(* 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/.
 *)

open ProofEngineTypes

(* The default of term is the thesis of the goal to be prooved *)
let reduction_tac ~reduction ~pattern:(what,hyp_patterns,goal_pattern)
 (proof,goal)
=
  let curi,metasenv,pbo,pty = proof in
  let metano,context,ty = CicUtil.lookup_meta goal metasenv in
  let replace where terms =
   let terms, terms' = 
     List.split (List.map (fun (context, t) -> t, reduction context t) terms)
   in
    ProofEngineReduction.replace ~equality:(==) ~what:terms ~with_what:terms'
     ~where:where in
  let find_pattern_for name =
    try Some (snd(List.find (fun (n, pat) -> Cic.Name n = name) hyp_patterns))
    with Not_found -> None in
  let ty' = 
   let terms =
    ProofEngineHelpers.select ~context ~term:ty ~pattern:(what,goal_pattern)
   in
    replace ty terms in
  let context_len = List.length context in
  let context' =
    if hyp_patterns <> [] then
    List.fold_right
     (fun entry context ->
       match entry with
         None -> None::context
       | Some (name,Cic.Decl term) ->
           (match find_pattern_for name with
           | None -> entry::context
           | Some pat -> 
              try
               let what =
                match what with
                   None -> None
                 | Some what ->
                    let what,subst',metasenv' =
                     CicMetaSubst.delift_rels [] metasenv
                      (context_len - List.length context) what
                    in
                     assert (subst' = []);
                     assert (metasenv' = metasenv);
                     Some what in
               let terms =
                ProofEngineHelpers.select ~context ~term ~pattern:(what,pat) in
               let term' = replace term terms in
                Some (name,Cic.Decl term') :: context
              with
               CicMetaSubst.DeliftingARelWouldCaptureAFreeVariable ->
                raise
                 (ProofEngineTypes.Fail
                   ("The term the user wants to convert is not closed " ^
                    "in the context of the position of the substitution.")))
       | Some (name,Cic.Def (term, ty)) ->
           (match find_pattern_for name with
           | None -> entry::context
           | Some pat -> 
              try
               let what =
                match what with
                   None -> None
                 | Some what ->
                    let what,subst',metasenv' =
                     CicMetaSubst.delift_rels [] metasenv
                      (context_len - List.length context) what
                    in
                     assert (subst' = []);
                     assert (metasenv' = metasenv);
                     Some what in
               let terms =
                ProofEngineHelpers.select ~context ~term ~pattern:(what,pat) in
               let term' = replace term terms in
               let ty' =
                match ty with
                   None -> None
                 | Some ty ->
                    let terms = 
                     ProofEngineHelpers.select
                      ~context ~term:ty ~pattern:(what,pat)
                    in
                     Some (replace ty terms)
               in
                Some (name,Cic.Def (term',ty')) :: context
              with
               CicMetaSubst.DeliftingARelWouldCaptureAFreeVariable ->
                raise
                 (ProofEngineTypes.Fail
                   ("The term the user wants to convert is not closed " ^
                    "in the context of the position of the substitution.")))
     ) context []
   else
    context
  in
  let metasenv' = 
    List.map (function 
      | (n,_,_) when n = metano -> (metano,context',ty')
      | _ as t -> t
    ) metasenv
  in
  (curi,metasenv',pbo,pty), [metano]
;;

let simpl_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:ProofEngineReduction.simpl ~pattern);;

let reduce_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:ProofEngineReduction.reduce ~pattern);;
  
let whd_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:CicReduction.whd ~pattern);;

let normalize_tac ~pattern = 
 mk_tactic (reduction_tac ~reduction:CicReduction.normalize ~pattern );;

let fold_tac ~reduction ~pattern =
(*
 let fold_tac ~reduction ~pattern:(hyp_patterns,goal_pattern) ~term (proof,goal)
 =
  let curi,metasenv,pbo,pty = proof in
  let metano,context,ty = CicUtil.lookup_meta goal metasenv in
   let term' = reduction context term in
    let replace =
     ProofEngineReduction.replace ~equality:(=) ~what:[term'] ~with_what:[term]
    in
     let ty' = replace ty in
     let metasenv' =
      let context' =
       if also_in_hypotheses then
        List.map
         (function
             Some (n,Cic.Decl t) -> Some (n,Cic.Decl (replace t))
           | Some (n,Cic.Def (t,None))  -> Some (n,Cic.Def ((replace t),None))
           | None -> None
           | Some (_,Cic.Def (_,Some _)) -> assert false
         ) context
       else
        context
      in
       List.map
        (function
            (n,_,_) when n = metano -> (metano,context',ty')
          | _ as t -> t
        ) metasenv
      
     in
      (curi,metasenv',pbo,pty), [metano]
 in
  mk_tactic (fold_tac ~reduction ~pattern ~term)
*) assert false
;;