ladill-hosting/app/Support/MailboxPricing.php

<?php

namespace App\Support;

/** Storage-tier pricing for mailboxes (config/email.php quota_tiers). */
class MailboxPricing
{
    /** @return array<int,array{mb:int,price_minor:int,label:string}> */
    public static function tiers(): array
    {
        return array_map(fn ($t) => [
            'mb' => (int) $t['mb'],
            'price_minor' => (int) $t['price_minor'],
            'label' => self::label((int) $t['mb']),
        ], (array) config('email.quota_tiers', []));
    }

    public static function isValidQuota(int $mb): bool
    {
        foreach (self::tiers() as $t) {
            if ($t['mb'] === $mb) {
                return true;
            }
        }

        return false;
    }

    public static function priceMinorFor(int $mb): int
    {
        foreach (self::tiers() as $t) {
            if ($t['mb'] === $mb) {
                return $t['price_minor'];
            }
        }

        return 0;
    }

    /** A tier is free when its monthly price is zero (the 1 GB plan). */
    public static function isFree(int $mb): bool
    {
        return self::priceMinorFor($mb) === 0;
    }

    /** The smallest free tier's quota (the default for new mailboxes). */
    public static function freeQuotaMb(): int
    {
        foreach (self::tiers() as $t) {
            if ($t['price_minor'] === 0) {
                return $t['mb'];
            }
        }

        return self::tiers()[0]['mb'] ?? 1024;
    }

    public static function defaultQuotaMb(): int
    {
        $default = (int) config('email.default_quota_mb', 1024);

        return self::isValidQuota($default) ? $default : self::freeQuotaMb();
    }

    public static function label(int $mb): string
    {
        return $mb % 1024 === 0 ? ($mb / 1024).' GB' : $mb.' MB';
    }
}