Implement flash messages, refactor candidate retrieval, and enhance quiz functionality

src/Repository/CandidateRepository.php

@@ -29,6 +29,11 @@ class CandidateRepository extends ServiceEntityRepository
             return null;
         }
 
-        return $this->findOneBy(['season' => $season, 'name' => $name]);
+        return $this->createQueryBuilder('c')
+            ->where('c.season = :season')
+            ->andWhere('lower(c.name) = lower(:name)')
+            ->setParameter('season', $season)
+            ->setParameter('name', $name)
+            ->getQuery()->getOneOrNullResult();
     }
 }

src/Repository/QuestionRepository.php

@@ -4,6 +4,8 @@ declare(strict_types=1);
 
 namespace App\Repository;
 
+use App\Entity\Candidate;
+use App\Entity\GivenAnswer;
 use App\Entity\Question;
 use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
 use Doctrine\Persistence\ManagerRegistry;
@@ -17,4 +19,25 @@ class QuestionRepository extends ServiceEntityRepository
     {
         parent::__construct($registry, Question::class);
     }
+
+    public function findNextQuestionForCandidate(Candidate $candidate): Question
+    {
+        $qb = $this->createQueryBuilder('q');
+
+        return $qb->join('q.quiz', 'qz')
+            ->andWhere($qb->expr()->notIn('q.id', $this->getEntityManager()->createQueryBuilder()
+                ->select('ga.id')
+                ->from(GivenAnswer::class, 'ga')
+                ->join('ga.answer', 'a')
+                ->join('a.question', 'q1')
+                ->andWhere($qb->expr()->isNotNull('ga.answer'))
+                ->andWhere('ga.candidate = :candidate')
+                ->andWhere('q1.quiz = :quiz')
+                ->getDQL()))
+            ->andWhere('qz = :quiz')
+            ->setMaxResults(1)
+            ->setParameter('candidate', $candidate)
+            ->setParameter('quiz', $candidate->getSeason()->getActiveQuiz())
+        ->getQuery()->getSingleResult();
+    }
 }