<?php
declare(strict_types=1);

namespace Cf7stg;

final class PhoneParser
{
    /**
     * Extract and normalize the first phone number from arbitrary text.
     *
     * @return array{e164:string,pretty:string,is_russian:bool}|null
     */
    public static function parse(string $text): ?array
    {
        $text = (string)$text;
        if ($text === '') {
            return null;
        }

        // Find a run of digits, spaces, dashes, parens, dots and a leading '+',
        // with at least 10 digits in total. Walk candidates left-to-right and
        // pick the first that yields 10 or 11 digits.
        // NOTE: the space class is a literal ' ' — not '\s'. If '\s' is used
        // a newline or tab between two adjacent form fields (phone value,
        // then checkbox value) would bleed into the phone and append extra
        // digits. MessageFormatter/Classifier flatten fields with "\n" before
        // calling us, so this matters in practice.
        if (!preg_match_all('/\+?[\d][\d ().\-]{8,}/u', $text, $m)) {
            return null;
        }

        foreach ($m[0] as $candidate) {
            $digits = preg_replace('/\D+/', '', $candidate) ?? '';
            $plus = strpos($candidate, '+') === 0;

            // Russian detection & normalization
            if (!$plus && strlen($digits) === 11 && $digits[0] === '8') {
                $digits = '7' . substr($digits, 1);
            }
            if (!$plus && strlen($digits) === 10 && preg_match('/^[3-9]/', $digits)) {
                // Bare 10-digit RU mobile/landline area code
                $digits = '7' . $digits;
            }

            if (strlen($digits) < 10 || strlen($digits) > 15) {
                continue;
            }

            $e164 = '+' . $digits;
            $is_ru = (strlen($digits) === 11 && $digits[0] === '7');

            return [
                'e164'       => $e164,
                'pretty'     => self::format_pretty($e164, $is_ru),
                'is_russian' => $is_ru,
            ];
        }

        return null;
    }

    private static function format_pretty(string $e164, bool $is_ru): string
    {
        if ($is_ru) {
            // +7 XXX XXX-XX-XX → "+7 (XXX) XXX-XX-XX"
            $d = substr($e164, 2);
            return sprintf(
                '+7 (%s) %s-%s-%s',
                substr($d, 0, 3),
                substr($d, 3, 3),
                substr($d, 6, 2),
                substr($d, 8, 2)
            );
        }
        return $e164;
    }
}