FEATURE: Anonymize User. A way to remove a user but keep their topics and posts.

app/services/user_anonymizer.rb

@@ -0,0 +1,63 @@
+class UserAnonymizer
+  def initialize(user, actor=nil)
+    @user = user
+    @actor = actor
+  end
+
+  def self.make_anonymous(user, actor=nil)
+    self.new(user, actor).make_anonymous
+  end
+
+  def make_anonymous
+    User.transaction do
+      prev_email = @user.email
+      prev_username = @user.username
+
+      if !UsernameChanger.change(@user, make_anon_username)
+        raise "Failed to change username"
+      end
+
+      @user.reload
+      @user.password = SecureRandom.hex
+      @user.email = "#{@user.username}@example.com"
+      @user.name = nil
+      @user.date_of_birth = nil
+      @user.title = nil
+      @user.email_digests = false
+      @user.email_private_messages = false
+      @user.email_direct = false
+      @user.email_always = false
+      @user.mailing_list_mode = false
+      @user.save
+
+      profile = @user.user_profile
+      profile.destroy if profile
+      @user.create_user_profile
+
+      @user.user_avatar.try(:destroy)
+      @user.twitter_user_info.try(:destroy)
+      @user.google_user_info.try(:destroy)
+      @user.github_user_info.try(:destroy)
+      @user.facebook_user_info.try(:destroy)
+      @user.single_sign_on_record.try(:destroy)
+      @user.oauth2_user_info.try(:destroy)
+      @user.user_open_ids.find_each { |x| x.destroy }
+      @user.api_key.try(:destroy)
+
+      UserHistory.create( action: UserHistory.actions[:anonymize_user],
+                          target_user_id: @user.id,
+                          acting_user_id: @actor ? @actor.id : @user.id,
+                          email: prev_email,
+                          details: "username: #{prev_username}" )
+    end
+    @user
+  end
+
+  def make_anon_username
+    100.times do
+      new_username = "anon#{(SecureRandom.random_number * 100000000).to_i}"
+      return new_username unless User.where(username_lower: new_username).exists?
+    end
+    raise "Failed to generate an anon username"
+  end
+end

app/services/username_changer.rb

@@ -0,0 +1,23 @@
+class UsernameChanger
+
+  def initialize(user, new_username, actor=nil)
+    @user = user
+    @new_username = new_username
+    @actor = actor
+  end
+
+  def self.change(user, new_username, actor=nil)
+    self.new(user, new_username, actor).change
+  end
+
+  def change
+    if @actor && @actor != @user
+      StaffActionLogger.new(@actor).log_username_change(@user, @user.username, @new_username)
+    end
+
+    # future work: update mentions and quotes
+
+    @user.username = @new_username
+    @user.save
+  end
+end