discourse/app/controllers/notifications_controller.rb

require_dependency 'notification_serializer'

class NotificationsController < ApplicationController

  before_action :ensure_logged_in

  def index
    user =
      if params[:username] && !params[:recent]
        user_record = User.find_by(username: params[:username].to_s)
        raise Discourse::NotFound if !user_record
        user_record
      else
        current_user
      end

    guardian.ensure_can_see_notifications!(user)

    if params[:recent].present?
      limit = (params[:limit] || 15).to_i
      limit = 50 if limit > 50

      notifications = Notification.recent_report(current_user, limit)
      changed = false

      if notifications.present?
        # ordering can be off due to PMs
        max_id = notifications.map(&:id).max
        changed = current_user.saw_notification_id(max_id) unless params.has_key?(:silent)
      end
      user.reload
      user.publish_notifications_state if changed

      render_json_dump(notifications: serialize_data(notifications, NotificationSerializer),
                       seen_notification_id: current_user.seen_notification_id)
    else
      offset = params[:offset].to_i

      notifications = Notification.where(user_id: user.id)
        .visible
        .includes(:topic)
        .order(created_at: :desc)

      total_rows = notifications.dup.count
      notifications = notifications.offset(offset).limit(60)
      render_json_dump(notifications: serialize_data(notifications, NotificationSerializer),
                       total_rows_notifications: total_rows,
                       seen_notification_id: user.seen_notification_id,
                       load_more_notifications: notifications_path(username: user.username, offset: offset + 60))
    end

  end

  def mark_read
    if params[:id]
      Notification.read(current_user, [params[:id].to_i])
    else
      Notification.where(user_id: current_user.id).includes(:topic).where(read: false).update_all(read: true)
      current_user.saw_notification_id(Notification.recent_report(current_user, 1).max.try(:id))
      current_user.reload
      current_user.publish_notifications_state
    end

    render json: success_json
  end

end