[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