[Enhancement] Optionally use the YouTube API for improved fast indexing (#282)

* Started adding youtube API for fast indexing

* Hooked youtube API into fast indexing

* Added youtube_api_key to settings

* Added youtube api key to settings UI

* Added tests

* Refactored the youtube api module

* More refactor

* Changed editing mode name from basic to standard

* [WIP] started on copy changes

* Updated copy

test/pinchflat/fast_indexing/youtube_api_test.exs

@@ -0,0 +1,85 @@
+defmodule Pinchflat.FastIndexing.YoutubeApiTest do
+  use Pinchflat.DataCase
+
+  import Pinchflat.SourcesFixtures
+
+  alias Pinchflat.Settings
+  alias Pinchflat.FastIndexing.YoutubeApi
+
+  describe "enabled?/0" do
+    test "returns true if the user has set a YouTube API key" do
+      Settings.set(youtube_api_key: "test_key")
+
+      assert YoutubeApi.enabled?()
+    end
+
+    test "returns false if the user has not set an API key" do
+      Settings.set(youtube_api_key: nil)
+
+      refute YoutubeApi.enabled?()
+    end
+  end
+
+  describe "get_recent_media_ids/1" do
+    setup do
+      source = source_fixture()
+      Settings.set(youtube_api_key: "test_key")
+
+      {:ok, source: source}
+    end
+
+    test "calls the expected URL", %{source: source} do
+      expect(HTTPClientMock, :get, fn url, headers ->
+        api_base = "https://youtube.googleapis.com/youtube/v3/playlistItems"
+        request_url = "#{api_base}?part=contentDetails&maxResults=50&playlistId=#{source.collection_id}&key=test_key"
+
+        assert url == request_url
+        assert headers == [accept: "application/json"]
+
+        {:ok, "{}"}
+      end)
+
+      assert {:ok, _} = YoutubeApi.get_recent_media_ids(source)
+    end
+
+    test "replaces channel IDs with playlist IDs if needed" do
+      source = source_fixture(collection_id: "UC_ABC123")
+
+      expect(HTTPClientMock, :get, fn url, _headers ->
+        assert url =~ "playlistId=UU_ABC123&"
+
+        {:ok, "{}"}
+      end)
+
+      assert {:ok, _} = YoutubeApi.get_recent_media_ids(source)
+    end
+
+    test "returns an empty list if no media is returned", %{source: source} do
+      expect(HTTPClientMock, :get, fn _url, _headers -> {:ok, "{}"} end)
+
+      assert {:ok, []} = YoutubeApi.get_recent_media_ids(source)
+    end
+
+    test "returns media IDs if present", %{source: source} do
+      expect(HTTPClientMock, :get, fn _url, _headers ->
+        {:ok,
+         """
+           {
+             "items": [
+               {"contentDetails": {"videoId": "test_1"}},
+               {"contentDetails": {"videoId": "test_2"}}
+             ]
+           }
+         """}
+      end)
+
+      assert {:ok, ["test_1", "test_2"]} = YoutubeApi.get_recent_media_ids(source)
+    end
+
+    test "returns an error if the HTTP request fails", %{source: source} do
+      expect(HTTPClientMock, :get, fn _url, _headers -> {:error, "error"} end)
+
+      assert {:error, "error"} = YoutubeApi.get_recent_media_ids(source)
+    end
+  end
+end