open Pure

(** Default logger *)
let log = Logging.pure_utils_log

(** We use this type as a key for lookups *)
type regular_fun_id = A.fun_id * T.RegionGroupId.id option
[@@deriving show, ord]

(** We use this type as a key for lookups *)
type fun_loop_id = A.FunDeclId.id * LoopId.id option [@@deriving show, ord]

module RegularFunIdOrderedType = struct
  type t = regular_fun_id

  let compare = compare_regular_fun_id
  let to_string = show_regular_fun_id
  let pp_t = pp_regular_fun_id
  let show_t = show_regular_fun_id
end

module RegularFunIdMap = Collections.MakeMap (RegularFunIdOrderedType)

module FunOrOpIdOrderedType = struct
  type t = fun_or_op_id

  let compare = compare_fun_or_op_id
  let to_string = show_fun_or_op_id
  let pp_t = pp_fun_or_op_id
  let show_t = show_fun_or_op_id
end

module FunOrOpIdMap = Collections.MakeMap (FunOrOpIdOrderedType)
module FunOrOpIdSet = Collections.MakeSet (FunOrOpIdOrderedType)

module FunLoopIdOrderedType = struct
  type t = fun_loop_id

  let compare = compare_fun_loop_id
  let to_string = show_fun_loop_id
  let pp_t = pp_fun_loop_id
  let show_t = show_fun_loop_id
end

module FunLoopIdMap = Collections.MakeMap (FunLoopIdOrderedType)
module FunLoopIdSet = Collections.MakeSet (FunLoopIdOrderedType)

let dest_arrow_ty (ty : ty) : ty * ty =
  match ty with
  | Arrow (arg_ty, ret_ty) -> (arg_ty, ret_ty)
  | _ -> raise (Failure "Unreachable")

let compute_primitive_value_ty (cv : primitive_value) : ty =
  match cv with
  | PV.Scalar sv -> Integer sv.PV.int_ty
  | Bool _ -> Bool
  | Char _ -> Char
  | String _ -> Str

let mk_typed_pattern_from_primitive_value (cv : primitive_value) : typed_pattern
    =
  let ty = compute_primitive_value_ty cv in
  { value = PatConstant cv; ty }

let mk_let (monadic : bool) (lv : typed_pattern) (re : texpression)
    (next_e : texpression) : texpression =
  let e = Let (monadic, lv, re, next_e) in
  let ty = next_e.ty in
  { e; ty }

(** Type substitution *)
let ty_substitute (tsubst : TypeVarId.id -> ty) (ty : ty) : ty =
  let obj =
    object
      inherit [_] map_ty
      method! visit_TypeVar _ var_id = tsubst var_id
    end
  in
  obj#visit_ty () ty

let make_type_subst (vars : type_var list) (tys : ty list) : TypeVarId.id -> ty
    =
  let ls = List.combine vars tys in
  let mp =
    List.fold_left
      (fun mp (k, v) -> TypeVarId.Map.add (k : type_var).index v mp)
      TypeVarId.Map.empty ls
  in
  fun id -> TypeVarId.Map.find id mp

(** Retrieve the list of fields for the given variant of a {!type:Aeneas.Pure.type_decl}.

    Raises [Invalid_argument] if the arguments are incorrect.
 *)
let type_decl_get_fields (def : type_decl)
    (opt_variant_id : VariantId.id option) : field list =
  match (def.kind, opt_variant_id) with
  | Enum variants, Some variant_id -> (VariantId.nth variants variant_id).fields
  | Struct fields, None -> fields
  | _ ->
      let opt_variant_id =
        match opt_variant_id with None -> "None" | Some _ -> "Some"
      in
      raise
        (Invalid_argument
           ("The variant id should be [Some] if and only if the definition is \
             an enumeration:\n\
             - def: " ^ show_type_decl def ^ "\n- opt_variant_id: "
          ^ opt_variant_id))

(** Instantiate the type variables for the chosen variant in an ADT definition,
    and return the list of the types of its fields *)
let type_decl_get_instantiated_fields_types (def : type_decl)
    (opt_variant_id : VariantId.id option) (types : ty list) : ty list =
  let ty_subst = make_type_subst def.type_params types in
  let fields = type_decl_get_fields def opt_variant_id in
  List.map (fun f -> ty_substitute ty_subst f.field_ty) fields

let fun_sig_substitute (tsubst : TypeVarId.id -> ty) (sg : fun_sig) :
    inst_fun_sig =
  let subst = ty_substitute tsubst in
  let inputs = List.map subst sg.inputs in
  let output = subst sg.output in
  let doutputs = List.map subst sg.doutputs in
  let info = sg.info in
  { inputs; output; doutputs; info }

(** We use this to check whether we need to add parentheses around expressions.
    We only look for outer monadic let-bindings.
    This is used when printing the branches of [if ... then ... else ...].

    Rem.: this function will *fail* if there are {!constructor:Aeneas.Pure.expression.Loop} nodes (you should call
    it on an expression where those nodes have been eliminated).
 *)
let rec let_group_requires_parentheses (e : texpression) : bool =
  match e.e with
  | Var _ | Const _ | App _ | Abs _ | Qualif _ -> false
  | Let (monadic, _, _, next_e) ->
      if monadic then true else let_group_requires_parentheses next_e
  | Switch (_, _) -> false
  | Meta (_, next_e) -> let_group_requires_parentheses next_e
  | Loop _ ->
      (* Should have been eliminated *)
      raise (Failure "Unreachable")

let is_var (e : texpression) : bool =
  match e.e with Var _ -> true | _ -> false

let as_var (e : texpression) : VarId.id =
  match e.e with Var v -> v | _ -> raise (Failure "Unreachable")

let is_global (e : texpression) : bool =
  match e.e with Qualif { id = Global _; _ } -> true | _ -> false

let is_const (e : texpression) : bool =
  match e.e with Const _ -> true | _ -> false

let ty_as_adt (ty : ty) : type_id * ty list =
  match ty with
  | Adt (id, tys) -> (id, tys)
  | _ -> raise (Failure "Unreachable")

(** Remove the external occurrences of {!Meta} *)
let rec unmeta (e : texpression) : texpression =
  match e.e with Meta (_, e) -> unmeta e | _ -> e

(** Remove *all* the meta information *)
let remove_meta (e : texpression) : texpression =
  let obj =
    object
      inherit [_] map_expression as super
      method! visit_Meta env _ e = super#visit_expression env e.e
    end
  in
  obj#visit_texpression () e

let mk_arrow (ty0 : ty) (ty1 : ty) : ty = Arrow (ty0, ty1)

(** Construct a type as a list of arrows: ty1 -> ... tyn  *)
let mk_arrows (inputs : ty list) (output : ty) =
  let rec aux (tys : ty list) : ty =
    match tys with [] -> output | ty :: tys' -> Arrow (ty, aux tys')
  in
  aux inputs

(** Destruct an expression into a list of nested lets *)
let rec destruct_lets (e : texpression) :
    (bool * typed_pattern * texpression) list * texpression =
  match e.e with
  | Let (monadic, lv, re, next_e) ->
      let lets, last_e = destruct_lets next_e in
      ((monadic, lv, re) :: lets, last_e)
  | _ -> ([], e)

(** Destruct an [App] expression into an expression and a list of arguments.

    We simply destruct the expression as long as it is of the form [App (f, x)].
 *)
let destruct_apps (e : texpression) : texpression * texpression list =
  let rec aux (args : texpression list) (e : texpression) :
      texpression * texpression list =
    match e.e with App (f, x) -> aux (x :: args) f | _ -> (e, args)
  in
  aux [] e

(** Make an [App (app, arg)] expression *)
let mk_app (app : texpression) (arg : texpression) : texpression =
  match app.ty with
  | Arrow (ty0, ty1) ->
      (* Sanity check *)
      assert (ty0 = arg.ty);
      let e = App (app, arg) in
      let ty = ty1 in
      { e; ty }
  | _ -> raise (Failure "Expected an arrow type")

(** The reverse of {!destruct_apps} *)
let mk_apps (app : texpression) (args : texpression list) : texpression =
  List.fold_left (fun app arg -> mk_app app arg) app args

(** Destruct an expression into a qualif identifier and a list of arguments,
 *  if possible *)
let opt_destruct_qualif_app (e : texpression) :
    (qualif * texpression list) option =
  let app, args = destruct_apps e in
  match app.e with Qualif qualif -> Some (qualif, args) | _ -> None

(** Destruct an expression into a qualif identifier and a list of arguments *)
let destruct_qualif_app (e : texpression) : qualif * texpression list =
  Option.get (opt_destruct_qualif_app e)

(** Destruct an expression into a function call, if possible *)
let opt_destruct_function_call (e : texpression) :
    (fun_or_op_id * ty list * texpression list) option =
  match opt_destruct_qualif_app e with
  | None -> None
  | Some (qualif, args) -> (
      match qualif.id with
      | FunOrOp fun_id -> Some (fun_id, qualif.type_args, args)
      | _ -> None)

let opt_destruct_result (ty : ty) : ty option =
  match ty with
  | Adt (Assumed Result, tys) -> Some (Collections.List.to_cons_nil tys)
  | _ -> None

let destruct_result (ty : ty) : ty = Option.get (opt_destruct_result ty)

let opt_destruct_tuple (ty : ty) : ty list option =
  match ty with Adt (Tuple, tys) -> Some tys | _ -> None

let mk_abs (x : typed_pattern) (e : texpression) : texpression =
  let ty = Arrow (x.ty, e.ty) in
  let e = Abs (x, e) in
  { e; ty }

let rec destruct_abs_list (e : texpression) : typed_pattern list * texpression =
  match e.e with
  | Abs (x, e') ->
      let xl, e'' = destruct_abs_list e' in
      (x :: xl, e'')
  | _ -> ([], e)

let destruct_arrow (ty : ty) : ty * ty =
  match ty with
  | Arrow (ty0, ty1) -> (ty0, ty1)
  | _ -> raise (Failure "Not an arrow type")

let rec destruct_arrows (ty : ty) : ty list * ty =
  match ty with
  | Arrow (ty0, ty1) ->
      let tys, out_ty = destruct_arrows ty1 in
      (ty0 :: tys, out_ty)
  | _ -> ([], ty)

let get_switch_body_ty (sb : switch_body) : ty =
  match sb with
  | If (e_then, _) -> e_then.ty
  | Match branches ->
      (* There should be at least one branch *)
      (List.hd branches).branch.ty

let map_switch_body_branches (f : texpression -> texpression) (sb : switch_body)
    : switch_body =
  match sb with
  | If (e_then, e_else) -> If (f e_then, f e_else)
  | Match branches ->
      Match
        (List.map
           (fun (b : match_branch) -> { b with branch = f b.branch })
           branches)

let iter_switch_body_branches (f : texpression -> unit) (sb : switch_body) :
    unit =
  match sb with
  | If (e_then, e_else) ->
      f e_then;
      f e_else
  | Match branches -> List.iter (fun (b : match_branch) -> f b.branch) branches

let mk_switch (scrut : texpression) (sb : switch_body) : texpression =
  (* Sanity check: the scrutinee has the proper type *)
  (match sb with
  | If (_, _) -> assert (scrut.ty = Bool)
  | Match branches ->
      List.iter
        (fun (b : match_branch) -> assert (b.pat.ty = scrut.ty))
        branches);
  (* Sanity check: all the branches have the same type *)
  let ty = get_switch_body_ty sb in
  iter_switch_body_branches (fun e -> assert (e.ty = ty)) sb;
  (* Put together *)
  let e = Switch (scrut, sb) in
  { e; ty }

(** Make a "simplified" tuple type from a list of types:
    - if there is exactly one type, just return it
    - if there is > one type: wrap them in a tuple
 *)
let mk_simpl_tuple_ty (tys : ty list) : ty =
  match tys with [ ty ] -> ty | _ -> Adt (Tuple, tys)

let mk_bool_ty : ty = Bool
let mk_unit_ty : ty = Adt (Tuple, [])

let mk_unit_rvalue : texpression =
  let id = AdtCons { adt_id = Tuple; variant_id = None } in
  let qualif = { id; type_args = [] } in
  let e = Qualif qualif in
  let ty = mk_unit_ty in
  { e; ty }

let mk_texpression_from_var (v : var) : texpression =
  let e = Var v.id in
  let ty = v.ty in
  { e; ty }

let mk_typed_pattern_from_var (v : var) (mp : mplace option) : typed_pattern =
  let value = PatVar (v, mp) in
  let ty = v.ty in
  { value; ty }

let mk_dummy_pattern (ty : ty) : typed_pattern =
  let value = PatDummy in
  { value; ty }

let mk_meta (m : meta) (e : texpression) : texpression =
  let ty = e.ty in
  let e = Meta (m, e) in
  { e; ty }

let mk_mplace_texpression (mp : mplace) (e : texpression) : texpression =
  mk_meta (MPlace mp) e

let mk_opt_mplace_texpression (mp : mplace option) (e : texpression) :
    texpression =
  match mp with None -> e | Some mp -> mk_mplace_texpression mp e

(** Make a "simplified" tuple value from a list of values:
    - if there is exactly one value, just return it
    - if there is > one value: wrap them in a tuple
 *)
let mk_simpl_tuple_pattern (vl : typed_pattern list) : typed_pattern =
  match vl with
  | [ v ] -> v
  | _ ->
      let tys = List.map (fun (v : typed_pattern) -> v.ty) vl in
      let ty = Adt (Tuple, tys) in
      let value = PatAdt { variant_id = None; field_values = vl } in
      { value; ty }

(** Similar to {!mk_simpl_tuple_pattern} *)
let mk_simpl_tuple_texpression (vl : texpression list) : texpression =
  match vl with
  | [ v ] -> v
  | _ ->
      (* Compute the types of the fields, and the type of the tuple constructor *)
      let tys = List.map (fun (v : texpression) -> v.ty) vl in
      let ty = Adt (Tuple, tys) in
      let ty = mk_arrows tys ty in
      (* Construct the tuple constructor qualifier *)
      let id = AdtCons { adt_id = Tuple; variant_id = None } in
      let qualif = { id; type_args = tys } in
      (* Put everything together *)
      let cons = { e = Qualif qualif; ty } in
      mk_apps cons vl

let mk_adt_pattern (adt_ty : ty) (variant_id : VariantId.id option)
    (vl : typed_pattern list) : typed_pattern =
  let value = PatAdt { variant_id; field_values = vl } in
  { value; ty = adt_ty }

let ty_as_integer (t : ty) : T.integer_type =
  match t with Integer int_ty -> int_ty | _ -> raise (Failure "Unreachable")

(* TODO: move *)
let type_decl_is_enum (def : T.type_decl) : bool =
  match def.kind with T.Struct _ -> false | Enum _ -> true | Opaque -> false

let mk_state_ty : ty = Adt (Assumed State, [])
let mk_result_ty (ty : ty) : ty = Adt (Assumed Result, [ ty ])
let mk_error_ty : ty = Adt (Assumed Error, [])
let mk_fuel_ty : ty = Adt (Assumed Fuel, [])

let mk_error (error : VariantId.id) : texpression =
  let ty = mk_error_ty in
  let id = AdtCons { adt_id = Assumed Error; variant_id = Some error } in
  let qualif = { id; type_args = [] } in
  let e = Qualif qualif in
  { e; ty }

let unwrap_result_ty (ty : ty) : ty =
  match ty with
  | Adt (Assumed Result, [ ty ]) -> ty
  | _ -> raise (Failure "not a result type")

let mk_result_fail_texpression (error : texpression) (ty : ty) : texpression =
  let type_args = [ ty ] in
  let ty = Adt (Assumed Result, type_args) in
  let id =
    AdtCons { adt_id = Assumed Result; variant_id = Some result_fail_id }
  in
  let qualif = { id; type_args } in
  let cons_e = Qualif qualif in
  let cons_ty = mk_arrow error.ty ty in
  let cons = { e = cons_e; ty = cons_ty } in
  mk_app cons error

let mk_result_fail_texpression_with_error_id (error : VariantId.id) (ty : ty) :
    texpression =
  let error = mk_error error in
  mk_result_fail_texpression error ty

let mk_result_return_texpression (v : texpression) : texpression =
  let type_args = [ v.ty ] in
  let ty = Adt (Assumed Result, type_args) in
  let id =
    AdtCons { adt_id = Assumed Result; variant_id = Some result_return_id }
  in
  let qualif = { id; type_args } in
  let cons_e = Qualif qualif in
  let cons_ty = mk_arrow v.ty ty in
  let cons = { e = cons_e; ty = cons_ty } in
  mk_app cons v

(** Create a [Fail err] pattern which captures the error *)
let mk_result_fail_pattern (error_pat : pattern) (ty : ty) : typed_pattern =
  let error_pat : typed_pattern = { value = error_pat; ty = mk_error_ty } in
  let ty = Adt (Assumed Result, [ ty ]) in
  let value =
    PatAdt { variant_id = Some result_fail_id; field_values = [ error_pat ] }
  in
  { value; ty }

(** Create a [Fail _] pattern (we ignore the error) *)
let mk_result_fail_pattern_ignore_error (ty : ty) : typed_pattern =
  let error_pat : pattern = PatDummy in
  mk_result_fail_pattern error_pat ty

let mk_result_return_pattern (v : typed_pattern) : typed_pattern =
  let ty = Adt (Assumed Result, [ v.ty ]) in
  let value =
    PatAdt { variant_id = Some result_return_id; field_values = [ v ] }
  in
  { value; ty }

let opt_unmeta_mplace (e : texpression) : mplace option * texpression =
  match e.e with Meta (MPlace mp, e) -> (Some mp, e) | _ -> (None, e)

let mk_state_var (id : VarId.id) : var =
  { id; basename = Some ConstStrings.state_basename; ty = mk_state_ty }

let mk_state_texpression (id : VarId.id) : texpression =
  { e = Var id; ty = mk_state_ty }

let mk_fuel_var (id : VarId.id) : var =
  { id; basename = Some ConstStrings.fuel_basename; ty = mk_fuel_ty }

let mk_fuel_texpression (id : VarId.id) : texpression =
  { e = Var id; ty = mk_fuel_ty }

let rec typed_pattern_to_texpression (pat : typed_pattern) : texpression option
    =
  let e_opt =
    match pat.value with
    | PatConstant pv -> Some (Const pv)
    | PatVar (v, _) -> Some (Var v.id)
    | PatDummy -> None
    | PatAdt av ->
        let fields = List.map typed_pattern_to_texpression av.field_values in
        if List.mem None fields then None
        else
          let fields_values = List.map (fun e -> Option.get e) fields in

          (* Retrieve the type id and the type args from the pat type (simpler this way *)
          let adt_id, type_args = ty_as_adt pat.ty in

          (* Create the constructor *)
          let qualif_id = AdtCons { adt_id; variant_id = av.variant_id } in
          let qualif = { id = qualif_id; type_args } in
          let cons_e = Qualif qualif in
          let field_tys =
            List.map (fun (v : texpression) -> v.ty) fields_values
          in
          let cons_ty = mk_arrows field_tys pat.ty in
          let cons = { e = cons_e; ty = cons_ty } in

          (* Apply the constructor *)
          Some (mk_apps cons fields_values).e
  in
  match e_opt with None -> None | Some e -> Some { e; ty = pat.ty }