feat: step 11 done

lib/bds/cli_sync/watcher.ex

@@ -0,0 +1,73 @@
+defmodule BDS.CliSync.Watcher do
+  @moduledoc false
+
+  use GenServer
+
+  alias BDS.CliSync
+
+  @topic "entity:changed"
+  @default_poll_interval_ms 100
+
+  def start_link(opts \\ []) do
+    case Keyword.pop(opts, :name, __MODULE__) do
+      {nil, init_opts} -> GenServer.start_link(__MODULE__, init_opts)
+      {name, init_opts} -> GenServer.start_link(__MODULE__, init_opts, name: name)
+    end
+  end
+
+  def topic, do: @topic
+
+  def poll_now(server \\ __MODULE__) do
+    GenServer.call(server, :poll_now)
+  end
+
+  @impl true
+  def init(opts) do
+    state = %{
+      poll_interval_ms: normalize_positive_integer(Keyword.get(opts, :poll_interval_ms), @default_poll_interval_ms),
+      pubsub: Keyword.get(opts, :pubsub, BDS.PubSub)
+    }
+
+    {:ok, schedule_poll(state)}
+  end
+
+  @impl true
+  def handle_call(:poll_now, _from, state) do
+    {:reply, :ok, process_notifications(state)}
+  end
+
+  @impl true
+  def handle_info(:poll, state) do
+    {:noreply,
+     state
+     |> process_notifications()
+     |> schedule_poll()}
+  end
+
+  defp process_notifications(state) do
+    {:ok, notifications} = CliSync.db_file_change_detected()
+    {:ok, _pruned} = CliSync.prune_notifications()
+
+    Enum.each(notifications, fn notification ->
+      Phoenix.PubSub.broadcast(state.pubsub, topic(), {:entity_changed, notification_payload(notification)})
+    end)
+
+    state
+  end
+
+  defp notification_payload(notification) do
+    %{
+      entity: notification.entity_type,
+      entity_id: notification.entity_id,
+      action: notification.action
+    }
+  end
+
+  defp schedule_poll(state) do
+    Process.send_after(self(), :poll, state.poll_interval_ms)
+    state
+  end
+
+  defp normalize_positive_integer(value, _default) when is_integer(value) and value > 0, do: value
+  defp normalize_positive_integer(_value, default), do: default
+end