(* 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 induction_tac ~term ~status:((proof,goal) as status) =
  let module C = Cic in
  let module R = CicReduction in
  let module P = PrimitiveTactics in
  let module T = Tacticals in
  let module S = ProofEngineStructuralRules in
  let module U = UriManager in
   let (_,metasenv,_,_) = proof in
    let _,context,ty = List.find (function (m,_,_) -> m=goal) metasenv in
     let termty = T.type_of_aux' metasenv context term in
     let uri,exp_named_subst,typeno,args =
      match termty with
         C.MutInd (uri,typeno,exp_named_subst) -> (uri,exp_named_subst,typeno,[])
       | C.Appl ((C.MutInd (uri,typeno,exp_named_subst))::args) -> (uri,exp_named_subst,typeno,args)
       | _ -> raise (ProofEngineTypes.Fail "Induction: Not an Inductive Type to Eliminate")
     in
      let eliminator_uri =
       let base = U.buri_of_uri uri in
       let name =
        match CicEnvironment.get_obj uri with
           C.InductiveDefinition (tys,_,_) ->
            let (name,_,_,_) = List.nth tys typeno in
             name
         | _ -> assert false
       in
       let ext =
        match T.type_of_aux' metasenv context ty with
           C.Sort C.Prop -> "_ind"
         | C.Sort C.Set  -> "_rec"
         | C.Sort C.Type -> "_rect"
         | _ -> assert false
       in
        U.uri_of_string (base ^ "/" ^ name ^ ext ^ ".con")
      in 
       apply_tac ~term:(C.Const (eliminator_uri , exp_named_subst))	(* come mi devo comportare con gli args??? *)
;;
*)

let elim_type_tac ~term ~status =
  let module C = Cic in
  let module P = PrimitiveTactics in
  let module T = Tacticals in
   T.thens
    ~start: (P.cut_tac ~term)
    ~continuations:[ P.elim_intros_simpl_tac ~term:(C.Rel 1) ; T.id_tac ]
    ~status
;;

(* Questa era gia' in ring.ml!!!! NB: adesso in ring non c'e' piu' :-)
let elim_type_tac ~term ~status =
  warn "in Ring.elim_type_tac";
  Tacticals.thens ~start:(cut_tac ~term)
   ~continuations:[elim_simpl_intros_tac ~term:(Cic.Rel 1) ; Tacticals.id_tac] ~status
*)


(* PROVE DI DECOMPOSE

(* in realta' non so bene cosa contiene la lista what, io ho supposto contenga dei term (Const uri) *)
let decompose_tac ~what ~where ~status:((proof,goal) as status) =
  let module C = Cic in
  let module R = CicReduction in
  let module P = PrimitiveTactics in
  let module T = Tacticals in
  let module S = ProofEngineStructuralRules in

   let rec decomposing ty what =
    match (what) with
       [] -> C.Implicit (* qui mi servirebbe un termine per cui elim_simpl_intros fallisce *)
     | hd::tl as what ->
        match ty with
           (C.Appl (hd::_)) -> hd
         | _ -> decomposing ty tl
    in

   let (_,metasenv,_,_) = proof in
    let _,context,_ = List.find (function (m,_,_) -> m=goal) metasenv in
     T.repeat_tactic
       ~tactic:(T.then_
                   ~start:(P.elim_simpl_intros_tac ~term:(decomposing (R.whd context where) what))
                   ~continuation:(S.clear ~hyp:(Some ((C.Name "name"), (C.Decl where))))                (* ma che ipotesi sto cancellando??? *)
               )
       ~status
;;


let decompose_tac ~clist ~status:((proof,goal) as status) =
  let module C = Cic in
  let module R = CicReduction in
  let module P = PrimitiveTactics in
  let module T = Tacticals in
  let module S = ProofEngineStructuralRules in
   let (_,metasenv,_,_) = proof in
    let _,context,ty = List.find (function (m,_,_) -> m=goal) metasenv in

     let rec repeat_elim ~term ~status =                (* term -> status -> proof * (goal list) *)
      try
       let (proof, goallist) =
        T.then_
           ~start:(P.elim_simpl_intros_tac ~term)
           ~continuation:(S.clear ~hyp:(Some ((C.Name "name"), (C.Decl ty))))                (* non so che ipotesi sto cancellando??? *)
           ~status
        in
         let rec step proof goallist =
          match goallist with
             [] -> (proof, [])
           | hd::tl ->
              let (proof', goallist') = repeat_elim ~term ~status:(proof, hd) in
               let (proof'', goallist'') = step proof' tl in
                proof'', goallist'@goallist''
          in
           step proof goallist
       with
        (Fail _) -> T.id_tac

    in
                                                                  let rec decomposing ty clist =             (* term -> (term list) -> bool *)
      match (clist) with
        [] -> false
      | hd::tl as clist ->
         match ty with
           (C.Appl (hd::_)) -> true
         | _ -> decomposing ty tl

      in
       let term = decomposing (R.whd context ty) clist in
        if (term == C.Implicit)
         then (Fail "Decompose: nothing to decompose or no application")
         else repeat_elim ~term ~status
;;
*)

let decompose_tac ~clist ~status =
  let module C = Cic in
  let module R = CicReduction in
  let module P = PrimitiveTactics in
  let module T = Tacticals in
  let module S = ProofEngineStructuralRules in

   let rec choose ty =
    function
       [] -> C.Implicit (* a cosa serve? *)
     | hd::tl ->
        match ty with
           (C.Appl (hd::_)) -> hd
         | _ -> choose ty tl
     in

    let decompose_one_tac ~clist ~status:((proof,goal) as status) =
     let (_,metasenv,_,_) = proof in
      let _,context,ty = List.find (function (m,_,_) -> m=goal) metasenv in
       let term = choose (R.whd context ty) clist in
        if (term == C.Implicit)
         then raise (ProofEngineTypes.Fail "Decompose: nothing to decompose or no application")
         else T.then_
                 ~start:(P.elim_intros_simpl_tac ~term)
                 ~continuation:(S.clear ~hyp:(List.hd context))
(*				(S.clear ~hyp:(Some ((C.Name "FOO") , (C.Decl ty))))                (* ma che ipotesi sto cancellando??? *)*)
                 ~status
     in
      T.repeat_tactic ~tactic:(decompose_one_tac ~clist) ~status
;;