after invited_user introduced

invite_redeemer.rb

InviteRedeemer = Struct.new(:invite) do

  def redeem
    result = invited_user
    Invite.transaction do
      if mark_invite_redeemed == 1
        # Create the user if we are redeeming the invite and the user doesn't exist
        result = create_user_if_missing

        # If there are topic invites for private topics
        allow_access_to_private_topics

        # Check for other invites by the same email. Don't redeem them, but approve their
        # topics.
        approve_topic_invitations

        send_welcome_message

        # Notify the invitee
        notify_invitee
      end
    end

    result
  end


  #private

  def invited_user
    @invited_user ||= get_existing_user
  end

  def mark_invite_redeemed
    # Avoid a race condition
    # Return true if 1 row was updated
    Invite.update_all('redeemed_at = CURRENT_TIMESTAMP',
                      ['id = ? AND redeemed_at IS NULL AND created_at >= ?',
                       invite.id,
                       SiteSetting.invite_expiry_days.days.ago])
  end

  def create_user_if_missing
    result = invited_user
    result ||= User.create_for_email(invite.email, trust_level: SiteSetting.default_invitee_trust_level)
    result.send_welcome_message = false
    result
  end

  def get_existing_user
    User.where(email: invite.email).first
  end

  def allow_access_to_private_topics
    invite.topics.private_messages.each do |t|
      t.topic_allowed_users.create(user_id: invited_user.id)
    end
  end

  def approve_topic_invitations
    Invite.where('invites.email = ? and invites.id != ?', invite.email, invite.id).includes(:topics).where(topics: {archetype: Archetype::private_message}).each do |i|
      i.topics.each do |t|
        t.topic_allowed_users.create(user_id: invited_user.id)
      end
    end
  end

  def send_welcome_message(result)
    if Invite.update_all(['user_id = ?', result.id], ['email = ?', invite.email]) == 1
      result.send_welcome_message = true
    end
  end

  def notify_invitee
    invite.invited_by.notifications.create(notification_type: Notification.types[:invitee_accepted],
                                           data: {display_username: invited_user.username}.to_json)
  end
end