Add YouTube API key testing in settings

Allow users to test their YouTube API key directly from the settings page
by clicking a button. Uses a LiveView component that provides visual
feedback on whether the key is valid.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/pinchflat/fast_indexing/youtube_api.ex

@@ -23,6 +23,39 @@ defmodule Pinchflat.FastIndexing.YoutubeApi do
   @impl YoutubeBehaviour
   def enabled?, do: Enum.any?(api_keys())
 
+  @doc """
+  Tests if a YouTube API key is valid by making a simple API request.
+
+  Returns :ok | {:error, binary()}
+  """
+  @impl YoutubeBehaviour
+  def test_api_key(api_key) when is_binary(api_key) do
+    # Use a well-known public playlist (YouTube's "Popular Right Now" uploads playlist)
+    # to test if the API key is valid
+    test_playlist_id = "PLrAXtmErZgOeiKm4sgNOknGvNjby9efdf"
+    url = "https://youtube.googleapis.com/youtube/v3/playlistItems?part=id&maxResults=1&playlistId=#{test_playlist_id}&key=#{api_key}"
+
+    case http_client().get(url, accept: "application/json") do
+      {:ok, response} ->
+        case Phoenix.json_library().decode(response) do
+          {:ok, %{"error" => %{"message" => message}}} ->
+            {:error, message}
+
+          {:ok, %{"items" => _}} ->
+            :ok
+
+          {:ok, _} ->
+            :ok
+
+          {:error, _} ->
+            {:error, "Invalid JSON response"}
+        end
+
+      {:error, reason} ->
+        {:error, "Request failed: #{inspect(reason)}"}
+    end
+  end
+
   @doc """
   Fetches the recent media IDs from the YouTube API for a given source.
 

lib/pinchflat/fast_indexing/youtube_behaviour.ex

@@ -8,4 +8,5 @@ defmodule Pinchflat.FastIndexing.YoutubeBehaviour do
 
   @callback enabled?() :: boolean()
   @callback get_recent_media_ids(%Source{}) :: {:ok, [String.t()]} | {:error, String.t()}
+  @callback test_api_key(String.t()) :: :ok | {:error, String.t()}
 end

lib/pinchflat_web/controllers/settings/setting_html/setting_form.html.heex

@@ -32,15 +32,11 @@
         Extractor Settings
       </h3>
 
-      <.input
-        field={f[:youtube_api_key]}
-        placeholder="ABC123,DEF456"
-        type="text"
-        label="YouTube API Key(s)"
-        help={youtube_api_help()}
-        html_help={true}
-        inputclass="font-mono text-sm mr-4"
-      />
+      {live_render(
+        @conn,
+        Pinchflat.Settings.YoutubeApiKeyLive,
+        session: %{"value" => f[:youtube_api_key].value}
+      )}
 
       <.input
         field={f[:extractor_sleep_interval_seconds]}

lib/pinchflat_web/controllers/settings/setting_html/youtube_api_key_live.ex

@@ -0,0 +1,81 @@
+defmodule Pinchflat.Settings.YoutubeApiKeyLive do
+  use PinchflatWeb, :live_view
+
+  alias PinchflatWeb.Settings.SettingHTML
+
+  def render(assigns) do
+    ~H"""
+    <.input
+      type="text"
+      id="setting_youtube_api_key"
+      name="setting[youtube_api_key]"
+      value={@value}
+      label="YouTube API Key(s)"
+      help={SettingHTML.youtube_api_help()}
+      html_help={true}
+      inputclass="font-mono text-sm mr-4"
+      placeholder="ABC123,DEF456"
+      phx-change="youtube_api_key_changed"
+    >
+      <:input_append>
+        <.icon_button icon_name={@icon_name} class="h-12 w-12" phx-click="test_youtube_api_key" tooltip={@tooltip} />
+      </:input_append>
+    </.input>
+    """
+  end
+
+  def mount(_params, session, socket) do
+    new_assigns = %{
+      value: session["value"],
+      icon_name: "hero-play",
+      tooltip: "Test API Key"
+    }
+
+    {:ok, assign(socket, new_assigns)}
+  end
+
+  def handle_event("test_youtube_api_key", _params, %{assigns: assigns} = socket) do
+    case test_api_key(assigns.value) do
+      :ok ->
+        Process.send_after(self(), :reset_button_icon, 4_000)
+        {:noreply, assign(socket, %{icon_name: "hero-check", tooltip: "Success!"})}
+
+      {:error, reason} ->
+        Process.send_after(self(), :reset_button_icon, 4_000)
+        {:noreply, assign(socket, %{icon_name: "hero-x-mark", tooltip: reason})}
+    end
+  end
+
+  def handle_event("youtube_api_key_changed", %{"setting" => setting}, socket) do
+    {:noreply, assign(socket, %{value: setting["youtube_api_key"]})}
+  end
+
+  def handle_info(:reset_button_icon, socket) do
+    {:noreply, assign(socket, %{icon_name: "hero-play", tooltip: "Test API Key"})}
+  end
+
+  defp test_api_key(nil), do: {:error, "No API key provided"}
+  defp test_api_key(""), do: {:error, "No API key provided"}
+
+  defp test_api_key(keys_string) do
+    # Test the first API key provided
+    first_key =
+      keys_string
+      |> String.split(",")
+      |> Enum.map(&String.trim/1)
+      |> Enum.reject(&(&1 == ""))
+      |> List.first()
+
+    case first_key do
+      nil ->
+        {:error, "No API key provided"}
+
+      key ->
+        youtube_api().test_api_key(key)
+    end
+  end
+
+  defp youtube_api do
+    Application.get_env(:pinchflat, :youtube_api, Pinchflat.FastIndexing.YoutubeApi)
+  end
+end