(* 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 PEH = ProofEngineHelpers 
module U  = CicUniv
module S = CicSubstitution
module PT = PrimitiveTactics
module T = Tacticals
module FNG = FreshNamesGenerator

let fail_msg1 = "no applicable simplification"

let error msg = raise (PET.Fail msg)

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

let strip_dependent_prods metasenv context t =
   let irl = MI.identity_relocation_list_for_metavariable context in
   let mk_meta metasenv  t =  
      let index = MI.new_meta metasenv [] in
      let metasenv = [index, context, t] @ metasenv in
      metasenv, Cic.Meta (index, irl)
   in
   let rec aux metasenv metas = function
      | Cic.Prod (Cic.Name _ as name, t1, t2) ->  
         let metasenv, meta = mk_meta metasenv t1 in    
	 aux metasenv (meta :: metas) (S.subst meta t2)
      | Cic.Prod (Cic.Anonymous, t1, _)       -> 
         let metasenv, meta = mk_meta metasenv t1 in	 
	 metasenv, metas, Some meta  
      | t                                     -> metasenv, metas, None 
   in
   aux metasenv [] t
   
let lapply_tac ?(mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name ~subst:[]) 
               (* ?(substs = []) *) ?to_what what =
   let letin_tac term = PT.letin_tac ~mk_fresh_name_callback term in   
   let lapply_tac (proof, goal) =
      let xuri, metasenv, u, t = proof in
      let _, context, _ = CicUtil.lookup_meta goal metasenv in
      let lemma, _ = TC.type_of_aux' metasenv context what U.empty_ugraph in
      let lemma = FNG.clean_dummy_dependent_types lemma in
      match strip_dependent_prods metasenv context lemma with
         | metasenv, metas, Some meta ->
	    let pippo =  Cic.Appl (what :: List.rev (meta :: metas)) in
	    Printf.eprintf "lapply: %s\n" (CicPp.ppterm pippo); flush stderr;
	    let outer_tac = letin_tac pippo in	 
	    let status = (xuri, metasenv, u, t), goal in
	    PET.apply_tactic outer_tac status
         | metasenv, metas, None      ->
	    failwith "lapply_tac: not implemented"
   in
   PET.mk_tactic lapply_tac
	 
(* 

   

let skip_metas p =
   let rec aux conts p =
      if p <= 0 then conts else aux (T.id_tac :: conts) (pred p) 
   in
   aux [] p
   
let get_conclusion context t =
   let rec aux p context = function 
      | Cic.Prod (name, t1, t2)  -> 
         aux (succ p) (Some (name, Cic.Decl t1) :: context) t2
      | Cic.LetIn (name, u1, t2) -> 
         aux (succ p) (Some (name, Cic.Def (u1, None)) :: context) t2
     | Cic.Cast (t2, t1)         -> aux p context t2
     | t                         -> p, context, t
   in aux 0 context t

let get_conclusion_dependences context t =
   let p, context, conclusion = get_conclusion context t in
   let rec aux l q = 
      if q <= 0 then l else 
      let b = TC.does_not_occur context (pred q) q conclusion in
      aux (b :: l) (pred q)
   in
   aux [] p

let solve_independents ?with_what deps =
  let rec aux p conts = function
     | []          -> p, conts
     | true :: tl  -> 
        let cont = PT.apply_tac ~term:(Cic.Rel (succ p)) in
	aux (succ p) (cont :: conts) tl
     | false :: tl -> aux (succ p) conts tl
   in 
   let p, conts = aux 0 [] deps in
   match with_what with
      | None   -> conts
      | Some t -> PT.apply_tac ~term:(S.lift p t) :: conts
	 
let lapply_tac ?(mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name ~subst:[]) 
               (* ?(substs = []) *) ?to_what what =
   let cut_tac term = PT.cut_tac ~mk_fresh_name_callback term in
   let intros_tac () = PT.intros_tac ~mk_fresh_name_callback () in
   let solve_conclusion_tac ?with_what p deps = 
      T.then_ ~start:(intros_tac ())
	      ~continuation:(  
         T.thens ~start:(PT.apply_tac what)
	         ~continuations:( [ T.id_tac; T.id_tac; T.id_tac ]
(*	    skip_metas p @ solve_independents ?with_what deps *) 
	 )
      )
   in
   let lapply_tac (proof, goal) =
      let xuri, metasenv, u, t = proof in
      let _, context, _ = CicUtil.lookup_meta goal metasenv in
      let lemma, _ = TC.type_of_aux' metasenv context what U.empty_ugraph in
      let lemma = FNG.clean_dummy_dependent_types lemma in
      match strip_dependent_prods metasenv context lemma with
         | metasenv, p, Some premise, conclusion ->
	    let deps = get_conclusion_dependences context conclusion in
	    let inner_tac = match to_what with
	       | None      -> 
	          T.thens ~start:(cut_tac premise)
		          ~continuations:[
                     solve_conclusion_tac ~with_what:(Cic.Rel 1) p deps;
	             T.id_tac
	          ]
	       | Some with_what -> 
                  solve_conclusion_tac ~with_what p deps
	    in	    
	    let outer_tac =
	       T.thens ~start:(cut_tac conclusion)
	               ~continuations:[T.id_tac; T.id_tac (* inner_tac *)]
	    in
*)   
(* fwd **********************************************************************)

let fwd_simpl_tac ~what ~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, _ = TC.type_of_aux' metasenv context what U.empty_ugraph 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