<?php
declare(strict_types=1);

namespace Cf7stg;

/**
 * Heuristic detection of name/email/etc. when form field keys are not
 * the standard CF7 ones (your-name, your-email, ...). Used as a fallback
 * for custom-themed forms where fields are called text-211, name_user,
 * и т.п.
 */
final class FieldDetector
{
    /**
     * Scan values for something that plausibly looks like a human name:
     * letters (any script), optional spaces/hyphens/apostrophes/dots,
     * no digits, no URLs, no emails, length 2..80.
     */
    public static function find_name(array $fields): string
    {
        foreach ($fields as $v) {
            if (is_array($v)) {
                $v = implode(' ', array_map('strval', $v));
            }
            $v = trim((string)$v);
            if ($v === '') continue;
            $len = mb_strlen($v);
            if ($len < 2 || $len > 80) continue;
            if (preg_match('/\d/u', $v)) continue;
            if (preg_match('#https?://|www\.|@#iu', $v)) continue;
            // Must start with a letter and contain only letter-like characters
            if (preg_match('/^\p{L}[\p{L}\s\.\-\']{1,79}$/u', $v)) {
                return $v;
            }
        }
        return '';
    }

    /**
     * First value that looks like an email address.
     */
    public static function find_email(array $fields): string
    {
        foreach ($fields as $v) {
            if (is_array($v)) {
                $v = implode(' ', array_map('strval', $v));
            }
            $v = trim((string)$v);
            if ($v === '') continue;
            if (preg_match('/^\S+@\S+\.\S+$/u', $v)) {
                return $v;
            }
        }
        return '';
    }
}