Log site setting changes and show in admin

app/services/staff_action_logger.rb

@@ -7,26 +7,39 @@ class StaffActionLogger
 
   def log_user_deletion(deleted_user, opts={})
     raise Discourse::InvalidParameters.new('user is nil') unless deleted_user and deleted_user.is_a?(User)
-    StaffActionLog.create(
+    StaffActionLog.create( params(opts).merge({
       action: StaffActionLog.actions[:delete_user],
-      context: opts[:context], # should be the url from where the staff member deleted the user
-      staff_user_id: @admin.id,
       target_user_id: deleted_user.id,
       email: deleted_user.email,
       ip_address: deleted_user.ip_address,
       details: [:id, :username, :name, :created_at, :trust_level, :last_seen_at, :last_emailed_at].map { |x| "#{x}: #{deleted_user.send(x)}" }.join(', ')
-    )
+    }))
   end
 
   def log_trust_level_change(user, old_trust_level, new_trust_level, opts={})
     raise Discourse::InvalidParameters.new('user is nil') unless user and user.is_a?(User)
     raise Discourse::InvalidParameters.new('old trust level is invalid') unless TrustLevel.levels.values.include? old_trust_level
     raise Discourse::InvalidParameters.new('new trust level is invalid') unless TrustLevel.levels.values.include? new_trust_level
-    StaffActionLog.create!(
+    StaffActionLog.create!( params(opts).merge({
       action: StaffActionLog.actions[:change_trust_level],
-      staff_user_id: @admin.id,
       target_user_id: user.id,
       details: "old trust level: #{old_trust_level}, new trust level: #{new_trust_level}"
-    )
+    }))
+  end
+
+  def log_site_setting_change(setting_name, previous_value, new_value, opts={})
+    raise Discourse::InvalidParameters.new('setting_name is invalid') unless setting_name.present? and SiteSetting.respond_to?(setting_name)
+    StaffActionLog.create( params(opts).merge({
+      action: StaffActionLog.actions[:change_site_setting],
+      subject: setting_name,
+      previous_value: previous_value,
+      new_value: new_value
+    }))
+  end
+
+  private
+
+  def params(opts)
+    {staff_user_id: @admin.id, context: opts[:context]}
   end
 end