(* This file is part of the Catala compiler, a specification language for tax
   and social benefits computation rules. Copyright (C) 2022 Inria, contributor:
   Aymeric Fromherz <aymeric.fromherz@inria.fr>, 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. *)

(** Common code for handling the IO of all proof backends supported *)

open Shared_ast

module type Backend = sig
  val init_backend : unit -> unit

  type backend_context

  val make_context : decl_ctx -> backend_context

  type vc_encoding

  val print_encoding : vc_encoding -> string

  type model
  type solver_result = ProvenTrue | ProvenFalse of model option | Unknown

  val solve_vc_encoding : backend_context -> vc_encoding -> solver_result
  val print_model : backend_context -> model -> string
  val is_model_empty : model -> bool

  val translate_expr :
    backend_context -> typed Dcalc.Ast.expr -> backend_context * vc_encoding

  val encode_asserts :
    backend_context -> typed Dcalc.Ast.expr -> backend_context
end

module type BackendIO = sig
  val init_backend : unit -> unit

  type backend_context

  val make_context : decl_ctx -> backend_context

  type vc_encoding

  val translate_expr :
    backend_context -> typed Dcalc.Ast.expr -> backend_context * vc_encoding

  val encode_asserts :
    backend_context -> typed Dcalc.Ast.expr -> backend_context

  type model

  type vc_encoding_result =
    | Success of vc_encoding * backend_context
    | Fail of string

  val print_negative_result :
    Conditions.verification_condition ->
    backend_context ->
    model option ->
    string

  val encode_and_check_vc :
    decl_ctx -> Conditions.verification_condition * vc_encoding_result -> bool
  (** [encode_and_check_vc] spawns a new Z3 solver and tries to solve the
      expression [vc]. Returns [true] if the vs was proven true and [false]
      otherwise. **)
end

module MakeBackendIO : functor (B : Backend) ->
  BackendIO
    with type vc_encoding = B.vc_encoding
     and type backend_context = B.backend_context
     and type model = B.model