(* This file is part of the Catala compiler, a specification language for tax
   and social benefits computation rules. Copyright (C) 2020 Inria, contributor:
   Denis Merigoux <denis.merigoux@inria.fr>

   Licensed under the Apache License, Version 2.0 (the "License"); you may not
   use this file except in compliance with the License. You may obtain a copy of
   the License at

   http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   License for the specific language governing permissions and limitations under
   the License. *)

open Catala_utils
open Shared_ast
module D = Dcalc.Ast
module A = Ast

let translate_var : 'm D.expr Var.t -> 'm A.expr Var.t = Var.translate

let rec translate_default
    (exceptions : 'm D.expr list)
    (just : 'm D.expr)
    (cons : 'm D.expr)
    (mark_default : 'm mark) : 'm A.expr boxed =
  let exceptions =
    List.map
      (fun except -> Expr.thunk_term (translate_expr except) (Mark.get except))
      exceptions
  in
  let pos = Expr.mark_pos mark_default in
  let exceptions =
    Expr.make_app
      (Expr.eop Op.HandleDefault
         [TAny, pos; TAny, pos; TAny, pos]
         (Expr.no_mark mark_default))
      [
        Expr.earray exceptions mark_default;
        Expr.thunk_term (translate_expr just) (Mark.get just);
        Expr.thunk_term (translate_expr cons) (Mark.get cons);
      ]
      pos
  in
  exceptions

and translate_expr (e : 'm D.expr) : 'm A.expr boxed =
  let m = Mark.get e in
  match Mark.remove e with
  | EEmptyError -> Expr.eraise EmptyError m
  | EErrorOnEmpty arg ->
    Expr.ecatch (translate_expr arg) EmptyError
      (Expr.eraise NoValueProvided m)
      m
  | EDefault { excepts; just; cons } ->
    translate_default excepts just cons (Mark.get e)
  | EPureDefault e -> translate_expr e
  | EOp { op; tys } -> Expr.eop (Operator.translate op) tys m
  | ( ELit _ | EApp _ | EArray _ | EVar _ | EExternal _ | EAbs _ | EIfThenElse _
    | ETuple _ | ETupleAccess _ | EInj _ | EAssert _ | EStruct _
    | EStructAccess _ | EMatch _ ) as e ->
    Expr.map ~f:translate_expr (Mark.add m e)
  | _ -> .

let translate_program (prg : 'm D.program) : 'm A.program =
  Bindlib.unbox (Program.map_exprs ~f:translate_expr ~varf:translate_var prg)