(*
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *)

(** Utility module for translating unary and binary operations and compound assignments *)

open! IStd
module L = Logging

(* Returns a pair ([binary_expression], instructions) for binary operator representing a *)
(* CompoundAssignment. "binary_expression" is returned when we are calculating an expression*)
(* "instructions" is not empty when the binary operator is actually a statement like an *)
(* assignment. *)
let compound_assignment_binary_operation_instruction boi_kind (e1, t1) typ e2 loc =
  let instrs =
    let bop =
      match boi_kind with
      | `AddAssign ->
          if Typ.is_pointer t1 then Binop.PlusPI else Binop.PlusA (Typ.get_ikind_opt typ)
      | `SubAssign ->
          if Typ.is_pointer t1 then Binop.MinusPI else Binop.MinusA (Typ.get_ikind_opt typ)
      | `MulAssign ->
          Binop.Mult (Typ.get_ikind_opt typ)
      | `DivAssign ->
          Binop.Div
      | `ShlAssign ->
          Binop.Shiftlt
      | `ShrAssign ->
          Binop.Shiftrt
      | `RemAssign ->
          Binop.Mod
      | `AndAssign ->
          Binop.BAnd
      | `OrAssign ->
          Binop.BOr
      | `XorAssign ->
          Binop.BXor
    in
    let id = Ident.create_fresh Ident.knormal in
    [Sil.Load (id, e1, typ, loc); Sil.Store (e1, typ, Exp.BinOp (bop, Exp.Var id, e2), loc)]
  in
  (e1, instrs)


(** Returns a pair ([binary_expression], instructions). "binary_expression" is returned when we are
   calculating an expression "instructions" is not empty when the binary operator is actually a
   statement like an assignment. *)
let binary_operation_instruction source_range boi ((e1, t1) as e1_with_typ) typ (e2, t2) loc =
  let binop_exp ?(change_order = false) op =
    if change_order then Exp.BinOp (op, e2, e1) else Exp.BinOp (op, e1, e2)
  in
  match boi.Clang_ast_t.boi_kind with
  (* Note: Pointers to members that are not statically known are not
     expressible in Sil. The translation of the PtrMem ops treats the field as
     an integer offset, which is itself semantically ok though too low-level,
     but the translation of the argument expressions does not compute such
     offsets and instead passes the member pointer at type 'void'. *)
  | `PtrMemD | `PtrMemI ->
      CFrontend_config.unimplemented __POS__ source_range
        "Pointer-to-member constructs are unsupported. Got '%a'."
        (Pp.to_string ~f:Clang_ast_j.string_of_binary_operator_info)
        boi
  | `Add ->
      if Typ.is_pointer t1 then (binop_exp Binop.PlusPI, [])
      else if Typ.is_pointer t2 then (binop_exp ~change_order:true Binop.PlusPI, [])
      else (binop_exp (Binop.PlusA (Typ.get_ikind_opt typ)), [])
  | `Mul ->
      (binop_exp (Binop.Mult (Typ.get_ikind_opt typ)), [])
  | `Div ->
      (binop_exp Binop.Div, [])
  | `Rem ->
      (binop_exp Binop.Mod, [])
  | `Sub ->
      if Typ.is_pointer t1 then
        if Typ.is_pointer t2 then (binop_exp Binop.MinusPP, []) else (binop_exp Binop.MinusPI, [])
      else (binop_exp (Binop.MinusA (Typ.get_ikind_opt typ)), [])
  | `Shl ->
      (binop_exp Binop.Shiftlt, [])
  | `Shr ->
      (binop_exp Binop.Shiftrt, [])
  | `Or ->
      (binop_exp Binop.BOr, [])
  | `And ->
      (binop_exp Binop.BAnd, [])
  | `Xor ->
      (binop_exp Binop.BXor, [])
  | `LT ->
      (binop_exp Binop.Lt, [])
  | `GT ->
      (binop_exp Binop.Gt, [])
  | `LE ->
      (binop_exp Binop.Le, [])
  | `GE ->
      (binop_exp Binop.Ge, [])
  | `NE ->
      (binop_exp Binop.Ne, [])
  | `EQ ->
      (binop_exp Binop.Eq, [])
  | `LAnd ->
      (binop_exp Binop.LAnd, [])
  | `LOr ->
      (binop_exp Binop.LOr, [])
  | `Assign ->
      (e1, [Sil.Store (e1, typ, e2, loc)])
  | `Cmp ->
      CFrontend_config.unimplemented __POS__ source_range "C++20 spaceship operator <=>"
      (* C++20 spaceship operator <=>, TODO *)
  | `Comma ->
      (e2, []) (* C99 6.5.17-2 *)
  | ( `MulAssign
    | `DivAssign
    | `RemAssign
    | `AddAssign
    | `SubAssign
    | `ShlAssign
    | `ShrAssign
    | `AndAssign
    | `XorAssign
    | `OrAssign ) as boi_kind ->
      compound_assignment_binary_operation_instruction boi_kind e1_with_typ typ e2 loc


let unary_operation_instruction translation_unit_context uoi e typ loc =
  let un_exp op = Exp.UnOp (op, e, Some typ) in
  match uoi.Clang_ast_t.uoi_kind with
  | `PostInc ->
      let id = Ident.create_fresh Ident.knormal in
      let instr1 = Sil.Load (id, e, typ, loc) in
      let bop = if Typ.is_pointer typ then Binop.PlusPI else Binop.PlusA (Typ.get_ikind_opt typ) in
      let e_plus_1 = Exp.BinOp (bop, Exp.Var id, Exp.Const (Const.Cint IntLit.one)) in
      (Exp.Var id, [instr1; Sil.Store (e, typ, e_plus_1, loc)])
  | `PreInc ->
      let id = Ident.create_fresh Ident.knormal in
      let instr1 = Sil.Load (id, e, typ, loc) in
      let bop = if Typ.is_pointer typ then Binop.PlusPI else Binop.PlusA (Typ.get_ikind_opt typ) in
      let e_plus_1 = Exp.BinOp (bop, Exp.Var id, Exp.Const (Const.Cint IntLit.one)) in
      let exp =
        if CGeneral_utils.is_cpp_translation translation_unit_context then e else e_plus_1
      in
      (exp, [instr1; Sil.Store (e, typ, e_plus_1, loc)])
  | `PostDec ->
      let id = Ident.create_fresh Ident.knormal in
      let instr1 = Sil.Load (id, e, typ, loc) in
      let bop =
        if Typ.is_pointer typ then Binop.MinusPI else Binop.MinusA (Typ.get_ikind_opt typ)
      in
      let e_minus_1 = Exp.BinOp (bop, Exp.Var id, Exp.Const (Const.Cint IntLit.one)) in
      (Exp.Var id, [instr1; Sil.Store (e, typ, e_minus_1, loc)])
  | `PreDec ->
      let id = Ident.create_fresh Ident.knormal in
      let instr1 = Sil.Load (id, e, typ, loc) in
      let bop =
        if Typ.is_pointer typ then Binop.MinusPI else Binop.MinusA (Typ.get_ikind_opt typ)
      in
      let e_minus_1 = Exp.BinOp (bop, Exp.Var id, Exp.Const (Const.Cint IntLit.one)) in
      let exp =
        if CGeneral_utils.is_cpp_translation translation_unit_context then e else e_minus_1
      in
      (exp, [instr1; Sil.Store (e, typ, e_minus_1, loc)])
  | `Not ->
      (un_exp Unop.BNot, [])
  | `Minus ->
      (un_exp Unop.Neg, [])
  | `Plus ->
      (e, [])
  | `LNot ->
      (un_exp Unop.LNot, [])
  | `Deref ->
      (* Actual dereferencing is handled by implicit cast from rvalue to lvalue *)
      (e, [])
  | `AddrOf ->
      (e, [])
  | `Real | `Imag | `Extension | `Coawait ->
      let uok = Clang_ast_j.string_of_unary_operator_kind uoi.Clang_ast_t.uoi_kind in
      L.(debug Capture Medium)
        "@\n\
         WARNING: Missing translation for Unary Operator Kind %s. The construct has been \
         ignored...@\n"
        uok ;
      (e, [])


let bin_op_to_string boi =
  match boi.Clang_ast_t.boi_kind with
  | `PtrMemD ->
      "PtrMemD"
  | `PtrMemI ->
      "PtrMemI"
  | `Mul ->
      "Mul"
  | `Div ->
      "Div"
  | `Rem ->
      "Rem"
  | `Add ->
      "Add"
  | `Sub ->
      "Sub"
  | `Shl ->
      "Shl"
  | `Shr ->
      "Shr"
  | `LT ->
      "LT"
  | `GT ->
      "GT"
  | `LE ->
      "LE"
  | `GE ->
      "GE"
  | `EQ ->
      "EQ"
  | `NE ->
      "NE"
  | `And ->
      "And"
  | `Xor ->
      "Xor"
  | `Or ->
      "Or"
  | `LAnd ->
      "LAnd"
  | `LOr ->
      "LOr"
  | `Assign ->
      "Assign"
  | `MulAssign ->
      "MulAssign"
  | `DivAssign ->
      "DivAssign"
  | `RemAssign ->
      "RemAssing"
  | `AddAssign ->
      "AddAssign"
  | `SubAssign ->
      "SubAssign"
  | `ShlAssign ->
      "ShlAssign"
  | `ShrAssign ->
      "ShrAssign"
  | `AndAssign ->
      "AndAssign"
  | `XorAssign ->
      "XorAssign"
  | `OrAssign ->
      "OrAssign"
  | `Cmp ->
      "Cmp"
  | `Comma ->
      "Comma"


let sil_const_plus_one const =
  match const with
  | Exp.Const (Const.Cint n) ->
      Exp.Const (Const.Cint (IntLit.add n IntLit.one))
  | _ ->
      Exp.BinOp (Binop.PlusA None, const, Exp.Const (Const.Cint IntLit.one))