feat: warn about overlapping bookings instead of refusing them

src/Controller/Booking/CreateController.php

@@ -7,10 +7,10 @@ namespace App\Controller\Booking;
 use App\Config\BookingHorizon;
 use App\Controller\Traits\BoardResponseTrait;
 use App\Controller\Traits\CurrentUserTrait;
+use App\Controller\Traits\OverlapWarningTrait;
 use App\Entity\BookingSeries;
 use App\Entity\Resource;
 use App\Enum\RecurrenceRule;
-use App\Exception\AlreadyHoldingResourceException;
 use App\Exception\ResourceAlreadyBookedException;
 use App\Form\BookingRequest;
 use App\Form\BookingType;
@@ -34,6 +34,7 @@ final class CreateController extends AbstractController
     use BoardResponseTrait;
     use CurrentUserTrait;
     use HxTrait;
+    use OverlapWarningTrait;
 
     public function __construct(
         private readonly BoardContextFactory $boardContext,
@@ -91,12 +92,14 @@ final class CreateController extends AbstractController
                     : null;
 
                 if (null === $result) {
-                    $this->manager->book($this->currentUser(), $resource, $data->date, $data->timeRange());
+                    $booking = $this->manager->book($this->currentUser(), $resource, $data->date, $data->timeRange());
                     $this->addFlash('success', \sprintf('%s gebucht (%s).', $resource->getLabel(), $data->timeRange()));
+                    $this->warnAboutOverlaps($booking);
                 } else {
                     $this->flashSeriesResult($result, $resource);
+                    $this->warnAboutSeriesOverlaps($result);
                 }
-            } catch (AlreadyHoldingResourceException|ResourceAlreadyBookedException $e) {
+            } catch (ResourceAlreadyBookedException $e) {
                 return $this->invalidModal($form, $resource, $e->getMessage());
             }
 

src/Controller/Booking/EditController.php

@@ -6,12 +6,13 @@ namespace App\Controller\Booking;
 
 use App\Controller\Traits\BoardResponseTrait;
 use App\Controller\Traits\CurrentUserTrait;
+use App\Controller\Traits\OverlapWarningTrait;
 use App\Entity\Booking;
-use App\Exception\AlreadyHoldingResourceException;
 use App\Exception\ResourceAlreadyBookedException;
 use App\Form\BookingRequest;
 use App\Form\BookingType;
 use App\Htmx\HxTrait;
+use App\Repository\BookingRepository;
 use App\Service\BoardContextFactory;
 use App\Service\BookingManager;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
@@ -26,10 +27,12 @@ final class EditController extends AbstractController
     use BoardResponseTrait;
     use CurrentUserTrait;
     use HxTrait;
+    use OverlapWarningTrait;
 
     public function __construct(
         private readonly BoardContextFactory $boardContext,
         private readonly BookingManager $manager,
+        private readonly BookingRepository $bookings,
     ) {
     }
 
@@ -58,11 +61,13 @@ final class EditController extends AbstractController
         if ($form->isSubmitted() && $form->isValid()) {
             try {
                 $this->manager->reschedule($booking, $data->timeRange());
-            } catch (AlreadyHoldingResourceException|ResourceAlreadyBookedException $e) {
+            } catch (ResourceAlreadyBookedException $e) {
                 return $this->invalidModal($form, $booking, $e->getMessage());
             }
 
             $this->addFlash('success', \sprintf('%s geändert (%s).', $booking->getResource()->getLabel(), $booking->getTimeRange()));
+            // Moving a booking can create an overlap that was not there when it was made.
+            $this->warnAboutOverlaps($booking);
 
             return $this->boardResponse($booking->getResource()->getType(), $booking->getDate(), $boardTime);
         }

src/Controller/Traits/OverlapWarningTrait.php

@@ -0,0 +1,157 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Controller\Traits;
+
+use App\Entity\Booking;
+use App\Model\SeriesResult;
+
+/**
+ * The hint shown after somebody books a second resource of the same kind for a span they already
+ * hold one for.
+ *
+ * Holding two desks at once is allowed -- one of them is usually for the customer you are
+ * meeting -- so this is not a guard and never refuses anything; BookingManager explains what is
+ * still refused. It only says out loud what just happened, because the alternative is finding
+ * out on the day.
+ *
+ * Only same-kind overlaps are reported. A desk next to a parking space next to a monitor is the
+ * everyday combination, and a toast on every one of those would train everybody to ignore the
+ * toast that matters.
+ *
+ * Expects the using controller to extend AbstractController and to inject
+ * App\Repository\BookingRepository as $bookings.
+ */
+trait OverlapWarningTrait
+{
+    private function warnAboutOverlaps(Booking $booking): void
+    {
+        $clashes = $this->bookings->findOverlappingForUser(
+            $booking->getUser(),
+            $booking->getDate(),
+            $booking->getTimeRange(),
+            $booking->getResource()->getType(),
+            $booking,
+        );
+
+        if ([] === $clashes) {
+            return;
+        }
+
+        $day = $booking->getDate()->format('d.m.Y');
+
+        if (1 === \count($clashes)) {
+            $this->addFlash('warning', \sprintf(
+                'Hinweis: Du hast am %s zur gleichen Zeit bereits %s gebucht (%s).',
+                $day,
+                $clashes[0]->getResource()->getLabel(),
+                $clashes[0]->getTimeRange(),
+            ));
+
+            return;
+        }
+
+        $this->addFlash('warning', \sprintf(
+            'Hinweis: Du hast am %s zur gleichen Zeit bereits %d weitere %s gebucht: %s.',
+            $day,
+            \count($clashes),
+            $booking->getResource()->getType()->plural(),
+            implode(', ', self::labelsOf($clashes)),
+        ));
+    }
+
+    /**
+     * The same hint for a whole series, aggregated into one flash -- a weekly series running to
+     * the horizon must not fire a toast per occurrence.
+     */
+    private function warnAboutSeriesOverlaps(SeriesResult $result): void
+    {
+        if ($result->isCompletelyBlocked()) {
+            return;
+        }
+
+        $series = $result->series;
+        $created = $result->created;
+        $type = $series->getResource()->getType();
+
+        $clashes = $this->bookings->findOverlappingForUserInRange(
+            $series->getUser(),
+            $created[0]->getDate(),
+            $created[array_key_last($created)]->getDate(),
+            $series->getTimeRange(),
+            $type,
+            $series,
+        );
+
+        // One query covers the whole window, so it also returns days between two occurrences --
+        // days this series never landed on. Only the ones it did are news.
+        $days = [];
+        foreach ($clashes as $clash) {
+            $days[$clash->getDate()->format('Y-m-d')][] = $clash;
+        }
+
+        $days = array_intersect_key($days, array_flip(array_map(
+            static fn (Booking $booking): string => $booking->getDate()->format('Y-m-d'),
+            $created,
+        )));
+
+        if ([] === $days) {
+            return;
+        }
+
+        if (1 === \count($days)) {
+            $date = array_key_first($days);
+
+            $this->addFlash('warning', \sprintf(
+                'Hinweis: Am %s hast du zur gleichen Zeit bereits %s gebucht.',
+                (new \DateTimeImmutable($date))->format('j.n.'),
+                implode(', ', self::labelsOf($days[$date])),
+            ));
+
+            return;
+        }
+
+        $this->addFlash('warning', \sprintf(
+            'Hinweis: An %d von %d Terminen hast du zur gleichen Zeit bereits andere %s gebucht (%s).',
+            \count($days),
+            \count($created),
+            $type->plural(),
+            self::shortDates(array_keys($days)),
+        ));
+    }
+
+    /**
+     * @param list<Booking> $bookings
+     *
+     * @return list<string>
+     */
+    private static function labelsOf(array $bookings): array
+    {
+        return array_values(array_unique(array_map(
+            static fn (Booking $booking): string => $booking->getResource()->getLabel(),
+            $bookings,
+        )));
+    }
+
+    /**
+     * Cut off after a handful: a series can clash on two dozen days, and a toast listing them all
+     * would cover the board it is reporting on.
+     *
+     * @param list<string> $dates Y-m-d
+     */
+    private static function shortDates(array $dates): string
+    {
+        $shown = \array_slice($dates, 0, 5);
+        $formatted = array_map(
+            static fn (string $date): string => (new \DateTimeImmutable($date))->format('j.n.'),
+            $shown,
+        );
+
+        if (\count($dates) > \count($shown)) {
+            $formatted[] = '…';
+        }
+
+        return implode(', ', $formatted);
+    }
+}

src/Exception/AlreadyHoldingResourceException.php

@@ -1,26 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace App\Exception;
-
-use App\Entity\Booking;
-
-/**
- * One person may not hold two resources of the same kind at overlapping times. A desk in the
- * morning and a different one in the afternoon is fine -- only the overlap is refused.
- */
-final class AlreadyHoldingResourceException extends \RuntimeException
-{
-    public function __construct(public readonly Booking $existing)
-    {
-        $time = $existing->getTimeRange();
-
-        parent::__construct(\sprintf(
-            'Du hast am %s bereits %s gebucht (%s).',
-            $existing->getDate()->format('d.m.Y'),
-            $existing->getResource()->getLabel(),
-            $time,
-        ));
-    }
-}

src/Repository/BookingRepository.php

@@ -75,9 +75,16 @@ class BookingRepository extends ServiceEntityRepository
     }
 
     /**
-     * One person may not hold two resources of the same kind at the same time -- but they may
-     * well hold a desk in the morning and a different one in the afternoon, so this is an
-     * overlap test rather than a per-day test.
+     * What else the same person already holds of the same kind in that span.
+     *
+     * This used to be a guard -- one desk per person at a time -- and is now the input to a
+     * hint: holding two desks at once is a real thing people do, a second one for a customer
+     * they are meeting. Nothing here refuses anything, so it returns every clash rather than
+     * the first one, and it is deliberately limited to the same kind: a desk next to a parking
+     * space next to a monitor is the everyday combination, and warning about that would train
+     * everybody to ignore the warning that matters.
+     *
+     * @return list<Booking>
      */
     public function findOverlappingForUser(
         User $user,
@@ -85,25 +92,57 @@ class BookingRepository extends ServiceEntityRepository
         TimeRange $time,
         ResourceType $type,
         ?Booking $ignore = null,
-    ): ?Booking {
-        $qb = $this->createQueryBuilder('b')
-            ->addSelect('r')
-            ->join('b.resource', 'r')
-            ->andWhere('b.user = :user')
+    ): array {
+        $qb = self::restrictToUserOverlap(
+            $this->createQueryBuilder('b'),
+            $user,
+            $time,
+            $type,
+        )
             ->andWhere('b.date = :date')
-            ->andWhere('r.type = :type')
-            ->setParameter('user', $user)
             ->setParameter('date', $date->setTime(0, 0))
-            ->setParameter('type', $type)
-            ->setMaxResults(1);
-
-        self::restrictToOverlap($qb, $time);
+            ->addOrderBy('r.label', 'ASC');
 
         if (null !== $ignore && null !== $ignore->getId()) {
             $qb->andWhere('b.id != :ignore')->setParameter('ignore', $ignore->getId());
         }
 
-        return $qb->getQuery()->getOneOrNullResult();
+        return $qb->getQuery()->getResult();
+    }
+
+    /**
+     * The same hint across a span of days, which is what a series needs -- one query rather than
+     * one per occurrence, so a weekly series running to the horizon stays a single round trip.
+     *
+     * Occurrences of $exclude are left out: a series overlapping itself is not news.
+     *
+     * @return list<Booking>
+     */
+    public function findOverlappingForUserInRange(
+        User $user,
+        \DateTimeImmutable $from,
+        \DateTimeImmutable $to,
+        TimeRange $time,
+        ResourceType $type,
+        ?BookingSeries $exclude = null,
+    ): array {
+        $qb = self::restrictToUserOverlap(
+            $this->createQueryBuilder('b'),
+            $user,
+            $time,
+            $type,
+        )
+            ->andWhere('b.date BETWEEN :from AND :to')
+            ->setParameter('from', $from->setTime(0, 0))
+            ->setParameter('to', $to->setTime(0, 0))
+            ->orderBy('b.date', 'ASC')
+            ->addOrderBy('r.label', 'ASC');
+
+        if (null !== $exclude) {
+            $qb->andWhere('b.series IS NULL OR b.series != :exclude')->setParameter('exclude', $exclude);
+        }
+
+        return $qb->getQuery()->getResult();
     }
 
     /**
@@ -237,6 +276,24 @@ class BookingRepository extends ServiceEntityRepository
             ->getResult();
     }
 
+    /**
+     * What the two per-user overlap finders share: one person, one kind, spans that collide.
+     * The resource is eager-selected because both callers name it in the message they build.
+     */
+    private static function restrictToUserOverlap(QueryBuilder $qb, User $user, TimeRange $time, ResourceType $type): QueryBuilder
+    {
+        $qb->addSelect('r')
+            ->join('b.resource', 'r')
+            ->andWhere('b.user = :user')
+            ->andWhere('r.type = :type')
+            ->setParameter('user', $user)
+            ->setParameter('type', $type);
+
+        self::restrictToOverlap($qb, $time);
+
+        return $qb;
+    }
+
     /**
      * Half-open overlap, the same test as TimeRange::overlaps(): two spans collide unless one
      * ends at or before the other begins. Written once here so the SQL and the PHP cannot drift.

src/Service/BookingManager.php

@@ -8,7 +8,6 @@ use App\Entity\Booking;
 use App\Entity\BookingSeries;
 use App\Entity\Resource;
 use App\Entity\User;
-use App\Exception\AlreadyHoldingResourceException;
 use App\Exception\ResourceAlreadyBookedException;
 use App\Model\SeriesResult;
 use App\Model\TimeRange;
@@ -32,9 +31,12 @@ use Doctrine\ORM\EntityManagerInterface;
  * protection now lives in code, so it belongs to this class alone: nothing else may persist a
  * Booking.
  *
- * The per-user rule ("not two desks at once") is deliberately NOT covered by the lock: it spans
- * resources, and locking every resource would serialise the whole app to protect against a user
- * racing themselves in two browser tabs.
+ * **What is NOT guarded here.** One person holding two desks at the same time used to be refused
+ * from this class. It is allowed now: booking a second desk for a customer you are meeting is a
+ * real thing people do, and the refusal only ever landed after the modal was filled in, since
+ * the floor plan offers every free desk regardless of what you already hold. Overlaps of that
+ * kind are now reported as a warning flash once the booking exists -- see OverlapWarningTrait.
+ * The only conflict left here is the physical one: two people, or two spans, on one resource.
  */
 final readonly class BookingManager
 {
@@ -45,8 +47,7 @@ final readonly class BookingManager
     }
 
     /**
-     * @throws AlreadyHoldingResourceException if the user already holds a resource of this kind in that span
-     * @throws ResourceAlreadyBookedException  if somebody else does
+     * @throws ResourceAlreadyBookedException if the resource is not free for that span
      */
     public function book(User $user, Resource $resource, \DateTimeImmutable $date, ?TimeRange $time = null): Booking
     {
@@ -56,7 +57,7 @@ final readonly class BookingManager
         return $this->em->wrapInTransaction(function () use ($user, $resource, $date, $time): Booking {
             $this->em->lock($resource, LockMode::PESSIMISTIC_WRITE);
 
-            $this->assertFree($user, $resource, $date, $time);
+            $this->assertFree($resource, $date, $time);
 
             $booking = new Booking($user, $resource, $date, $time);
             $this->em->persist($booking);
@@ -87,8 +88,8 @@ final readonly class BookingManager
 
             foreach ($series->occurrences() as $date) {
                 try {
-                    $this->assertFree($user, $resource, $date, $time);
-                } catch (AlreadyHoldingResourceException|ResourceAlreadyBookedException $e) {
+                    $this->assertFree($resource, $date, $time);
+                } catch (ResourceAlreadyBookedException $e) {
                     $skipped[$date->format('Y-m-d')] = $e->getMessage();
 
                     continue;
@@ -118,7 +119,7 @@ final readonly class BookingManager
             $resource = $booking->getResource();
             $this->em->lock($resource, LockMode::PESSIMISTIC_WRITE);
 
-            $this->assertFree($booking->getUser(), $resource, $booking->getDate(), $time, $booking);
+            $this->assertFree($resource, $booking->getDate(), $time, $booking);
 
             $booking->changeTime($time);
             $this->em->flush();
@@ -161,21 +162,14 @@ final readonly class BookingManager
     }
 
     /**
-     * @throws AlreadyHoldingResourceException
      * @throws ResourceAlreadyBookedException
      */
     private function assertFree(
-        User $user,
         Resource $resource,
         \DateTimeImmutable $date,
         TimeRange $time,
         ?Booking $ignore = null,
     ): void {
-        $mine = $this->bookings->findOverlappingForUser($user, $date, $time, $resource->getType(), $ignore);
-        if (null !== $mine) {
-            throw new AlreadyHoldingResourceException($mine);
-        }
-
         foreach ($this->bookings->findOverlapping($resource, $date, $time) as $clash) {
             if (null !== $ignore && $clash->getId() === $ignore->getId()) {
                 continue;