(* Copyright (C) 2004, 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://helm.cs.unibo.it/
 *)

open Printf

module Constr = MetadataConstraints

let locate ~(dbh:Dbi.connection) name =
  let query =
    dbh#prepare (sprintf "SELECT value FROM %s WHERE source = \"%s\""
      MetadataTypes.name_tbl name)
  in
  query#execute [];
  List.map (function [`String s] -> s | _ -> assert false) (query#fetchall ())

let match_term ~(dbh:Dbi.connection) ty =
  let metadata = MetadataExtractor.compute ~body:None ~ty in
  Constr.at_least ~dbh metadata

let nonvar (_, s) =
  let len = String.length s in
  let suffix = String.sub s (len-4) 4 in
  not (suffix  = ".var")

let ( ** ) x y = int_of_float ((float_of_int x) ** (float_of_int y))

let signature_of_hypothesis context =
  List.fold_left
    (fun set hyp ->
      match hyp with
      | None -> set
      | Some (_, Cic.Decl t)
      | Some (_, Cic.Def (t, _)) ->
          Constr.StringSet.union set (Constr.constants_of t))
    Constr.StringSet.empty context

let hint ~(dbh:Dbi.connection) ?signature ((proof, goal) as status) =
  let (_, metasenv, _, _) = proof in
  let (_, context, ty) = CicUtil.lookup_meta goal metasenv in
  let (uris, (main, sig_constants)) =
    match signature with
    | Some signature -> (Constr.sigmatch ~dbh signature, signature)
    | None -> (Constr.cmatch' ~dbh ty, Constr.signature_of ty)
  in
  let uris = List.filter nonvar uris in
(*
  let concl_constants =
    match main with
    | None -> sig_constants
    | Some (main, types) ->
        List.fold_right Constr.StringSet.add sig_constants (main :: types)
  in
*)
  let types_constants =
    match main with
    | None -> Constr.StringSet.empty
    | Some (main, types) ->
        List.fold_right Constr.StringSet.add (main :: types)
          Constr.StringSet.empty
  in
  let hyp_constants =
    Constr.StringSet.diff (signature_of_hypothesis context) types_constants
  in
  let other_constants = Constr.StringSet.union sig_constants hyp_constants in
  let uris = 
    if (List.length uris < 2 ** (Constr.StringSet.cardinal other_constants))
    then begin
      prerr_endline
        "MetadataQuery: large signature, falling back to old method";
      List.filter (Filter_auto.filter_new_constants ~dbh all_constants main)
        uris
    end else
      Filter_auto.filter_uris ~dbh all_constants uris main
  in
  List.map
    (fun uri ->
      (uri,
       ProofEngineTypes.apply_tactic
        (PrimitiveTactics.apply_tac ~term:(CicUtil.term_of_uri uri))
        status))