Struct example

defmodule Book do
  @behaviour XDR.Declaration

  defstruct file_name: XDR.String, file_size: XDR.Int

  @type t :: %Book{file_name: XDR.String.t(), file_size: XDR.Int.t()}

  def new(file_name, file_size) do
    %Book{file_name: file_name, file_size: file_size}
  end

  @impl XDR.Declaration
  def encode_xdr(struct_file) do
    component_keyword = struct_file |> Map.from_struct() |> Map.to_list()

    XDR.Struct.new(component_keyword)
    |> XDR.Struct.encode_xdr()
  end

  @impl XDR.Declaration
  def encode_xdr!(struct_file) do
    encode_xdr(struct_file) |> elem(1)
  end

  @impl XDR.Declaration
  def decode_xdr(bytes, opts \\ nil)
  def decode_xdr(bytes, _opts) do
    component_keyword = Book.__struct__() |> Map.from_struct() |> Map.to_list()

    XDR.Struct.decode_xdr!(bytes, %{components: component_keyword})
    |> perform_struct()
  end

  @impl XDR.Declaration
  @spec decode_xdr!(bytes :: binary, struct :: map()) :: {t(), binary()}
  def decode_xdr!(bytes, struct), do: decode_xdr(bytes, struct) |> elem(1)

  defp perform_struct({components, rest}) do
    struct_components = components.components
    struct = Book.new(struct_components[:file_name], struct_components[:file_size])

    {:ok, {struct, rest}}
  end
end