<?php

namespace App\Services;

class DateNormalizer
{
    /**
     * Normalize a raw date string to Y-m-d (ISO) or return null if unparseable.
     * Accepted examples: 30.10.2025, 30/10/2025, 30-10-2025, 1/2/25, 2025-10-30
     */
    public static function toDate(?string $raw): ?string
    {
        if ($raw === null) {
            return null;
        }
        $raw = trim($raw);
        if ($raw === '') {
            return null;
        }

        // Common European and ISO formats first (day-first, then ISO)
        $candidates = [
            'd.m.Y', 'd.m.y',
            'd/m/Y', 'd/m/y',
            'd-m-Y', 'd-m-y',
            'Y-m-d', 'Y/m/d', 'Y.m.d',
        ];

        foreach ($candidates as $fmt) {
            $dt = \DateTime::createFromFormat($fmt, $raw);
            if ($dt instanceof \DateTime) {
                $errors = \DateTime::getLastErrors();
                if ((int) ($errors['warning_count'] ?? 0) === 0 && (int) ($errors['error_count'] ?? 0) === 0) {
                    // Adjust two-digit years to reasonable century (00-69 => 2000-2069, 70-99 => 1970-1999)
                    $year = (int) $dt->format('Y');
                    if ($year < 100) {
                        $year += ($year <= 69) ? 2000 : 1900;
                        // Rebuild date with corrected year
                        $month = (int) $dt->format('m');
                        $day = (int) $dt->format('d');
                        return sprintf('%04d-%02d-%02d', $year, $month, $day);
                    }
                    return $dt->format('Y-m-d');
                }
            }
        }

        // Fallback: strtotime (permissive). If fails, return null.
        $ts = @strtotime($raw);
        if ($ts === false) {
            return null;
        }

        return date('Y-m-d', $ts);
    }
}