exception XsltProcessorCouldNotSend;;
exception XsltProcessorCouldNotReceive;;

let portserver = 12345;;
let portclient = 12346;;
let time_to_wait = 10;;

let rec process uri usecache mode =
 let module U = Unix in
  let uri = UriManager.string_of_uri uri in
  let pid = string_of_int (U.getpid ())
  and filename' =
   let uri' = Str.replace_first (Str.regexp ".*:") "" uri in
    Str.global_replace (Str.regexp "/") "_"
     (Str.global_replace (Str.regexp "_") "__" uri')
  in let tmpfile = "/tmp/helm_" ^ filename' ^ "_" ^ pid in
   (* test if the cache can be used *)
   let tmp_file_exists = Sys.file_exists tmpfile in
    if usecache && tmp_file_exists then
     tmpfile
    else
     let url = Configuration.getter_url ^ uri in
      (* purge the cache if asked to *)
      if not usecache && tmp_file_exists then
        Sys.remove tmpfile ;
      let string_to_send = mode ^ " " ^ url ^ " " ^ tmpfile in
      (* next function is for looping in case the server is not responding *)
      let rec contact_server () =
       let socketclient = U.socket U.PF_INET U.SOCK_DGRAM 0
       and socketserver = U.socket U.PF_INET U.SOCK_DGRAM 0 in
        let bounded = ref false in
         while not !bounded do
          try
           U.bind socketclient (U.ADDR_INET(U.inet_addr_any,portclient)) ;
           bounded := true
          with _ ->
           print_endline "Port unavailable. Retrying..." ; flush stdout ;
           U.sleep 5  (* wait hoping the inetaddr is released *)
         done ;
         let n =
          U.sendto socketserver string_to_send 0 (String.length string_to_send)
           [] (U.ADDR_INET(U.inet_addr_any,portserver))
         in
          if n = -1 then raise XsltProcessorCouldNotSend ;
          U.close socketserver ;
          let process_signal _ = U.close socketclient in
          Sys.set_signal Sys.sigalrm (Sys.Signal_handle process_signal) ;
          (* if the server does not respond, repeat the query *)
          ignore (U.alarm time_to_wait) ;
          try
           if U.recv socketclient "" 0 0 [] = -1 then
            raise XsltProcessorCouldNotReceive ;
           ignore (U.alarm 0) ; (* stop the bomb *)
           Sys.set_signal Sys.sigalrm Sys.Signal_default ;
           U.close socketclient ;
           tmpfile
          with
           U.Unix_error(_,"recv",_) ->
            print_endline "Xaland server not responding. Retrying..." ;
            flush stdout;
            contact_server ()
        in
         contact_server ()
;;