event.rb

require 'json_serialized_field'

class Event < ActiveRecord::Base
  include JSONSerializedField

  attr_accessible :lat, :lng, :payload, :user_id, :user, :expires_at

  acts_as_mappable

  json_serialize :payload

  belongs_to :user
  belongs_to :agent, :counter_cache => true, :touch => :last_event_at

  scope :recent, lambda { |timespan = 12.hours.ago|
    where("events.created_at > ?", timespan)
  }

  def reemit!
    agent.create_event :payload => payload, :lat => lat, :lng => lng
  end

  def self.cleanup_expired!
    affected_agents = Event.where("expires_at IS NOT NULL AND expires_at < ?", Time.now).group("agent_id").pluck(:agent_id)
    Event.where("expires_at IS NOT NULL AND expires_at < ?", Time.now).delete_all
    Agent.where(:id => affected_agents).update_all "events_count = (select count(*) from events where agent_id = agents.id)"
  end
end