Various idiomatic User refactorings.

app/models/user.rb

@@ -66,16 +66,14 @@ class User < ActiveRecord::Base
   end
 
   def self.sanitize_username!(name)
-    name.gsub!(/^[^A-Za-z0-9]+|[^A-Za-z0-9_]+$/, "")
+    name.gsub!(/^[^[:alnum:]]+|\W+$/, "")
-    name.gsub!(/[^A-Za-z0-9_]+/, "_")
+    name.gsub!(/\W+/, "_")
   end
 
-  def self.pad_missing_chars_with_1s!(name)
-    missing_chars = User.username_length.begin - name.length
-    name << ('1' * missing_chars) if missing_chars > 0
-  end
 
   def self.find_available_username_based_on(name)
+    sanitize_username!(name)
+    name = rightsize_username(name)
     i = 1
     attempt = name
     until username_available?(attempt)
@@ -100,14 +98,13 @@ class User < ActiveRecord::Base
       name = Regexp.last_match[2] if ['i', 'me'].include?(name)
     end
 
-    sanitize_username!(name)
-    pad_missing_chars_with_1s!(name)
-
-    # Trim extra length
-    name = name[0..User.username_length.end-1]
     find_available_username_based_on(name)
   end
 
+  def self.rightsize_username(name)
+    name.ljust(username_length.begin, '1')[0,username_length.end]
+  end
+
   def self.new_from_params(params)
     user = User.new
     user.name = params[:name]