Show current visitors

assets/js/stats/index.js

@@ -125,4 +125,13 @@ if (domainEl) {
         router.updateLinkHandlers()
       })
   })
+
+  setInterval(function() {
+    fetch(`/api/${domain}/current-visitors`)
+      .then(res => res.json())
+      .then((res) => {
+        console.log(res)
+        document.getElementById('current-visitors').innerHTML = res
+      })
+  }, 10000)
 }

lib/plausible/stats/stats.ex

@@ -181,6 +181,15 @@ defmodule Plausible.Stats do
     )
   end
 
+  def current_visitors(site) do
+    Repo.one(
+      from p in Plausible.Pageview,
+      where: p.inserted_at >= fragment("(now() at time zone 'utc') - '5 minutes'::interval"),
+      where: p.hostname == ^site.domain,
+      select: count(p.user_id, :distinct)
+    )
+  end
+
   defp base_query(site, query) do
     {:ok, first} = NaiveDateTime.new(query.date_range.first, ~T[00:00:00])
     first_datetime = Timex.to_datetime(first, site.timezone)

lib/plausible_web/controllers/stats_controller.ex

@@ -23,12 +23,14 @@ defmodule PlausibleWeb.StatsController do
 
           {conn, params} = fetch_period(conn, site)
           query = Stats.Query.from(site.timezone, params)
+          current_visitors = Stats.current_visitors(site)
 
           conn
           |> assign(:skip_plausible_tracking, !demo)
           |> render("stats.html",
             site: site,
             query: query,
+            current_visitors: current_visitors,
             title: "Plausible · " <> site.domain
     )
         else
@@ -295,6 +297,16 @@ defmodule PlausibleWeb.StatsController do
     end
   end
 
+  def current_visitors(conn, %{"domain" => domain}) do
+    site = Repo.get_by(Plausible.Site, domain: domain)
+
+    if site && current_user_can_access?(conn, site) do
+      json(conn, Stats.current_visitors(site))
+    else
+      render_error(conn, 404)
+    end
+  end
+
   defp current_user_can_access?(_conn, %Plausible.Site{public: true}) do
     true
   end

lib/plausible_web/router.ex

@@ -42,6 +42,7 @@ defmodule PlausibleWeb.Router do
     get "/:domain/operating-systems", StatsController, :operating_systems
     get "/:domain/browsers", StatsController, :browsers
     get "/:domain/compare", StatsController, :compare
+    get "/:domain/current-visitors", StatsController, :current_visitors
   end
 
   scope "/", PlausibleWeb do

lib/plausible_web/templates/stats/stats.html.eex

@@ -1,7 +1,15 @@
 <div class="pt-12"></div>
 <div class="container pb-32" data-site-domain="<%= @site.domain %>">
   <div class="w-full sm:flex justify-between items-center">
-    <h2 class="text-center sm:text-left sm:mr-8">Analytics for <%= link(@site.domain, to: "//" <> @site.domain, target: "_blank") %></h2>
+    <div class="w-full sm:flex items-center">
+      <h2 class="text-center sm:text-left sm:mr-8">Analytics for <%= link(@site.domain, to: "//" <> @site.domain, target: "_blank") %></h2>
+      <div class="text-sm font-bold text-grey-darker">
+        <svg class="w-2 mr-1 fill-current text-green" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg">
+          <circle cx="8" cy="8" r="8"/>
+        </svg>
+        <span id="current-visitors"><%= @current_visitors %></span> current visitors
+      </div>
+    </div>
     <div class="mt-4 sm:mt-0">
       <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/flatpickr/dist/flatpickr.min.css">
       <script src="https://cdn.jsdelivr.net/npm/flatpickr"></script>

test/plausible/stats/stats_test.exs

@@ -143,6 +143,48 @@ defmodule Plausible.StatsTest do
     end
   end
 
+  describe "current_visitors" do
+    test "counts user ids seen in the last 5 minutes" do
+      site = insert(:site)
+
+      insert(:pageview, %{
+        hostname: site.domain,
+        user_id: UUID.uuid4(),
+      })
+
+      insert(:pageview, %{
+        hostname: site.domain,
+        user_id: UUID.uuid4(),
+        inserted_at: Timex.now() |> Timex.shift(minutes: -4)
+      })
+
+      insert(:pageview, %{
+        hostname: site.domain,
+        user_id: UUID.uuid4(),
+        inserted_at: Timex.now() |> Timex.shift(minutes: -6)
+      })
+
+      assert Stats.current_visitors(site) == 2
+    end
+
+    test "counts unique user ids" do
+      site = insert(:site)
+      id = UUID.uuid4()
+
+      insert(:pageview, %{
+        hostname: site.domain,
+        user_id: id,
+      })
+
+      insert(:pageview, %{
+        hostname: site.domain,
+        user_id: id,
+      })
+
+      assert Stats.current_visitors(site) == 1
+    end
+  end
+
   defp months_ago(months) do
     Timex.now() |> Timex.shift(months: -months)
   end