The output_filter_base85 class is used to represent the processing
  * necessary to pre-MIME BASE85 encode an output stream.
  */
class output_filter_base85:
    public output_filter
{
public:
    /**
      * The destructor.
      */
    virtual ~output_filter_base85();

    /**
      * The create class method is used to create new dynamically
      * allocated instances of this class.
      *
      * @param deeper
      *     The deeper output, the place this filter writes the filtered
      *     output.
      */
    static pointer create(const output::pointer &deeper);

protected:
    // See base class for documentation.
    nstring type_name(void) const;

    // See base class for documentation.
    long ftell_inner(void) const;

    // See base class for documentation.
    void write_inner(const void *data, size_t length);

    // See base class for documentation.
    void end_of_line_inner(void);

private:
    /**
      * The constructor.  It's private on purpose, use the "create"
      * class method instead.
      *
      * @param deeper
      *     The deeper output, the place this filter writes the filtered
      *     output.
      */
    output_filter_base85(const output::pointer &deeper);

    /**
      * The accumulator instance variable is used to remember the
      * four bytes being encoded, as a single 32-bit number.
      */
    unsigned long accumulator;

    /**
      * The accumulator_nbytes instance variable is used to remember
      * how many of the four bytes are present in the #accumulator
      * at the moment.
      */
    unsigned accumulator_nbytes;

    /**
      * The column instance variable is used to remember the
      * character column of the output position, used to break long
      * lines.  Position of the newline is not significant.
      */
    unsigned column;

    /**
      * The content_length instance variable is used to remember how
      * many bytes of binary data have been presented so far.
      */
    unsigned long content_length;

    /**
      * The check_xor instance variable is used to remember a
      * running XOR check of the data so far.
      */
    unsigned long check_xor;

    /**
      * The check_sum instance variable is used to remember a
      * running total of all the bytes (plus one each) of the data
      * so far.
      */
    unsigned long check_sum;

                                                            /**
      * The check_rot instance variable is used to remember a cyclic
      * rum of all the data so far.
      */
    unsigned long check_rot;

    /**
      * The bol instance variable is used to remember whether or not we
      * are positioned at the beginning of a line.
      */
    bool bol;

     /**
       * The char_out method is used to write out a character, and
       * then also a newline if the line becomes too long (uses
       * #column to keep track).
       */
    void char_out(unsigned char c);

    /**
       * The word_out method is used to encode and output the
       * #accumulator word, once there are 4 bytes present.
       */
    void word_out(unsigned long word);

    /**
       * The encode method is used to remember the various sums, and
       * outpout a word every 4 bytes.
       */
    void encode(unsigned char c);

    /**
      * The default constructor.  Do not use.
      */
    output_filter_base85();

    /**
      * The copy constructor.  Do not use.
      */
    output_filter_base85(const output_filter_base85 &);

    /**
      * The assignment operator.  Do not use.
      */
    output_filter_base85 operator=(const output_filter_base85 &);
};

// vim: set ts=8 sw=4 et :
#endif // LIBAEGIS_OUTPUT_FILTER_BASE85_H