(* Copyright (C) 2004-2005, 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/
 *)

(* $Id$ *)

open Printf

let add_obj ~basedir uri obj status =
 let lemmas = LibrarySync.add_obj uri obj basedir in
  {status with GrafiteTypes.objects = uri::status.GrafiteTypes.objects},
   lemmas

let add_coercion ~basedir ~add_composites status uri =
 let compounds = LibrarySync.add_coercion ~add_composites ~basedir uri in
  {status with GrafiteTypes.coercions = uri :: status.GrafiteTypes.coercions},
   compounds
 
module OrderedUri =
struct
  type t = UriManager.uri * string
  let compare (u1, _) (u2, _) = UriManager.compare u1 u2
end

module UriSet = Set.Make (OrderedUri)

  (** @return l2 \ l1 *)
let uri_list_diff l2 l1 =
  let module S = UriManager.UriSet in
  let s1 = List.fold_left (fun set uri -> S.add uri set) S.empty l1 in
  let s2 = List.fold_left (fun set uri -> S.add uri set) S.empty l2 in
  let diff = S.diff s2 s1 in
  S.fold (fun uri uris -> uri :: uris) diff []

let time_travel ~present ~past =
  let objs_to_remove =
   uri_list_diff present.GrafiteTypes.objects past.GrafiteTypes.objects in
  let coercions_to_remove =
   uri_list_diff present.GrafiteTypes.coercions past.GrafiteTypes.coercions
  in
   List.iter (fun uri -> LibrarySync.remove_coercion uri) coercions_to_remove;
   List.iter LibrarySync.remove_obj objs_to_remove

let init () =
  LibrarySync.remove_all_coercions ();
  LibraryObjects.reset_defaults ();
  {
    GrafiteTypes.moo_content_rev = [];
    proof_status = GrafiteTypes.No_proof;
    options = GrafiteTypes.no_options;
    objects = [];
    coercions = [];
  }