/* GNU mailutils - a suite of utilities for electronic mail
   Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Library Public License as published by
   the Free Software Foundation; either version 2, 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 Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <mailutils/sys/pop3.h>
#include <mailutils/error.h>

/* Read a complete line from the pop server. Transform CRLF to LF, remove
   the stuff byte termination octet ".", put a null in the buffer
   when done.  And Do a select() (stream_is_readready()) for the timeout.  */
static int
pop3_getline (pop3_t pop3)
{
  size_t n = 0;
  size_t total = pop3->io.ptr - pop3->io.buf;
  int status = 0;

  /* Must get a full line before bailing out.  */
  do
    {
      /* Timeout with select(), note that we have to reset select()
	 since on linux tv is modified when error.  */
      if (pop3->timeout)
	{
	  int ready = stream_is_readready (pop3->carrier, pop3->timeout);
	  if (ready == 0)
	    return MU_ERROR_TIMEOUT;
	}

      status = stream_readline (pop3->carrier, pop3->io.buf + total,
				pop3->io.len - total, pop3->io.offset, &n);
      if (status != 0)
	return status;
      pop3->io.offset += n;

      /* The server went away:  It maybe a timeout and some pop server
	 does not send the -ERR.  Consider this like an error.  */
      if (n == 0)
	return MU_ERROR_IO;

      total += n;
      pop3->io.nl = memchr (pop3->io.buf, '\n', total);
      if (pop3->io.nl == NULL)  /* Do we have a full line.  */
	{
	  /* Allocate a bigger buffer ?  */
	  if (total >= pop3->io.len - 1)
	    {
	      pop3->io.len *= 2;
	      pop3->io.buf = realloc (pop3->io.buf, pop3->io.len + 1);
	      if (pop3->io.buf == NULL)
		return MU_ERROR_NO_MEMORY;
	    }
	}
      pop3->io.ptr = pop3->io.buf + total;
    }
  while (pop3->io.nl == NULL); /* Bail only if we have a complete line.  */

  /* When examining a multi-line response, the client checks to see if the
     line begins with the termination octet "."(DOT). If yes and if octets
     other than CRLF follow, the first octet of the line (the termination
     octet) is stripped away.  */
  if (total >= 3  && pop3->io.buf[0] == '.')
    {
      if (pop3->io.buf[1] != '\r' && pop3->io.buf[2] != '\n')
	{
	  memmove (pop3->io.buf, pop3->io.buf + 1, total - 1);
	  pop3->io.ptr--;
	  pop3->io.nl--;
	}
      /* And if CRLF immediately follows the termination character, then
	 the response from the POP server is ended and the line containing
	 ".CRLF" is not considered part of the multi-line response.  */
      else if (pop3->io.buf[1] == '\r' && pop3->io.buf[2] == '\n')
	{
	  pop3->io.buf[0] = '\0';
	  pop3->io.ptr = pop3->io.buf;
	  pop3->io.nl = NULL;
	}
    }
  /* \r\n --> \n\0, conversion.  */
  if (pop3->io.nl > pop3->io.buf)
    {
      *(pop3->io.nl - 1) = '\n';
      *(pop3->io.nl) = '\0';
      pop3->io.ptr = pop3->io.nl;
    }
  return status;
} /* if need to fill up.  */

/* Call pop3_getline() for the dirty work,  and consume i.e. put
   in the user buffer only buflen. If buflen == 0 or buffer == NULL
   nothing is consume, the data is save for another call to pop3_readline()
   with a buffer != NULL.
  */
int
pop3_readline (pop3_t pop3, char *buffer, size_t buflen, size_t *pnread)
{
  size_t nread = 0;
  size_t n = 0;
  int status = 0;

  /* Do we need to fill up? Yes if no NL or the buffer is empty.  */
  if (pop3->carrier && (pop3->io.nl == NULL || pop3->io.ptr == pop3->io.buf))
    {
      status = pop3_getline (pop3);
      if (status != 0)
	return status;
    }

  /* How much we can copy ?  */
  n = pop3->io.ptr - pop3->io.buf;

  /* Consume the line?  */
  if (buffer && buflen)
    {
      buflen--; /* For the null.  */
      if (buflen)
	{
	  int nleft = buflen - n;
	  /* We got more then requested.  */
	  if (nleft < 0)
	    {
	      size_t sentinel;
	      nread = buflen;
	      sentinel = pop3->io.ptr - (pop3->io.buf + nread);
	      memcpy (buffer, pop3->io.buf, nread);
	      memmove (pop3->io.buf, pop3->io.buf + nread, sentinel);
	      pop3->io.ptr = pop3->io.buf + sentinel;
	    }
	  else
	    {
	      /* Drain our buffer.  */;
	      nread = n;
	      memcpy (buffer, pop3->io.buf, nread);
	      pop3->io.ptr = pop3->io.buf;
	      /* Clear of all residue.  */
	      memset (pop3->io.buf, '\0', pop3->io.len);
	    }
	}
      buffer[nread] = '\0';
    }
  else
    nread = n;

  if (pnread)
    *pnread = nread;
  return status;
}