(* Copyright (C) 2000, HELM Team.
 * 
 * This file is part of HELM, an Hypertextual, Electronic
 * Library of Mathematics, developed at the Computer Science
 * Department, University of Bologna, Italy.
 * 
 * HELM is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * HELM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HELM; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA  02111-1307, USA.
 * 
 * For details, see the HELM World-Wide-Web page,
 * http://cs.unibo.it/helm/.
 *)

(*
 * gestione della connessione al database
 *)

(*
 * le eccezioni lanciate dalle funzioni init e pgc sono
 * definite nel modulo Mathql 
 *)
open Mathql;;

(*
 * paramentri della connessione
 *
 * TODO: bisogna scegliere se questi parametri vengono
 * passati come argomento
 *)
(*let connection_param = "dbname=helm";;*)
let connection_param = "host=dotto.cs.unibo.it dbname=helm user=helm";;

(*
 * connessione al db
 *)
let conn = ref None;;

(*
 * controllo sulla connessione
 *)
let pgc () =
   match !conn with
      None -> raise (MQInvalidConnection connection_param)
   |  Some c -> c
;;

(*
 * inizializzazione della connessione
 *
 * TODO
 * passare i parametri della connessione come argomento di init
 *)
let init () =
   try (
    conn := Some (new Postgres.connection connection_param);
   ) with
    _ -> raise (MQConnectionFailed ("init: " ^ connection_param))
;;

(*
 * chiusura della connessione
 *)
let close () =
   match !conn with
      None -> ()
   |  Some c -> c#close
;;