[Enhancement] Download image when using playlists with media center apps (#313)

* [WIP] started adding calls for downloading posters for playlists

* Updated source image parser to work with playlists

lib/pinchflat/metadata/source_image_parser.ex

@@ -20,29 +20,49 @@ defmodule Pinchflat.Metadata.SourceImageParser do
   def store_source_images(base_directory, source_metadata) do
     (source_metadata["thumbnails"] || [])
     |> Enum.filter(&(&1["filepath"] != nil))
-    |> select_useful_images()
+    |> select_useful_images(source_metadata)
     |> Enum.map(&move_image(&1, base_directory))
     |> Enum.into(%{})
   end
 
-  defp select_useful_images(images) do
+  defp select_useful_images(images, source_metadata) do
     labelled_images =
-      Enum.reduce(images, [], fn image_map, acc ->
+      Enum.reduce(images, %{}, fn image_map, acc ->
         case image_map do
-          %{"id" => "avatar_uncropped"} ->
-            acc ++ [{:poster, :poster_filepath, image_map["filepath"]}]
-
-          %{"id" => "banner_uncropped"} ->
-            acc ++ [{:fanart, :fanart_filepath, image_map["filepath"]}]
-
-          _ ->
-            acc
+          %{"id" => "avatar_uncropped"} -> put_image_key(acc, :poster, image_map["filepath"])
+          %{"id" => "banner_uncropped"} -> put_image_key(acc, :fanart, image_map["filepath"])
+          _ -> acc
         end
       end)
 
     labelled_images
-    |> Enum.concat([{:banner, :banner_filepath, determine_best_banner(images)}])
-    |> Enum.filter(fn {_, _, tmp_filepath} -> tmp_filepath end)
+    |> add_fallback_poster(source_metadata)
+    |> put_image_key(:banner, determine_best_banner(images))
+    |> Enum.filter(fn {_key, attrs} -> attrs.current_filepath end)
+  end
+
+  # If a poster is set, short-circuit and return the images as-is
+  defp add_fallback_poster(%{poster: _} = images, _), do: images
+
+  # If a poster is NOT set, see if we can find a suitable image to use as a fallback
+  defp add_fallback_poster(images, source_metadata) do
+    case source_metadata["entries"] do
+      nil -> images
+      [] -> images
+      [first_entry | _] -> add_poster_from_entry_thumbnail(images, first_entry)
+    end
+  end
+
+  defp add_poster_from_entry_thumbnail(images, entry) do
+    thumbnail =
+      (entry["thumbnails"] || [])
+      |> Enum.reverse()
+      |> Enum.find(& &1["filepath"])
+
+    case thumbnail do
+      nil -> images
+      _ -> put_image_key(images, :poster, thumbnail["filepath"])
+    end
   end
 
   defp determine_best_banner(images) do
@@ -58,12 +78,22 @@ defmodule Pinchflat.Metadata.SourceImageParser do
     Map.get(best_candidate || %{}, "filepath")
   end
 
-  defp move_image({filename, source_attr_name, tmp_filepath}, base_directory) do
-    extension = Path.extname(tmp_filepath)
-    final_filepath = Path.join([base_directory, "#{filename}#{extension}"])
+  defp move_image({_key, attrs}, base_directory) do
+    extension = Path.extname(attrs.current_filepath)
+    final_filepath = Path.join([base_directory, "#{attrs.final_filename}#{extension}"])
 
-    FilesystemUtils.cp_p!(tmp_filepath, final_filepath)
+    FilesystemUtils.cp_p!(attrs.current_filepath, final_filepath)
 
-    {source_attr_name, final_filepath}
+    {attrs.attribute_name, final_filepath}
+  end
+
+  defp put_image_key(map, key, image) do
+    attribute_atom = String.to_existing_atom("#{key}_filepath")
+
+    Map.put(map, key, %{
+      attribute_name: attribute_atom,
+      final_filename: to_string(key),
+      current_filepath: image
+    })
   end
 end

lib/pinchflat/metadata/source_metadata_storage_worker.ex

@@ -77,10 +77,8 @@ defmodule Pinchflat.Metadata.SourceMetadataStorageWorker do
 
   defp fetch_source_metadata_and_images(series_directory, source) do
     metadata_directory = MetadataFileHelpers.metadata_directory_for(source)
-    tmp_output_path = "#{tmp_directory()}/#{StringUtils.random_string(16)}/source_image.%(ext)S"
-    opts = [:write_all_thumbnails, convert_thumbnails: "jpg", output: tmp_output_path]
 
-    {:ok, metadata} = MediaCollection.get_source_metadata(source.original_url, opts)
+    {:ok, metadata} = fetch_metadata_for_source(source)
     metadata_image_attrs = SourceImageParser.store_source_images(metadata_directory, metadata)
 
     if source.media_profile.download_source_images && series_directory do
@@ -110,6 +108,20 @@ defmodule Pinchflat.Metadata.SourceMetadataStorageWorker do
     end
   end
 
+  defp fetch_metadata_for_source(source) do
+    tmp_output_path = "#{tmp_directory()}/#{StringUtils.random_string(16)}/source_image.%(ext)S"
+    base_opts = [convert_thumbnails: "jpg", output: tmp_output_path]
+
+    opts =
+      if source.collection_type == :channel do
+        base_opts ++ [:write_all_thumbnails, playlist_items: 0]
+      else
+        base_opts ++ [:write_thumbnail, playlist_items: 1]
+      end
+
+    MediaCollection.get_source_metadata(source.original_url, opts)
+  end
+
   defp tmp_directory do
     Application.get_env(:pinchflat, :tmpfile_directory)
   end

lib/pinchflat/yt_dlp/media_collection.ex

@@ -99,10 +99,21 @@ defmodule Pinchflat.YtDlp.MediaCollection do
   as a compressed blob for possible future use. That's why it's not getting formatted like
   `get_source_details/1`
 
+  ! IMPORTANT ! - you'll always want to set `playlist_items: int` in `addl_opts.
+  This is great if you want to also return details about the videos in the playlists,
+  but it should be set in all cases to not over-fetch data.
+  For channels you should usually set this to 0 since channels return all the
+  metadata we need without needing to fetch the videos. On the other hand, playlists
+  don't return very useful images so you can set this to 1 to get the first video's
+  images, for instance.
+
   Returns {:ok, map()} | {:error, any, ...}.
   """
-  def get_source_metadata(source_url, addl_opts \\ []) do
-    opts = [playlist_items: 0] ++ addl_opts
+  def get_source_metadata(source_url, addl_opts \\ [playlist_items: 0]) do
+    # This only validates that the `playlist_items` key is present. It's otherwise unused
+    _playlist_items = Keyword.fetch!(addl_opts, :playlist_items)
+
+    opts = [:skip_download] ++ addl_opts
     output_template = "playlist:%()j"
 
     with {:ok, output} <- backend_runner().run(source_url, opts, output_template),