vaccins/lib/vaccins_web/live/index.ex

defmodule VaccinsWeb.IndexLive do
  use VaccinsWeb, :live_view
  alias Vaccins.{LocationStore, Search}

  @refresh_period_ms 30 * 1000

  @impl true
  def mount(_params, _session, socket) do
    locations = LocationStore.get_locations()

    {:ok,
     socket
     |> assign(
       locations: locations,
       locations_with_early_slots: MapSet.new(),
       locations_with_slots: MapSet.new(),
       pending: %{},
       location_cs: LocationStore.LocationRaw.changeset(%{}),
       display_cs: false
     )
     |> trigger_global_refresh
     |> trigger_periodic_refresh}
  end

  @impl true
  def handle_params(%{}, _url, socket), do: {:noreply, socket}

  @impl true
  def handle_event("add_location", %{"location_raw" => params}, socket) do
    case params |> LocationStore.add_location() do
      :ok -> {:noreply, socket |> push_patch(to: Routes.index_path(socket, :index))}
      {:error, cs} -> {:noreply, socket |> assign(location_cs: cs)}
    end
  end

  def handle_event("trigger_all", _, socket) do
    {:noreply, socket |> trigger_global_refresh}
  end

  def handle_event("toggle_form", _, socket = %{assigns: %{display_cs: display}}),
    do: {:noreply, socket |> assign(display_cs: not display)}

  @impl true
  def handle_info({:query_sent, id, ref}, socket = %{assigns: %{pending: pending}}) do
    {:noreply, socket |> assign(pending: pending |> Map.put(ref, id))}
  end

  def handle_info(:periodic_refresh, socket),
    do:
      {:noreply,
       socket
       |> trigger_global_refresh
       |> trigger_periodic_refresh}

  def handle_info({:location_has_slots, id, true}, socket) do
    {:noreply, socket |> update(:locations_with_early_slots, &(&1 |> MapSet.put(id)))}
  end

  def handle_info({:location_has_slots, id, false}, socket) do
    {:noreply, socket |> update(:locations_with_slots, &(&1 |> MapSet.put(id)))}
  end

  def handle_info({:location_no_more_slots, id}, socket) do
    {:noreply,
     socket
     |> update(:locations_with_slots, &(&1 |> MapSet.delete(id)))
     |> update(:locations_with_early_slots, &(&1 |> MapSet.delete(id)))}
  end

  def handle_info({:location_deleted, _}, socket),
    do: socket |> push_patch(to: Routes.index_path(socket, :index))

  @impl true
  def handle_info(
        {:query_result, ref, res},
        socket = %{assigns: %{locations: valid, pending: pending}}
      ) do
    id = pending |> Map.get(ref)
    send_update(VaccinsWeb.LocationComponent, id: id, availabilities: res)
    {:noreply, socket |> assign(pending: pending |> Map.delete(ref))}
  end

  defp trigger_global_refresh(socket = %{assigns: %{locations: locations}}) do
    locations
    |> Enum.each(&send_update(VaccinsWeb.LocationComponent, id: &1.id, force_refresh: true))

    socket
  end

  defp trigger_periodic_refresh(socket) do
    Process.send_after(self(), :periodic_refresh, @refresh_period_ms)
    socket
  end

  defp locations_by_availability(
         assigns = %{
           locations: locations,
           locations_with_slots: with_slots,
           locations_with_early_slots: with_early_slots
         }
       ) do
    locations
    |> Enum.sort(fn e1, e2 ->
      e1_has_early_spot? = e1.id in with_early_slots
      e1_has_spot? = e1.id in with_slots
      e2_has_early_spot? = e2.id in with_early_slots
      e2_has_spot? = e2.id in with_slots

      res =
        cond do
          e2_has_early_spot? -> false
          e2_has_spot? and not e1_has_early_spot? -> false
          e2_has_spot? and e1_has_spot? -> false
          true -> true
        end
    end)
  end
end