Calculate Age in PHP

AgeCalculation.php

<?php

declare(strict_types=1);

namespace App;

use App\Models\Age;
use Carbon\Carbon;

class AgeCalculator
{
    public const FEB_28 = 59;

    public const MAX_MONTHS = 12;

    /**
     * Demonstrate a more classic approach to age calculation.
     *
     * @param Carbon $dateOfBirth
     * @return Age
     */
    public function __invoke(Carbon $dateOfBirth): array
    {
        $currentDateTime = Carbon::now();

        // Indicates whether dob year has extra day compare to present date i.e. Leap years.
        $extraDay = $dateOfBirth->isLeapYear()
            && !$currentDateTime->isLeapYear()
            && $dateOfBirth->dayOfYear > self::FEB_28 ? 1 : 0;

        // Indicates whether dob has already been celebrated this year.
        $hasDobOccurred = $currentDateTime->dayOfYear >= $dateOfBirth->dayOfYear - $extraDay;

        $age = [
            'years' => ($currentDateTime->year - $dateOfBirth->year - ($hasDobOccurred ? 0 : 1)),
        ];

        // Calculate months.
        if ($hasDobOccurred) {
            $age['months']  = $currentDateTime->month - $dateOfBirth->month;

            if ($age['months'] > 0 & $currentDateTime->day < $dateOfBirth->day) {
                --$age['months'];
            }
        } else {
            $age['months'] = self::MAX_MONTHS - 1 - abs($currentDateTime->month - $dateOfBirth->month);
        }

        // Calculate days.
        $currentMonth = $dateOfBirth->month + $age['months'];

        if ($currentMonth > self::MAX_MONTHS) {
            $currentMonth = abs($currentMonth - self::MAX_MONTHS);
        }

        if ($currentMonth === $currentDateTime->month) {
            $age['days'] = ($currentDateTime->day - ($dateOfBirth->day - $extraDay));
        } else {
            $age['days'] = (
                cal_days_in_month(CAL_GREGORIAN, $currentMonth, $dateOfBirth->year + $age['years']) -
                ($dateOfBirth->day - ($hasDobOccurred ? $extraDay : 0)) + $currentDateTime->day
            );
        }

        return $age;
    }

    /**
     * Demonstrate calculate age simple taking into account leap year.
     *
     * @param Carbon $dateOfBirth
     * @return int
     */
    public function age(Carbon $dateOfBirth): int
    {
        $today = Carbon::today();

        $age = $today->year - $dateOfBirth->year;

        if ($dateOfBirth->toDate() > $today->addYears(-$age)) {
            $age--;
        }

        return $age;
    }

    /**
     * Demonstrate Carbon age calculation.
     *
     * @param string $datOfBirth
     * @return int
     */
    public function CarbonAge(string $datOfBirth): int
    {
        return Carbon::parse($datOfBirth)->age;
    }

    /**
     * Demonstrate Carbon date difference in days.
     *
     * @param Carbon $dateOfBirth
     * @return int
     */
    public function days(Carbon $dateOfBirth): int
    {
        return $dateOfBirth->diffInDays(Carbon::now());
    }

    /**
     * Demonstrate Carbon date difference in hours.
     *
     * @param Carbon $dateOfBirth
     * @return int
     */
    public function hours(Carbon $dateOfBirth): int
    {
        return $dateOfBirth->diffInHours(Carbon::now());
    }

    /**
     * Demonstrate Carbon date difference in seconds.
     *
     * @param Carbon $dateOfBirth
     * @return int
     */
    public function seconds(Carbon $dateOfBirth): int
    {
        return $dateOfBirth->diffInSeconds(Carbon::now());
    }

    /**
     * Demonstrate Carbon's parsing a date diff in a string format.
     *
     * @param Carbon $dateOfBirth
     * @return string
     */
    public function toHumanReadable(Carbon $dateOfBirth): string
    {
        return $dateOfBirth->diff(Carbon::now())->format('I am %y years, %m months ,%d days and %h hours old.');
    }
}