add schedule rescheduling

backend/app/Schedule/EloquentScheduleRepository.php

@@ -38,6 +38,39 @@ class EloquentScheduleRepository implements ScheduleRepository
         });
     }
 
+    public function reschedule(RescheduleScheduleDto $dto): Schedule
+    {
+        return DB::transaction(function () use ($dto): Schedule {
+            $model = ScheduleModel::query()
+                ->where('id', $dto->scheduleId)
+                ->where('user_id', $dto->user->getId())
+                ->lockForUpdate()
+                ->first();
+            if ($model === null) {
+                throw new DomainException(
+                    "Schedule with id {$dto->scheduleId} not found",
+                );
+            }
+
+            $model->start_date = $dto->startDate->format('Y-m-d');
+            $model->target_date = $dto->targetDate->format('Y-m-d');
+            $model->save();
+
+            foreach ($dto->assignments as $assignmentDto) {
+                ScheduleAssignmentModel::query()
+                    ->where('id', $assignmentDto->id)
+                    ->where('schedule_id', $dto->scheduleId)
+                    ->whereNull('completed_at')
+                    ->update([
+                        'scheduled_date' => $assignmentDto->scheduledDate
+                            ->format('Y-m-d'),
+                    ]);
+            }
+
+            return $this->toDomain($model, $dto->user);
+        });
+    }
+
     public function findForUser(int $id, User $user): ?Schedule
     {
         $model = ScheduleModel::query()

backend/app/Schedule/RescheduleScheduleAssignmentDto.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace App\Schedule;
+
+use DateTimeImmutable;
+
+final readonly class RescheduleScheduleAssignmentDto
+{
+    public function __construct(
+        public int $id,
+        public DateTimeImmutable $scheduledDate,
+    ) {}
+}

backend/app/Schedule/RescheduleScheduleDto.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Schedule;
+
+use App\User\User;
+use DateTimeImmutable;
+
+final readonly class RescheduleScheduleDto
+{
+    /**
+     * @param list<RescheduleScheduleAssignmentDto> $assignments
+     */
+    public function __construct(
+        public int $scheduleId,
+        public User $user,
+        public DateTimeImmutable $startDate,
+        public DateTimeImmutable $targetDate,
+        public array $assignments,
+    ) {}
+}

backend/app/Schedule/ScheduleRepository.php

@@ -9,6 +9,8 @@ interface ScheduleRepository
 {
     public function create(CreateScheduleDto $dto): Schedule;
 
+    public function reschedule(RescheduleScheduleDto $dto): Schedule;
+
     public function findForUser(int $id, User $user): ?Schedule;
 
     /**

backend/app/Schedule/UseCases/RescheduleSchedule/RescheduleSchedule.php

@@ -0,0 +1,132 @@
+<?php
+
+namespace App\Schedule\UseCases\RescheduleSchedule;
+
+use App\Exceptions\BadRequestException;
+use App\Exceptions\NotFoundException;
+use App\Schedule\EvenDistributionScheduler;
+use App\Schedule\RescheduleScheduleAssignmentDto;
+use App\Schedule\RescheduleScheduleDto;
+use App\Schedule\Schedule;
+use App\Schedule\ScheduleAssignment;
+use App\Schedule\ScheduleRepository;
+use App\Schedule\WorkloadPlacement;
+use DateTimeImmutable;
+use DateTimeZone;
+
+class RescheduleSchedule
+{
+    public function __construct(
+        private ScheduleRepository $scheduleRepository,
+        private EvenDistributionScheduler $evenDistributionScheduler,
+    ) {}
+
+    /**
+     * @throws BadRequestException
+     * @throws NotFoundException
+     */
+    public function execute(RescheduleScheduleRequest $request): Schedule
+    {
+        $schedule = $this->scheduleRepository->findForUser(
+            $request->scheduleId,
+            $request->user,
+        );
+        if ($schedule === null) {
+            throw new NotFoundException('schedule not found');
+        }
+
+        $startDate = $this->parseDate($request->startDate, 'startDate');
+        $targetDate = $this->parseDate($request->targetDate, 'targetDate');
+        if ($targetDate < $startDate) {
+            throw new BadRequestException(
+                'targetDate must not be before startDate',
+            );
+        }
+        $workloadPlacement = $this->workloadPlacement(
+            $request->workloadPlacement,
+        );
+        $unfinishedAssignments = array_values(array_filter(
+            $schedule->getAssignments(),
+            function (ScheduleAssignment $assignment): bool {
+                return $assignment->getCompletedAt() === null;
+            },
+        ));
+        if ($unfinishedAssignments === []) {
+            throw new BadRequestException(
+                'schedule has no unfinished assignments',
+            );
+        }
+
+        $scheduledDates = $this->evenDistributionScheduler->scheduledDates(
+            assignmentCount: count($unfinishedAssignments),
+            startDate: $startDate,
+            targetDate: $targetDate,
+            workloadPlacement: $workloadPlacement,
+        );
+        $assignmentDtos = [];
+        foreach ($unfinishedAssignments as $index => $assignment) {
+            $assignmentDtos[] = new RescheduleScheduleAssignmentDto(
+                id: $assignment->getId(),
+                scheduledDate: $scheduledDates[$index],
+            );
+        }
+
+        return $this->scheduleRepository->reschedule(
+            new RescheduleScheduleDto(
+                scheduleId: $schedule->getId(),
+                user: $request->user,
+                startDate: $startDate,
+                targetDate: $targetDate,
+                assignments: $assignmentDtos,
+            ),
+        );
+    }
+
+    /**
+     * @throws BadRequestException
+     */
+    private function parseDate(?string $value, string $field): DateTimeImmutable
+    {
+        if ($value === null || $value === '') {
+            throw new BadRequestException("{$field} is required");
+        }
+
+        $date = DateTimeImmutable::createFromFormat(
+            '!Y-m-d',
+            $value,
+            new DateTimeZone('UTC'),
+        );
+        $errors = DateTimeImmutable::getLastErrors();
+        if (
+            $date === false
+            || $date->format('Y-m-d') !== $value
+            || ($errors !== false
+                && ($errors['warning_count'] > 0 || $errors['error_count'] > 0))
+        ) {
+            throw new BadRequestException(
+                "{$field} must be a valid date in YYYY-MM-DD format",
+            );
+        }
+
+        return $date;
+    }
+
+    /**
+     * @throws BadRequestException
+     */
+    private function workloadPlacement(?string $value): WorkloadPlacement
+    {
+        if ($value === null) {
+            return WorkloadPlacement::Middle;
+        }
+
+        $workloadPlacement = WorkloadPlacement::tryFrom($value);
+        if ($workloadPlacement === null) {
+            throw new BadRequestException(
+                'workloadPlacement must be start, middle, or end',
+            );
+        }
+
+        return $workloadPlacement;
+    }
+}

backend/app/Schedule/UseCases/RescheduleSchedule/RescheduleScheduleRequest.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace App\Schedule\UseCases\RescheduleSchedule;
+
+use App\User\User;
+
+final readonly class RescheduleScheduleRequest
+{
+    public function __construct(
+        public int $scheduleId,
+        public User $user,
+        public ?string $startDate,
+        public ?string $targetDate,
+        public ?string $workloadPlacement,
+    ) {}
+}