add support for deleting user accounts

app/models/favorite.rb

@@ -4,7 +4,11 @@ class Favorite < ActiveRecord::Base
 
   # this is necessary because there's no trigger for deleting favorites
   def self.destroy_all(hash)
-    connection.execute("delete from favorites_#{hash[:user_id] % 100} where user_id = #{hash[:user_id]} and post_id = #{hash[:post_id]}")
+    if hash[:user_id] && hash[:post_id]
+      connection.execute("delete from favorites_#{hash[:user_id] % 100} where user_id = #{hash[:user_id]} and post_id = #{hash[:post_id]}")
+    elsif hash[:user_id]
+      connection.execute("delete from favorites_#{hash[:user_id] % 100} where user_id = #{hash[:user_id]}")
+    end
   end
 
   def self.add(post, user)

app/models/user.rb

@@ -616,6 +616,35 @@ class User < ActiveRecord::Base
     end
   end
 
+  module DeletionMethods
+    def delete!
+      scramble_password
+      remove_all_favorites
+      rename_for_delete
+    end
+
+    def rename_for_delete
+      alt_name = "user#{id}"
+      n = 0
+      while User.where(:name => alt_name).exists?
+        alt_name = "user#{id}_#{n}"
+        n += 1
+      end
+      update_attribute(:name, alt_name)
+
+    end
+
+    def scramble_password
+      update_attribute(:bcrypt_password_hash, User.bcrypt(SecureRandom.hex(16)))
+    end
+
+    def remove_all_favorites
+      Post.tag_match("fav:#{name}").find_each do |post|
+        Favorite.remove(post, self)
+      end
+    end
+  end
+
   include BanMethods
   include NameMethods
   include PasswordMethods
@@ -629,6 +658,7 @@ class User < ActiveRecord::Base
   include InvitationMethods
   include ApiMethods
   extend SearchMethods
+  include DeletionMethods
 
   def initialize_default_image_size
     self.default_image_size = "large"

test/unit/user_test.rb

@@ -14,6 +14,29 @@ class UserTest < ActiveSupport::TestCase
       CurrentUser.ip_addr = nil
     end
 
+    context "that has been deleted" do
+      setup do
+        @post = FactoryGirl.create(:post)
+        Favorite.add(@post, @user)
+        @user.delete!
+        @post.reload
+      end
+
+      should "rename the user" do
+        assert_equal("user#{@user.id}", @user.name)
+      end
+
+      should "remove all favorites" do
+        assert_equal(0, @user.favorite_count)
+        assert_equal(0, Favorite.for_user(@user.id).count)
+        assert_equal("", @post.fav_string)
+      end
+
+      should "reset the password" do
+        assert_nil(User.authenticate(@user.name, "password"))
+      end
+    end
+
     context "favoriting a post" do
       setup do
         @user.update_column(:favorite_count, 999)