add save cookie

README.md

@@ -58,6 +58,7 @@ You can get a session in a few different ways:
     # pass in the tracking code directly
     AARRR(cookies["_utmarrr"])
 
+You should then save the session to cookie: `AARRR(request.env).save(response)`
 
 ### Tracking vs Completion events
 

lib/aarrr/config.rb

@@ -31,6 +31,7 @@ def option(name, options = {})
     # default some options with defaults
     option :database_name, :default => "metrics"
     option :cookie_name, :default => "_utmarr"
+    option :cookie_expiration, :default => 60*24*60*60
     option :user_collection_name, :default => "aarrr_users"
     option :event_collection_name, :default => "aarrr_events"
 

lib/aarrr/session.rb

@@ -46,6 +46,15 @@ def track!(event_name, options = {})
       })
     end
 
+    # save a cookie to the response
+    def save(response)
+      response.set_cookie(AARRR::Config.cookie_name, {
+        :value => self.id,
+        :path => "/",
+        :expires => Time.now+AARRR::Config.cookie_expiration
+      })
+    end
+
     protected
 
     # mark update