Events: implement creation of new contests

app/controllers/contests_controller.rb

@@ -10,7 +10,7 @@ class ContestsController < ApplicationController
   def index
     authorize :contest
 
-    @contests = current_user.contests.includes([ :contestants, puzzles: [ :image_attachment ] ]).order(created_at: :desc)
+    @contests = current_user.contests.where(event: nil).includes([ :contestants, puzzles: [ :image_attachment ] ]).order(created_at: :desc)
     @title = I18n.t("contests.index.title", username: current_user.username)
   end
 
@@ -125,6 +125,9 @@ class ContestsController < ApplicationController
     authorize :contest
 
     @contest = Contest.new
+    if params.key?(:event)
+      @contest.event_id = params[:event]
+    end
     @title = I18n.t("contests.new.title")
     @nonav = true
   end
@@ -136,6 +139,18 @@ class ContestsController < ApplicationController
     @contest.lang = @current_user.lang
     @contest.ranking_mode = "actual"
     @contest.user_id = current_user.id
+
+    # Check if the provided event_id exists and belongs to the current user. If not, remove
+    # the link to the event.
+    begin
+      event = Event.find(@contest.event_id)
+      if current_user != event.user
+        @contest.event_id = nil
+      end
+    rescue
+      @contest.event_id = nil
+    end
+
     if @contest.save
       redirect_to "/contests/#{@contest.id}/settings/general", notice: t("contests.new.notice")
     else
@@ -274,7 +289,7 @@ class ContestsController < ApplicationController
   end
 
   def new_contest_params
-    params.expect(contest: [ :name, :duration ])
+    params.expect(contest: [ :name, :duration, :event_id ])
   end
 
   def settings_general_params