/* mailwatch.c   by Michael Thorpe   2000-04-28 */

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

#define TTY "/dev/tty63"
#define SLEEP 5
#define USAGE "usage: mailwatch [-d] [<# beeps>] <file|dir>\n"

int main(int argc,char **argv) {
   int d=0,in,io,n=3,t,u;
   struct stat ss;
   off_t os=0;
   char *s;
   DIR *dir;
   struct dirent *sd;

   if(argc>=2 && argv[1][0]=='-') {
      if(argv[1][1] != 'd' || argv[1][2] != '\0') {
         write(2,USAGE,strlen(USAGE));
         return(1);
      }
      d=1;
      argv++;
      argc--;
   }
   if(argc>2 && isdigit(argv[1][0])) {
      for(t=0;argv[1][t];t++)
         if(!isdigit(argv[1][t]))
            break;
      if(0==argv[1][t]) {
         n=atoi(argv[1]);
         argv++;
         argc--;
      }
   }
   if(argc != 2) {
      write(2,USAGE,strlen(USAGE));
      return(1);
   }
   s=argv[1];

   close(0);
   if(d) {
      close(1);
      if(fork())
         return(0);
      setsid();
      if(0>(t=open(TTY,O_WRONLY|O_NOCTTY))) {
         write(2,"Couldn't open "TTY"\n",15+strlen(TTY));
         return(-1);
      }
   } else
      t=1;
   close(2);
   nice(20);
   d=strlen(s);
   if(s[d-1]=='/') {
      io=0;
      while(1) {
         if(0==(dir=opendir(s))) {
            if(mkdir(s,0700)) {
               write(t,"\07Failed to create maildir\n",26);
               return(-1);
            }
            in=0;
         } else {
            in=0;
            while((sd=readdir(dir)))
               if(strcmp(sd->d_name,".") && strcmp(sd->d_name,".."))
                  in++;
            closedir(dir);
         }
         if(in>io) {
            for(d=n;d;d--) {
               write(t,"\07",1);
               if(d)
                  usleep(150000);
            }
         }
         io=in;
         sleep(SLEEP);
      }
   } else {
      while(1) {
         if(0 != stat(s,&ss)) {
            if(0>(u=creat(s,0600))) {
               write(t,"\07Failed to create mailbox\n",26);
               return(-1);
            } else
               close(u);
            ss.st_size=0;
         }
         if(os<ss.st_size) {
            for(d=n;d;d--) {
               write(t,"\07",1);
               if(d)
                  usleep(150000);
            }
         }
         os=ss.st_size;
         sleep(SLEEP);
      }
   }

   return(-1);
}