add watcher count to tag on current user's profile

lib/philomena_web/controllers/profile_controller.ex

@@ -10,6 +10,7 @@ defmodule PhilomenaWeb.ProfileController do
   alias Philomena.Posts.Post
   alias Philomena.Comments.Comment
   alias Philomena.Interactions
+  alias Philomena.Tags.Tag
   alias Philomena.Repo
   import Ecto.Query
 
@@ -36,6 +37,14 @@ defmodule PhilomenaWeb.ProfileController do
       )
 
     tags = tags(conn.assigns.user.public_links)
+
+    watcher_counts =
+      Tag
+      |> join(:inner_lateral, [t], _ in fragment("SELECT count(*) FROM users WHERE watched_tag_ids @> ARRAY[?]", t.id))
+      |> select([t, c], {t.id, c.count})
+      |> Repo.all()
+      |> Map.new()
+
     recent_artwork = recent_artwork(conn, tags)
 
     recent_comments =
@@ -118,6 +127,7 @@ defmodule PhilomenaWeb.ProfileController do
       recent_posts: recent_posts,
       recent_galleries: recent_galleries,
       statistics: statistics,
+      watcher_counts: watcher_counts,
       about_me: about_me,
       tags: tags,
       bans: bans,

lib/philomena_web/templates/profile/show.html.slime

@@ -53,12 +53,20 @@
       .block__header
         span.block__header__title User Links
       = for link <- @user.verified_links, link.public or can?(@conn, :edit, link) do
+        - watchers = @watcher_counts[link.tag.id] || 0
+
         .block__content.alternating-color.break-word
           .center
             = if link.tag do
               .tag_list = render PhilomenaWeb.TagView, "_tag.html", tag: link.tag, conn: @conn
             = link(link.uri, to: link.uri)
 
+            = if current?(@user, @conn.assigns.current_user) do
+              br
+              ' Watched by
+              => watchers
+              = pluralize("user", "users", watchers)
+
     .block
       .block__header
         span.block__header__title Badges