module Js = Js_of_ocaml.Js
module App = Editor_app

module M = struct

  type t = unit

  let update
    : t -> State.t -> State.t
    = fun _ state ->

      (* Save this as a json element. The text may contains UTF-16 characters,
         which will raise an error in the btoa function.

         As an easy solution, we convert them into UTF-8 through the native
         OCaml representation of string.
      *)
      let json = State.Storage.to_json ()
                 |> Jstr.to_string (* Encode into UTF-8 *)
                 |> Obj.magic      (* Then type the element again as a string. *)
      in
      Elements.Transfert.send
        ~mime_type:(Jstr.v "application/json")
        ~filename:(Jstr.v "export.json")
        json;

      (* The function does not actually update the state, and return it
         unchanged *)
      state

end

(** Create a new element *)
let create
  : unit -> App.event
  = fun () ->
    App.E
      ( ()
      , (module M : App.Event with type t = M.t ))