defmodule PopularApp.EmailSender do
  use GenServer

  def start_link do
    GenServer.start_link(__MODULE__, :ok, name: __MODULE__)
  end

  def init(:ok) do
    {:ok, %{last_sent: nil, last_data: nil}}
  end

  # Public API for callers - convenience wrapper around `cast`
  def send_email(data) do
    GenServer.cast(__MODULE__, {:send_email, data})
  end

  # Server functions
  def handle_cast({:send_email, data}, state) do
    data
    |> send_email()

    {:noreply, %{last_sent: calendar.local_time(), last_data: data}}
  end

  defp send_email(data) do
    # extract to, from, etc from `data`
    # send email through your provider
  end
end