(*
 * implementazione dei comandi USE/USED BY
 *)

open Utility;;
open Dbconn;;

(*
 * implementazione dei comandi USE/USED BY
 *
 * parametri:
 * alist: string list list; lista su cui eseguire il comando USE/USED BY
 * asvar: string; nome della variabile del comando use
 * usek: string; nome della tabella in cui ricercare le occorrenze;
 *               la distinzione fra l'esecuzione del comando USE e USED BY
 *               sta nell'utilizzo della tabella 'backPointer' per USE
 *               e 'refObj' per USED BY
 *
 * output: string list list; lista su cui e' stato eseguito il 
 *                           comando USE/USED BY
 *
 * TODO
 * USE e USED BY sono identici dal punto di vista algoritmico, per questo
 * sono stati accorpati in una sola funzione; stilisticamente, sarebbe meglio
 * avere due implementazioni distinte...
 *)
let use_ex alist asvar usek =
 let c = pgc () in
  List.fold_left
   (fun parziale xres ->
    let r1 = pgresult_to_string (c#exec
     ("select att0 from property where att2='" ^ usek ^ "'"))
    and r2 = pgresult_to_string (c#exec
     "select att0 from property where att2='position'")
    and r3 = pgresult_to_string (c#exec
     "select att0 from property where att2='occurrence'")
    in
     let res = c#exec (
      "select distinct t" ^ r3 ^ ".att1, t" ^ r2 ^ ".att1 " ^
      "from t" ^ r3 ^ ", t" ^ r2 ^ ", t" ^ r1 ^ " " ^
      "where " ^ "t" ^ r1 ^ ".att0 = '" ^ (List.hd xres) ^ "' and t" ^ r1 ^
      ".att1 = t" ^ r2 ^ ".att0 and t" ^ r1 ^ ".att1 = t" ^ r3 ^
      ".att0")
     in
      parziale
      @
      if not (List.mem asvar (List.tl (List.hd alist))) then
       List.map
        (fun l -> [List.hd l] @ List.tl xres @ List.tl l)
        res#get_list
      else
       List.map
        (fun l ->
         let t =
          match xres with
             hd::tl -> (List.hd l)::tl
          |  [] -> []
         in
	  List.map
           snd
	   (Utility.set_assoc
	    asvar
	    (List.hd (List.tl l))
	    (List.combine (List.hd alist) t)
	   )
        )
        (List.find_all
         (fun l ->
          let currv =
           List.hd (List.tl l)
          and xresv =
           try (
            List.assoc
             asvar
             (List.combine
              (List.tl (List.hd alist))
              (List.tl xres)
             )
           ) with
            Not_found -> ""
          in
           xresv = "" or xresv = currv
         )
         res#get_list
        )
   )
   [ (List.hd alist)
     @
     if not (List.mem asvar (List.tl (List.hd alist))) then
      [asvar]
     else
      []
   ]
   (List.tl alist)
;;

(** TEST **)

(*
let use_ex alist asvar = 
 if (List.find_all asvar (List.tl (List.hd alist))) = [] then
  use_ex_nc alist asvar
 else
  use_ex_co alist asvar
;;

List.map
 (fun l -> 
  let t =
   match xres with
      hd::tl -> (List.hd l)::tl
   |  [] -> []
  in
   let hash = List.combine (List.hd alist) t in
    snd (set_assoc asvar (snd l) hash)
 )
 (List.find_all
  (fun l ->
   let currv =
    List.hd (List.tl l)
   and xresv =
    try (
     List.assoc asvar (List.combine (List.tl (List.hd alist)) (List.tl xres))
    ) with
     Not_found -> ""
   in
    xresv = "" or xresv = currv
  )
  res#get_list
 )
;;
*)