(* A server for "fortunes". Clients may add new fortunes, on the way back from 
   chinese restaurants, and retrieve fortunes one at a time. The database is    
   pickled to survive server outages. *)

module FortuneServer;

let writeList =
  proc(list)
    let w = wr_open(fileSys, "fortune.obq");
    pickle_write(w, list);
    wr_close(w)
  end;

let readList =
  proc()
    try
      let r = rd_open(fileSys, "fortune.obq");
      let a = pickle_read(r);
      rd_close(r);
      a
    else []
    end
  end;

var i = -1;

let fortune =
  {protected, serialized,
     list =>
        readList(),
        
     tell => 
       meth(self)
         if #(self.list) is 0 then "<bad luck>"
         else  
           i := i+1;
           if i >= #(self.list) then i:=0 end;
           self.list[i]
         end
       end,
       
     learn =>
       meth(self, t)
         self.list := self.list @ [t];
         writeList(self.list);
       end,
  };

net_export("fortune","", fortune);