open Errors
open Identifiers
module C = Collections
module T = Types
module V = Values
module E = Expressions
module A = CfimAst
open SymbolicAst

let synthesize_symbolic_expansion (sv : V.symbolic_value)
    (seel : V.symbolic_expansion option list) (exprl : expression list option) :
    expression option =
  match exprl with
  | None -> None
  | Some exprl ->
      let ls = List.combine seel exprl in
      (* Match on the symbolic value type to know which can of expansion happened *)
      let expansion =
        match sv.V.sv_ty with
        | T.Bool -> (
            (* Boolean expansion: there should be two branches *)
            match ls with
            | [
             (Some (V.SeConcrete (V.Bool true)), true_exp);
             (Some (V.SeConcrete (V.Bool false)), false_exp);
            ] ->
                ExpandBool (true_exp, false_exp)
            | _ -> failwith "Ill-formed boolean expansion")
        | T.Integer int_ty ->
            (* Switch over an integer: split between the "regular" branches
               and the "otherwise" branch (which should be the last branch) *)
            let branches, otherwise = C.List.pop_last ls in
            (* For all the regular branches, the symbolic value should have
             * been expanded to a constant *)
            let get_scalar (see : V.symbolic_expansion option) : V.scalar_value
                =
              match see with
              | Some (V.SeConcrete (V.Scalar cv)) ->
                  assert (cv.V.int_ty = int_ty);
                  cv
              | _ -> failwith "Unreachable"
            in
            let branches =
              List.map (fun (see, exp) -> (get_scalar see, exp)) branches
            in
            (* For the otherwise branch, the symbolic value should have been left
             * unchanged *)
            let otherwise_see, otherwise = otherwise in
            assert (otherwise_see = None);
            (* Return *)
            ExpandInt (int_ty, branches, otherwise)
        | T.Adt (adt_id, regions, types) -> (
            (* An ADT expansion can lead to branching: check if this is the case *)
            match ls with
            | [] -> failwith "Ill-formed ADT expansion"
            | [ (see, exp) ] ->
                (* No branching *)
                ExpandNoBranch (Option.get see, exp)
            | ls ->
                (* Branching: it is necessarily an enumeration expansion *)
                let get_variant (see : V.symbolic_expansion option) :
                    T.VariantId.id option * V.symbolic_value list =
                  match see with
                  | Some (V.SeAdt (vid, fields)) -> (vid, fields)
                  | _ -> failwith "Ill-formed branching ADT expansion"
                in
                let exp =
                  List.map
                    (fun (see, exp) ->
                      let vid, fields = get_variant see in
                      (vid, fields, exp))
                    ls
                in
                ExpandEnum exp)
        | T.Ref (r, ty, rkind) -> (
            (* Reference expansion: there should be one branch *)
            match ls with
            | [ (Some see, exp) ] -> ExpandNoBranch (see, exp)
            | _ -> failwith "Ill-formed borrow expansion")
        | T.TypeVar _ | Char | Never | Str | Array _ | Slice _ ->
            failwith "Ill-formed symbolic expansion"
      in
      Some (Expansion (sv, expansion))

let synthesize_symbolic_expansion_no_branching (sv : V.symbolic_value)
    (see : V.symbolic_expansion) (expr : expression option) : expression option
    =
  let exprl = match expr with None -> None | Some expr -> Some [ expr ] in
  synthesize_symbolic_expansion sv [ Some see ] exprl