Refactor banner logic into BannerHelper module

app/helpers/banner_helper.rb

@@ -0,0 +1,54 @@
+module BannerHelper
+
+  # returns the least recently seen banner that is not hidden
+  def next_banner()
+    active_banners = {
+      :sotmus2016 => {
+        :id => 'sotmus2016',
+        :alt => 'State of the Map US 2016',
+        :link => 'http://stateofthemap.us/',
+        :img => 'banners/sotmus-2016.jpg'
+      },
+      :sotm2016 => {
+        :id => 'sotm2016',
+        :alt => 'State of the Map 2016',
+        :link => 'http://2016.stateofthemap.org/',
+        :img => 'banners/sotm-2016.jpg'
+      }
+    }
+
+    bannerKey = nil
+    cookieKey = nil
+    queuePos = 9999
+
+    active_banners.each do |k, v|
+      ckey = cookie_id(v[:id]).to_sym
+      cval = cookies[ckey] || 0
+      next if cval == 'hide'
+
+
+      # rotate all banner queue positions
+      index = cval.to_i
+      if index > 0
+        cookies[ckey] = index - 1
+      end
+
+      # pick banner with mininum queue position
+      if index <= queuePos
+        bannerKey = k
+        cookieKey = ckey
+        queuePos = index
+      end
+    end
+
+    unless bannerKey.nil?
+      cookies[cookieKey] = active_banners.length   # bump to end of queue
+      active_banners[bannerKey]
+    end
+  end
+
+  def cookie_id(key)
+    "_osm_banner_#{key}"
+  end
+
+end