/*
 * Copyright (c) 2001, Robert Collins.
 *
 *     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 2 of the License, or
 *     (at your option) any later version.
 *
 *     A copy of the GNU General Public License can be found at
 *     http://www.gnu.org/
 *
 * Written by Robert Collins  <rbtcollins@hotmail.com>
 *
 */

#ifndef SETUP_IO_STREAM_MEMORY_H
#define SETUP_IO_STREAM_MEMORY_H

/* needed to parse */
#include <errno.h>

/* this is a stream class that simply abstracts the issue of maintaining
 * amemory buffer.
 * It's not as efficient as if can be, but that can be fixed without affecting 
 * the API. 
 */

class memblock
{
public:
  memblock () : next (0), len (0), data (0) {};
  memblock (size_t size) : next (0), len (size) {data = new unsigned char[size]; if (!data) len = 0;};
  ~memblock ();
  memblock *next;
  size_t len;
  unsigned char *data;
};

class io_stream_memory :public io_stream
{
public:
  io_stream_memory () : lasterr (0), mtime(0),length (0), head(), tail (&head), pos_block (head.next), pos_block_offset (0), pos (0) {};
  /* set the modification time of a file - returns 1 on failure
   * may distrupt internal state - use after all important io is complete
   */
  virtual int set_mtime (time_t newmtime)
    {mtime = newmtime; return 0;};
  /* get the mtime for a file TODO make this a stat(0 style call */
  virtual time_t get_mtime () {return mtime;};
  virtual mode_t get_mode () {return 0;};
  /* returns the _current_ size. */
  virtual size_t get_size () {return length;};
  /* read data (duh!) */
  virtual ssize_t read (void *buffer, size_t len);
  /* provide data to (double duh!) */
  virtual ssize_t write (const void *buffer, size_t len);
  /* read data without removing it from the class's internal buffer */
  virtual ssize_t peek (void *buffer, size_t len);
  /* ever read the f* functions from libc ? */
  virtual long tell () {return pos;};
  virtual int seek (long where, io_stream_seek_t whence) { if (whence != IO_SEEK_SET) { lasterr = EINVAL; return -1;} ssize_t count=0; pos = 0; pos_block = head.next; pos_block_offset = 0; while (count < where && pos < length) {pos_block_offset++; if (pos_block_offset == pos_block->len) {pos_block = pos_block->next; pos_block_offset = 0;}pos++;count++;}return 0;};
    
  /* try guessing this one */
  virtual int error ();
//  virtual const char* next_file_name() = NULL;
  /* if you are still needing these hints... give up now! */
  virtual ~ io_stream_memory ();
private:
  int lasterr;
  time_t mtime;
  size_t length;
  memblock head;
  memblock *tail;
  memblock *pos_block;
  size_t pos_block_offset;
  size_t pos;
};

#endif /* SETUP_IO_STREAM_MEMORY_H */