(* Copyright (C) 2002, 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/.
 *)

let search_theorems_in_context ~status:((proof,goal) as status) =
  let module C = Cic in
  let module R = CicReduction in
  let module S = CicSubstitution in
  prerr_endline "Entro in search_context";
  let _,metasenv,_,_ = proof in
  let _,context,ty = CicUtil.lookup_meta goal metasenv in
  let rec find n = function 
      [] -> []
    | hd::tl ->
	let res =
	  try 
            Some (PrimitiveTactics.apply_tac ~status ~term:(C.Rel n)) 
	  with 
	    ProofEngineTypes.Fail _ -> None in
	(match res with
	  Some res -> res::(find (n+1) tl)
	| None -> find (n+1) tl)
  in
  try 
    let res = find 1 context in
    prerr_endline "Ho finito context";
    res 
  with Failure s -> 
    prerr_endline ("SIAM QUI = " ^ s); []
;;     


exception NotApplicableTheorem;;
exception MaxDepth;;

let depth = 5;;

let rec auto_tac mqi_handle level proof goal = 
prerr_endline "Entro in Auto_rec";
if level = 0 then
  (* (proof, [goal]) *)
  (prerr_endline ("NON ci credo");
   raise MaxDepth)
else 
  (* choices is a list of pairs proof and goallist *)
  let choices  =
    (search_theorems_in_context ~status:(proof,goal))@ 
    (TacticChaser.searchTheorems mqi_handle ~status:(proof,goal)) 
  in
  let rec try_choices = function
    [] -> raise NotApplicableTheorem
  | (proof,goallist)::tl ->
prerr_endline ("GOALLIST = " ^ string_of_int (List.length goallist));
       (try 
          List.fold_left 
            (fun proof goal ->
              (* It may happen that to close the first open goal
                 also some other goals are closed *)
              let _,metasenv,_,_ = proof in
               if List.exists (fun (i,_,_) -> i = goal) metasenv then
                let newproof =
                 auto_tac mqi_handle (level-1) proof goal
                in
                 newproof
               else
                (* goal already closed *)
                proof)
          proof goallist
        with 
	| MaxDepth
        | NotApplicableTheorem ->
            try_choices tl) in
 try_choices choices;;

let auto_tac mqi_handle ~status:(proof,goal) = 
  prerr_endline "Entro in Auto";
  try 
    let proof = auto_tac mqi_handle depth proof goal in
prerr_endline "AUTO_TAC HA FINITO";
    (proof,[])
  with 
  | MaxDepth -> assert false (* this should happens only if depth is 0 above *)
  | NotApplicableTheorem -> 
      prerr_endline("No applicable theorem");
      raise (ProofEngineTypes.Fail "No Applicable theorem");;

(* TODO se ce n'e' piu' di una, prende la prima che trova... sarebbe meglio
chiedere: find dovrebbe restituire una lista di hyp (?) da passare all'utonto con una
funzione di callback che restituisce la (sola) hyp da applicare *)

let assumption_tac ~status:((proof,goal) as status) =
  let module C = Cic in
  let module R = CicReduction in
  let module S = CicSubstitution in
   let _,metasenv,_,_ = proof in
    let _,context,ty = CicUtil.lookup_meta goal metasenv in
     let rec find n = function 
        hd::tl -> 
         (match hd with
             (Some (_, C.Decl t)) when
               (R.are_convertible context (S.lift n t) ty) -> n
           | (Some (_, C.Def (_,Some ty'))) when
               (R.are_convertible context ty' ty) -> n
           | (Some (_, C.Def (t,None))) when
               (R.are_convertible context
                (CicTypeChecker.type_of_aux' metasenv context (S.lift n t)) ty) -> n 
           | _ -> find (n+1) tl
         )
      | [] -> raise (ProofEngineTypes.Fail "Assumption: No such assumption")
     in PrimitiveTactics.apply_tac ~status ~term:(C.Rel (find 1 context))
;;

(* ANCORA DA DEBUGGARE *)

exception AllSelectedTermsMustBeConvertible;;

(* serve una funzione che cerchi nel ty dal basso a partire da term, i lambda
e li aggiunga nel context, poi si conta la lunghezza di questo nuovo
contesto e si lifta di tot... COSA SIGNIFICA TUTTO CIO'?????? *)

let generalize_tac
 ?(mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name)
 terms ~status:((proof,goal) as status)
=
  let module C = Cic in
  let module P = PrimitiveTactics in
  let module T = Tacticals in
   let _,metasenv,_,_ = proof in
   let _,context,ty = CicUtil.lookup_meta goal metasenv in
    let typ =
     match terms with
        [] -> assert false
      | he::tl ->
         (* We need to check that all the convertibility of all the terms *)
         List.iter
          (function t ->
            if not (CicReduction.are_convertible context he t) then 
             raise AllSelectedTermsMustBeConvertible
          ) tl ;
         (CicTypeChecker.type_of_aux' metasenv context he)
    in
     T.thens 
      ~start:
        (P.cut_tac 
         (C.Prod(
           (mk_fresh_name_callback metasenv context C.Anonymous typ), 
           typ,
           (ProofEngineReduction.replace_lifting_csc 1
             ~equality:(==) 
             ~what:terms
             ~with_what:(List.map (function _ -> C.Rel 1) terms)
             ~where:ty)
         )))
      ~continuations: [(P.apply_tac ~term:(C.Rel 1)) ; T.id_tac]
      ~status
;;