[Enhancement] Delete media after "x" days (#160)

* [Enhancement] Adds ability to stop media from re-downloading (#159)

* Added column

* Added methods for ignoring media items from future download

* Added new deletion options to controller and UI

* Added controller actions and UI for editing a media item

* Added column to sources

* Added retention period to form

* [WIP] getting retention methods in place

* Hooked up retention worker

* Added column and UI to prevent automatic deletion

* Docs

* Removed unused backfill worker

* Added edit links to media item tabs on source view

* Clarified form wording

* Form wording (again)

lib/pinchflat/downloading/media_retention_worker.ex

@@ -0,0 +1,33 @@
+defmodule Pinchflat.Downloading.MediaRetentionWorker do
+  @moduledoc false
+
+  use Oban.Worker,
+    queue: :local_metadata,
+    unique: [period: :infinity, states: [:available, :scheduled, :retryable, :executing]],
+    tags: ["media_item", "local_metadata"]
+
+  require Logger
+
+  alias Pinchflat.Media
+
+  @doc """
+  Deletes media items that are past their retention date and prevents
+  them from being re-downloaded.
+
+  This worker is scheduled to run daily via the Oban Cron plugin.
+
+  Returns :ok
+  """
+  @impl Oban.Worker
+  def perform(%Oban.Job{}) do
+    cullable_media = Media.list_cullable_media_items()
+    Logger.info("Culling #{length(cullable_media)} media items past their retention date")
+
+    Enum.each(cullable_media, fn media_item ->
+      Media.delete_media_files(media_item, %{
+        prevent_download: true,
+        culled_at: DateTime.utc_now()
+      })
+    end)
+  end
+end