<?php

declare(strict_types=1);

function validate_email_address(string $email): ?string
{
    $email = trim($email);
    return filter_var($email, FILTER_VALIDATE_EMAIL) ? $email : null;
}

function validate_url_value(string $url): ?string
{
    $url = trim($url);
    if (!filter_var($url, FILTER_VALIDATE_URL)) {
        return null;
    }
    $scheme = parse_url($url, PHP_URL_SCHEME);
    return in_array($scheme, ['http', 'https'], true) ? rtrim($url, '/') : null;
}

function normalise_domain(string $domain): ?string
{
    $domain = strtolower(trim($domain));
    $domain = preg_replace('/^https?:\/\//', '', $domain);
    $domain = explode('/', $domain)[0];
    $domain = preg_replace('/:\d+$/', '', $domain);
    if ($domain === 'localhost') {
        return $domain;
    }
    return preg_match('/^(?:[a-z0-9-]+\.)+[a-z]{2,}$/', $domain) ? $domain : null;
}

function domains_from_text(string $text): array
{
    $domains = [];
    foreach (preg_split('/[\r\n,]+/', $text) ?: [] as $candidate) {
        $domain = normalise_domain($candidate);
        if ($domain !== null) {
            $domains[$domain] = $domain;
        }
    }
    return array_values($domains);
}

function validate_timezone_name(string $timezone): string
{
    return in_array($timezone, DateTimeZone::listIdentifiers(), true) ? $timezone : 'UTC';
}

function validate_currency_code(string $currency): string
{
    $currency = strtoupper(trim($currency));
    return preg_match('/^[A-Z]{3}$/', $currency) ? $currency : 'EUR';
}