defmodule Wiki.MetricGenerator do
  use GenServer
  alias Wiki.Repo
  alias Wiki.Content.{Page, PageLink, Upload}

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

  @impl true
  def init(state) do
    update_metrics()

    # 5 minutes
    Process.send_after(self(), :update, 5 * 60 * 1000)

    {:ok, state}
  end

  @impl true
  def handle_info(:update, state) do
    update_metrics()
    {:noreply, state}
  end

  def update_metrics do
    pages = Repo.aggregate(Page, :count)
    uploads = Repo.aggregate(Upload, :count)
    links = Repo.aggregate(PageLink, :count)
    :telemetry.execute([:wiki, :pages], %{count: pages})
    :telemetry.execute([:wiki, :uploads], %{count: uploads})
    :telemetry.execute([:wiki, :links], %{count: links})
  end
end