users: add ability to undelete accounts.

Add ability to undelete accounts from within the console. Their password is reset, their name is
restored to their last known user name, and a mod action is logged.

app/logical/user_deletion.rb

@@ -42,6 +42,15 @@ class UserDeletion
     true
   end
 
+  def undelete!
+    user.with_lock do
+      user.update!(is_deleted: false, password: password)
+      UserNameChangeRequest.create!(user: user, desired_name: user.user_name_change_requests.order(id: :desc).first.original_name, original_name: user.name)
+      ModAction.log("undeleted user ##{user.id}", :user_undelete, subject: user, user: deleter)
+      UserEvent.create_from_request!(user, :user_undeletion, request) if request.present?
+    end
+  end
+
   # Calls `delete_user`.
   def async_delete_user
     DeleteUserJob.perform_later(user)

app/models/mod_action.rb

@@ -17,6 +17,7 @@ class ModAction < ApplicationRecord
   # Misc:     6-19
   enum category: {
     user_delete: 2,
+    user_undelete: 3,
     user_ban: 4,
     user_unban: 5,
     user_name_change: 6,

app/models/user_event.rb

@@ -15,6 +15,7 @@ class UserEvent < ApplicationRecord
     logout: 100,
     user_creation: 200,
     user_deletion: 300,
+    user_undeletion: 310,
     password_reset: 400,
     password_change: 500,
     email_change: 600,

app/views/user_actions/index.html.erb

@@ -116,6 +116,8 @@
               <%= link_to_user user %> created their account.
             <% when "user_deletion" %>
               <%= link_to_user user %> deleted their account.
+            <% when "user_undeletion" %>
+              <%= link_to_user user %>'s account was undeleted.
             <% when "password_reset" %>
               <%= link_to_user user %> reset their password.
             <% when "password_change" %>

test/unit/user_deletion_test.rb

@@ -172,4 +172,29 @@ class UserDeletionTest < ActiveSupport::TestCase
       assert_equal(0, ModAction.count)
     end
   end
+
+  context "undeleting a user's account" do
+    should "restore the user's name and reset their password" do
+      @user = create(:user, name: "fumimi", password: "hunter2")
+      @deletion = UserDeletion.new(user: @user, deleter: create(:owner_user), password: "hunter2")
+
+      @deletion.delete!
+      assert_equal("user_#{@user.id}", @user.reload.name)
+      assert_equal(true, @user.is_deleted)
+      assert_equal(false, @user.authenticate_password("hunter2").present?)
+      assert_equal("deleted user ##{@user.id}", ModAction.last.description)
+      assert_equal("user_delete", ModAction.last.category)
+      assert_equal(@deletion.deleter, ModAction.last.creator)
+      assert_equal(@user, ModAction.last.subject)
+
+      @deletion.undelete!
+      assert_equal("fumimi", @user.reload.name)
+      assert_equal(false, @user.is_deleted)
+      assert_equal(true, @user.authenticate_password("hunter2").present?)
+      assert_equal("undeleted user ##{@user.id}", ModAction.last.description)
+      assert_equal("user_undelete", ModAction.last.category)
+      assert_equal(@deletion.deleter, ModAction.last.creator)
+      assert_equal(@user, ModAction.last.subject)
+    end
+  end
 end