Refactor banner logic into BannerHelper module

app/views/layouts/_banner.html.erb

@@ -1,41 +1,4 @@
-<% active_banners = {
-  :sotmus2016 => {
-    :alt => 'State of the Map US 2016',
-    :link => 'http://stateofthemap.us/',
-    :img => 'banners/sotmus-2016.jpg'
-  },
-  :sotm2016 => {
-    :alt => 'State of the Map 2016',
-    :link => 'http://2016.stateofthemap.org/',
-    :img => 'banners/sotm-2016.jpg'
-  }
-}
-
-bannerSym = nil
-cookieStr = nil
-queuePos = 9999
-
-# pick least recently seen banner that is not hidden
-active_banners.each_key do |k|
-  c = '_osm_banner_' + k.to_s
-  val = cookies[c.to_sym] || 0
-  next if val == 'hide'
-
-  if val.to_i > 0
-    cookies[c.to_sym] = val.to_i - 1
-  end
-
-  if val.to_i <= queuePos
-    bannerSym = k
-    cookieStr = c
-    queuePos = val.to_i
-  end
-end
-
-unless bannerSym.nil?
-  banner = active_banners[bannerSym]
-  cookies[cookieStr.to_sym] = active_banners.length   # bump to end of queue
-%>
+<% unless (banner = next_banner()).nil? %>
 <%= link_to (image_tag banner[:img], :alt => banner[:alt], :title => banner[:alt]), banner[:link] %>
-<div class="close-wrap" id="<%= cookieStr %>"><span class="icon close"></span></div>
+<div class="close-wrap" id="<%= cookie_id(banner[:id]) %>"><span class="icon close"></span></div>
 <% end %>