(***********************************************************************)
(*                                                                     *)
(*                               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 2013-03-09 19:17:26 CET by Kim Nguyen>
*)

open Ast
open Auto
open Utils


let ( => ) a b = (a, b)
let ( ++ ) a b = Ata.SFormula.or_ a b
let ( %% ) a b = Ata.SFormula.and_ a b
let ( @: ) a b = StateSet.add a b
(*
let add_attribute_prefix test =
  if QNameSet.is_finite test then
    QNameSet.fold (fun tag acc ->
      QNameSet.add (QName.add_attribute_prefix tag) acc)
      test QNameSet.empty
  else test
*)

module F = Ata.SFormula


let node_set = QNameSet.remove QName.document QNameSet.any
let star_set = QNameSet.diff QNameSet.any (
  List.fold_right (QNameSet.add)
    [ QName.document; QName.text; QName.attribute_map ]
    QNameSet.empty)
let attribute = QNameSet.singleton QName.attribute_map
let root_set = QNameSet.singleton QName.document

(* [compile_axis_test axis test q phi trans states] Takes an xpath
   [axis] and node [test], a formula [phi], a list of [trans]itions
   and a set of [states] and returns a formula [phi'], a new set of
   transitions, and a new set of states such that [phi'] holds iff
   there exists a node reachable through [axis]::[test] where [phi]
   holds.
*)

let compile_axis_test ?(block_attr=true) axis test phi trans states =
  let q = State.make () in
  let phi_attr = if block_attr then F.not_ F.is_attribute else F.true_ in
  let phi', trans', states' =
    match axis with
    | Self ->
        (F.stay q,
         (q, [  test => phi ]) :: trans,
         states)

    | Child ->
        (F.first_child q,
         (q, [ test => phi %% phi_attr;
               QNameSet.any => F.next_sibling q ]) :: trans,
         states)

    | Descendant self ->
        ((if self then F.stay q else F.first_child q),
         (q, [ test => phi %% phi_attr;
               QNameSet.any => F.first_child q ++ F.next_sibling q;
             ]) :: trans,
         states)

    | Parent ->
        let q' = State.make () in
        let move = F.parent q ++ F.previous_sibling q' in
        (move,
         (q, [ test => phi ])
         :: (q', [ QNameSet.any => move ]) :: trans,
         (q' @: states))

    | Ancestor self ->
        let q' = State.make () in
        let move = F.parent q ++ F.previous_sibling q' in
        (if self then F.stay q else move),
        (q, [ test => phi;
              QNameSet.any => move ])
        :: (q', [ QNameSet.any => move ]) :: trans,
        (q' @: states)

    | FollowingSibling | PrecedingSibling ->
        let move =
          if axis = PrecedingSibling then
            F.previous_sibling q
          else F.next_sibling q
        in
        move,
        (q, [ test => phi %% phi_attr;
              QNameSet.any => move ]) :: trans,
        states

    | Attribute ->
        (F.first_child q,
         (q, [ test => phi %% F.is_attribute;
               QNameSet.any => F.next_sibling q]) :: trans,
         states)
    | _ -> assert false

  in
  phi', trans', q @: states'


let compile_rev_axis_test block_attr axis test phi trans states =
  match axis with
  | Attribute ->
      compile_axis_test
        ~block_attr:false Parent test phi trans states
  | _ -> compile_axis_test
      ~block_attr:block_attr (invert_axis axis) test phi trans states

let rec compile_expr e trans states =
  match e with
  | Binop (e1, (And|Or as op), e2) ->
      let phi1, trans1, states1 = compile_expr e1 trans states in
      let phi2, trans2, states2 = compile_expr e2 trans1 states1 in
      (if op = Or then phi1 ++ phi2 else phi1 %% phi2),
      trans2,
      states2
  | Fun_call (f, [ e0 ]) when (QName.to_string f) = "not" ->
      let phi, trans0, states0 = compile_expr e0 trans states in
      (Ata.SFormula.not_ phi),
      trans0,
      states0
  | Path p -> compile_path p trans states

  | _ -> assert false
and compile_path paths trans states =
  List.fold_left (fun (aphi, atrans, astates) p ->
    let phi, ntrans, nstates = compile_single_path p atrans astates in
    (Ata.SFormula.or_ phi aphi),
    ntrans,
    nstates) (Ata.SFormula.false_,trans,states) paths

and compile_single_path p trans states =
  let steps =
    match p with
    | Absolute steps ->
        (Ancestor false, QNameSet.singleton QName.document, [])::steps
    | Relative steps -> steps
  in
  compile_step_list steps trans states

and compile_step_list l trans states =
  match l with
  | [] -> Ata.SFormula.true_, trans, states
  | (axis, test, elist) :: ll ->
      let phi0, trans0, states0 = compile_step_list ll trans states in
      let phi1, trans1, states1 =
        compile_axis_test axis test phi0 trans0 states0
      in
      List.fold_left (fun (aphi, atrans, astates) e ->
        let ephi, etrans, estates = compile_expr e atrans astates in
        aphi %% ephi, etrans, estates) (phi1, trans1, states1) elist

let compile_top_level_step_list l trans states =
  let rec loop l trans states block_attr phi_above =
    match l with
    | (axis, test, elist) :: [] ->
        let phi0, trans0, states0 =
          compile_rev_axis_test
            block_attr axis QNameSet.any phi_above trans states
        in
        let phi1, trans1, states1 =
          List.fold_left (fun (aphi, atrans, astates) e ->
            let ephi, etrans, estates = compile_expr e atrans astates in
            aphi %% ephi, etrans, estates) (phi0, trans0, states0) elist
        in
        let phi' =
          if axis = Attribute then
            F.is_attribute
          else
            F.not_ F.is_attribute
        in
        let _, trans2, states2 =
          compile_axis_test Self test (phi1 %% phi') trans1 states1
          in
        let marking_state =
          StateSet.choose (StateSet.diff states2 states1)
        in
        marking_state, trans2, states2
    | (axis, test, elist) :: ll ->
        let phi0, trans0, states0 =
          compile_rev_axis_test
            block_attr axis QNameSet.any phi_above trans states
        in
        let phi1, trans1, states1 =
          compile_axis_test Self test phi0 trans0 states0
        in
          let phi2, trans2, states2 =
            List.fold_left (fun (aphi, atrans, astates) e ->
              let ephi, etrans, estates = compile_expr e atrans astates in
              aphi %% ephi, etrans, estates) (phi1, trans1, states1) elist
          in
          loop ll trans2 states2 (axis != Attribute) phi2
    | _ -> assert false
  in
  let phi0, trans0, states0 =
    compile_axis_test
      Self
      (QNameSet.singleton QName.document)
      Ata.SFormula.true_
      trans
      states
  in
  loop l trans0 states0 true phi0
;;


let path p =
  let mstates, trans, states = List.fold_left (fun (ams, atrs, asts) p ->
    let ms, natrs, nasts =
      match p with
      | Absolute l | Relative l -> compile_top_level_step_list l atrs asts
    in
    (StateSet.add ms ams), natrs, nasts) (StateSet.empty, [], StateSet.empty) p
  in
  let a = Ata.create () in
  a.Ata.states <- states;
  a.Ata.selection_states <- mstates;
  List.iter (fun (q, l) ->
    List.iter (fun (lab, phi) ->
      Ata.add_trans a q lab phi
    ) l) trans;
  Ata.complete_transitions a;
  Ata.normalize_negations a;
  a