vaccins/lib/vaccins_web/live/location_component.ex

defmodule VaccinsWeb.LocationComponent do
  use VaccinsWeb, :live_component
  alias Vaccins.{LocationStore, Search}

  @impl true
  def mount(socket),
    do:
      {:ok,
       socket
       |> assign(
         slots_after: [],
         slots_before: [],
         loading: false,
         last_refresh_date: nil
       )}

  @impl true
  def update(assigns, socket) do
    {force_refresh, assigns} = assigns |> Map.pop(:force_refresh)
    assigns = assigns |> integrate_availabilities

    if is_nil(force_refresh) do
      {:ok, socket |> assign(assigns) |> assign(loading: false) |> signal_availabilities}
    else
      trigger_and_signal_query(
        assigns |> Map.get(:location, socket.assigns.location),
        assigns.id
      )

      {:ok,
       socket |> assign(assigns) |> assign(loading: true, last_refresh_date: get_refresh_time())}
    end
  end

  @impl true
  def handle_event("trigger_query", _, socket = %{assigns: %{id: id, location: location}}) do
    trigger_and_signal_query(location, id)
    {:noreply, socket |> assign(loading: true, last_refresh_date: get_refresh_time())}
  end

  @impl true
  def render(assigns) do
    ~L"""
      <dl class="location">
        <dt>id</dt>
        <dd><%= @location.id %></dd>
        <dt>Status (<%= if @last_refresh_date, do: @last_refresh_date |> Time.to_string() %>) </dt>
        <dd>
          <%= cond do %>
            <%= @loading -> %>...
            <%= not has_slots?(assigns) -> %>Pas de créneau
            <%= has_slots?(assigns) -> %>Des dispos !
          <% end %>
        </dd>
        <dt>booking page</dt>
        <dd><%= link @location.booking_page, to: @location.booking_page %></dd>
        <%= if has_slots?(assigns) do %>
          <dt>Avant 24h</dt>
          <dd>
            <ul><%= for d <- @slots_before do %><li><%= d |> DateTime.to_string %></li><% end %></ul>
          </dd>
          <dt>Après 24h</dt>
          <dd>
            <ul><%= for d <- @slots_after do %><li><%= d |> DateTime.to_string %></li><% end %></ul>
          </dd>
        <% end %>
        <dt>test availability</dt>
        <dd><button phx-click="trigger_query" phx-target="<%= @myself %>">Trigger</button></dd>
      </dl>
    """
  end

  defp integrate_availabilities(assigns = %{availabilities: {:error, reason}}),
    do: assigns

  defp integrate_availabilities(assigns = %{availabilities: {:ok, after_slots}})
       when is_list(after_slots),
       do:
         assigns
         |> Map.put(:slots_after, after_slots |> Enum.take(5))

  defp integrate_availabilities(assigns = %{availabilities: {:ok, before_slots, after_slots}})
       when is_list(before_slots),
       do:
         assigns
         |> Map.put(:slots_after, after_slots |> Enum.take(5))
         |> Map.put(:slots_before, before_slots)

  defp integrate_availabilities(assigns), do: assigns

  defp has_slots?(assigns = %{slots_before: before, slots_after: after_}),
    do: not (before |> Enum.empty?() and after_ |> Enum.empty?())

  defp trigger_and_signal_query(location, id) do
    ref = Search.async_trigger_query(location)
    send(self(), {:query_sent, id, ref})
  end

  defp get_refresh_time() do
    with {:ok, now} <-
           DateTime.utc_now() |> DateTime.shift_zone("Europe/Paris", Tzdata.TimeZoneDatabase),
         do: now |> DateTime.to_time() |> Time.truncate(:second)
  end

  defp signal_availabilities(socket = %{assigns: %{loading: false, slots_after: slots_after}}) do
    cond do
      socket.assigns |> has_slots? ->
        send(self(), {:location_has_slots, socket.assigns.id, not (slots_after |> Enum.empty?())})

      true ->
        send(self(), {:location_no_more_slots, socket.assigns.id})
    end

    socket
  end

  defp signal_availabilities(socket), do: socket
end