#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

/* Vorgaben, wenn unvollständiger Pfad angegeben */
#define USER "/~heha"
#define HOME "h/heha"

#define abs(x) ((x)>0?(x):-(x))

typedef struct _FL {
 struct _FL *next;
 char fn[1];
}FL;


typedef struct {
 char *dir;
 int curfile;
 int slide, slidetime;
} OPTIONS;


OPTIONS o;


char *mygetenv(char *name) {
 char *ret=getenv(name);
 return ret?ret:"";
}


void modifyserver(void) {
 char *sn=mygetenv("SERVER_NAME");
 char *sp=mygetenv("SERVER_PORT");
 char fn[128];

 if (strcmp(sp, "80")) {
  sprintf(fn, "%s:%s", sn, sp);
  setenv("SERVER_NAME", fn, 1);
 }
}


int cmp(const void *a, const void *b) {
 return strcmp((*(FL**)a)->fn, (*(FL**)b)->fn);
}


int mkopt(void) {
 char *go=getenv("go");
 char *sl=getenv("slide");
 char *nr=getenv("Nr");
 char *ti=getenv("Zeit");
 char sn[128], *p;

 if (nr) sscanf(nr, "%d", &o.curfile); else o.curfile=1;
 if (ti) sscanf(ti, "%d", &o.slidetime); else o.slidetime=5;

 if (go) {
  if (!strncmp(go, "Zum A", 5)) o.curfile=1;
  else if (!strncmp(go, "Zur", 3)) o.curfile--;
  else if (!strncmp(go, "Vor", 3)) o.curfile++;
  else if (!strncmp(go, "Zum E", 5)) o.curfile=-1;
  else if (!strncmp(go, "Zu ", 3)) ;	/*NOP*/
  else return -1;
 }

 if (sl && strcmp(sl, "Slideshow anhalten")) o.slide=1;

 if (getenv("raus")) {
  strcpy(sn, mygetenv("SCRIPT_NAME"));
  p=strrchr(sn, '/');
  if (p) strcpy(p+1, "showdir.cgi");
  printf("Location: http://%s%s\n\n",
    mygetenv("SERVER_NAME"), mygetenv("PATH_INFO"));
  exit(0);
 }

 o.dir=getenv("PATH_INFO");
 o.dir=o.dir?o.dir:"";
 return 0;
}


void parsequery(void) {
 char *p, *querystring, *p2, *pval, *ppvald, *ppvals;
 int c;

 p=getenv("QUERY_STRING");
 if (!p) return;
 p=querystring=strdup(p);

 while (p) {
  p2=strchr(p, '&');
  if (p2) *p2++='\0';
  pval=strchr(p, '=');
  if (pval) {
   *pval='\0';
   pval++;
  } else pval=p+strlen(p);

  for (ppvals=ppvald=pval; *ppvals; ppvals++, ppvald++) {
   switch (*ppvals) {
    case '+': {
     *ppvald=' ';
    }break;
    case '%': {
     sscanf(ppvals+1, "%2X", (unsigned int *)&c);
     *ppvald=(char)c;
     ppvals+=2;
    }break;
    default: {
     *ppvald=*ppvals;
    }
   }
  }
  setenv(p, pval, 0);
  p=p2;
 }
 free(querystring);
}


void redir(void) {
 char *pathinfo=getenv("PATH_INFO");
 char *qs=getenv("QUERY_STRING");

 if (!pathinfo || pathinfo[strlen(pathinfo)-1]!='/') {
  printf("Location: http://%s%s%s/%s%s\n\n",
    getenv("SERVER_NAME"), getenv("SCRIPT_NAME"),
    pathinfo?pathinfo:"", (qs && strlen(qs))?"?":"", qs);
  exit(0);
 }
}


int intresholds(int x, int l, int h) {
 if (x<l) x=h;
 if (x>h) x=l;
 return x;
}


int main(void) {
 char lfsp[PATH_MAX], nfsp[PATH_MAX], *p;
 FL *anker=NULL, *neu, **field, **pfield;
 DIR *dir;
 struct dirent *d;
 struct stat statbuf;
 int cFiles=0, i, next, prev;
 char *pathinfo=getenv("PATH_INFO");

 char *ext[]={"bmp", "gif", "ico", "jpg", "jpeg", "pbm", "pcx", "pgm", "png",
   "pnm", "tif", "tiff", ""}, **pext;

 modifyserver();
 redir();

 memset(&o, 0, sizeof(OPTIONS));
 parsequery();
 mkopt();

 printf("Content-type: text/html\n\n");

/* printf("%s<BR>", pathinfo);*/
/* strcpy(lfsp, getenv("SCRIPT_FILENAME"));*/
 strcpy(lfsp, "/afs/tu-chemnitz.de/home/urz/");
 if (pathinfo[1]!='~') strcat(lfsp, HOME);
 else {
  char hlp[4096], *p;
  
  strcpy(hlp, pathinfo+2);
  p=strstr(hlp, "/");
  if (!p) return -1;
  *p='\0';
  lfsp[strlen(lfsp)+1]='\0';
  lfsp[strlen(lfsp)]=*hlp;
  strcat(lfsp, "/");
  strcat(lfsp, hlp);
 }
 strcat(lfsp, "/public_html");

 if (pathinfo[1]!='~') {
  strcpy(nfsp, USER);
  strcat(lfsp, pathinfo);
  strcat(nfsp, pathinfo);
 } else {
  *nfsp='\0';
  strcat(nfsp, pathinfo);
  strcpy(pathinfo, strstr(pathinfo+1, "/"));
  strcat(lfsp, pathinfo);
 }

/* p=strstr(lfsp, "/cgi-bin/");
 if (!*p) return -1;
 *p='\0';
 strcpy(nfsp, USER);
 strcat(lfsp, o.dir);
 strcat(nfsp, o.dir);*/
/* printf("%s<BR>", lfsp);
 printf("%s<BR>", nfsp);
 printf("%s<BR>", pathinfo);*/

 if (chdir(lfsp)) return -1;
 dir=opendir(".");
 if (!dir) return -1;

 while ((d=readdir(dir))) {
  if (!strncmp(d->d_name, "index.htm", 9)) {
   printf("<HTML><HEAD><META http-equiv=\"refresh\" "
     "content=\"0; url=%s/%s\"></HEAD></HTML>", nfsp, d->d_name);
   closedir(dir);
   return 0;
  }
  if (stat(d->d_name, &statbuf)) continue;
  if (!S_ISREG(statbuf.st_mode)) continue;
  p=strrchr(d->d_name, '.');
  if (!p) continue;
  p++;
  pext=ext;
  while (**pext) {
   if (!strcmp(p, *pext)) {
    neu=malloc(sizeof(FL)+strlen(d->d_name));
    neu->next=anker;
    strcpy(neu->fn, d->d_name);
    anker=neu;
    cFiles++;
    break;
   }
   pext++;
  }
 }
 closedir(dir);
 if (!cFiles) {
  printf("Keine Bilder im Verzeichnis %s.", nfsp);
  return 0;
 }

 o.curfile=intresholds(o.curfile, 1, cFiles);

 field=malloc(cFiles*sizeof(FL*));
 neu=anker;
 for (i=0, pfield=field, neu=anker; i<cFiles; i++) {
  *pfield=neu;
  pfield++;
  neu=neu->next;
 }

 qsort(field, cFiles, sizeof(FL*), cmp);

 printf("<HTML>\n"
   "<HEAD>\n");
 if (o.slide) {
  o.curfile=intresholds(o.curfile+((o.slidetime<0)?-1:1), 1, cFiles);
  printf(" <META http-equiv=\"refresh\" "
    "content=\"%d; "
    "url=./?Nr=%d&Zeit=%d&slide\">",
    abs(o.slidetime), o.curfile, /*o.slidetime>0?"Vor":"Zur", */o.slidetime);
 }

 printf(" <META http-equiv=\"Content-Type\" "
   "content=\"text/html; charset=iso-8859-1\">\n"
   " <TITLE>");
 if (o.slide) printf("Slideshow - ");
 printf("%s (Bild %d/%d)</TITLE>\n"

   "</HEAD>\n"
   "<BODY>\n"
   " <DIV align=center>\n"
   "  <FORM name=\"SlideForm\" action=\"./\">\n"
   "   <NOSCRIPT>\n"
   "    <INPUT type=submit name=\"go\" value=\"Zu Bild Nr.\" "
     "title=\"Dieser Button wird nicht gebraucht, wenn Sie Javascript "
     "angeschalten haben.\">\n"
   "   </NOSCRIPT>\n"
   "   <SELECT name=\"Nr\" size=\"1\" title=\"Direktauswahl\" "
     "onChange=\"document.SlideForm.submit()\">\n",
   field[o.curfile-1]->fn, o.curfile, cFiles);
 for (i=0; i<cFiles; i++)
   printf("    <OPTION%s>%d: %s</OPTION>\n", (i+1==o.curfile)?" selected":"",
     i+1, field[i]->fn);


 next=intresholds(o.curfile+1, 1, cFiles);
 prev=intresholds(o.curfile-1, 1, cFiles);
 printf("   </SELECT> &nbsp; &nbsp;\n"
   "   <INPUT type=submit name=\"go\" value=\"Zum Anfang\"%s title=\"1: %s\">\n"
   "   <INPUT type=submit name=\"go\" value=\"Zurück\" title=\"%d: %s\">\n"
   "   <INPUT type=submit name=\"go\" value=\"Vorwärts\" title=\"%d: %s\">\n"
   "   <INPUT type=submit name=\"go\" value=\"Zum Ende\"%s title=\"%d: %s\"> "
     "&nbsp; &nbsp;\n",
   o.curfile==1?" disabled":"", field[0]->fn,
   prev, field[prev-1]->fn,  next, field[next-1]->fn,
   o.curfile==cFiles?" disabled":"", cFiles, field[cFiles-1]->fn);
 printf(
   "   <INPUT type=text name=\"Zeit\" value=\"%d s\" size=5 maxlength=5%s>\n"
   "   <INPUT type=submit name=\"slide\" value=\"Slideshow %s\" "
     "title=\"%d Sekunden pro Durchlauf\"> &nbsp; &nbsp;\n"
   "   <INPUT type=submit name=\"raus\" value=\"Verzeichnisübersicht\" "
     "title=\"Gehe zu Verzeichnisübersicht\">\n"
   "  </FORM>\n"
   "  <IMG src=\"%s%s\">"
   " </DIV>\n"
   "</HTML>\n",
   o.slidetime, o.slide?" disabled":"",
   o.slide?"anhalten":"starten", abs(cFiles*o.slidetime),
   nfsp, field[o.curfile-1]->fn);

 return 0;
}

#undef abs