Escape fragment identifiers in wikipedia URLs

Fixes #967

app/helpers/browse_helper.rb

@@ -1,3 +1,5 @@
+require "uri"
+
 module BrowseHelper
   def printable_name(object, version = false)
     if object.id.is_a?(Array)
@@ -133,17 +135,19 @@ module BrowseHelper
       return nil
     end
 
-    if value =~ /^([^#]*)(#.*)/
+    if value =~ /^([^#]*)#(.*)/
       # Contains a reference to a section of the wikipedia article
       # Must break it up to correctly build the url
       value = $1
-      section = $2
+      section = "#" + $2
+      encoded_section = "#" + URI.encode($2.gsub(" ", "_")).gsub("%3A", ":").gsub("%", ".")
     else
       section = ""
+      encoded_section = ""
     end
 
     {
-      :url => "http://#{lang}.wikipedia.org/wiki/#{value}?uselang=#{I18n.locale}#{section}",
+      :url => "http://#{lang}.wikipedia.org/wiki/#{value}?uselang=#{I18n.locale}#{encoded_section}",
       :title => value + section
     }
   end

test/helpers/browse_helper_test.rb

@@ -188,6 +188,14 @@ class BrowseHelperTest < ActionView::TestCase
     assert_equal "http://fr.wikipedia.org/wiki/de:Test?uselang=en", link[:url]
     assert_equal "de:Test", link[:title]
 
+    link = wikipedia_link("wikipedia", "de:Englischer Garten (München)#Japanisches Teehaus")
+    assert_equal "http://de.wikipedia.org/wiki/de:Englischer Garten (München)?uselang=en#Japanisches_Teehaus", link[:url]
+    assert_equal "de:Englischer Garten (München)#Japanisches Teehaus", link[:title]
+
+    link = wikipedia_link("wikipedia", "de:Alte Brücke (Heidelberg)#Brückenaffe")
+    assert_equal "http://de.wikipedia.org/wiki/de:Alte Brücke (Heidelberg)?uselang=en#Br.C3.BCckenaffe", link[:url]
+    assert_equal "de:Alte Brücke (Heidelberg)#Brückenaffe", link[:title]
+
     I18n.locale = "pt-BR"
 
     link = wikipedia_link("wikipedia", "zh-classical:Test#Section")