add workload placement

backend/app/Http/Controllers/ScheduleController.php

@@ -44,6 +44,9 @@ class ScheduleController extends Controller
                     levelId: $input->integer('levelId'),
                     startDate: $input->string('startDate'),
                     targetDate: $input->string('targetDate'),
+                    workloadPlacement: $input->string(
+                        'workloadPlacement',
+                    ),
                 ),
             );
         } catch (BadRequestException $exception) {

backend/app/Schedule/EvenDistributionScheduler.php

@@ -0,0 +1,114 @@
+<?php
+
+namespace App\Schedule;
+
+use DateTimeImmutable;
+
+class EvenDistributionScheduler
+{
+    /**
+     * @return list<DateTimeImmutable>
+     */
+    public function scheduledDates(
+        int $assignmentCount,
+        DateTimeImmutable $startDate,
+        DateTimeImmutable $targetDate,
+        WorkloadPlacement $workloadPlacement,
+    ): array {
+        $differenceInDays = $startDate->diff($targetDate)->days;
+        $dayCount = $differenceInDays + 1;
+
+        if ($assignmentCount < $dayCount) {
+            return $this->sparseDates(
+                assignmentCount: $assignmentCount,
+                dayCount: $dayCount,
+                startDate: $startDate,
+            );
+        }
+
+        return $this->dailyDates(
+            assignmentCount: $assignmentCount,
+            dayCount: $dayCount,
+            startDate: $startDate,
+            workloadPlacement: $workloadPlacement,
+        );
+    }
+
+    /**
+     * @return list<DateTimeImmutable>
+     */
+    private function sparseDates(
+        int $assignmentCount,
+        int $dayCount,
+        DateTimeImmutable $startDate,
+    ): array {
+        if ($assignmentCount === 1) {
+            return [$startDate];
+        }
+
+        $dates = [];
+        for ($assignmentIndex = 0;
+            $assignmentIndex < $assignmentCount;
+            $assignmentIndex++
+        ) {
+            $scaledIndex = $assignmentIndex * ($dayCount - 1)
+                / ($assignmentCount - 1);
+            $dayIndex = (int) floor($scaledIndex + 0.5);
+            $dates[] = $startDate->modify("+{$dayIndex} days");
+        }
+
+        return $dates;
+    }
+
+    /**
+     * @return list<DateTimeImmutable>
+     */
+    private function dailyDates(
+        int $assignmentCount,
+        int $dayCount,
+        DateTimeImmutable $startDate,
+        WorkloadPlacement $workloadPlacement,
+    ): array {
+        $assignmentsPerDay = intdiv($assignmentCount, $dayCount);
+        $heavierDayCount = $assignmentCount % $dayCount;
+        $heavierBlockStart = $this->heavierBlockStart(
+            dayCount: $dayCount,
+            heavierDayCount: $heavierDayCount,
+            workloadPlacement: $workloadPlacement,
+        );
+        $dates = [];
+
+        for ($dayIndex = 0; $dayIndex < $dayCount; $dayIndex++) {
+            $assignmentCountForDay = $assignmentsPerDay;
+            if (
+                $dayIndex >= $heavierBlockStart
+                && $dayIndex < $heavierBlockStart + $heavierDayCount
+            ) {
+                $assignmentCountForDay++;
+            }
+
+            $date = $startDate->modify("+{$dayIndex} days");
+            for ($index = 0; $index < $assignmentCountForDay; $index++) {
+                $dates[] = $date;
+            }
+        }
+
+        return $dates;
+    }
+
+    private function heavierBlockStart(
+        int $dayCount,
+        int $heavierDayCount,
+        WorkloadPlacement $workloadPlacement,
+    ): int {
+        if ($workloadPlacement === WorkloadPlacement::Start) {
+            return 0;
+        }
+
+        if ($workloadPlacement === WorkloadPlacement::End) {
+            return $dayCount - $heavierDayCount;
+        }
+
+        return intdiv($dayCount - $heavierDayCount, 2);
+    }
+}

backend/app/Schedule/UseCases/CreateSchedule/CreateSchedule.php

@@ -8,8 +8,10 @@ use App\Exceptions\BadRequestException;
 use App\Exceptions\NotFoundException;
 use App\Schedule\CreateScheduleAssignmentDto;
 use App\Schedule\CreateScheduleDto;
+use App\Schedule\EvenDistributionScheduler;
 use App\Schedule\Schedule;
 use App\Schedule\ScheduleRepository;
+use App\Schedule\WorkloadPlacement;
 use App\Set\Set;
 use App\Set\SetLevelRepository;
 use App\Set\SetRepository;
@@ -23,6 +25,7 @@ class CreateSchedule
         private SetLevelRepository $setLevelRepository,
         private ElementRepository $elementRepository,
         private ScheduleRepository $scheduleRepository,
+        private EvenDistributionScheduler $evenDistributionScheduler,
     ) {}
 
     /**
@@ -61,6 +64,9 @@ class CreateSchedule
                 'targetDate must not be before startDate',
             );
         }
+        $workloadPlacement = $this->workloadPlacement(
+            $request->workloadPlacement,
+        );
 
         $elements = array_values(array_filter(
             $this->orderedElements($set),
@@ -72,10 +78,15 @@ class CreateSchedule
             throw new BadRequestException('level has no elements');
         }
 
-        $assignments = $this->assignments(
-            elements: $elements,
+        $scheduledDates = $this->evenDistributionScheduler->scheduledDates(
+            assignmentCount: count($elements),
             startDate: $startDate,
             targetDate: $targetDate,
+            workloadPlacement: $workloadPlacement,
+        );
+        $assignments = $this->assignments(
+            elements: $elements,
+            scheduledDates: $scheduledDates,
         );
 
         return $this->scheduleRepository->create(new CreateScheduleDto(
@@ -144,29 +155,21 @@ class CreateSchedule
 
     /**
      * @param list<Element> $elements
+     * @param list<DateTimeImmutable> $scheduledDates
      * @return list<CreateScheduleAssignmentDto>
      */
     private function assignments(
         array $elements,
-        DateTimeImmutable $startDate,
-        DateTimeImmutable $targetDate,
+        array $scheduledDates,
     ): array {
-        $differenceInDays = $startDate->diff($targetDate)->days;
-        $dayCount = $differenceInDays + 1;
-        $elementCount = count($elements);
         $assignments = [];
 
         foreach ($elements as $index => $element) {
-            $dayIndex = $this->dayIndex(
-                elementIndex: $index,
-                elementCount: $elementCount,
-                dayCount: $dayCount,
-            );
             $assignments[] = new CreateScheduleAssignmentDto(
                 name: $element->getName(),
                 kind: $element->getKind(),
                 path: $this->elementPath($element),
-                scheduledDate: $startDate->modify("+{$dayIndex} days"),
+                scheduledDate: $scheduledDates[$index],
                 position: $index + 1,
             );
         }
@@ -190,25 +193,6 @@ class CreateSchedule
         return $path;
     }
 
-    private function dayIndex(
-        int $elementIndex,
-        int $elementCount,
-        int $dayCount,
-    ): int {
-        if ($elementCount === 1 || $dayCount === 1) {
-            return 0;
-        }
-
-        if ($elementCount < $dayCount) {
-            $scaledIndex = $elementIndex * ($dayCount - 1)
-                / ($elementCount - 1);
-
-            return (int) floor($scaledIndex + 0.5);
-        }
-
-        return intdiv($elementIndex * $dayCount, $elementCount);
-    }
-
     /**
      * @throws BadRequestException
      */
@@ -237,4 +221,23 @@ class CreateSchedule
 
         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/CreateSchedule/CreateScheduleRequest.php

@@ -12,5 +12,6 @@ final readonly class CreateScheduleRequest
         public ?int $levelId,
         public ?string $startDate,
         public ?string $targetDate,
+        public ?string $workloadPlacement,
     ) {}
 }

backend/app/Schedule/WorkloadPlacement.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace App\Schedule;
+
+enum WorkloadPlacement: string
+{
+    case Start = 'start';
+    case Middle = 'middle';
+    case End = 'end';
+}