require 'bigbro/railtie' if defined? Rails
require 'bigbro/version'

module BigBro

  module Helpers
    # Embeds the optimized Analytics code and the noscript tag with
    # the direct path to the __utm.gif image into the current page.
    #
    # If the `:track` option is set to false, the current page load
    # is *not* automatically tracked: you should track it later via
    # the JS API.
    #
    def analytics(options = {})
      return if BigBro.disabled?

      track = options.has_key?(:track) ? options[:track] : true

      ga_host = BigBro.host_for(request)
      ga_cmds = [['_setAccount', BigBro.account]]
      ga_cmds.push ['_setDomainName', BigBro.domain] if BigBro.domain
      ga_cmds.concat(options[:commands]) if options[:commands]
      ga_cmds.push ['_trackPageview']    if track

      code = ''
      code.concat javascript_tag(%(
        var _gaq = #{ga_cmds.to_json};
        try {
          (function(d,t,a) {
            var g=d.createElement(t),s=d.getElementsByTagName(t)[0];
            g[a]=a;g.src='#{ga_host}/ga.js';s.parentNode.insertBefore(g,s);
          })(document, 'script', 'async');
        } catch (err) {}
      ))

      code.concat(content_tag(:noscript,
        image_tag(BigBro.noscript_image_path_for(request, ga_host),
                  :border => '0', :alt => '').html_safe
      ))

      return code.html_safe
    end
  end

  class << self
    attr_accessor :account, :domain, :disabled

    # Sets the Analytics account and *enforces* it to be set
    # in production mode.
    #
    # If you're developing and want to run your local copy
    # in production mode, you can either pass an invalid
    # account (e.g. to check how the JS code is generated)
    # or pass the :disabled option set to true.
    #
    # In test mode, the account is always set to the dummy
    # "UA-420-THEBRAIN" string.
    #
    # Sets the 'UA-12345-67' account:
    #
    #   BigBro.set(:account => 'UA-12345-67')
    #
    # Sets the 'UA-12345-67' account and the 'foo.com' domain:
    #
    #   BigBro.set(:account => 'UA-12345-67', :domain => 'foo.com')
    #
    # Disables analytics code generation:
    #
    #   BigBro.set(:disabled => true)
    #
    def set(options = {})
      self.account, self.disabled, self.domain =
        options.values_at(:account, :disabled, :domain)

      if Rails.env.production?
        if self.account.blank? && !self.disabled
          raise ArgumentError, 'BigBro: analytics configuration missing'
        end
      elsif Rails.env.test?
        self.account = 'UA-420-THEBRAIN'
      end
    end

    # In development mode the Analytics code is always disabled,
    # or it can be disabled manually via the configuration.
    #
    # If no account is set, the code disables itself. Maybe the
    # check in the set() method should be moved here, we'll see.
    #
    def disabled?
      self.disabled || self.account.blank? || Rails.env.development?
    end

    # Returns the analytics host for the given request (SSL or not)
    #
    def host_for(request)
      (request.ssl? ? 'https://ssl' : 'http://www') + '.google-analytics.com'
    end

    # Returns the noscript image path for the given request and GA Host
    #
    def noscript_image_path_for(request, ga_host)
      cookie = rand(   89_999_999) +    10_000_000
      req_no = rand(8_999_999_999) + 1_000_000_000
      random = rand(1_147_483_647) + 1_000_000_000
      now    = Time.now.to_i

      referer = request.referer.blank? ? '-' : CGI.escape(request.referer)
      path    = request.path.blank?    ? '/' : CGI.escape(request.path)

      utmcc =
        "__utma%3D#{cookie}.#{random}.#{now}.#{now}.#{now}.2%3B%2B" \
        "__utmz%3D#{cookie}.#{now}.2.2."                            \
          "utmccn%3D(direct)%7C"       \
          "utmcsr%3D(direct)%7C"       \
          "utmcmd%3D(none)%3B%2B"      \
       "__utmv%3D#{cookie}.noscript%3B"

      "#{ga_host}/__utm.gif?"    \
        "utmn=#{req_no}&"        \
        "utmac=#{account}&"      \
        "utmhn=#{request.host}&" \
        "utmr=#{referer}&"       \
        "utmp=#{path}&"          \
        "utmcc=#{utmcc}&"        \
        'utmwv=1&'               \
        'utmje=0&'               \
        'utmsr=-&'               \
        'utmsc=-&'               \
        'utmul=-&'               \
        'utmfl=-&'               \
        'utmdt=-'
    end
  end

  module TestHelpers
    # Asserts the GA <script> tag, with not much effort;
    # Asserts the noscript tag with the descendant img.
    #
    def assert_analytics
      host = BigBro.host_for(@request)

      assert_tag :tag => 'script', :content => /#{host}\/ga.js/

      assert_tag :tag => 'noscript',
        :descendant => {
          :tag => 'img',
          :attributes => {
            :src => /#{host}\/__utm.gif\?/,
            :border => '0',
            :alt => ''
          }
        }
    end
  end
end