(* 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/.
 *)

(*
 *
 *)

open Dbconn;;
open Utility;;
open Intersect;;


let getpid p =
  if (p = "refObj") then "F"
  else "B"
;;

(*
 * implementazione delle funzioni dublin core
 *)
let rec property_ex rop path inv = function
    [] -> []
  | s::tl -> let mprop = fst path in
             print_endline mprop;
             let prop = List.hd (snd path) in
             match mprop with
	       
	       "refObj" (* in base al valore di prop restituisco i valori del relativo campo della tabella relativa all'uri rappresentata da s *)
	     | "backPointer" ->
	       print_endline mprop;
	       let mpid = getpid mprop in
	       let res =
	       let c = pgc () in
	       let tv = pgresult_to_string (c#exec ("select id from registry where uri='" ^ s ^ "'")) in
	       let q = "select t" ^ tv ^ "." ^ prop ^  "  from t" ^ tv ^ " where prop_id= '" ^ mpid ^ "'" in
                print_endline q;
		pgresult_to_string_list (c#exec q)
	       in
	         append (res,(property_ex rop path inv tl))
	       
                          (*Rimane da capire cosa restituire  nelle inverse!!!!*)
			   
	       
             | "refRel"
	     | "refSort" ->
	     if inv then     (* restituisco gli uri che il valore della prop richiesta uguale a s *)
               let res =
               let c = pgc () in
	       let q = ("select h" ^ mprop ^ ".uri from h" ^ mprop ^ " where h" ^ mprop ^ "." ^ prop ^ "= '" ^ s ^ "'") in
	         print_endline q;
		 pgresult_to_string_list (c#exec q)
               in
                 append (res,(property_ex rop path inv tl))
               
	     else
	       let res =         (* restituisco il valore della prop relativo all'uri rappresentato da s*)
               let c = pgc () in
               let q = ("select h" ^ mprop ^ "." ^ prop ^" from h" ^ mprop ^ " where h" ^ mprop ^ ".uri = '" ^ s ^ "'") in
                 pgresult_to_string_list (c#exec q)
	       in
                 append (res,(property_ex rop path inv tl))
	       
	     
	     
	     | _ ->        (* metadati DC  !!!! Controllare se i nomi delle tabelle cominciano con h !!!!*)
	     if inv then
               let res =
               let c = pgc () in
	       let q = ("select " ^ mprop ^ ".uri from " ^ mprop ^ " where " ^ mprop ^ ".value = '" ^ s ^ "'") in
	         pgresult_to_string_list (c#exec q)
               in
                 append (res,(property_ex rop path inv tl))
             else
	       let res =
               let c = pgc () in
	       let q = ("select " ^ mprop ^ ".value from " ^ mprop ^ " where " ^ mprop ^ ".uri = '" ^ s ^ "'") in
	         pgresult_to_string_list (c#exec q)
               in
                 append (res,(property_ex rop path inv tl))

;;