Public scoreboard stopwatch feature

#10

app/controllers/contests_controller.rb

@@ -3,7 +3,7 @@ class ContestsController < ApplicationController
   include ContestantsConcern
 
   before_action :set_contest, only: %i[ destroy show ]
-  before_action :set_settings_contest, only: %i[ settings_general_edit settings_general_update settings_public_edit settings_public_update settings_onsite_edit settings_onsite_update settings_online_edit settings_online_update settings_categories_edit ]
+  before_action :set_settings_contest, only: %i[ stopwatch stopwatch_continue stopwatch_pause stopwatch_reset stopwatch_start settings_general_edit settings_general_update settings_public_edit settings_public_update settings_onsite_edit settings_onsite_update settings_online_edit settings_online_update settings_categories_edit ]
   before_action :offline_setup, only: %i[ offline_new offline_create offline_edit offline_update offline_completed ]
   skip_before_action :require_authentication, only: %i[ scoreboard offline_new offline_create offline_edit offline_update offline_completed ]
 
@@ -80,6 +80,47 @@ class ContestsController < ApplicationController
     end
   end
 
+  def stopwatch
+    authorize @contest
+  end
+
+  def stopwatch_continue
+    authorize @contest
+
+    pause_duration = Time.now() - @contest.pause_time
+    @contest.start_time = @contest.start_time + pause_duration
+    @contest.pause_time = nil
+    @contest.save
+    redirect_to "/contests/#{@contest.id}/stopwatch"
+  end
+
+  def stopwatch_pause
+    authorize @contest
+    authorize @contest
+
+    @contest.pause_time = Time.now()
+    @contest.save
+    redirect_to "/contests/#{@contest.id}/stopwatch"
+  end
+
+  def stopwatch_reset
+    authorize @contest
+
+    @contest.start_time = nil
+    @contest.pause_time = nil
+    @contest.save
+    redirect_to "/contests/#{@contest.id}/stopwatch"
+  end
+
+  def stopwatch_start
+    authorize @contest
+
+    @contest.start_time = Time.now()
+    @contest.pause_time = nil
+    @contest.save
+    redirect_to "/contests/#{@contest.id}/stopwatch"
+  end
+
   def new
     authorize :contest
 
@@ -241,7 +282,7 @@ class ContestsController < ApplicationController
   end
 
   def settings_public_params
-    params.expect(contest: [ :public, :ranking_mode ])
+    params.expect(contest: [ :public, :ranking_mode, :show_stopwatch ])
   end
 
   def settings_onsite_params