Gab Social. All are welcome.

app/validators/follow_limit_validator.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class FollowLimitValidator < ActiveModel::Validator
+  LIMIT = ENV.fetch('MAX_FOLLOWS_THRESHOLD', 7_500).to_i
+  RATIO = ENV.fetch('MAX_FOLLOWS_RATIO', 1.1).to_f
+
+  def validate(follow)
+    return if follow.account.nil? || !follow.account.local?
+    follow.errors.add(:base, I18n.t('users.follow_limit_reached', limit: self.class.limit_for_account(follow.account))) if limit_reached?(follow.account)
+  end
+
+  class << self
+    def limit_for_account(account)
+      if account.following_count < LIMIT
+        LIMIT
+      else
+        [(account.followers_count * RATIO).round, LIMIT].max
+      end
+    end
+  end
+
+  private
+
+  def limit_reached?(account)
+    account.following_count >= self.class.limit_for_account(account)
+  end
+end