fix(recurring-invoices): scale scheduled generation

app/Services/Document/RecurringInvoiceScheduleService.php

@@ -0,0 +1,78 @@
+<?php
+
+namespace App\Services\Document;
+
+use App\Models\CompanySetting;
+use Carbon\Carbon;
+use Cron\CronExpression;
+use DateTimeZone;
+
+class RecurringInvoiceScheduleService
+{
+    /** @var array<int, string> */
+    private array $companyTimezones = [];
+
+    public function companyTimezone(int $companyId): string
+    {
+        if (isset($this->companyTimezones[$companyId])) {
+            return $this->companyTimezones[$companyId];
+        }
+
+        $timezone = CompanySetting::getSetting('time_zone', $companyId) ?: config('app.timezone', 'UTC');
+
+        try {
+            new DateTimeZone($timezone);
+        } catch (\Exception) {
+            $timezone = $this->applicationTimezone();
+        }
+
+        return $this->companyTimezones[$companyId] = $timezone;
+    }
+
+    public function applicationTimezone(): string
+    {
+        $timezone = config('app.timezone', 'UTC');
+
+        try {
+            new DateTimeZone($timezone);
+
+            return $timezone;
+        } catch (\Exception) {
+            return 'UTC';
+        }
+    }
+
+    public function firstFutureOccurrence(string $frequency, string $startsAt, int $companyId, ?Carbon $now = null): Carbon
+    {
+        $timezone = $this->companyTimezone($companyId);
+        $start = Carbon::parse($startsAt, $timezone);
+        $now = ($now ?: Carbon::now($this->applicationTimezone()))->copy()->setTimezone($timezone);
+
+        if ($start->greaterThan($now)
+            && $start->second === 0
+            && (new CronExpression($frequency))->isDue($start, $timezone)) {
+            return $start;
+        }
+
+        return $this->nextOccurrence($frequency, $start->greaterThan($now) ? $start : $now, $timezone);
+    }
+
+    public function nextOccurrence(string $frequency, Carbon $after, string $timezone): Carbon
+    {
+        $cron = new CronExpression($frequency);
+
+        return Carbon::instance($cron->getNextRunDate($after, 0, false, $timezone))
+            ->setTimezone($timezone);
+    }
+
+    public function fromStored(string $date, int $companyId): Carbon
+    {
+        return Carbon::parse($date, $this->applicationTimezone())
+            ->setTimezone($this->companyTimezone($companyId));
+    }
+
+    public function toStored(Carbon $date): string
+    {
+        return $date->copy()->setTimezone($this->applicationTimezone())->format('Y-m-d H:i:s');
+    }
+}