Add breakdown of usage by source to admin UI for hashtags (#11517)

Allows determining where the majority of posts in a hashtag come
from on a given day at a glance.

app/controllers/admin/tags_controller.rb

@@ -4,6 +4,8 @@ module Admin
   class TagsController < BaseController
     before_action :set_tags, only: :index
     before_action :set_tag, except: :index
+    before_action :set_usage_by_domain, except: :index
+    before_action :set_counters, except: :index
 
     def index
       authorize :tag, :index?
@@ -33,6 +35,21 @@ module Admin
       @tag = Tag.find(params[:id])
     end
 
+    def set_usage_by_domain
+      @usage_by_domain = @tag.statuses
+                             .where(visibility: :public)
+                             .where(Status.arel_table[:id].gteq(Mastodon::Snowflake.id_at(Time.now.utc.beginning_of_day)))
+                             .joins(:account)
+                             .group('accounts.domain')
+                             .reorder('statuses_count desc')
+                             .pluck('accounts.domain, count(*) AS statuses_count')
+    end
+
+    def set_counters
+      @accounts_today = @tag.history.first[:accounts]
+      @accounts_week  = Redis.current.pfcount(*current_week_days.map { |day| "activity:tags:#{@tag.id}:#{day}:accounts" })
+    end
+
     def filtered_tags
       scope = Tag
       scope = scope.discoverable if filter_params[:context] == 'directory'
@@ -49,5 +66,13 @@ module Admin
     def tag_params
       params.require(:tag).permit(:name, :trendable, :usable, :listable)
     end
+
+    def current_week_days
+      now = Time.now.utc.beginning_of_day.to_date
+
+      (Date.commercial(now.cwyear, now.cweek)..now).map do |date|
+        date.to_time.utc.beginning_of_day.to_i
+      end
+    end
   end
 end