_visitor.rb

require 'ipaddr'

# This is a class that tracks visits on a site internally. 
# One of the major demands was determining where the visitor came from.
class Visitor < ActiveRecord::Base
  validates_presence_of :entry_uri
  validates_presence_of :exit_uri
  validates_presence_of :ip

  def self.recognizes_source(source_name, options = nil)
    @@recognizers ||= []
    source_class = "#{source_name}_recognizer".classify.constantize
    @@recognizers << source_class.new(options)
  end

  recognizes_source :direct_visit
  recognizes_source :mail
  recognizes_source :yandex_direct
  recognizes_source :search_engines
  recognizes_source :referring_site, :host => 'marketgid.com', :as => 'marketgid'
  recognizes_source :referring_site, :host => 'ru.redtram.com', :as => 'redtram'

  def self.new_visit!(ip, user_agent, referer_uri, entry_uri)
    visitor = Visitor.new(
      :ip => ip, 
      :user_agent => user_agent, 
      :referer_uri => referer_uri, 
      :entry_uri => entry_uri,
      :pages_count => 0
    )
    recognize_source(visitor)
    visitor.visit_page!(entry_uri)
    visitor
  end

  def visit_page!(page_uri)
    update_attributes!(
      :pages_count => pages_count+1,
      :exit_uri => page_uri
    )
  end

  def ip=(new_ip)
    if new_ip.is_a? String
      self[:ip] = IPAddr.new(new_ip).to_i
    elsif new_ip.is_a? Integer
      self[:ip] = IPAddr.new(new_ip, Socket::AF_INET).to_i
    else
      raise 'IP address should be a string or an integer'
    end
  end
  
  def self.search_queries_for_url(url)
    url.gsub!(/\/$/,'')
    Rails.cache.fetch("queries_for_#{Digest::MD5.hexdigest(url)}", :expires_in => 1.day) do
      find(:all,
        :conditions => ['entry_uri=? AND source LIKE "search_%"', url],
        :group => 'lower(query)',
        :select => '* ,count(*) as weight',
        :order => 'weight DESC',
        :limit => 15).map{|v| v.query}
    end
  end
  
  def self.recognize_source(visitor)
    @@recognizers.each do |recognizer|
      recognizer.recognize(visitor)
      return unless visitor.source.blank?
    end
  end

  before_create :generate_key
private
  def generate_key
    self[:key] = ActiveSupport::SecureRandom.hex(8)
  end
end

referring_site_recognizer.rb

require 'uri'
require 'cgi'
require 'iconv'

class ReferringSiteRecognizer < SourceRecognizer
  def initialize(options = {})
    @host = options[:host]
    @as = options.fetch(:as, @host)
  end

  def recognize(visitor)
    begin
      host = URI.parse(visitor.referer_uri).host
      visitor.source = @as if (host == @host || host == "www.#{@host}")
    rescue URI::InvalidURIError
    end
  end
end

search_engines_recognizer.rb

require 'uri'
require 'cgi'
require 'iconv'

class SearchEnginesRecognizer < SourceRecognizer
  def recognize(visitor)
    begin
      uri = URI.parse(visitor.referer_uri)
      fullpath = uri.host.to_s + uri.path.to_s.gsub(/\/$/,'')
      if (engine = @@engines_map[fullpath])
        params = CGI.parse(uri.query)
        if (query = params[engine[:param]])
          encoding = engine[:encoding].is_a?(Proc) ? engine[:encoding].call(params) : engine[:encoding]
          query = (encoding == 'UTF8') ? query.to_s : Iconv.conv('UTF8', encoding, query.to_s)
          begin
            Iconv.conv('UTF8','UTF8',query)
          rescue Iconv::IllegalSequence
            #hoping it's CP1251
            query = Iconv.conv('UTF8//TRANSLIT//IGNORE', 'CP1251', query)
          end
          visitor.source = "search_#{engine[:engine]}"
          visitor.query = query.strip
          return
        end
      end
    rescue URI::InvalidURIError
    end
  end

  def self.engines
    @@engines_map
  end

private
  @@engines_map = {
    'go.mail.ru/search' => {:engine => 'mail.ru',:encoding => lambda{|p| (p['utf8in']==['1'])||(p['fr']==['oprtb']) ? 'UTF8' : 'CP1251'}, :param => 'q'},
    'meta.ua/search.asp' => {:engine => 'meta.ua', :encoding => 'CP1251', :param => 'q'},
    'nigma.ru/index.php' => {:engine => 'nigma.ru', :encoding => 'UTF8', :param => 's'},
    'nova.rambler.ru/search' => {:engine => 'rambler.ru', :encoding => 'UTF8', :param => 'query'},
    'search.i.ua' => {:engine => 'yandex.ru', :encoding => 'CP1251', :param => 'q'},
    'search.ru.redtram.com' => {:engine => 'redtram.com', :encoding => 'UTF8', :param => 'q'},
    'search.ukr.net/yandex/bs.php' => {:engine => 'yandex.ru', :encoding => 'UTF8', :param => 'search_query'},
    'search.ukr.net/yandex/search.php' => {:engine => 'yandex.ru', :encoding => 'UTF8', :param => 'search_query'},
    'www.bing.com/search' => {:engine => 'bing.com', :encoding => 'UTF8', :param => 'q'},
    'www.google.com.ua/search' => {:engine => 'google.com', :encoding => 'UTF8', :param => 'q'},
    'www.google.com/search' => {:engine => 'google.com', :encoding => 'UTF8', :param => 'q'},
    'www.google.ru/search' => {:engine => 'google.com', :encoding => 'UTF8', :param => 'q'},
    'www.nigma.ru/index.php' => {:engine => 'nigma.ru', :encoding => 'UTF8', :param => 's'},
    'www.yandex.ru/yandsearch' => {:engine => 'yandex.ru', :encoding => 'UTF8', :param => 'text'},
    'yandex.ru/yandsearch' => {:engine => 'yandex.ru', :encoding => 'UTF8', :param => 'text'},
    'yandex.ua/yandsearch' => {:engine => 'yandex.ru', :encoding => 'UTF8', :param => 'text'},
  }
end