(* 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/.
 *)

(*
 * implementazione del'interprete MathQL
 *)
open Mathql;;
open Eval;;
open Utility;;
open Dbconn;;
open Pattern;;
open Union;;
open Intersect;;
open Diff;;
open Sortedby;;
open Use;;
open Select;;

let fi_to_string fi =
 match fi with
    (None, _)   ->
     ""
 |  (Some i, y) ->
     "#xpointer(1/"       ^
     string_of_int i      ^
     (
      match y with
         None   ->
          ""
      |  Some j ->
          "/" ^ (string_of_int j)
     )                    ^
     ")"
;;

(*
 * inizializzazione della connessione al database
 *)
let init () = Dbconn.init ();;

(*
 * esecuzione di una query
 *
 * parametri:
 * q
 *
 * output: string list list; risultato internto formato da uri + contesto.
 *)
let rec execute_ex q =
   match q with
      MQSelect (apvar, alist, abool) ->
       select_ex apvar (execute_ex alist) abool
   |  MQUsedBy (alist, asvar) ->
       use_ex (execute_ex alist) asvar "refObj"
   |  MQUse (alist, asvar) ->
       use_ex (execute_ex alist) asvar "backPointer"
   |  MQPattern (apreamble, apattern, afragid) ->
       let _ = print_endline ("*********" ^ (fi_to_string afragid)); flush stdout in
       pattern_ex apreamble apattern afragid
   |  MQUnion (l1, l2) ->
       union_ex (execute_ex l1) (execute_ex l2)
   |  MQDiff (l1, l2) ->
       diff_ex (execute_ex l1) (execute_ex l2)
   |  MQSortedBy (l, o, f) ->
       sortedby_ex (execute_ex l) o f
   |  MQIntersect (l1, l2) ->
       intersect_ex (execute_ex l1) (execute_ex l2)
;;

(*
 * converte il risultato interno di una query (uri + contesto)
 * in un risultato di sole uri
 *
 * parametri:
 * l: string list list;
 *
 * output: mqresult;
 *
 * note:
 * il tipo del risultato mantenuto internamente e' diverso dal tipo di risultato
 * restituito in output poiche', mentre chi effettua le query vuole come risultato
 * solo le eventuali uri che soddisfano le query stesse, internamente ad una uri
 * sono associati anche i valori delle variabili che ancora non sono state valutate
 * perche', ad esempio, si trovano in altri rami dell'albero.
 *
 * Esempio:
 * SELECT x IN USE PATTERN "cic:/**.con" POSITION $a WHERE $a IS MainConclusion
 * L'albero corrispondente a questa query e':
 *
 *                  SELECT
 *                /   |    \
 *               x   USE    IS
 *                  /   \    /\
 *           PATTERN    $a  $a MainConclusion
 *
 * Nel momento in cui si esegue il ramo USE non sono noti i vincoli sullla variabile $a
 * percui e' necessario considerare, oltre alle uri, i valori della variabile per i quali
 * la uri puo' far parte del risultato.
 *)
let xres_to_res l =
 let tmp = List.map List.hd (List.tl l) in
  MQRefs
   (List.map
    (function l ->
      match Str.split (Str.regexp ":\|#\|/") l with
         hd::tl -> (
          match List.rev tl with
             ")"::n::"xpointer(1"::tail    ->
              (
               hd,
               List.fold_left
                (fun par t ->
                 match par with
                    [] -> [MQString t] 
                 |  _  -> (MQString t) :: MQSlash :: par
                )
                []
                tail, 
               (Some (int_of_string n), None)
              )
          |  ")"::n::m::"xpointer(1"::tail ->
              (
               hd,
               List.fold_left
                (fun par t ->
                 match par with
                    [] -> [MQString t] 
                 |  _  -> (MQString t) :: MQSlash :: par
                )
                []
                tail,
               (Some (int_of_string m), Some (int_of_string n))
              )
          |  tail                          ->
              (
               hd,
               List.fold_left
                (fun par t ->
                 match par with
                    [] -> [MQString t] 
                 |  _  -> (MQString t) :: MQSlash :: par
                )
                []
                tail, 
               (None, None)
              )
      )  
      |  [] -> assert false
    )
    tmp
   )
;;


(*
 * 
 *)
let execute q =
 match q with
    MQList qq -> xres_to_res (execute_ex qq)
;;

(*
 * chiusura della connessione al database
 *)
let close () = Dbconn.close ();;