(********************************************************************)
(*                                                                  *)
(*  The Why3 Verification Platform   /   The Why3 Development Team  *)
(*  Copyright 2010-2022 --  Inria - CNRS - Paris-Saclay University  *)
(*                                                                  *)
(*  This software is distributed under the terms of the GNU Lesser  *)
(*  General Public License version 2.1, with the special exception  *)
(*  on linking described in file LICENSE.                           *)
(*                                                                  *)
(********************************************************************)

open Domain

module Make(A:DOMAIN) = struct
  type t = A.t list
  type man = A.man
  type env = A.env

  let create_manager = A.create_manager

  let hash _ _ = assert false
  let is_eq _ _ _ = assert false

  let bottom _ _ = []

  let top m e = [A.top m e]

  let canonicalize _ _ = () (*List.iter (A.canonicalize m)*)

  let print fmt = List.iter (fun b ->
      A.print fmt b;
      Format.fprintf fmt "@.";)

  let is_bottom man t =
    List.map (A.is_bottom man) t
    |> List.fold_left ( && ) true

  let is_leq man a b =
    (* not correct, we can have a <= b and this function saying no *)
    let one_in_many t =
      List.map (A.is_leq man t) b
      |> List.fold_left ( || ) false
    in
    List.map one_in_many a
    |> List.fold_left (&&) true

  let cleanup man a =
    List.filter (fun t -> not (A.is_bottom man t)) a

  let threshold = 10


  let join_one man = function
    | [] -> None
    | t::q -> Some (List.fold_left (A.join man) t q)

  let unwrap_domain = function
    | None -> []
    | Some t -> [t]

  let join_precise man a b =
    List.fold_left (fun a t ->
        let find_precise_join e =
          A.is_join_precise man t e
        in
        let a, found = List.fold_left (fun (a, found) e ->
            match find_precise_join e with
            | None -> e::a, found
            | Some c -> c::a, true
          ) ([], false) a in
        if found then
          a
        else
          t::a
      ) a b

  let cleanup_hard man c =
    let rec zip a = function
      | [] -> a
      | t::q ->
        let p = List.map (A.is_leq man t) (q @ a)
                |> List.fold_left (||) false in
        if p then
          zip a q
        else
          zip (t::a) q
    in
    zip [] c |> join_precise man []


  let join man a b =
    let a = cleanup man a in
    let b = cleanup man b in
    let a =
      if List.length a > threshold then
        join_one man a |> unwrap_domain
      else a
    in
    let b =
      if List.length b > threshold then
        join_one man b |> unwrap_domain
      else b
    in
    (* FIXME: violent *)
    let c = join_precise man a b in
    (*let c = ref c in
    let d = ref (cleanup_hard man !c) in
    while (List.length !d < List.length !c) do
      let tmp = cleanup_hard man !c in
      c := !d;
      d := tmp;
    done;
    !c*)
    cleanup_hard man c

  let is_join_precise man a b = Some (join man a b)




  let join_list man t =
    match t with
    | [] -> []
    | [t] -> t
    | t::q ->
      List.fold_left (join man) t q


  (* used once by loop, so it can be costly *)
  let widening man a b =
    let a = cleanup man a in
    let b = cleanup man b in
    let a =
      if List.length a > threshold then
        join_one man a |> unwrap_domain
      else a
    in
    let b =
      if List.length b > threshold then
        join_one man b |> unwrap_domain
      else b
    in
    let b_leq = List.map (fun b ->
        b, try
          List.find (fun a ->
              A.is_leq man a b) a
        with
        | Not_found -> b
      ) b
    in
    List.map (fun (k, v) ->
        A.widening man v k) b_leq |> cleanup man

  let meet_lincons_array man t e  = List.map (fun t -> A.meet_lincons_array man t e) t

  let forget_array man t a b =
    List.map (fun t -> A.forget_array man t a b) t

  let assign_linexpr man t v l t_ =
    (* FIXME: what if t_ <> None? *)
    assert (t_ = None);
    List.map (fun t -> A.assign_linexpr man t v l None) t

  let to_term env kn man t var_mapping =
    let t = cleanup_hard man t in
    let f = A.to_term env kn in
    let t = List.map (fun t -> f man t var_mapping) t
    |> Term.t_or_simp_l in
    t

  let push_label man env i t = List.map (A.push_label man env i) t

  let to_lincons_array man t =
    match join_one man t with
    | None -> assert false
    | Some t -> A.to_lincons_array man t

  let get_linexpr man t v =
    match join_one man t with
    | None -> None
    | Some s ->
      A.get_linexpr man s v

end
