Dialyzer is our friend again :-)

Messages.Time.ex

defmodule Messages.Time do
  use Timex
  alias Timex.DateTime

  @spec timestamp() :: DateTime.t
  def timestamp, do: DateTime.now(:utc)

  @spec timestamp_iso8601() :: String.t
  @dialyzer {:nowarn_function, timestamp_iso8601: 0}
  def timestamp_iso8601 do
    case DateTime.now(:utc) do
      ts = %DateTime{day: _d, hour: _h, millisecond: _ms, minute: _m, month: _mo, second: _s, year: _y} ->
        timestamp_iso8601(ts)
      _ ->
        ""
    end
  end

  @spec timestamp_iso8601(Timex.Convertable.t) :: String.t | no_return
  def timestamp_iso8601(ts) do
    ts
      |> Timex.format!("{ISO:Extended}")
      |> String.replace("+00:00", "Z")
  end

  def parse_timestamp(ts) do
    {:ok, %DateTime{}} = Timex.parse(ts, "{ISO:Extended}")
  end

  def to_seconds(ts) do
    DateTime.to_secs(ts)
  end
end