Add option to restrict a problem to a set of languages.

This is especially useful for output-only problems (part of #2521).

webapp/migrations/Version20250228123717.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20250228123717 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Add option to restrict a problem to a set of languages.';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // this up() migration is auto-generated, please modify it to your needs
+        $this->addSql('CREATE TABLE problemlanguage (probid INT UNSIGNED NOT NULL COMMENT \'Problem ID\', langid VARCHAR(32) NOT NULL COMMENT \'Language ID (string)\', INDEX IDX_46B150BBEF049279 (probid), INDEX IDX_46B150BB2271845 (langid), PRIMARY KEY(probid, langid)) DEFAULT CHARACTER SET utf8mb4 COLLATE `utf8mb4_unicode_ci` ENGINE = InnoDB');
+        $this->addSql('ALTER TABLE problemlanguage ADD CONSTRAINT FK_46B150BBEF049279 FOREIGN KEY (probid) REFERENCES problem (probid) ON DELETE CASCADE');
+        $this->addSql('ALTER TABLE problemlanguage ADD CONSTRAINT FK_46B150BB2271845 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // this down() migration is auto-generated, please modify it to your needs
+        $this->addSql('ALTER TABLE problemlanguage DROP FOREIGN KEY FK_46B150BBEF049279');
+        $this->addSql('ALTER TABLE problemlanguage DROP FOREIGN KEY FK_46B150BB2271845');
+        $this->addSql('DROP TABLE problemlanguage');
+    }
+
+    public function isTransactional(): bool
+    {
+        return false;
+    }
+}

webapp/src/Entity/Language.php

@@ -156,6 +156,13 @@ class Language extends BaseApiEntity implements
     #[Serializer\Exclude]
     private Collection $contests;
 
+    /**
+     * @var Collection<int, Problem>
+     */
+    #[ORM\ManyToMany(targetEntity: Problem::class, mappedBy: 'languages')]
+    #[Serializer\Exclude]
+    private Collection $problems;
+
     /**
      * @param Collection<int, Version> $versions
      */
@@ -394,6 +401,7 @@ public function __construct()
         $this->submissions = new ArrayCollection();
         $this->versions = new ArrayCollection();
         $this->contests = new ArrayCollection();
+        $this->problems = new ArrayCollection();
     }
 
     public function addSubmission(Submission $submission): Language
@@ -443,4 +451,23 @@ public function getContests(): Collection
     {
         return $this->contests;
     }
+
+    public function addProblem(Problem $problem): Language
+    {
+        $this->problems[] = $problem;
+        $problem->addLanguage($this);
+        return $this;
+    }
+
+    public function removeProblem(Problem $problem): Language
+    {
+        $this->problems->removeElement($problem);
+        $problem->removeLanguage($this);
+        return $this;
+    }
+
+    public function getProblems(): Collection
+    {
+        return $this->problems;
+    }
 }

webapp/src/Entity/Problem.php

@@ -191,6 +191,17 @@ class Problem extends BaseApiEntity implements
     #[Serializer\Exclude]
     private ?FileWithName $statementForApi = null;
 
+
+    /**
+     * @var Collection<int, Language>
+     */
+    #[ORM\ManyToMany(targetEntity: Language::class, inversedBy: 'problems')]
+    #[ORM\JoinTable(name: 'problemlanguage')]
+    #[ORM\JoinColumn(name: 'probid', referencedColumnName: 'probid', onDelete: 'CASCADE')]
+    #[ORM\InverseJoinColumn(name: 'langid', referencedColumnName: 'langid', onDelete: 'CASCADE')]
+    #[Serializer\Exclude]
+    private Collection $languages;
+
     public function setProbid(int $probid): Problem
     {
         $this->probid = $probid;
@@ -385,6 +396,7 @@ public function __construct()
         $this->clarifications     = new ArrayCollection();
         $this->contest_problems   = new ArrayCollection();
         $this->attachments        = new ArrayCollection();
+        $this->languages          = new ArrayCollection();
         $this->problemStatementContent = new ArrayCollection();
     }
 
@@ -541,4 +553,24 @@ public function getStatementForApi(): array
     {
         return array_filter([$this->statementForApi]);
     }
+
+    public function addLanguage(Language $language): Problem
+    {
+        $this->languages[] = $language;
+        return $this;
+    }
+
+    /**
+     * @return Collection<int, Language>
+     */
+    public function getLanguages(): Collection
+    {
+        return $this->languages;
+    }
+
+    public function removeLanguage(Language $language): Problem
+    {
+        $this->languages->removeElement($language);
+        return $this;
+    }
 }

webapp/src/Form/Type/LanguageType.php

@@ -5,6 +5,7 @@
 use App\Entity\Contest;
 use App\Entity\Executable;
 use App\Entity\Language;
+use App\Entity\Problem;
 use Doctrine\ORM\EntityRepository;
 use Symfony\Bridge\Doctrine\Form\Type\EntityType;
 use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
@@ -99,6 +100,16 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
                 ->createQueryBuilder('c')
                 ->orderBy('c.name'),
         ]);
+        $builder->add('problems', EntityType::class, [
+            'class'         => Problem::class,
+            'required'      => false,
+            'choice_label'  => 'name',
+            'multiple'      => true,
+            'by_reference'  => false,
+            'query_builder' => fn(EntityRepository $er) => $er
+                ->createQueryBuilder('p')
+                ->orderBy('p.name'),
+        ]);
         $builder->add('save', SubmitType::class);
 
         // Remove ID field when doing an edit.

webapp/src/Form/Type/ProblemType.php

@@ -3,6 +3,7 @@
 namespace App\Form\Type;
 
 use App\Entity\Executable;
+use App\Entity\Language;
 use App\Entity\Problem;
 use Doctrine\ORM\EntityRepository;
 use Symfony\Bridge\Doctrine\Form\Type\EntityType;
@@ -90,6 +91,13 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'required' => false,
             'help' => 'leave empty for default',
         ]);
+        $builder->add('languages', EntityType::class, [
+            'required' => false,
+            'class' => Language::class,
+            'multiple' => true,
+            'choice_label' => fn(Language $language) => sprintf('%s (%s)', $language->getName(), $language->getExternalid()),
+            'help' => 'List of languages that can be used for this problem. Leave empty to allow all languages that are enabled for this contest.',
+        ]);
         $builder->add('save', SubmitType::class);
 
         // Remove clearProblemstatement field when we do not have a problem text.

webapp/src/Service/SubmissionService.php

@@ -535,10 +535,22 @@ public function submitSolution(
             throw new BadRequestHttpException('Submissions for contest (temporarily) disabled');
         }
 
-        $allowedLanguages = $this->dj->getAllowedLanguagesForContest($contest);
-        if (!in_array($language, $allowedLanguages, true)) {
-            throw new BadRequestHttpException(
-                sprintf("Language '%s' not allowed for contest [c%d].", $language->getLangid(), $contest->getCid()));
+        // If there is a set of languages configured for the problem, it overrides the languages configured for the
+        // contest / globally. This is useful for restricting problems to be solved in specific languages, e.g.
+        // output-only problems.
+        $allowedLanguages = $problem->getProblem()->getLanguages();
+        if ($allowedLanguages->isEmpty()) {
+            $allowedLanguages = $this->dj->getAllowedLanguagesForContest($contest);
+            if (!in_array($language, $allowedLanguages, strict: true)) {
+                throw new BadRequestHttpException(
+                    sprintf("Language '%s' not allowed for contest [c%d].", $language->getLangid(), $contest->getCid()));
+            }
+        } else {
+            $allowedLanguages = $allowedLanguages->toArray();
+            if (!in_array($language, $allowedLanguages, strict: true)) {
+                throw new BadRequestHttpException(
+                    sprintf("Language '%s' not allowed for problem [p%d].", $language->getLangid(), $problem->getProbid()));
+            }
         }
 
         if ($language->getRequireEntryPoint() && empty($entryPoint)) {

webapp/templates/jury/problem.html.twig

@@ -116,6 +116,20 @@
                         <td>{{ type }}</td>
                     </tr>
                 {% endif %}
+                <tr>
+                    <th>Languages</th>
+                    <td>
+                        {% if problem.languages is empty %}
+                            <em>all languages enabled for the corresponding contest</em>
+                        {% else %}
+                            <ul>
+                                {% for language in problem.languages %}
+                                    <li><a href="{{ path('jury_language', {'langId': language.langid}) }}">{{ language.name }}</a></li>
+                                {% endfor %}
+                            </ul>
+                        {% endif %}
+                    </td>
+                </tr>
             </table>
         </div>
     </div>