middleware.rb in eeny-meeny-2.1.0

- old
+ new

@@ -22,24 +22,35 @@
       existing_set_cookie_header = env['Set-Cookie']
       # Prepare for experiments.
       @experiments.each do |experiment|
         # Skip inactive experiments
         next unless experiment.active?(now)
+        # Trigger experiment through query parmeters
+        cookie_name = EenyMeeny::Cookie.cookie_name(experiment)
+        has_experiment_trigger = EenyMeeny.config.query_parameters[:experiment] && request.params.has_key?(cookie_name)
         # skip experiments that already have a cookie
-        unless cookies.has_key?(EenyMeeny::Cookie.cookie_name(experiment))
-          env['Set-Cookie'] = ''
-          cookie = EenyMeeny::Cookie.create_for_experiment(experiment, @cookie_config)
+        if has_experiment_trigger || !cookies.has_key?(cookie_name)
+          cookie = if has_experiment_trigger
+                     # Trigger experiment variation through query parameter.
+                     EenyMeeny::Cookie.create_for_experiment_variation(experiment, request.params[cookie_name].to_sym, @cookie_config)
+                   else
+                     EenyMeeny::Cookie.create_for_experiment(experiment, @cookie_config)
+                   end
           # Set HTTP_COOKIE header to enable experiment on first pageview
-          Rack::Utils.set_cookie_header!(env,
-                                         cookie.name,
-                                         cookie.to_h)
-          env['HTTP_COOKIE'] = '' if env['HTTP_COOKIE'].nil?
-          env['HTTP_COOKIE'] += '; ' unless env['HTTP_COOKIE'].empty?
-          env['HTTP_COOKIE'] += env['Set-Cookie']
+          env = add_http_cookie(env, cookie, precede: has_experiment_trigger)
           new_cookies[cookie.name] = cookie
         end
       end
+      # Prepare smoke tests (if enabled through query parameters)
+      if EenyMeeny.config.query_parameters[:smoke_test]
+        if request.params.has_key?('smoke_test_id') && (request.params['smoke_test_id'] =~ /[A-Za-z_]+/)
+          # Set HTTP_COOKIE header to enable smoke test on first pageview
+          cookie = EenyMeeny::Cookie.create_for_smoke_test(request.params['smoke_test_id'])
+          env = add_http_cookie(env, cookie, precede: true)
+          new_cookies[cookie.name] = cookie
+        end
+      end
       # Clean up 'Set-Cookie' header.
       if existing_set_cookie_header.nil?
         env.delete('Set-Cookie')
       else
         env['Set-Cookie'] = existing_set_cookie_header
@@ -50,8 +61,25 @@
       # Add new cookies to 'Set-Cookie' header
       new_cookies.each do |key, value|
         response.set_cookie(key,value.to_h)
       end
       response.finish
+    end
+
+    private
+    def add_http_cookie(env, cookie, precede: false)
+      env['Set-Cookie'] = ''
+      Rack::Utils.set_cookie_header!(env,
+                                     cookie.name,
+                                     cookie.to_h)
+      env['HTTP_COOKIE'] = '' if env['HTTP_COOKIE'].nil?
+      if precede
+        # Prepend cookie to the 'HTTP_COOKIE' header. This ensures it overwrites existing cookies when present.
+        env['HTTP_COOKIE'] = env['Set-Cookie'] + '; ' + env['HTTP_COOKIE']
+      else
+        env['HTTP_COOKIE'] += '; ' unless env['HTTP_COOKIE'].empty?
+        env['HTTP_COOKIE'] += env['Set-Cookie']
+      end
+      env
     end
   end
 end