add gauge API

lib/camp_api/grist.ex

@@ -0,0 +1,21 @@
+defmodule CampApi.Grist do
+  @moduledoc false
+
+  @api_url "https://grist.interhacker.space/o/camp"
+
+  def get_records(doc, table) do
+    url = "#{@api_url}/api/docs/#{doc}/tables/#{table}/records"
+
+    request(:get, url)
+  end
+
+  defp request(method, url) do
+    Req.request(
+      method: method,
+      url: url,
+      headers: [
+        {"authorization", "Bearer " <> Application.fetch_env!(:camp_api, :grist)[:api_key]}
+      ]
+    )
+  end
+end

lib/camp_api/grist/gauge.ex

@@ -0,0 +1,14 @@
+defmodule CampApi.Grist.Gauge do
+  @moduledoc false
+
+  alias CampApi.Grist
+
+  @gauge_doc "wpwHRjzfdR9A"
+  @gauge_table "Infos"
+
+  def get() do
+    {:ok, %{body: %{"records" => records}}} = Grist.get_records(@gauge_doc, @gauge_table)
+
+    length(records)
+  end
+end