<?php

namespace App\Support;

use Carbon\CarbonInterface;
use DateTimeInterface;

/**
 * Lightweight Gregorian -> Jalali (Shamsi) converter, so the admin panel can show
 * Persian dates without pulling in an extra dependency. Only the conversion and a
 * couple of display formatters are implemented — enough for table columns and infolists.
 */
class Jalali
{
    private const MONTHS = [
        1 => 'فروردین', 2 => 'اردیبهشت', 3 => 'خرداد', 4 => 'تیر', 5 => 'مرداد', 6 => 'شهریور',
        7 => 'مهر', 8 => 'آبان', 9 => 'آذر', 10 => 'دی', 11 => 'بهمن', 12 => 'اسفند',
    ];

    /**
     * @return array{0: int, 1: int, 2: int} [year, month, day]
     */
    public static function fromGregorian(int $gy, int $gm, int $gd): array
    {
        $g_d_m = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];

        $gy2 = ($gm > 2) ? ($gy + 1) : $gy;
        $days = 355666 + (365 * $gy) + intdiv($gy2 + 3, 4) - intdiv($gy2 + 99, 100)
            + intdiv($gy2 + 399, 400) + $gd + $g_d_m[$gm - 1];

        $jy = -1595 + (33 * intdiv($days, 12053));
        $days %= 12053;

        $jy += 4 * intdiv($days, 1461);
        $days %= 1461;

        if ($days > 365) {
            $jy += intdiv($days - 1, 365);
            $days = ($days - 1) % 365;
        }

        if ($days < 186) {
            $jm = 1 + intdiv($days, 31);
            $jd = 1 + ($days % 31);
        } else {
            $jm = 7 + intdiv($days - 186, 30);
            $jd = 1 + (($days - 186) % 30);
        }

        return [$jy, $jm, $jd];
    }

    public static function date(DateTimeInterface|CarbonInterface|string|null $value): ?string
    {
        $date = self::normalize($value);

        if ($date === null) {
            return null;
        }

        [$jy, $jm, $jd] = self::fromGregorian((int) $date->format('Y'), (int) $date->format('n'), (int) $date->format('j'));

        return self::toPersianDigits(sprintf('%04d/%02d/%02d', $jy, $jm, $jd));
    }

    public static function dateTime(DateTimeInterface|CarbonInterface|string|null $value): ?string
    {
        $date = self::normalize($value);

        if ($date === null) {
            return null;
        }

        [$jy, $jm, $jd] = self::fromGregorian((int) $date->format('Y'), (int) $date->format('n'), (int) $date->format('j'));

        return self::toPersianDigits(sprintf(
            '%04d/%02d/%02d - %02d:%02d',
            $jy, $jm, $jd, (int) $date->format('H'), (int) $date->format('i')
        ));
    }

    public static function longDate(DateTimeInterface|CarbonInterface|string|null $value): ?string
    {
        $date = self::normalize($value);

        if ($date === null) {
            return null;
        }

        [$jy, $jm, $jd] = self::fromGregorian((int) $date->format('Y'), (int) $date->format('n'), (int) $date->format('j'));

        return self::toPersianDigits($jd.' '.self::MONTHS[$jm].' '.$jy);
    }

    private static function normalize(DateTimeInterface|CarbonInterface|string|null $value): ?DateTimeInterface
    {
        if ($value === null || $value === '') {
            return null;
        }

        if ($value instanceof DateTimeInterface) {
            return $value;
        }

        try {
            return new \DateTimeImmutable((string) $value);
        } catch (\Throwable) {
            return null;
        }
    }

    private static function toPersianDigits(string $value): string
    {
        return strtr($value, [
            '0' => '۰', '1' => '۱', '2' => '۲', '3' => '۳', '4' => '۴',
            '5' => '۵', '6' => '۶', '7' => '۷', '8' => '۸', '9' => '۹',
        ]);
    }
}