<?php

function isLoggedIn(): bool {
    return isset($_SESSION['isLoggedIn']) && $_SESSION['isLoggedIn'] === true;
}

function isAdmin(): bool {
    return isset($_SESSION['isAdmin']) && $_SESSION['isAdmin'] === true;
}

function requireAuth(string $redirectUrl = 'login.php'): void {
    if (!isLoggedIn()) {
        header('Location: ' . $redirectUrl . '?error=auth_required&redirect=' . urlencode($_SERVER['REQUEST_URI']));
        exit();
    }
}

function requireAdmin(string $redirectUrl = 'login.php'): void {
    if (!isAdmin()) {
        header('Location: ' . $redirectUrl . '?error=admin_required');
        exit();
    }
}

function getCurrentUser(): ?array {
    if (!isLoggedIn()) {
        return null;
    }

    return [
        'user_id' => $_SESSION['user_id'] ?? 0,
        'email' => $_SESSION['user_email'] ?? '',
        'full_name' => $_SESSION['full_name'] ?? '',
        'is_admin' => isAdmin()
    ];
}

function formatPrice(float $price): string {
    return number_format($price, 0, '', ' ') . ' ₽';
}

function e(string $str): string {
    return htmlspecialchars($str, ENT_QUOTES, 'UTF-8');
}

function generateOrderNumber(): string {
    return 'AET-' . date('Ymd') . '-' . strtoupper(substr(uniqid(), -6));
}

function generateSKU(string $productName): string {
    $prefix = strtoupper(substr(preg_replace('/[^a-zA-Z0-9]/', '', transliterate($productName)), 0, 6));
    return $prefix . '-' . rand(100, 999);
}

function transliterate(string $str): string {
    $converter = [
        'а' => 'a', 'б' => 'b', 'в' => 'v', 'г' => 'g', 'д' => 'd',
        'е' => 'e', 'ё' => 'e', 'ж' => 'zh', 'з' => 'z', 'и' => 'i',
        'й' => 'y', 'к' => 'k', 'л' => 'l', 'м' => 'm', 'н' => 'n',
        'о' => 'o', 'п' => 'p', 'р' => 'r', 'с' => 's', 'т' => 't',
        'у' => 'u', 'ф' => 'f', 'х' => 'h', 'ц' => 'c', 'ч' => 'ch',
        'ш' => 'sh', 'щ' => 'sch', 'ь' => '', 'ы' => 'y', 'ъ' => '',
        'э' => 'e', 'ю' => 'yu', 'я' => 'ya',
        'А' => 'A', 'Б' => 'B', 'В' => 'V', 'Г' => 'G', 'Д' => 'D',
        'Е' => 'E', 'Ё' => 'E', 'Ж' => 'Zh', 'З' => 'Z', 'И' => 'I',
        'Й' => 'Y', 'К' => 'K', 'Л' => 'L', 'М' => 'M', 'Н' => 'N',
        'О' => 'O', 'П' => 'P', 'Р' => 'R', 'С' => 'S', 'Т' => 'T',
        'У' => 'U', 'Ф' => 'F', 'Х' => 'H', 'Ц' => 'C', 'Ч' => 'Ch',
        'Ш' => 'Sh', 'Щ' => 'Sch', 'Ь' => '', 'Ы' => 'Y', 'Ъ' => '',
        'Э' => 'E', 'Ю' => 'Yu', 'Я' => 'Ya',
    ];
    return strtr($str, $converter);
}

function createSlug(string $str): string {
    $slug = transliterate($str);
    $slug = strtolower($slug);
    $slug = preg_replace('/[^a-z0-9]+/', '-', $slug);
    $slug = trim($slug, '-');
    return $slug;
}

function setFlashMessage(string $type, string $message): void {
    $_SESSION['flash_message'] = [
        'type' => $type,
        'message' => $message
    ];
}

function getFlashMessage(): ?array {
    if (isset($_SESSION['flash_message'])) {
        $message = $_SESSION['flash_message'];
        unset($_SESSION['flash_message']);
        return $message;
    }
    return null;
}