# Summarizes all stats for all tracked sessions and their actions for a given site in a given month.
class TrackableStat

  # Mongoid Config =============================================================================

  include Mongoid::Document
  include Mongoid::Timestamps

  references_many :trackable_sessions

  field :site
  field :bounces, :type => Integer, :default => 0
  field :clickthroughs, :type => Integer, :default => 0
  field :conversions, :type => Integer, :default => 0
  field :duration, :type => Integer, :default => 0
  field :new_visits, :type => Integer, :default => 0
  field :organic_visits, :type => Integer, :default => 0
  field :pageviews, :type => Integer, :default => 0
  field :ppc_visits, :type => Integer, :default => 0
  field :direct_visits, :type => Integer, :default => 0
  field :return_visits, :type => Integer, :default => 0
  field :search_visits, :type => Integer, :default => 0
  field :visits, :type => Integer, :default => 0

  index :site, :unique => false

  # Scopes =========================================================================================

  scope :by_site,         lambda { |site| { :where => { :site => site } } }
  scope :by_date,         lambda { |date| { :where => { :created_at => { '$gte' => date.beginning_of_month,  '$lte' => date.end_of_month } } } }
  scope :for_date_range,  lambda { |start_date,end_date| { :where => { :created_at => { '$gte' => start_date.beginning_of_month,  '$lte' => end_date.end_of_month } } } }
  scope :for_site,         lambda { |site| { :where => { :site => site } } }

  # Class Methods ==================================================================================

  # Returns the names of all sites that have been tracked, used in report filters.
  def self.sites
    TrackableStat.only(:site).map{|s| s.site.to_s.downcase}.uniq
  end

  # Instance Methods ===============================================================================

  # Increments the running tallies of the session- and action-attributes for a given site in a given
  # month. For example, an action's clickthroughs or conversions, or the kind of session (direct,
  # natural, paid, search).
  #
  # ==== Attributes
  #
  # * +:session+ - action as a string: 'click', 'clickthrough', 'conversion', 'mouseover', 'scroll', 'view'
  # * +:last_action+ - clickthrough destination
  # * +:previous_action+ - the referring URL
  #
  # ==== Examples
  #
  #    trackable_stat.touch( 'click', 'cnn.com', 'foo.com/cnn' )
  def touch(session, last_action, previous_action = nil)
    if previous_action.nil?
      # New session
      self.trackable_sessions << session
      self.clickthroughs  += 1 if last_action && last_action.clickthrough?
      self.conversions    += 1 if last_action && last_action.conversion?
      self.direct_visits  += 1 if session.kind == 'direct'
      self.new_visits     += 1 if session.new_visit
      self.organic_visits += 1 if session.kind == 'natural'
      self.pageviews      += 1
      self.ppc_visits     += 1 if session.kind == 'paid'
      self.return_visits  += 1 if ! session.new_visit
      self.search_visits  += 1 if session.kind == 'search'
      self.visits         += 1
      self.bounces        += 1 # Assume that it's a bounce until a second view is recorded
    else
      # Existing session
      self.clickthroughs  += 1 if last_action.clickthrough?
      self.conversions    += 1 if last_action.conversion?
      self.duration       += last_action.created_at - previous_action.created_at
      self.pageviews      += 1 if last_action.view?
      self.bounces        -= 1 if session.trackable_actions.count == 2
    end
    self.save
  end

end