REFACTOR: All kinds of permalinks should return relative URLs

Mixing relative and absolute URLs is unnecessary and confusing.

app/models/category.rb

@@ -946,6 +946,8 @@ class Category < ActiveRecord::Base
     end
   end
 
+  alias_method :relative_url, :url
+
   # If the name changes, try and update the category definition topic too if it's an exact match
   def rename_category_definition
     return if topic.blank?

app/models/permalink.rb

@@ -72,11 +72,11 @@ class Permalink < ActiveRecord::Base
 
   def target_url
     return external_url if external_url
-    return "#{Discourse.base_path}#{post.url}" if post
+    return post.relative_url if post
     return topic.relative_url if topic
-    return category.url if category
-    return tag.full_url if tag
-    return user.full_url if user
+    return category.relative_url if category
+    return tag.relative_url if tag
+    return user.relative_url if user
     nil
   end
 

app/models/tag.rb

@@ -210,6 +210,8 @@ class Tag < ActiveRecord::Base
     "#{Discourse.base_path}/tag/#{UrlHelper.encode_component(self.name)}"
   end
 
+  alias_method :relative_url, :url
+
   def full_url
     "#{Discourse.base_url}/tag/#{UrlHelper.encode_component(self.name)}"
   end

app/models/user.rb

@@ -1779,6 +1779,10 @@ class User < ActiveRecord::Base
     username_lower == User.normalize_username(another_username)
   end
 
+  def relative_url
+    "#{Discourse.base_path}/u/#{encoded_username}"
+  end
+
   def full_url
     "#{Discourse.base_url}/u/#{encoded_username}"
   end