(***********************************************************************)
(*                                                                     *)
(*                               TAToo                                 *)
(*                                                                     *)
(*                     Kim Nguyen, LRI UMR8623                         *)
(*                   Université Paris-Sud & CNRS                       *)
(*                                                                     *)
(*  Copyright 2010-2013 Université Paris-Sud and Centre National de la *)
(*  Recherche Scientifique. All rights reserved.  This file is         *)
(*  distributed under the terms of the GNU Lesser General Public       *)
(*  License, with the special exception on linking described in file   *)
(*  ../LICENSE.                                                        *)
(*                                                                     *)
(***********************************************************************)

(*
  Time-stamp: <Last modified on 2013-03-08 16:25:12 CET by Kim Nguyen>
*)

INCLUDE "utils.ml"
open Format
open Utils

module Make (T : Tree.Sig.S) = struct

  type cache = (int, StateSet.t) Hashtbl.t

  let get c t n =
    try Hashtbl.find c (T.preorder t n)
    with Not_found -> StateSet.empty

  let set c t n v = Hashtbl.replace c (T.preorder t n) v

  let eval_trans l ctx acc =
    List.fold_left (fun (acct, accs) ((q, phi) as trs) ->
      if StateSet.mem q accs then (acct, accs) else
      if Ata.SFormula.eval ctx phi then
        (acct, StateSet.add q accs)
      else
        (trs::acct, accs)
    ) ([], acc) l

  let top_down_run auto tree node cache i =
    let redo = ref false in
    let rec loop node is_left =
      if node != T.nil then begin
        let parent = T.parent tree node in
        let fc = T.first_child tree node in
        let ns = T.next_sibling tree node in
        let states0 = get cache tree node in
        let tag = T.tag tree node in
        let trans0 = Ata.get_trans auto auto.Ata.states tag in
        let parent_states = if parent == T.nil then auto.Ata.top_states else get cache tree parent in
        let fc_states = if fc == T.nil then auto.Ata.bottom_states else get cache tree fc in
        let ns_states = if ns == T.nil then auto.Ata.bottom_states else get cache tree ns in
        let is_root = parent == T.nil in
        let ctx0 =
          if is_left then
            Ata.make_ctx fc_states ns_states parent_states  StateSet.empty states0 is_left is_root
          else
            Ata.make_ctx fc_states ns_states StateSet.empty parent_states states0 is_left is_root
        in
        eprintf "-- [Iteration % 4d] --\n node: %a\n context: %a\n%!"
          i T.print_node node Ata.print_ctx ctx0;
        List.iter (fun (q, phi) -> eprintf " %a -> %a\n" State.print q Ata.SFormula.print phi) trans0;
        eprintf "----------------------\n%!";
        let trans1, states1 = eval_trans trans0 ctx0 StateSet.empty in
        if states1 != states0 then set cache tree node states1;
        let () = loop fc true in
        let ctx1 = {ctx0 with Ata.left = (get cache tree fc) ; Ata.epsilon = states1 } in
        let trans2, states2 = eval_trans trans1 ctx1 states1 in
        if states2 != states1 then set cache tree node states2;
        let () = loop ns false in
        let ctx2 = { ctx1 with Ata.right = (get cache tree ns); Ata.epsilon = states2 } in
        let _, states3 = eval_trans trans2 ctx2 states2 in
        if states3 != states2 then set cache tree node states3;
        if states0 != states3 && (not !redo) then redo := true
      end
    in
    loop node true;
    !redo

  let get_results auto tree node cache =
    let rec loop node acc =
      if node == T.nil then acc
      else
        let acc0 = loop (T.next_sibling tree node) acc in
        let acc1 = loop (T.first_child tree node) acc0 in

        if StateSet.intersect (get cache tree node) auto.Ata.selection_states then
          node::acc1
        else
          acc1
    in
    loop node []

  let eval auto tree node =
    let cache = Hashtbl.create 511 in
    let redo = ref true in
    let iter = ref 0 in
    while !redo do
      redo := top_down_run auto tree node cache !iter;
      incr iter;
    done;
    get_results auto tree node cache

end