/*
    HTTrack external callbacks example : changing the destination filename
    .c file

    How to build: (callback.so or callback.dll)
      With GNU-GCC:
        gcc -O -g3 -Wall -D_REENTRANT -shared -o mycallback.so callbacks-example.c -lhttrack2
      With MS-Visual C++:
        cl -LD -nologo -W3 -Zi -Zp4 -DWIN32 -Fe"mycallback.dll" callbacks-example.c libhttrack.lib

      Note: the httrack library linker option is only necessary when using libhttrack's functions inside the callback

    How to use:
      httrack --wrapper mycallback ..
*/

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

/* Standard httrack module includes */
#include "httrack-library.h"
#include "htsopt.h"
#include "htsdefines.h"

/* Local function definitions */
static int mysavename(t_hts_callbackarg * carg, httrackp * opt,
                      const char *adr_complete, const char *fil_complete,
                      const char *referer_adr, const char *referer_fil,
                      char *save);

/* external functions */
EXTERNAL_FUNCTION int hts_plug(httrackp * opt, const char *argv);

/* Options settings */
#include "htsopt.h"

/* TOLOWER */
#define TOLOWER_(a) (a >= 'A' && a <= 'Z') ? (a + ('a' - 'A')) : a
#define TOLOWER(a) ( TOLOWER_( (a) ) )

/*
  This sample just changes the destination filenames to ROT-13 equivalent ; that is,
  a -> n
  b -> o
  c -> p
  d -> q
  ..
  n -> a
  o -> b
  ..

  <parent> -> <link>
  This sample can be improved, for example, to make a map of a website.
*/

/* 
module entry point 
*/
EXTERNAL_FUNCTION int hts_plug(httrackp * opt, const char *argv) {
  const char *arg = strchr(argv, ',');

  if (arg != NULL)
    arg++;

  /* Plug callback functions */
  CHAIN_FUNCTION(opt, savename, mysavename, NULL);

  return 1;                     /* success */
}

static int mysavename(t_hts_callbackarg * carg, httrackp * opt,
                      const char *adr_complete, const char *fil_complete,
                      const char *referer_adr, const char *referer_fil,
                      char *save) {
  char *a;

  /* Call parent functions if multiple callbacks are chained. */
  if (CALLBACKARG_PREV_FUN(carg, savename) != NULL) {
    if (!CALLBACKARG_PREV_FUN(carg, savename)
        (CALLBACKARG_PREV_CARG(carg), opt, adr_complete, fil_complete,
         referer_adr, referer_fil, save)) {
      return 0;                 /* Abort */
    }
  }

  /* Process */
  for(a = save; *a != 0; a++) {
    char c = TOLOWER(*a);

    if (c >= 'a' && c <= 'z')
      *a = (((c - 'a') + 13) % 26) + 'a';       // ROT-13
  }

  return 1;                     /* success */
}