Add indicator for processed messages

app/models/completion.rb

@@ -10,28 +10,32 @@
 #  updated_at              :datetime         not null
 #  contest_id              :integer          not null
 #  contestant_id           :integer          not null
+#  message_id              :integer
 #  puzzle_id               :integer          not null
 #
 # Indexes
 #
 #  index_completions_on_contest_id     (contest_id)
 #  index_completions_on_contestant_id  (contestant_id)
+#  index_completions_on_message_id     (message_id)
 #  index_completions_on_puzzle_id      (puzzle_id)
 #
 # Foreign Keys
 #
 #  contest_id     (contest_id => contests.id)
 #  contestant_id  (contestant_id => contestants.id)
+#  message_id     (message_id => messages.id)
 #  puzzle_id      (puzzle_id => puzzles.id)
 #
 class Completion < ApplicationRecord
   belongs_to :contest
   belongs_to :contestant
   belongs_to :puzzle
+  belongs_to :message, optional: true
 
   before_save :add_time_seconds
 
-  validates :display_time_from_start, presence: true, format: { with: /\A((\d\d|\d):\d\d|\d\d|\d):\d\d\z/ }
+  validates :display_time_from_start, presence: true, format: { with: /\A(((\d\d|\d):\d\d|\d\d|\d):\d\d|\d\d|\d)\z/ }
   validates :puzzle_id, uniqueness: { scope: :contestant }
 
   def add_time_seconds