/*************************************************************************
*									 *
*	 YAP Prolog 							 *
*									 *
*	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
*									 *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
*									 *
**************************************************************************
*									 *
* File:		sockets.c							 *
* Last rev:	5/2/88							 *
* mods:									 *
* comments:	Input/Output C implemented predicates			 *
*									 *
*************************************************************************/
#ifdef SCCS
static char SccsId[] = "%W% %G%";
#endif

/*
 * This file includes the definition of a socket related IO.
 *
 */

#include "Yap.h"
#include "Yatom.h"
#include "YapHeap.h"
#include "yapio.h"
#include <stdlib.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_STDARG_H
#include <stdarg.h>
#endif
#ifdef _WIN32
#if HAVE_IO_H
/* Windows */
#include <io.h>
#endif 
#if HAVE_SOCKET
#include <winsock2.h>
#endif
#include <windows.h>
#ifndef S_ISDIR
#define S_ISDIR(x) (((x)&_S_IFDIR)==_S_IFDIR)
#endif
#endif
#include "iopreds.h"
#if __APPLE__
#include "fmemopen.h"
#define HAVE_FMEMOPEN 1
#define HAVE_OPEN_MEMSTREAM 1
FILE * open_memstream (char **buf, size_t *len);
#endif

#if HAVE_FMEMOPEN 
#define MAY_READ 1
#endif

#if HAVE_OPEN_MEMSTREAM  
#define MAY_READ 1
#define MAY_WRITE 1
#endif

#if !MAY_READ
static int MemGetc( int);

/* read from memory */
static int
MemGetc (int sno)
{
  register StreamDesc *s = &GLOBAL_Stream[sno];
  Int ch;
  int spos;

  spos = s->u.mem_string.pos;
  if (spos == s->u.mem_string.max_size) {
    return post_process_eof(s);
  } else {
    ch = s->u.mem_string.buf[spos];
    s->u.mem_string.pos = ++spos;
  }
  return post_process_read_char(ch, s);
}
#endif

#if !MAY_WRITE
static int MemPutc( int, int);

/* static */
static int
MemPutc(int sno, int ch)
{
  StreamDesc *s = &GLOBAL_Stream[sno];
#if MAC || _MSC_VER
  if (ch == 10)
    {
      ch = '\n';
    }
#endif
  s->u.mem_string.buf[s->u.mem_string.pos++] = ch;
  if (s->u.mem_string.pos >= s->u.mem_string.max_size -8) {
    int old_src = s->u.mem_string.src, new_src;

    /* oops, we have reached an overflow */
    Int new_max_size = s->u.mem_string.max_size + Yap_page_size;
    char *newbuf;

    if (old_src == MEM_BUF_CODE &&
	(newbuf = Yap_AllocAtomSpace(new_max_size*sizeof(char))) != NULL) {
      new_src = MEM_BUF_CODE;
#if HAVE_MEMMOVE
    memmove((void *)newbuf, (void *)s->u.mem_string.buf, (size_t)((s->u.mem_string.pos)*sizeof(char)));
#else
    {
      Int n = s->u.mem_string.pos;
      char *to = newbuf;
      char *from = s->u.mem_string.buf;
      while (n-- >= 0) {
	*to++ = *from++;
      }
    }
#endif
      Yap_FreeAtomSpace(s->u.mem_string.buf);
#if !HAVE_SYSTEM_MALLOC
    } else if ((newbuf = (ADDR)realloc(s->u.mem_string.buf, new_max_size*sizeof(char))) != NULL)  {
      new_src = MEM_BUF_MALLOC;
#endif
    } else {
      if (GLOBAL_Stream[sno].u.mem_string.error_handler) {
          CACHE_REGS
	LOCAL_Error_Size = new_max_size*sizeof(char);
	save_machine_regs();
	longjmp(*(jmp_buf *)GLOBAL_Stream[sno].u.mem_string.error_handler,1);
      } else {
	Yap_Error(RESOURCE_ERROR_HEAP, TermNil, "YAP could not grow heap for writing to string");
      }
      return -1;
    }
   if (old_src == MEM_BUF_CODE) {
    }
    s->u.mem_string.buf = newbuf;
    s->u.mem_string.max_size = new_max_size;
    s->u.mem_string.src = new_src;
  }
  count_output_char(ch,s);
  return ((int) ch);
}

#endif


 int
 Yap_open_buf_read_stream(const char *nbuf, size_t nchars, encoding_t *encp,  memBufSource src)
{
  CACHE_REGS
  int sno;
  StreamDesc *st;
  FILE *f;
  encoding_t encoding;
  stream_flags_t flags;
   
  sno = GetFreeStreamD();
  if (sno < 0)
    return (PlIOError (RESOURCE_ERROR_MAX_STREAMS,TermNil, "new stream not available for open_mem_read_stream/1"));
  st = GLOBAL_Stream+sno;
  if (encp)
    encoding = *encp;
  else
    encoding = LOCAL_encoding;
#if MAY_READ
  // like any file stream.
  f = fmemopen( (void *)nbuf, nchars, "r");
  flags = Input_Stream_f | InMemory_Stream_f | Seekable_Stream_f;
#else
  f = NULL;
  flags = Input_Stream_f | InMemory_Stream_f;
#endif
  Yap_initStream(sno, f, NULL, TermNil,
                        encoding,  flags, AtomRead);
  // like any file stream.
#if !MAY_READ
  /* currently these streams are not seekable */
  st->status = Input_Stream_f | InMemory_Stream_f;
  st->u.mem_string.pos = 0;
  st->u.mem_string.buf = (char *)nbuf;
  st->u.mem_string.max_size = nchars;
  st->u.mem_string.error_handler = NULL;
  st->u.mem_string.src = src;
#endif
  Yap_MemOps( st );
  UNLOCK(st->streamlock);
  return sno;
}

static Int
open_mem_read_stream (USES_REGS1)   /* $open_mem_read_stream(+List,-Stream) */
{
  Term t, ti;
  int sno;
  Int sl = 0, nchars = 0;
  char *nbuf;

  ti = Deref(ARG1);
  while (ti != TermNil) {
    if (IsVarTerm(ti)) {
      Yap_Error(INSTANTIATION_ERROR, ti, "open_mem_read_stream");
      return (FALSE);
    } else if (!IsPairTerm(ti)) {
      Yap_Error(TYPE_ERROR_LIST, ti, "open_mem_read_stream");
      return (FALSE);
    } else {
      sl++;
      ti = TailOfTerm(ti);
    }
  }
  while ((nbuf = (char *)Yap_AllocAtomSpace((sl+1)*sizeof(char))) == NULL) {
    if (!Yap_growheap(FALSE, (sl+1)*sizeof(char), NULL)) {
      Yap_Error(RESOURCE_ERROR_HEAP, TermNil,  LOCAL_ErrorMessage);
      return(FALSE);
    }
  }
  ti = Deref(ARG1);
  while (ti != TermNil) {
    Term ts = HeadOfTerm(ti);

    if (IsVarTerm(ts)) {
      Yap_Error(INSTANTIATION_ERROR, ARG1, "open_mem_read_stream");
      return (FALSE);
    } else if (!IsIntTerm(ts)) {
      Yap_Error(TYPE_ERROR_INTEGER, ARG1, "open_mem_read_stream");
      return (FALSE);
    }
    nbuf[nchars++] = IntOfTerm(ts);
    ti = TailOfTerm(ti);
  }
  nbuf[nchars] = '\0';
  sno = Yap_open_buf_read_stream(nbuf, nchars, &LOCAL_encoding, MEM_BUF_CODE);
  t = Yap_MkStream (sno);
  return (Yap_unify (ARG2, t));
}

int
Yap_open_buf_write_stream(char *buf, size_t nchars, encoding_t *encp,  memBufSource sr)
{
  CACHE_REGS
    int sno;
    StreamDesc *st;

    
    sno = GetFreeStreamD();
    if (sno < 0)
      return -1;
    if (!buf) {
      if (!nchars) {
	nchars = Yap_page_size;
      }
      buf = malloc( nchars );
    }
    st = GLOBAL_Stream+sno;
    st->nbuf = buf;
    if(!st->nbuf) {
      return -1;
    }
    st->nsize = nchars;
    st->linepos = 0;
    st->charcount = 0;
    st->linecount = 1;
    if (encp)
      st->encoding = *encp;
    else
      st->encoding = LOCAL_encoding;
    Yap_DefaultStreamOps( st );
#if MAY_WRITE
    st->file = open_memstream(&st->nbuf, &st->nsize);
    st->status = Output_Stream_f | InMemory_Stream_f|Seekable_Stream_f;
#else
    st->u.mem_string.pos = 0;
    st->u.mem_string.buf = nbuf;
    st->u.mem_string.max_size = nchars;
    st->status = Output_Stream_f | InMemory_Stream_f;
 #endif
    Yap_MemOps( st );
    UNLOCK(st->streamlock);
    return sno;
}

int
Yap_OpenBufWriteStream( USES_REGS1 )
{
  char *nbuf;
  size_t sz =  Yap_page_size;


  while ((nbuf = (char *)Yap_AllocAtomSpace(Yap_page_size*sizeof(char))) == NULL) {
    if (!Yap_growheap(FALSE, Yap_page_size*sizeof(char), NULL)) {
      Yap_Error(RESOURCE_ERROR_HEAP, TermNil,  LOCAL_ErrorMessage);
      return -1;
    }
  }
  return Yap_open_buf_write_stream(nbuf, sz, &GLOBAL_Stream[LOCAL_c_output_stream].encoding, 0);
}

static Int
open_mem_write_stream (USES_REGS1)   /* $open_mem_write_stream(-Stream) */
{
  Term t;
  int sno;

  sno = Yap_OpenBufWriteStream( PASS_REGS1 );
  if (sno == -1)
    return (PlIOError (SYSTEM_ERROR_INTERNAL,TermNil, "new stream not available for open_mem_read_stream/1"));
  t = Yap_MkStream (sno);
  return (Yap_unify (ARG1, t));
}

/** 
 * Yap_PeekMemwriteStream() shows the current buffer for a memory stream.
 * 
 * @param sno, the in-memory stream
 * 
 * @return temporary buffer, discarded by close and may be moved away
 * by other writes..
 */
char *
Yap_MemExportStreamPtr( int sno )
{
  char *s;
#if MAY_WRITE
  if (fflush(GLOBAL_Stream[sno].file) == 0)
    {
      s =  GLOBAL_Stream[sno].nbuf;
    return s;
  }
  return NULL;
#else
  return &GLOBAL_Stream[sno].u.mem_string;
#endif
}


static Int
peek_mem_write_stream ( USES_REGS1 )
{				/* '$peek_mem_write_stream'(+GLOBAL_Stream,?S0,?S) */
  Int sno = Yap_CheckStream (ARG1, (Output_Stream_f | InMemory_Stream_f), "close/2");
  Int i;
  Term tf = ARG2;
  CELL *HI;
  const char *ptr;

  if (sno < 0)
    return (FALSE);
 restart:
  HI = HR;
#if MAY_WRITE
  if (fflush(GLOBAL_Stream[sno].file) == 0) {
      ptr = GLOBAL_Stream[sno].nbuf;
      i = GLOBAL_Stream[sno].nsize;
    }
#else
  size_t pos;
    ptr = GLOBAL_Stream[sno].u.mem_string.buf;
    i = GLOBAL_Stream[sno].u.mem_string.pos;
#endif
  while (i > 0) {
    --i;
    tf = MkPairTerm(MkIntTerm(ptr[i]),tf);
    if (HR + 1024 >= ASP) {
      UNLOCK(GLOBAL_Stream[sno].streamlock);
      HR = HI;
      if (!Yap_gcl((ASP-HI)*sizeof(CELL), 3, ENV, Yap_gcP()) ) {
	UNLOCK(GLOBAL_Stream[sno].streamlock);
	Yap_Error(RESOURCE_ERROR_STACK, TermNil, LOCAL_ErrorMessage);
	return(FALSE);
      }
      i = GLOBAL_Stream[sno].u.mem_string.pos;
      tf = ARG2;
      LOCK(GLOBAL_Stream[sno].streamlock);
      goto restart;
    }
  }
  UNLOCK(GLOBAL_Stream[sno].streamlock);
  return (Yap_unify(ARG3,tf));
}

void
 Yap_MemOps(  StreamDesc *st )
{
#if MAY_WRITE
  st->stream_putc = FilePutc;
#else
 st->stream_putc = MemPutc;
#endif

#if MAY_READ
  st->stream_getc = PlGetc;
#else
  st->stream_getc = MemGetc;
#endif
}

void
Yap_InitMems( void )
{
    CACHE_REGS
  Term cm = CurrentModule;
  CurrentModule = CHARSIO_MODULE;
  Yap_InitCPred ("open_mem_read_stream", 2, open_mem_read_stream, SyncPredFlag);
  Yap_InitCPred ("open_mem_write_stream", 1, open_mem_write_stream, SyncPredFlag);
  Yap_InitCPred ("peek_mem_write_stream", 3, peek_mem_write_stream, SyncPredFlag);
  CurrentModule = cm;
}