Use Transforms to serve covers at the right size

lib/music_library_web/controllers/cover_controller.ex

@@ -2,38 +2,32 @@ defmodule MusicLibraryWeb.CoverController do
   use MusicLibraryWeb, :controller
 
   alias MusicLibrary.Assets
-  alias MusicLibrary.Assets.Asset
+  alias MusicLibrary.Assets.Transform
   alias MusicLibrary.Records.Cover
 
   # 1 year in seconds
   @cache_duration 60 * 60 * 24 * 365
 
-  def show(conn, %{"hash" => hash, "size" => size}) do
-    case Assets.get(hash) do
+  def show(conn, %{"transform_payload" => payload}) do
+    transform = Transform.decode!(payload)
+
+    case Assets.get(transform.hash) do
       nil ->
         not_found(conn)
 
       %{content: content} ->
-        # TODO: find a way to cache computation, or pre-compute thumb and store it
-        {:ok, thumb_data} = Cover.resize(content, String.to_integer(size))
-        hash = Asset.hash(thumb_data)
+        image_data =
+          if transform.width do
+            # TODO: find a way to cache computation, or pre-compute thumb and store it
+            {:ok, thumb_data} = Cover.resize(content, transform.width)
+            thumb_data
+          else
+            content
+          end
 
         case get_req_header(conn, "if-none-match") do
-          [^hash] -> extend_cache(conn)
-          _ -> respond_with_cache(conn, thumb_data, hash)
-        end
-    end
-  end
-
-  def show(conn, %{"hash" => hash}) do
-    case Assets.get(hash) do
-      nil ->
-        not_found(conn)
-
-      asset ->
-        case get_req_header(conn, "if-none-match") do
-          [^hash] -> extend_cache(conn)
-          _ -> respond_with_cache(conn, asset)
+          [^payload] -> extend_cache(conn)
+          _ -> respond_with_cache(conn, image_data, payload)
         end
     end
   end
@@ -50,14 +44,6 @@ defmodule MusicLibraryWeb.CoverController do
     |> send_resp(304, "")
   end
 
-  defp respond_with_cache(conn, asset) do
-    conn
-    |> put_resp_content_type(asset.format, "utf-8")
-    |> put_resp_header("cache-control", "public, max-age=#{@cache_duration}")
-    |> put_resp_header("etag", asset.hash)
-    |> send_resp(200, asset.content)
-  end
-
   defp respond_with_cache(conn, data, etag) do
     conn
     |> put_resp_content_type("image/jpeg", "utf-8")