Sinatra port of Percent Mobile's rails helper for analytics

percent-mobile-helper.rb

require 'sinatra/base'
require 'cgi'

module Sinatra

  # http://code.percentmobile.com/snippet/ruby_on_rails/percent_mobile/lib/percent_mobile_helper.rb
  module PercentMobileHelper

    PERCENT_MOBILE_COOKIE_PATH="/"
    PERCENT_MOBILE_VISIT_DURATION=60*60
    PERCENT_MOBILE_VERSION="rails_26062010"
    PERCENT_MOBILE_COOKIE_NAME="_percent_mobile_c"

    def percent_mobile_track(id,url="")
      percent_mobile_u=new_random
      percent_mobile_v=new_random

      if request.cookies[:PERCENT_MOBILE_COOKIE_NAME] and request.cookies[:PERCENT_MOBILE_COOKIE_NAME]=~/(\d+)[01]_(\d+)_(\d+)[01]/
      	percent_mobile_u=$1+"0";
      	percent_mobile_v=$3+"0" if $2.to_i>Time.new().to_i
    	end    
    	response.set_cookie(PERCENT_MOBILE_COOKIE_NAME, {
    	  :value=>percent_mobile_u+'_'+(Time.new().to_i+PERCENT_MOBILE_VISIT_DURATION).to_s+'_'+percent_mobile_v,
    	  :expires=> Time.now + 365 * 24 * 60 * 60,
    	  :path=>PERCENT_MOBILE_COOKIE_PATH
    	  })
      subdomain=""
      # for _subdomain in request.subdomains 
      #   subdomain+=_subdomain+"." 
      # end         
      url = request.scheme+'://'+subdomain+request.host+request.fullpath if url==""

      referer=""        
      referer = request.env["HTTP_REFERER"] if request.env["HTTP_REFERER"]

      image_url="#{request.scheme}://tracking.percentmobile.com/pixel/#{id}/#{rand(0xffff)}.gif?v=#{PERCENT_MOBILE_VERSION}&us=#{percent_mobile_u}&vi=#{percent_mobile_v}&url=#{CGI::escape(url)}&referer=#{CGI::escape(referer)}";			

      if request.env["HTTP_USER_AGENT"] and request.env["HTTP_USER_AGENT"]=~/iPhone/
        return "<script type='text/javascript'>
        <!--
                	{
        		var m='';var s=document.createElement('style');var d=document.createElement('div');d.id='pm_IS_#{id}';
        	        s.innerText='@media (-webkit-min-device-pixel-ratio:2) {#'+d.id+'{display:none !important;}}';
        	        document.documentElement.appendChild(s).appendChild(d);
        	        var r=getComputedStyle(d,null).getPropertyValue('display')=='none';
        	        s.parentNode.removeChild(s);d.parentNode.removeChild(d);
        		if(r){m='&m=4';}else{r=new Date().getTime();for(var s=0;new Date().getTime()-r<20;s++){Math.random();}m = '&m='+((s>1000)?'3':'2');}
                        new Image().src='#{image_url}'+m;
                	}
                	-->
          </script>"
    	else
    	  return "<img src='#{image_url.gsub('&','&amp;')}' width='2' height='2' alt='.' />";
  	  end
    end

    private
    def new_random
      rand(2147583646).to_s+"1"
    end
  end

  helpers PercentMobileHelper

end