class Watcher
  include Mongoid::Document
  include Mongoid::Timestamps

  field :email

  embedded_in :app, inverse_of: :watchers
  belongs_to :user

  validate :ensure_user_or_email

  before_validation :clear_unused_watcher_type

  attr_accessor :watcher_type

  def watcher_type
    @watcher_type ||= email.present? ? 'email' : 'user'
  end

  def label
    user ? user.name : email
  end

  def address
    user.try(:email) || email
  end

protected

  def ensure_user_or_email
    errors.add(:base, "You must specify either a user or an email address") unless user.present? || email.present?
  end

  def clear_unused_watcher_type
    case watcher_type
    when 'user'
      self.email = nil
    when 'email'
      self.user = self.user_id = nil
    end
  end
end