<?php

declare(strict_types=1);

namespace Shared\Helpers;

use Carbon\CarbonImmutable;
use Carbon\CarbonInterface;
use Shared\Helpers\Exceptions\InvalidDateFormatException;

final class DatesHelper
{
    private const string FRENCH_DATE_REGEX = '/^\d{4}-\d{2}-\d{2}$/';

    private const string FRENCH_DATE_INVERT_REGEX = '/^\d{2}-\d{2}-\d{4}$/';

    private const string ISO8601_REGEX = '/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z$/';

    private const string RFC3339_REGEX = '/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d+)?(?:Z|[+\-]\d{2}:\d{2})$/';

    private function __construct()
    {
        // Static class
    }

    /**
     * Vérifie si la date actuelle se situe dans l'intervalle donné (en UTC).
     */
    public static function isIn(?CarbonInterface $from, ?CarbonInterface $to): bool
    {
        $now = CarbonImmutable::now(new \DateTimeZone('UTC'));

        return match (true) {
            $from !== null && $to !== null   => $now->between($from, $to),
            $from !== null                   => $now->greaterThanOrEqualTo($from),
            $to   !== null                   => $now->lessThanOrEqualTo($to),
            default                          => false,
        };
    }

    public static function toRfc3339(\DateTimeInterface | string $datetime): string
    {
        $dt = is_string($datetime) ? self::parseDateTime($datetime) : $datetime;

        if ($dt instanceof \DateTimeImmutable) {
            $dt = $dt->setTimezone(new \DateTimeZone('UTC'));
        } elseif ($dt instanceof \DateTime) {
            $dt = (clone $dt)->setTimezone(new \DateTimeZone('UTC'));
        }

        return $dt->format(\DATE_RFC3339);
    }

    public static function toNullableRfc3339(\DateTimeInterface | string | null $datetime): ?string
    {
        return $datetime !== null ? self::toRfc3339($datetime) : null;
    }

    public static function parseDateTime(string $datetime): \DateTimeInterface
    {
        $datetime = trim($datetime);

        /** @var \DateTimeInterface|null */
        $output = null;

        switch (true) {
            case (bool) preg_match(self::FRENCH_DATE_REGEX, $datetime):
                $output = self::parseFrench($datetime);
                break;
            case (bool) preg_match(self::FRENCH_DATE_INVERT_REGEX, $datetime):
                $output = self::parseFrenchInverted($datetime);
                break;
            case (bool) preg_match(self::ISO8601_REGEX, $datetime):
                $output = self::parseIso8601($datetime);
                break;
            case (bool) preg_match(self::RFC3339_REGEX, $datetime):
                $output = self::parseRfc3339($datetime);
                break;
            default:
                try {
                    $output = (new \DateTimeImmutable($datetime, new \DateTimeZone('UTC')))->setTimezone(new \DateTimeZone('UTC'));
                } catch (\Exception) {
                    throw InvalidDateFormatException::forDateString($datetime);
                }
        }

        return $output;
    }

    protected static function parseFrench(string $datetime): \DateTimeInterface
    {
        $dt = \DateTimeImmutable::createFromFormat('Y-m-d H:i:s', $datetime . ' 00:00:00', new \DateTimeZone('UTC'));

        return $dt ?: self::parseFallback($datetime);
    }

    protected static function parseFrenchInverted(string $datetime): \DateTimeInterface
    {
        $dt = \DateTimeImmutable::createFromFormat('d-m-Y H:i:s', $datetime . ' 00:00:00', new \DateTimeZone('UTC'));

        return $dt ?: self::parseFallback($datetime);
    }

    protected static function parseRfc3339(string $datetime): \DateTimeInterface
    {
        $dt = \DateTimeImmutable::createFromFormat(\DateTimeInterface::RFC3339, $datetime);
        if ($dt !== false) {
            return $dt->setTimezone(new \DateTimeZone('UTC'));
        }

        $dt = \DateTimeImmutable::createFromFormat('Y-m-d\TH:i:s.uP', $datetime);

        return $dt ? $dt->setTimezone(new \DateTimeZone('UTC')) : self::parseFallback($datetime);
    }

    protected static function parseIso8601(string $datetime): \DateTimeInterface
    {
        $dt = \DateTimeImmutable::createFromFormat(\DateTimeInterface::ATOM, $datetime);

        return $dt ? $dt->setTimezone(new \DateTimeZone('UTC')) : self::parseFallback($datetime);
    }

    protected static function parseFallback(string $datetime): \DateTimeInterface
    {
        try {
            return (new \DateTimeImmutable($datetime, new \DateTimeZone('UTC')))->setTimezone(new \DateTimeZone('UTC'));
        } catch (\Throwable) {
            throw InvalidDateFormatException::forDateString($datetime);
        }
    }
}