Fixed Calendar Converter for Laravel with tests

api.php

<?php

// These are the routes I added to get the data

Route::get('fixed-calendar/today', [FixedCalendarController::class, 'today'])
    ->name('fixed-calendar.today');
Route::get('fixed-calendar/{year}/{month}/{day}', [FixedCalendarController::class, 'date'])
    ->name('fixed-calendar.date');

FixedCalendarController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\JsonResponse;
use Illuminate\Support\Carbon;
use Illuminate\Support\Number;

/**
 * Class to handle determining the Fixed Calendar date.
 * https://en.wikipedia.org/wiki/International_Fixed_Calendar
 * 
 * I have also added some fun information about the origins/meanings of our month and day names
 */
class FixedCalendarController extends Controller
{
    /**
     * Standard names for the months
     */
    protected array $months = [
        'January',
        'February',
        'March',
        'April',
        'May',
        'June',
        'Sol',
        'July',
        'August',
        'September',
        'October',
        'November',
        'December',
    ];

    /**
     * Origin names for the months
     */
    protected array $originMonths = [
        'Janus',
        'Purification',
        'Mars',
        'Opening',
        'Maia',
        'Juno',
        'Sun',
        'Julius Ceaser',
        'Augustus Ceaser',
        'Seventh',
        'Eighth',
        'Ninth',
        'Tenth',
    ];

    /**
     * Standard names for the days
     */
    protected array $days = [
        'Sunday',
        'Monday',
        'Tuesday',
        'Wednesday',
        'Thursday',
        'Friday',
        'Saturday',
    ];

    /**
     * Origin names for the days
     */
    protected array $originDays = [
        'Sun',
        'Moon',
        'Mars',
        'Mercury',
        'Jupiter',
        'Venus',
        'Saturn',
    ];

    /**
     * Default return value for Leap Day
     */
    protected array $leapDay = [
        'day' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Leap Day',
            'origin' => 'Leap Day',
        ],
        'week' => [
            'index' => -1,
            'number' => 0,
        ],
        'month' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Leap Day',
            'origin' => 'Leap Day',
        ],
        'year' => [
            'number' => null,
            'he' => null,
        ],
    ];

    /**
     * Default return value for Year Day
     */
    protected array $yearDay = [
        'day' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Year Day',
            'origin' => 'Year Day',
        ],
        'week' => [
            'index' => -1,
            'number' => 0,
        ],
        'month' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Year Day',
            'origin' => 'Year Day',
        ],
        'year' => [
            'number' => null,
            'he' => null,
        ],
    ];

    /**
     * Function to determine the Fixed Calendar date data from the given Gregorian Date
     */
    public function determineDate(Carbon $date): array
    {
        $dayOfYear = $date->dayOfYear;

        // check for leap year
        if ($date->isLeapYear()) {

            // check if Leap Day
            if ($dayOfYear == 169) {
                return $this->formatSpecialDay($this->leapDay, $date);
            }

            // Any day after the Gregorian Leap Day needs to be shifted by 1
            if ($dayOfYear > 60) {
                $dayOfYear -= 1;
            }
        }

        // check if Year Day
        if ($dayOfYear == 365) {
            return $this->formatSpecialDay($this->yearDay, $date);
        }

        // calculate values
        $monthIndex = intdiv($date->dayOfYear - 1, 28);
        $dayOfMonth = ($dayOfYear % 28);
        $dayOfMonth = $dayOfMonth == 0 ? 28 : $dayOfMonth; // for the 28th day
        $weekOfMonthIndex = intdiv($dayOfMonth - 1, 7);
        $dayOfWeek = ($dayOfMonth % 7);
        $dayOfWeek = $dayOfWeek == 0 ? 7 : $dayOfWeek; // for the 7th day
        $dayOfWeekIndex = $dayOfWeek - 1;

        $data = [
            'day' => [
                'index' => $dayOfMonth - 1,
                'number' => $dayOfMonth,
                'name' => $this->days[$dayOfWeekIndex],
                'origin' => $this->originDays[$dayOfWeekIndex],
            ],
            'week' => [
                'index' => $weekOfMonthIndex,
                'number' => $weekOfMonthIndex + 1,
            ],
            'month' => [
                'index' => $monthIndex,
                'number' => $monthIndex + 1,
                'name' => $this->months[$monthIndex],
                'origin' => $this->originMonths[$monthIndex],
            ],
            'year' => [
                'number' => $date->year,
                'he' => $date->year + 10000,
            ],
        ];

        $data['funText'] = $this->formatFunText($data);
        $data['fixedText'] = $this->formatFixedText($data);

        return $data;
    }

    /**
     * Format the fixed data into a human readable string
     * Examples:
     *    - Sunday, August 1st, 2026
     *    - Year Day, 2026
     */
    public function formatFixedText($data)
    {
        return sprintf('%s, %s %s, %u',
            $data['day']['name'],
            $data['month']['name'],
            Number::ordinal($data['day']['number']),
            $data['year']['number']
        );
    }

    /**
     * Format the fixed data into a human readable string with origin names and Human Era years
     * Examples:
     *    - Sun Day of the 1st week, 1st day of Augustus Ceaser Month, 12026 HE
     *    - Year Day, 12026 HE
     */
    public function formatFunText($data)
    {
        return sprintf('%s Day of the %s week, %s day of %s Month, %u HE',
            $data['day']['origin'],
            Number::ordinal($data['week']['number']),
            Number::ordinal($data['day']['number']),
            $data['month']['origin'],
            $data['year']['he']
        );
    }

    /**
     * Format the output of the special days
     */
    protected function formatSpecialDay(array $dateObject, Carbon $date): array
    {
        $he = $date->year + 10000;
        $dateObject['year'] = [
            'number' => $date->year,
            'he' => $he,
        ];
        $dateObject['funText'] = "{$dateObject['day']['name']}, {$he} HE";
        $dateObject['fixedText'] = "{$dateObject['day']['name']}, {$date->year}";
        return $dateObject;
    }

    /**
     * Route endpoint to get today's Fixed Calendar data
     */
    public function today(): JsonResponse
    {
        $now = Carbon::now();

        return response()->json($this->determineDate($now));
    }

    /**
     * Route endpoint to get a specific dates Fixed Calendar data
     */
    public function date($year, $month, $day): JsonResponse
    {
        $date = Carbon::createFromDate($year, $month, $day);

        return response()->json($this->determineDate($date));
    }
}

FixedCalendarTest.php

<?php

use App\Http\Controllers\FixedCalendarController;
use Illuminate\Support\Carbon;

test('2026-08-13', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2026, 8, 13);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 0,
            'number' => 1,
            'name' => 'Sunday',
            'origin' => 'Sun',
        ],
        'week' => [
            'index' => 0,
            'number' => 1,
        ],
        'month' => [
            'index' => 8,
            'number' => 9,
            'name' => 'August',
            'origin' => 'Augustus Ceaser',
        ],
        'year' => [
            'number' => 2026,
            'he' => 12026,
        ],
        'funText' => 'Sun Day of the 1st week, 1st day of Augustus Ceaser Month, 12026 HE',
        'fixedText' => 'Sunday, August 1st, 2026',
    ]);
});

test('2026-12-19', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2026, 12, 19);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 16,
            'number' => 17,
            'name' => 'Tuesday',
            'origin' => 'Mars',
        ],
        'week' => [
            'index' => 2,
            'number' => 3,
        ],
        'month' => [
            'index' => 12,
            'number' => 13,
            'name' => 'December',
            'origin' => 'Tenth',
        ],
        'year' => [
            'number' => 2026,
            'he' => 12026,
        ],
        'funText' => 'Mars Day of the 3rd week, 17th day of Tenth Month, 12026 HE',
        'fixedText' => 'Tuesday, December 17th, 2026',
    ]);
});

test('2026-04-28', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2026, 4, 28);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 5,
            'number' => 6,
            'name' => 'Friday',
            'origin' => 'Venus',
        ],
        'week' => [
            'index' => 0,
            'number' => 1,
        ],
        'month' => [
            'index' => 4,
            'number' => 5,
            'name' => 'May',
            'origin' => 'Maia',
        ],
        'year' => [
            'number' => 2026,
            'he' => 12026,
        ],
        'funText' => 'Venus Day of the 1st week, 6th day of Maia Month, 12026 HE',
        'fixedText' => 'Friday, May 6th, 2026',
    ]);
});

test('2026-04-19', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2026, 4, 19);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 24,
            'number' => 25,
            'name' => 'Wednesday',
            'origin' => 'Mercury',
        ],
        'week' => [
            'index' => 3,
            'number' => 4,
        ],
        'month' => [
            'index' => 3,
            'number' => 4,
            'name' => 'April',
            'origin' => 'Opening',
        ],
        'year' => [
            'number' => 2026,
            'he' => 12026,
        ],
        'funText' => 'Mercury Day of the 4th week, 25th day of Opening Month, 12026 HE',
        'fixedText' => 'Wednesday, April 25th, 2026',
    ]);
});

test('2026-06-17 - Not Leap Day', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2026, 6, 17);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 27,
            'number' => 28,
            'name' => 'Saturday',
            'origin' => 'Saturn',
        ],
        'week' => [
            'index' => 3,
            'number' => 4,
        ],
        'month' => [
            'index' => 5,
            'number' => 6,
            'name' => 'June',
            'origin' => 'Juno',
        ],
        'year' => [
            'number' => 2026,
            'he' => 12026,
        ],
        'funText' => 'Saturn Day of the 4th week, 28th day of Juno Month, 12026 HE',
        'fixedText' => 'Saturday, June 28th, 2026',
    ]);
});

test('2026-06-18', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2026, 6, 18);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 0,
            'number' => 1,
            'name' => 'Sunday',
            'origin' => 'Sun',
        ],
        'week' => [
            'index' => 0,
            'number' => 1,
        ],
        'month' => [
            'index' => 6,
            'number' => 7,
            'name' => 'Sol',
            'origin' => 'Sun',
        ],
        'year' => [
            'number' => 2026,
            'he' => 12026,
        ],
        'funText' => 'Sun Day of the 1st week, 1st day of Sun Month, 12026 HE',
        'fixedText' => 'Sunday, Sol 1st, 2026',
    ]);
});

test('2026-12-31 - Year Day', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2026, 12, 31);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Year Day',
            'origin' => 'Year Day',
        ],
        'week' => [
            'index' => -1,
            'number' => 0,
        ],
        'month' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Year Day',
            'origin' => 'Year Day',
        ],
        'year' => [
            'number' => 2026,
            'he' => 12026,
        ],
        'funText' => 'Year Day, 12026 HE',
        'fixedText' => 'Year Day, 2026',
    ]);
});

test('2028-08-13', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 8, 13);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 0,
            'number' => 1,
            'name' => 'Sunday',
            'origin' => 'Sun',
        ],
        'week' => [
            'index' => 0,
            'number' => 1,
        ],
        'month' => [
            'index' => 8,
            'number' => 9,
            'name' => 'August',
            'origin' => 'Augustus Ceaser',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Sun Day of the 1st week, 1st day of Augustus Ceaser Month, 12028 HE',
        'fixedText' => 'Sunday, August 1st, 2028',
    ]);
});

test('2028-12-19', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 12, 19);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 16,
            'number' => 17,
            'name' => 'Tuesday',
            'origin' => 'Mars',
        ],
        'week' => [
            'index' => 2,
            'number' => 3,
        ],
        'month' => [
            'index' => 12,
            'number' => 13,
            'name' => 'December',
            'origin' => 'Tenth',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Mars Day of the 3rd week, 17th day of Tenth Month, 12028 HE',
        'fixedText' => 'Tuesday, December 17th, 2028',
    ]);
});

test('2028-04-28', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 4, 28);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 5,
            'number' => 6,
            'name' => 'Friday',
            'origin' => 'Venus',
        ],
        'week' => [
            'index' => 0,
            'number' => 1,
        ],
        'month' => [
            'index' => 4,
            'number' => 5,
            'name' => 'May',
            'origin' => 'Maia',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Venus Day of the 1st week, 6th day of Maia Month, 12028 HE',
        'fixedText' => 'Friday, May 6th, 2028',
    ]);
});

test('2028-04-19', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 4, 19);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 24,
            'number' => 25,
            'name' => 'Wednesday',
            'origin' => 'Mercury',
        ],
        'week' => [
            'index' => 3,
            'number' => 4,
        ],
        'month' => [
            'index' => 3,
            'number' => 4,
            'name' => 'April',
            'origin' => 'Opening',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Mercury Day of the 4th week, 25th day of Opening Month, 12028 HE',
        'fixedText' => 'Wednesday, April 25th, 2028',
    ]);
});

test('2028-12-31 - Year Day', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 12, 31);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Year Day',
            'origin' => 'Year Day',
        ],
        'week' => [
            'index' => -1,
            'number' => 0,
        ],
        'month' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Year Day',
            'origin' => 'Year Day',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Year Day, 12028 HE',
        'fixedText' => 'Year Day, 2028',
    ]);
});

test('2028-02-29 - Gregorian Leap Day', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 2, 29);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 3,
            'number' => 4,
            'name' => 'Wednesday',
            'origin' => 'Mercury',
        ],
        'week' => [
            'index' => 0,
            'number' => 1,
        ],
        'month' => [
            'index' => 2,
            'number' => 3,
            'name' => 'March',
            'origin' => 'Mars',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Mercury Day of the 1st week, 4th day of Mars Month, 12028 HE',
        'fixedText' => 'Wednesday, March 4th, 2028',
    ]);
});

test('2028-06-17 - Leap Day', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 6, 17);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Leap Day',
            'origin' => 'Leap Day',
        ],
        'week' => [
            'index' => -1,
            'number' => 0,
        ],
        'month' => [
            'index' => -1,
            'number' => 0,
            'name' => 'Leap Day',
            'origin' => 'Leap Day',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Leap Day, 12028 HE',
        'fixedText' => 'Leap Day, 2028',
    ]);
});

test('2028-06-18', function () {
    $fixedCal = new FixedCalendarController;
    $date = Carbon::createFromDate(2028, 6, 18);
    $fixedCalDate = $fixedCal->determineDate($date);

    expect($fixedCalDate)->toBe([
        'day' => [
            'index' => 0,
            'number' => 1,
            'name' => 'Sunday',
            'origin' => 'Sun',
        ],
        'week' => [
            'index' => 0,
            'number' => 1,
        ],
        'month' => [
            'index' => 6,
            'number' => 7,
            'name' => 'Sol',
            'origin' => 'Sun',
        ],
        'year' => [
            'number' => 2028,
            'he' => 12028,
        ],
        'funText' => 'Sun Day of the 1st week, 1st day of Sun Month, 12028 HE',
        'fixedText' => 'Sunday, Sol 1st, 2028',
    ]);
});