Refactor logic for determining per page upload location. Resolves #1830 (#1831)

* Refactor logic for determining per page upload location. Add tests.

* Add per page upload test for  context

lib/gollum/app.rb

@@ -241,22 +241,9 @@ module Precious
           tempfile = params[:file][:tempfile]
         end
         halt 500 unless tempfile.is_a? Tempfile
+        
+        dir = wiki.per_page_uploads ? find_per_page_upload_subdir(request.referer, request.host_with_port, wiki.base_path) : 'uploads'
 
-        if wiki.per_page_uploads
-          dir = request.referer.match(/^https?:\/\/#{request.host_with_port}\/(.*)/)[1]          
-          # remove base path if it is set
-          dir.sub!(/^#{wiki.base_path}/, '') if wiki.base_path
-          # remove base_url and gollum/* subpath if necessary
-          dir.sub!(/^\/gollum\/[-\w]+\//, '')
-          # remove file extension
-          dir.sub!(/#{::File.extname(dir)}$/, '')
-          # revert escaped whitespaces
-          dir.gsub!(/%20/, ' ')
-          dir = ::File.join('uploads', dir)
-        else
-          # store all uploads together
-          dir = 'uploads'
-        end
         halt 500 if dir.include?('..')
         halt 500 unless Pathname(dir).relative?
 

lib/gollum/helpers.rb

@@ -5,6 +5,20 @@ module Precious
   module Helpers
 
     EMOJI_PATHNAME = Pathname.new(Gemojione.images_path).freeze
+    
+    def find_per_page_upload_subdir(referer, host_with_port, base_path)
+      base = base_path ? remove_leading_and_trailing_slashes(base_path) : ''
+      dir = referer.match(/^https?:\/\/#{host_with_port}\/#{base}\/?(.*)/)[1]
+      
+      # remove gollum/* subpath if necessary
+      dir.sub!(/^gollum\/[-\w]+\//, '')
+      # remove file extension
+      dir.sub!(/#{::File.extname(dir)}$/, '')
+      # revert escaped whitespaces
+      dir.gsub!(/%20/, ' ')
+      
+      return ::File.join('uploads', dir)
+    end
 
     def sanitize_empty_params(param)
       [nil, ''].include?(param) ? nil : CGI.unescape(param)
@@ -14,6 +28,10 @@ module Precious
       # Check if name already has a format extension, and if so, strip it.
       Gollum::Page.valid_extension?(name) ? Gollum::Page.strip_filename(name) : name
     end
+    
+    def remove_leading_and_trailing_slashes(str)
+      str.sub(%r{^(/+)}, '').sub(%r{/+$}, '')
+    end
 
     # Remove all slashes from the start of string.
     # Remove all double slashes