Move error tracker notifier files to correct namespace

lib/error_tracker/error_notifier.ex

@@ -0,0 +1,135 @@
+defmodule ErrorTracker.ErrorNotifier do
+  @moduledoc false
+
+  use GenServer
+  require Logger
+
+  alias ErrorTracker.ErrorNotifier.Email
+
+  @cleanup_interval :timer.minutes(5)
+
+  def start_link(opts \\ []) do
+    GenServer.start_link(__MODULE__, opts, name: __MODULE__)
+  end
+
+  @impl true
+  def init(_opts) do
+    if has_valid_config?() do
+      attach_telemetry()
+      schedule_cleanup()
+      {:ok, %{errors: %{}}}
+    else
+      :ignore
+    end
+  end
+
+  @impl true
+  def handle_info({:telemetry_event, event_name, _measurements, metadata}, state) do
+    case event_name do
+      [:error_tracker, :error, :new] ->
+        reason = truncate_reason(metadata.occurrence.reason)
+        {_result, new_state} = maybe_notify(metadata.occurrence, "New Error! (#{reason})", state)
+        {:noreply, new_state}
+
+      [:error_tracker, :occurrence, :new] ->
+        reason = truncate_reason(metadata.occurrence.reason)
+        {_result, new_state} = maybe_notify(metadata.occurrence, "Error: #{reason}", state)
+        {:noreply, new_state}
+
+      _ ->
+        {:noreply, state}
+    end
+  end
+
+  def handle_info(:cleanup, state) do
+    schedule_cleanup()
+    {:noreply, cleanup_old_records(state)}
+  end
+
+  def handle_info(_msg, state), do: {:noreply, state}
+
+  @doc false
+  def handle_telemetry_event(event_name, measurements, metadata, _config) do
+    case Process.whereis(__MODULE__) do
+      nil -> :ok
+      pid -> send(pid, {:telemetry_event, event_name, measurements, metadata})
+    end
+  end
+
+  # -- Private --
+
+  defp attach_telemetry do
+    events = [
+      [:error_tracker, :error, :new],
+      [:error_tracker, :occurrence, :new]
+    ]
+
+    :telemetry.detach("error-tracker-notifications")
+
+    :telemetry.attach_many(
+      "error-tracker-notifications",
+      events,
+      &__MODULE__.handle_telemetry_event/4,
+      nil
+    )
+  end
+
+  defp maybe_notify(occurrence, header, state) do
+    error_id = occurrence.error_id
+    now = System.system_time(:second)
+    throttle_seconds = config()[:throttle_seconds] || 10
+
+    error_state = Map.get(state.errors, error_id, %{count: 0, last_time: 0})
+    time_since_last = now - error_state.last_time
+
+    if error_state.last_time == 0 || time_since_last >= throttle_seconds do
+      header_with_count = format_header_with_count(header, error_state.count)
+      result = Email.send(occurrence, header_with_count)
+      updated_errors = Map.put(state.errors, error_id, %{count: 0, last_time: now})
+      {result, %{state | errors: updated_errors}}
+    else
+      updated_error = %{count: error_state.count + 1, last_time: error_state.last_time}
+      updated_errors = Map.put(state.errors, error_id, updated_error)
+
+      Logger.debug("Throttled notification for error #{error_id}. Count: #{updated_error.count}")
+
+      {:throttled, %{state | errors: updated_errors}}
+    end
+  end
+
+  defp cleanup_old_records(state) do
+    now = System.system_time(:second)
+    one_hour_ago = now - 3600
+
+    cleaned_errors =
+      state.errors
+      |> Enum.filter(fn {_error_id, %{last_time: last_time}} -> last_time >= one_hour_ago end)
+      |> Map.new()
+
+    %{state | errors: cleaned_errors}
+  end
+
+  defp format_header_with_count(header, count) when count > 1,
+    do: "#{header} (#{count} occurrences)"
+
+  defp format_header_with_count(header, _count), do: header
+
+  defp schedule_cleanup do
+    Process.send_after(self(), :cleanup, @cleanup_interval)
+  end
+
+  defp truncate_reason(reason) when is_binary(reason) do
+    if String.length(reason) > 80, do: String.slice(reason, 0, 77) <> "...", else: reason
+  end
+
+  defp truncate_reason(reason), do: reason |> inspect() |> truncate_reason()
+
+  defp has_valid_config? do
+    conf = config()
+    not is_nil(conf[:from_email]) and not is_nil(conf[:to_email]) and not is_nil(conf[:mailer])
+  end
+
+  defp config do
+    Application.get_env(:music_library, __MODULE__, [])
+  end
+end