(* Copyright (C) 2003-2005, 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/.
 *)

module C = Cic
module D = Deannotate
module I = CicInspect

module P = ProceduralPreprocess

type conclusion = (int * int) option

(* debugging ****************************************************************)

let string_of_entry inverse =
   if I.S.mem 0 inverse then "C" else
   if I.S.is_empty inverse then "I" else "P"

let to_string (classes, rc) =
   let linearize = String.concat " " (List.map string_of_entry classes) in
   match rc with
      | None        -> linearize
      | Some (i, j) -> Printf.sprintf "%s %u %u" linearize i j

let out_table b =
   let map i (_, inverse) =
      let map i tl = Printf.sprintf "%2u" i :: tl in 
      let iset = String.concat " " (I.S.fold map inverse []) in
      Printf.eprintf "%2u|%s\n" i iset
   in
   Array.iteri map b;
   prerr_newline ()
   
(****************************************************************************)

let id x = x

let classify_conclusion = function
   | C.Rel i                -> Some (i, 0)
   | C.Appl (C.Rel i :: tl) -> Some (i, List.length tl)
   | _                      -> None

let classify c t =
try   
   let vs, h = P.split c t in
   let rc = classify_conclusion (List.hd vs) in
   let map (b, h) v = (I.get_rels_from_premise h v, I.S.empty) :: b, succ h in
   let l, h = List.fold_left map ([], 0) vs in
   let b = Array.of_list (List.rev l) in
   let mk_closure b h =
      let map j = if j < h then I.S.union (fst b.(j)) else id in 
      for i = pred h downto 0 do
         let direct, unused = b.(i) in
	 b.(i) <- I.S.fold map direct direct, unused 
      done; b
   in
   let b = mk_closure b h in
   let rec mk_inverse i direct =
      if I.S.is_empty direct then () else
      let j = I.S.choose direct in
      if j < h then
         let unused, inverse = b.(j) in 
         b.(j) <- unused, I.S.add i inverse
       else ();
       mk_inverse i (I.S.remove j direct)
   in
   let map i (direct, _) = mk_inverse i direct in
   Array.iteri map b;
(*   out_table b; *)
   List.rev_map snd (List.tl (Array.to_list b)), rc
with Invalid_argument _ -> failwith "Classify.classify"