/* This code derived from GLib, Copyright (C) 1997-2002
 * by the GLib team.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>
#include "sn-util.h"
#include "sn-internals.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <assert.h>

#ifndef	REALLOC_0_WORKS
static void*
standard_realloc (void* mem,
		  sn_size_t    n_bytes)
{
  if (!mem)
    return malloc (n_bytes);
  else
    return realloc (mem, n_bytes);
}
#endif	/* !REALLOC_0_WORKS */

#ifdef SANE_MALLOC_PROTOS
#  define standard_malloc	malloc
#  ifdef REALLOC_0_WORKS
#    define standard_realloc	realloc
#  endif /* REALLOC_0_WORKS */
#  define standard_free		free
#  define standard_calloc	calloc
#  define standard_try_malloc	malloc
#  define standard_try_realloc	realloc
#else	/* !SANE_MALLOC_PROTOS */
static void*
standard_malloc (sn_size_t n_bytes)
{
  return malloc (n_bytes);
}
#  ifdef REALLOC_0_WORKS
static void*
standard_realloc (void* mem,
		  sn_size_t    n_bytes)
{
  return realloc (mem, n_bytes);
}
#  endif /* REALLOC_0_WORKS */
static void
standard_free (void* mem)
{
  free (mem);
}
static void*
standard_calloc (sn_size_t n_blocks,
		 sn_size_t n_bytes)
{
  return calloc (n_blocks, n_bytes);
}
#define	standard_try_malloc	standard_malloc
#define	standard_try_realloc	standard_realloc
#endif	/* !SANE_MALLOC_PROTOS */


/* --- variables --- */
static SnMemVTable sn_mem_vtable = {
  standard_malloc,
  standard_realloc,
  standard_free,
  standard_calloc,
  standard_try_malloc,
  standard_try_realloc,
  NULL,
  NULL
};


/* --- functions --- */
void*
sn_malloc (sn_size_t n_bytes)
{
  if (n_bytes)
    {
      void* mem;

      mem = sn_mem_vtable.malloc (n_bytes);
      if (mem)
	return mem;

      fprintf (stderr,
               "libsn: failed to allocate %lu bytes",
               (unsigned long) n_bytes);
    }

  return NULL;
}

void*
sn_malloc0 (sn_size_t n_bytes)
{
  if (n_bytes)
    {
      void* mem;

      mem = sn_mem_vtable.calloc (1, n_bytes);
      if (mem)
	return mem;

      fprintf (stderr,
               "libsn: failed to allocate %lu bytes",
               (unsigned long) n_bytes);
    }

  return NULL;
}

void*
sn_realloc (void     *mem,
            sn_size_t n_bytes)
{
  if (n_bytes)
    {
      mem = sn_mem_vtable.realloc (mem, n_bytes);
      if (mem)
	return mem;

      fprintf (stderr,
               "libsn: failed to allocate %lu bytes",
               (unsigned long) n_bytes);
    }

  if (mem)
    sn_mem_vtable.free (mem);

  return NULL;
}

void
sn_free (void* mem)
{
  if (mem)
    sn_mem_vtable.free (mem);
}

void*
sn_try_malloc (sn_size_t n_bytes)
{
  if (n_bytes)
    return sn_mem_vtable.try_malloc (n_bytes);
  else
    return NULL;
}

void*
sn_try_realloc (void       *mem,
                sn_size_t   n_bytes)
{
  if (n_bytes)
    return sn_mem_vtable.try_realloc (mem, n_bytes);

  if (mem)
    sn_mem_vtable.free (mem);

  return NULL;
}

static void*
fallback_calloc (sn_size_t n_blocks,
		 sn_size_t n_block_bytes)
{
  sn_size_t l = n_blocks * n_block_bytes;
  void* mem = sn_mem_vtable.malloc (l);

  if (mem)
    memset (mem, 0, l);

  return mem;
}

static sn_bool_t vtable_set = FALSE;

sn_bool_t
sn_mem_is_system_malloc (void)
{
  return !vtable_set;
}

void
sn_mem_set_vtable (SnMemVTable *vtable)
{
  if (!vtable_set)
    {
      vtable_set = TRUE;
      if (vtable->malloc && vtable->realloc && vtable->free)
	{
	  sn_mem_vtable.malloc = vtable->malloc;
	  sn_mem_vtable.realloc = vtable->realloc;
	  sn_mem_vtable.free = vtable->free;
	  sn_mem_vtable.calloc = vtable->calloc ? vtable->calloc : fallback_calloc;
	  sn_mem_vtable.try_malloc = vtable->try_malloc ? vtable->try_malloc : sn_mem_vtable.malloc;
	  sn_mem_vtable.try_realloc = vtable->try_realloc ? vtable->try_realloc : sn_mem_vtable.realloc;
	}
      else
        {
          fprintf (stderr,
                   "libsn: memory allocation vtable lacks one of malloc(), realloc() or free()");
        }
    }
  else
    {
      fprintf (stderr,
               "libsn: memory allocation vtable can only be set once at startup");
    }
}

static SnUtf8ValidateFunc utf8_validator = NULL;

void
sn_set_utf8_validator (SnUtf8ValidateFunc validate_func)
{
  utf8_validator = validate_func;
}

sn_bool_t
sn_internal_utf8_validate (const char *str,
                           int         max_len)
{
  if (utf8_validator)
    {
      if (max_len < 0)
        max_len = strlen (str);
      return (* utf8_validator) (str, max_len);
    }
  else
    return TRUE;
}

char*
sn_internal_strdup (const char *str)
{
  char *s;

  s = sn_malloc (strlen (str) + 1);
  strcpy (s, str);

  return s;
}

char*
sn_internal_strndup (const char *str,
                     int         n)
{
  char *new_str;
  
  if (str)
    {
      new_str = sn_new (char, n + 1);
      strncpy (new_str, str, n);
      new_str[n] = '\0';
    }
  else
    new_str = NULL;

  return new_str;
}

void
sn_internal_strfreev (char **strings)
{
  int i;

  if (strings == NULL)
    return;
  
  i = 0;
  while (strings[i])
    {
      sn_free (strings[i]);
      ++i;
    }
  sn_free (strings);
}

unsigned long
sn_internal_string_to_ulong (const char* str)
{
  unsigned long retval;
  char *end;
  errno = 0;
  retval = strtoul (str, &end, 0);
  if (end == str || errno != 0)
    retval = 0;

  return retval;
}

/**
 * sn_internal_find_last_occurrence:
 * @haystack: a nul-terminated string.
 * @needle: the nul-terminated string to search for.
 *
 * Searches the string @haystack for the last occurrence
 * of the string @needle.
 *
 * Return value: a pointer to the found occurrence, or
 *    %NULL if not found.
 **/
char*
sn_internal_find_last_occurrence (const char* haystack, 
                                  const char* needle)
{
  int i;
  int needle_len;
  int haystack_len;
  const char *p;
      
  if (haystack == NULL)
    return NULL;
  if (needle == NULL)
    return NULL;

  needle_len = strlen (needle);
  haystack_len = strlen (haystack);

  if (needle_len == 0)
    return (char *)haystack;

  if (haystack_len < needle_len)
    return NULL;
  
  p = haystack + haystack_len - needle_len;

  while (p >= haystack)
    {
      for (i = 0; i < needle_len; i++)
        if (p[i] != needle[i])
          goto next;
      
      return (char *)p;
      
    next:
      p--;
    }
  
  return NULL;
}

void
sn_internal_append_to_string (char      **append_to,
                              int        *current_len,
                              const char *append)
{
  int len;
  char *end;

  assert (append != NULL);
  
  len = strlen (append);

  *append_to = sn_realloc (*append_to, *current_len + len + 1);
  
  end = *append_to + *current_len;
  strcpy (end, append);
  *current_len = *current_len + len;  
}