add tag fetch endpoint

assets/js/booru.js

@@ -43,9 +43,9 @@ function fetchAndPersistTags(tagIds) {
   for (let i = 0; i < tagIds.length; i += chunk) {
     const ids = tagIds.slice(i, i + chunk);
 
-    /*fetch(`${window.booru.apiEndpoint}tags/fetch_many.json?ids[]=${ids.join('&ids[]=')}`)
+    fetch(`/tags/fetch?ids[]=${ids.join('&ids[]=')}`)
       .then(response => response.json())
-      .then(data => data.tags.forEach(tag => persistTag(tag)));*/
+      .then(data => data.tags.forEach(tag => persistTag(tag)));
   }
 }
 

lib/philomena_web/controllers/tag/fetch_controller.ex

@@ -0,0 +1,39 @@
+defmodule PhilomenaWeb.Tag.FetchController do
+  use PhilomenaWeb, :controller
+
+  alias Philomena.Tags.Tag
+  alias Philomena.Repo
+  import Ecto.Query
+
+  def index(conn, %{"ids" => ids}) when is_list(ids) do
+    # limit amount to 50
+    ids = Enum.take(ids, 50)
+
+    tags =
+      Tag
+      |> where([t], t.id in ^ids)
+      |> Repo.all()
+      |> Enum.map(&tag_json/1)
+
+    conn
+    |> json(%{tags: tags})
+  end
+
+  defp tag_json(tag) do
+    %{
+      id: tag.id,
+      name: tag.name,
+      images: tag.images_count,
+      spoiler_image_uri: tag_image(tag)
+    }
+  end
+
+  defp tag_image(%{image: image}) when image not in [nil, ""],
+    do: tag_url_root() <> "/" <> image
+  defp tag_image(_other),
+    do: nil
+
+  defp tag_url_root do
+    Application.get_env(:philomena, :tag_url_root)
+  end
+end

lib/philomena_web/router.ex

@@ -123,6 +123,7 @@ defmodule PhilomenaWeb.Router do
     end
     scope "/tags", Tag, as: :tag do
       resources "/autocomplete", AutocompleteController, only: [:show], singleton: true
+      resources "/fetch", FetchController, only: [:index]
     end
     resources "/tags", TagController, only: [:index, :show]
     scope "/search", Search, as: :search do