fix(absence) : déduire les jours pris du report CP au changement de période

Au passage d'une période de référence, le report de l'"en cours
d'acquisition" (N) vers l'"acquis" (N-1) ne déduisait pas les jours
déjà pris : un salarié récupérait les CP qu'il avait consommés.

Le report ne porte désormais que les jours non pris. Les congés sont
imputés au plus ancien bucket d'abord (l'acquis N-2, qui expire de toute
façon au changement de période), donc seuls les jours pris au-delà
réduisent le report.

Ajoute AccrueLeaveCommandTest couvrant le report avec jour pris,
l'imputation oldest-first et le report intégral sans jour pris.

src/Module/Absence/Infrastructure/Command/AccrueLeaveCommand.php

@@ -111,9 +111,18 @@ class AccrueLeaveCommand extends Command
                 $previousBalance = null !== $previousPeriod
                     ? $this->balanceRepository->findOneForPeriod($user, AbsenceType::PaidLeave, $previousPeriod)
                     : null;
-                $balance->setAcquired(
-                    null !== $previousBalance ? $previousBalance->getAcquiring() : $profile->getInitialLeaveBalance(),
-                );
+
+                if (null !== $previousBalance) {
+                    // Only the days *not yet taken* carry over. Leave is charged
+                    // oldest-first: it first consumes the previous "acquired"
+                    // (N-2) bucket — which expires at roll-over anyway — so only
+                    // days taken beyond that bucket eat into the carry-over.
+                    $carryOver = $previousBalance->getAcquiring()
+                        - max(0.0, $previousBalance->getTaken() - $previousBalance->getAcquired());
+                    $balance->setAcquired(max(0.0, $carryOver));
+                } else {
+                    $balance->setAcquired($profile->getInitialLeaveBalance());
+                }
             }
 
             if ($monthKey === $balance->getLastAccruedMonth()) {

tests/Functional/Command/AccrueLeaveCommandTest.php

@@ -0,0 +1,120 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Functional\Command;
+
+use App\Module\Absence\Domain\Entity\AbsenceBalance;
+use App\Module\Absence\Domain\Enum\AbsenceType;
+use App\Module\Absence\Infrastructure\Command\AccrueLeaveCommand;
+use App\Module\Absence\Infrastructure\Doctrine\DoctrineAbsenceBalanceRepository;
+use App\Module\Core\Domain\Entity\User;
+use DateTimeImmutable;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+use Symfony\Component\Console\Tester\CommandTester;
+
+/**
+ * Covers the period roll-over: when a new reference period opens, the previous
+ * period's "en cours d'acquisition" (N) becomes the new "acquired" (N-1), but
+ * only for the days that were not already taken.
+ *
+ * @internal
+ */
+class AccrueLeaveCommandTest extends KernelTestCase
+{
+    private EntityManagerInterface $em;
+    private DoctrineAbsenceBalanceRepository $balances;
+
+    protected function setUp(): void
+    {
+        self::bootKernel();
+        $this->em       = self::getContainer()->get(EntityManagerInterface::class);
+        $this->balances = self::getContainer()->get(DoctrineAbsenceBalanceRepository::class);
+    }
+
+    /**
+     * Tristan's real case: 9.75 accruing, 1 day taken, nothing previously
+     * acquired → the day taken eats into the carry-over, so 8.75 rolls over
+     * (not 9.75).
+     */
+    public function testCarryOverDeductsTakenDays(): void
+    {
+        $user = $this->createEmployee();
+        $this->seedPreviousBalance($user, acquired: 0.0, acquiring: 9.75, taken: 1.0);
+
+        $this->runForJune2026();
+
+        $rolled = $this->balances->findOneForPeriod($user, AbsenceType::PaidLeave, '2026-2027');
+        self::assertNotNull($rolled);
+        self::assertEqualsWithDelta(8.75, $rolled->getAcquired(), 0.0001);
+    }
+
+    /**
+     * Leave is charged oldest-first: the 3 days taken come out of the expiring
+     * N-2 "acquired" bucket (5), so the full 10 accruing days carry over intact.
+     */
+    public function testCarryOverChargesOldestBucketFirst(): void
+    {
+        $user = $this->createEmployee();
+        $this->seedPreviousBalance($user, acquired: 5.0, acquiring: 10.0, taken: 3.0);
+
+        $this->runForJune2026();
+
+        $rolled = $this->balances->findOneForPeriod($user, AbsenceType::PaidLeave, '2026-2027');
+        self::assertNotNull($rolled);
+        self::assertEqualsWithDelta(10.0, $rolled->getAcquired(), 0.0001);
+    }
+
+    /** No day taken → the whole accruing bucket carries over. */
+    public function testFullCarryOverWhenNothingTaken(): void
+    {
+        $user = $this->createEmployee();
+        $this->seedPreviousBalance($user, acquired: 0.0, acquiring: 10.0, taken: 0.0);
+
+        $this->runForJune2026();
+
+        $rolled = $this->balances->findOneForPeriod($user, AbsenceType::PaidLeave, '2026-2027');
+        self::assertNotNull($rolled);
+        self::assertEqualsWithDelta(10.0, $rolled->getAcquired(), 0.0001);
+    }
+
+    private function createEmployee(): User
+    {
+        $user = new User();
+        $user->setUsername('accrue-test-'.uniqid());
+        $user->setPassword('x');
+        $user->setRoles(['ROLE_USER']);
+        $user->setIsEmployee(true);
+        $user->setHireDate(new DateTimeImmutable('2024-01-01'));
+        $user->setReferencePeriodStart('06-01');
+        $user->setAnnualLeaveDays(25.0);
+        $user->setWorkTimeRatio(1.0);
+        $user->setInitialLeaveBalance(0.0);
+        $this->em->persist($user);
+        $this->em->flush();
+
+        return $user;
+    }
+
+    private function seedPreviousBalance(User $user, float $acquired, float $acquiring, float $taken): void
+    {
+        $balance = new AbsenceBalance();
+        $balance->setUser($user);
+        $balance->setType(AbsenceType::PaidLeave);
+        $balance->setPeriod('2025-2026');
+        $balance->setAcquired($acquired);
+        $balance->setAcquiring($acquiring);
+        $balance->setTaken($taken);
+        $this->em->persist($balance);
+        $this->em->flush();
+    }
+
+    private function runForJune2026(): void
+    {
+        $command = self::getContainer()->get(AccrueLeaveCommand::class);
+        $tester  = new CommandTester($command);
+        $tester->execute(['--month' => '2026-06']);
+        self::assertSame(0, $tester->getStatusCode());
+    }
+}