reconstruction of the project

app/Services/Attendance/SemesterRangeService.php

@@ -0,0 +1,77 @@
+<?php
+
+namespace App\Services\Attendance;
+
+use Carbon\Carbon;
+
+class SemesterRangeService
+{
+    public function normalizeSemester(?string $semester): string
+    {
+        $value = strtolower(trim((string)$semester));
+
+        return match ($value) {
+            'fall', 'autumn' => 'Fall',
+            'spring' => 'Spring',
+            default => '',
+        };
+    }
+
+    public function getSchoolYearRange(string $schoolYear): array
+    {
+        [$startYear, $endYear] = $this->parseSchoolYear($schoolYear);
+
+        return [
+            Carbon::create($startYear, 9, 1)->toDateString(),
+            Carbon::create($endYear, 5, 31)->toDateString(),
+        ];
+    }
+
+    public function getSemesterRange(string $schoolYear, string $semester): ?array
+    {
+        [$startYear, $endYear] = $this->parseSchoolYear($schoolYear);
+        $semester = $this->normalizeSemester($semester);
+
+        return match ($semester) {
+            'Fall' => [
+                Carbon::create($startYear, 9, 21)->toDateString(),
+                Carbon::create($endYear, 1, 18)->toDateString(),
+            ],
+            'Spring' => [
+                Carbon::create($endYear, 1, 25)->toDateString(),
+                Carbon::create($endYear, 5, 31)->toDateString(),
+            ],
+            default => null,
+        };
+    }
+
+    public function buildSundayList(string $startDate, string $endDate): array
+    {
+        $start = Carbon::parse($startDate)->startOfDay();
+        $end = Carbon::parse($endDate)->startOfDay();
+
+        if ($start->dayOfWeek !== Carbon::SUNDAY) {
+            $start = $start->next(Carbon::SUNDAY);
+        }
+
+        $dates = [];
+        $cursor = $start->copy();
+
+        while ($cursor->lte($end)) {
+            $dates[] = $cursor->toDateString();
+            $cursor->addWeek();
+        }
+
+        return $dates;
+    }
+
+    protected function parseSchoolYear(string $schoolYear): array
+    {
+        if (preg_match('/^\s*(\d{4})\s*-\s*(\d{4})\s*$/', $schoolYear, $m)) {
+            return [(int)$m[1], (int)$m[2]];
+        }
+
+        $year = (int) date('Y');
+        return [$year, $year + 1];
+    }
+}