[Enhancement] Allow redownloading of files for existing media items (#239)

* Added ability to specify overwrite behaviour when downloading media

* Added helper for redownloading media items

* renamed media redownload worker to disambiguate it from similarly named methods

* Added new redownload option to source actions dropdown

* Refactored MediaQuery to use a __using__ macro

* docs

lib/pinchflat/downloading/media_quality_upgrade_worker.ex

@@ -0,0 +1,33 @@
+defmodule Pinchflat.Downloading.MediaQualityUpgradeWorker do
+  @moduledoc false
+
+  use Oban.Worker,
+    queue: :media_fetching,
+    unique: [period: :infinity, states: [:available, :scheduled, :retryable, :executing]],
+    tags: ["media_item", "media_fetching"]
+
+  require Logger
+
+  alias Pinchflat.Media
+  alias Pinchflat.Downloading.MediaDownloadWorker
+
+  @doc """
+  Redownloads media items that are eligible for redownload for the purpose
+  of upgrading the quality of the media or improving things like sponsorblock
+  segments.
+
+  This worker is scheduled to run daily via the Oban Cron plugin
+  and it should run _after_ the retention worker.
+
+  Returns :ok
+  """
+  @impl Oban.Worker
+  def perform(%Oban.Job{}) do
+    redownloadable_media = Media.list_redownloadable_media_items()
+    Logger.info("Redownloading #{length(redownloadable_media)} media items")
+
+    Enum.each(redownloadable_media, fn media_item ->
+      MediaDownloadWorker.kickoff_with_task(media_item, %{quality_upgrade?: true})
+    end)
+  end
+end