(* 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/.
 *)

module MI = CicMkImplicit
module TC = CicTypeChecker 
module PET = ProofEngineTypes 
module U  = CicUniv
module S = CicSubstitution
module PT = PrimitiveTactics

(*
let module R = CicReduction
*)

let fail_msg0 = "not a declaration of the current context"
let fail_msg1 = "no applicable simplification"

let error msg = raise (PET.Fail msg)

let rec declaration name = function 
   | []                                           -> error fail_msg0
   | Some (hyp, Cic.Decl ty) :: _ when hyp = name -> ty
   | _ :: tail                                    -> declaration name tail 

(* lapply *******************************************************************)

let lapply_tac ?(mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name ~subst:[])
               ?(substs = []) what =
   let rec strip_dependent_prods metasenv context ss = function
      | Cic.Prod (name, t1, t2) as t -> 
        if TC.does_not_occur context 0 1 t2 then metasenv, ss, t else 
	let metasenv, index = MI.mk_implicit metasenv [] context in 
	let rs = MI.identity_relocation_list_for_metavariable context in
        let e, s = Some (name, Cic.Decl t1), Some (Cic.Meta (index, rs)) in
	strip_dependent_prods metasenv (e :: context) (s :: ss) t2
      | t    -> metasenv, ss, t
   in
   let update_metasenv metasenv ((xuri, _, u,t), goal) =
      ((xuri, metasenv, u,t), goal)
   in
   let lapply_tac status =
      let (proof, goal) = status in
      let _,metasenv,_,_ = proof in
      let _,context,ty = CicUtil.lookup_meta goal metasenv in
      let lemma, _ = TC.type_of_aux' metasenv context what U.empty_ugraph in
      let metasenv, substs, stripped_lemma = strip_dependent_prods metasenv context [] lemma in
      let status = update_metasenv metasenv status in
      let holed_lemma = S.subst_meta substs stripped_lemma in      
      PET.apply_tactic (PT.cut_tac ~mk_fresh_name_callback holed_lemma) status
   in
   PET.mk_tactic lapply_tac

(* fwd **********************************************************************)

let fwd_simpl_tac ~hyp ~dbd =
   let fwd_simpl_tac status =
      let (proof, goal) = status in
      let _,metasenv,_,_ = proof in
      let _,context,ty = CicUtil.lookup_meta goal metasenv in
      let major = declaration hyp context in 
      match  MetadataQuery.fwd_simpl ~dbd major with
         | []       -> error fail_msg1
         | uri :: _ -> prerr_endline (UriManager.string_of_uri uri); (proof, [])  
   in
   PET.mk_tactic fwd_simpl_tac