tracker.rb

# frozen_string_literal: true

require 'rack'
require 'tilt'
require 'active_support/core_ext/class/attribute'
require 'active_support/core_ext/hash'
require 'active_support/json'
require 'active_support/inflector'

require 'rack/tracker/version'
require 'rack/tracker/extensions'
require 'rack/tracker/javascript_helper'
require 'rack/tracker/railtie' if defined?(Rails)
require 'rack/tracker/handler'
require 'rack/tracker/handler_delegator'
require 'rack/tracker/controller'
require 'rack/tracker/google_analytics/google_analytics'
require 'rack/tracker/google_global/google_global'
require 'rack/tracker/google_tag_manager/google_tag_manager'
require 'rack/tracker/google_adwords_conversion/google_adwords_conversion'
require 'rack/tracker/facebook/facebook'
require 'rack/tracker/facebook_pixel/facebook_pixel'
require 'rack/tracker/vwo/vwo'
require 'rack/tracker/go_squared/go_squared'
require 'rack/tracker/criteo/criteo'
require 'rack/tracker/zanox/zanox'
require 'rack/tracker/hotjar/hotjar'
require 'rack/tracker/bing/bing'
require 'rack/tracker/hubspot/hubspot'
require 'rack/tracker/drift/drift'
require 'rack/tracker/heap/heap'

module Rack
  class Tracker
    EVENT_TRACKING_KEY = 'tracker'

    def initialize(app, &block)
      @app = app
      @handlers = Rack::Tracker::HandlerSet.new(&block)
    end

    def call(env)
      @status, @headers, @body = @app.call(env)
      return [@status, @headers, @body] unless html?

      response = Rack::Response.new([], @status, @headers)

      env[EVENT_TRACKING_KEY] ||= {}

      if (session = env['rack.session'])
        env[EVENT_TRACKING_KEY].deep_merge!(session.delete(EVENT_TRACKING_KEY) || {}) { |_key, old, new| Array.wrap(old) + Array.wrap(new) }
      end

      session[EVENT_TRACKING_KEY] = env[EVENT_TRACKING_KEY] if response.redirection? && session

      @body.each { |fragment| response.write inject(env, fragment) }
      @body.close if @body.respond_to?(:close)

      response.finish
    end

    private

    def html?
      @headers['Content-Type'] =~ /html/
    end

    def inject(env, response)
      duplicated_response = response.dup
      @handlers.each(env) do |handler|
        handler.inject(duplicated_response)
      end
      duplicated_response
    end

    class HandlerSet
      Handler = Struct.new(:klass, :configuration) do
        def init(env)
          klass.new(env, configuration)
        end
      end

      def initialize(&block)
        @handlers = []
        instance_exec(&block) if block_given?
      end

      # setup the handler class with configuration options and make it ready for receiving the env during injection
      #
      # usage:
      #
      #   use Rack::Tracker do
      #     handler :google_analytics, { tracker: 'U-XXXXX-Y' }
      #   end
      #
      def handler(name, configuration = {})
        # we need here "something" (which is atm the handler struct)
        # to postpone the initialization of the handler,
        # to give it the env and configuration options when the result of the handler is injected into the response.
        @handlers << Handler.new(Rack::Tracker::HandlerDelegator.handler(name), configuration)
      end

      def each(env = {}, &block)
        @handlers.map { |h| h.init(env) }.each(&block)
      end
    end
  end
end