<?php
require_once __DIR__ . '/../config.php';

function readJsonFile($file) {
    if (!file_exists($file)) {
        return [];
    }

    $content = file_get_contents($file);
    if ($content === false || trim($content) === '') {
        return [];
    }

    $data = json_decode($content, true);
    return is_array($data) ? $data : [];
}

function writeJsonFile($file, $data) {
    $dir = dirname($file);
    if (!is_dir($dir)) {
        mkdir($dir, 0755, true);
    }

    file_put_contents($file, json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES));
}

function sanitize($input) {
    return trim(strip_tags((string) $input));
}

function escape($value) {
    return htmlspecialchars((string) $value, ENT_QUOTES, 'UTF-8');
}

function getUploadFilename($filename) {
    $filename = trim((string) $filename);
    if ($filename === '') {
        return '';
    }

    return basename($filename);
}

function getUploadPath($filename) {
    $filename = getUploadFilename($filename);
    if ($filename === '') {
        return null;
    }

    return rtrim(UPLOADS_DIR, '/\\') . '/' . $filename;
}

function getUploadUrl($filename) {
    $filename = getUploadFilename($filename);
    if ($filename === '') {
        return null;
    }

    return rtrim(UPLOADS_URL, '/\\') . '/' . rawurlencode($filename);
}

function setFlashMessage($key, $type, $message) {
    $key = trim((string) $key);
    $type = trim((string) $type);
    $message = trim((string) $message);

    if ($key === '' || $type === '' || $message === '') {
        return;
    }

    $_SESSION['flash_messages'][$key] = [
        'type' => $type,
        'message' => $message,
    ];
}

function consumeFlashMessage($key) {
    $key = trim((string) $key);
    if ($key === '') {
        return null;
    }

    $messages = $_SESSION['flash_messages'] ?? [];
    if (!is_array($messages) || !isset($messages[$key]) || !is_array($messages[$key])) {
        return null;
    }

    $message = $messages[$key];
    unset($_SESSION['flash_messages'][$key]);

    $type = trim((string) ($message['type'] ?? ''));
    $text = trim((string) ($message['message'] ?? ''));
    if ($type === '' || $text === '') {
        return null;
    }

    return [
        'type' => $type,
        'message' => $text,
    ];
}

function normalizeAdminUsername($username) {
    return trim((string) $username);
}

function normalizeAdminDescription($description) {
    return trim((string) $description);
}

function normalizeAdminEmail($email) {
    return strtolower(trim((string) $email));
}

function isValidAdminUsername($username) {
    $username = normalizeAdminUsername($username);
    return preg_match('/^[A-Za-z0-9][A-Za-z0-9._-]{2,49}$/', $username) === 1;
}

function isValidAdminDescription($description) {
    $description = normalizeAdminDescription($description);
    if ($description === '') {
        return false;
    }

    $length = function_exists('mb_strlen') ? mb_strlen($description) : strlen($description);
    return $length <= 120;
}

function isValidAdminEmail($email) {
    $email = normalizeAdminEmail($email);
    return $email !== '' && filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
}

function getDefaultAdminDescription($username) {
    return 'Admin';
}

function getDefaultAdminEmail() {
    $email = defined('ADMIN_EMAIL') ? normalizeAdminEmail(ADMIN_EMAIL) : '';
    return isValidAdminEmail($email) ? $email : '';
}

function getAdminAccounts() {
    $data = readJsonFile(ADMINS_FILE);
    $records = isset($data['admins']) && is_array($data['admins']) ? $data['admins'] : [];
    $accounts = [];

    foreach ($records as $username => $record) {
        $username = normalizeAdminUsername($username);
        if ($username === '') {
            continue;
        }

        if (is_string($record)) {
            $record = [
                'password_hash' => $record,
                'description' => getDefaultAdminDescription($username),
                'email' => getDefaultAdminEmail(),
            ];
        }

        if (!is_array($record)) {
            continue;
        }

        $hash = isset($record['password_hash']) ? (string) $record['password_hash'] : '';
        if ($hash === '') {
            continue;
        }

        $description = normalizeAdminDescription($record['description'] ?? getDefaultAdminDescription($username));
        if (!isValidAdminDescription($description)) {
            $description = getDefaultAdminDescription($username);
        }

        $email = normalizeAdminEmail($record['email'] ?? getDefaultAdminEmail());
        if (!isValidAdminEmail($email)) {
            $email = getDefaultAdminEmail();
        }

        $accounts[$username] = [
            'password_hash' => $hash,
            'description' => $description,
            'email' => $email,
        ];
    }

    ksort($accounts);
    return $accounts;
}

function getAdminUsers() {
    $users = [];
    foreach (getAdminAccounts() as $username => $record) {
        $users[$username] = $record['password_hash'];
    }
    return $users;
}

function saveAdminAccounts($accounts) {
    $result = [];

    foreach ($accounts as $username => $record) {
        $username = normalizeAdminUsername($username);
        if ($username === '' || !is_array($record)) {
            continue;
        }

        $hash = isset($record['password_hash']) ? (string) $record['password_hash'] : '';
        if ($hash === '') {
            continue;
        }

        $description = normalizeAdminDescription($record['description'] ?? getDefaultAdminDescription($username));
        if (!isValidAdminDescription($description)) {
            $description = getDefaultAdminDescription($username);
        }

        $email = normalizeAdminEmail($record['email'] ?? getDefaultAdminEmail());
        if (!isValidAdminEmail($email)) {
            $email = getDefaultAdminEmail();
        }

        $result[$username] = [
            'password_hash' => $hash,
            'description' => $description,
            'email' => $email,
        ];
    }

    ksort($result);
    writeJsonFile(ADMINS_FILE, ['admins' => $result]);
}

function getDefaultCategories() {
    return [
        ['id' => 'apparel', 'label' => 'Bekleidung'],
    ];
}

function normalizeCategoryId($id) {
    $id = trim((string) $id);
    if ($id === '') {
        return '';
    }

    if (function_exists('iconv')) {
        $converted = @iconv('UTF-8', 'ASCII//TRANSLIT//IGNORE', $id);
        if (is_string($converted) && $converted !== '') {
            $id = $converted;
        }
    }

    $id = strtolower($id);
    $id = preg_replace('/[^a-z0-9]+/', '-', $id);
    return trim((string) $id, '-');
}

function normalizeCategoryLabel($label) {
    return trim((string) $label);
}

function isValidCategoryLabel($label) {
    $label = normalizeCategoryLabel($label);
    if ($label === '') {
        return false;
    }

    $length = function_exists('mb_strlen') ? mb_strlen($label) : strlen($label);
    return $length <= 80;
}

function normalizeCategories($categories) {
    $normalized = [];
    if (!is_array($categories)) {
        $categories = [];
    }

    foreach ($categories as $category) {
        if (!is_array($category)) {
            continue;
        }

        $id = normalizeCategoryId($category['id'] ?? '');
        $label = normalizeCategoryLabel($category['label'] ?? '');
        if ($id === '' || !isValidCategoryLabel($label)) {
            continue;
        }

        $normalized[$id] = [
            'id' => $id,
            'label' => $label,
        ];
    }

    if (empty($normalized)) {
        foreach (getDefaultCategories() as $category) {
            $normalized[$category['id']] = $category;
        }
    }

    uasort($normalized, function ($left, $right) {
        return strcasecmp($left['label'], $right['label']);
    });

    return array_values($normalized);
}

function getCategories() {
    $data = readJsonFile(CATEGORIES_FILE);
    return normalizeCategories($data['categories'] ?? []);
}

function saveCategories($categories) {
    writeJsonFile(CATEGORIES_FILE, ['categories' => normalizeCategories($categories)]);
}

function getCategoryById($categoryId) {
    $categoryId = normalizeCategoryId($categoryId);
    foreach (getCategories() as $category) {
        if ($category['id'] === $categoryId) {
            return $category;
        }
    }
    return null;
}

function getCategoryLabel($categoryId) {
    $category = getCategoryById($categoryId);
    if ($category !== null) {
        return $category['label'];
    }
    return trim((string) $categoryId);
}

function getCategoryLabels($categoryIds) {
    $labels = [];
    foreach (normalizeProductCategoryIds($categoryIds) as $categoryId) {
        $labels[] = getCategoryLabel($categoryId);
    }
    return $labels;
}

function generateCategoryIdFromLabel($label, $existingCategories = []) {
    $baseId = normalizeCategoryId($label);
    if ($baseId === '') {
        $baseId = 'category';
    }

    $used = [];
    foreach (normalizeCategories($existingCategories) as $category) {
        $used[$category['id']] = true;
    }

    $candidate = $baseId;
    $counter = 2;
    while (isset($used[$candidate])) {
        $candidate = $baseId . '-' . $counter;
        $counter++;
    }

    return $candidate;
}

function isCategoryInUse($categoryId) {
    foreach (getProducts() as $product) {
        if (productHasCategory($product, $categoryId)) {
            return true;
        }
    }
    return false;
}

function normalizeProductCategoryIds($categoryValue) {
    if (is_array($categoryValue)) {
        $rawIds = $categoryValue;
    } elseif ($categoryValue === null || $categoryValue === '') {
        $rawIds = [];
    } else {
        $rawIds = [$categoryValue];
    }

    $normalized = [];
    foreach ($rawIds as $categoryId) {
        $categoryId = normalizeCategoryId($categoryId);
        if ($categoryId !== '') {
            $normalized[$categoryId] = $categoryId;
        }
    }

    return array_values($normalized);
}

function getProductCategoryIds($product) {
    if (isset($product['categories'])) {
        return normalizeProductCategoryIds($product['categories']);
    }
    return normalizeProductCategoryIds($product['category'] ?? []);
}

function productHasCategory($product, $categoryId) {
    $categoryId = normalizeCategoryId($categoryId);
    if ($categoryId === '') {
        return false;
    }
    return in_array($categoryId, getProductCategoryIds($product), true);
}

function getProductSizes($product) {
    if (isset($product['sizes']) && is_array($product['sizes'])) {
        $sizes = $product['sizes'];
    } elseif (isset($product['sizes']) && is_string($product['sizes'])) {
        $sizes = explode(',', $product['sizes']);
    } else {
        $sizes = [];
    }

    $normalized = [];
    foreach ($sizes as $size) {
        $size = trim((string) $size);
        if ($size !== '') {
            $normalized[$size] = $size;
        }
    }

    return array_values($normalized);
}

function productUsesSizeStock($product) {
    return !empty(getProductSizes($product));
}

function normalizeAvailabilityLabels($sizes, $labels) {
    $result = [];
    if (!is_array($labels)) {
        $labels = [];
    }

    foreach ($sizes as $size) {
        $text = trim((string) ($labels[$size] ?? ''));
        $result[$size] = $text;
    }

    return $result;
}

function getAvailabilityLabel($product, $size) {
    $labels = isset($product['availability_labels']) && is_array($product['availability_labels'])
        ? $product['availability_labels']
        : [];
    return trim((string) ($labels[$size] ?? ''));
}

function normalizeProductRecord($product, $defaultCategoryId = '') {
    if (!is_array($product)) {
        return null;
    }

    $productId = isset($product['id']) ? (int) $product['id'] : 0;
    $name = trim((string) ($product['name'] ?? ''));
    if ($productId <= 0 || $name === '') {
        return null;
    }

    $sizes = getProductSizes($product);
    if (empty($sizes)) {
        $sizes = ['Standard'];
    }

    $categories = getProductCategoryIds($product);
    if (empty($categories) && $defaultCategoryId !== '') {
        $categories = [$defaultCategoryId];
    }

    $availabilityLabels = normalizeAvailabilityLabels(
        $sizes,
        isset($product['availability_labels']) && is_array($product['availability_labels'])
            ? $product['availability_labels']
            : []
    );

    return [
        'id' => $productId,
        'name' => $name,
        'description' => trim((string) ($product['description'] ?? '')),
        'image' => trim((string) ($product['image'] ?? '')),
        'categories' => $categories,
        'sizes' => implode(',', $sizes),
        'availability_labels' => $availabilityLabels,
    ];
}

function getProducts() {
    $data = readJsonFile(PRODUCTS_FILE);
    $rawProducts = isset($data['products']) && is_array($data['products']) ? $data['products'] : [];
    $categories = getCategories();
    $defaultCategoryId = !empty($categories) ? $categories[0]['id'] : 'apparel';
    $products = [];

    foreach ($rawProducts as $product) {
        $normalized = normalizeProductRecord($product, $defaultCategoryId);
        if ($normalized !== null) {
            $products[] = $normalized;
        }
    }

    usort($products, function ($left, $right) {
        return strcasecmp($left['name'], $right['name']);
    });

    return $products;
}

function getProductById($id) {
    $id = (int) $id;
    foreach (getProducts() as $product) {
        if ((int) $product['id'] === $id) {
            return $product;
        }
    }
    return null;
}

function saveProducts($products) {
    $categories = getCategories();
    $defaultCategoryId = !empty($categories) ? $categories[0]['id'] : 'apparel';
    $normalized = [];

    foreach ($products as $product) {
        $record = normalizeProductRecord($product, $defaultCategoryId);
        if ($record !== null) {
            $normalized[] = $record;
        }
    }

    writeJsonFile(PRODUCTS_FILE, ['products' => array_values($normalized)]);
}

function getFaqFilePath(): string {
    $dataDir = defined('DATA_DIR') ? DATA_DIR : dirname(__DIR__) . '/data/';
    $defaultPath = rtrim($dataDir, '/\\') . '/faq.json';

    if (!defined('FAQ_FILE') || !is_string(FAQ_FILE) || FAQ_FILE === '') {
        return $defaultPath;
    }

    $configuredPath = FAQ_FILE;
    $normalizedDataDir = str_replace('\\', '/', rtrim($dataDir, '/\\')) . '/';
    $normalizedConfigured = str_replace('\\', '/', $configuredPath);

    if (strpos($normalizedConfigured, $normalizedDataDir) !== 0) {
        return $defaultPath;
    }

    return $configuredPath;
}

function getFaqContent(): string {
    $defaultContent = "# FAQ\n\nHier kann der FAQ-Inhalt im Admin-Bereich bearbeitet werden.";
    $data = readJsonFile(getFaqFilePath());

    if (!isset($data['content']) || !is_string($data['content'])) {
        return $defaultContent;
    }

    return $data['content'];
}

function saveFaqContent(string $markdown): void {
    writeJsonFile(getFaqFilePath(), ['content' => (string) $markdown]);
}

function renderFaqInlineMarkdown(string $text): string {
    $escaped = escape($text);
    $escaped = preg_replace('/\*\*(.+?)\*\*/s', '<strong>$1</strong>', $escaped);
    $escaped = preg_replace('/(?<!\*)\*(?!\s)(.+?)(?<!\s)\*(?!\*)/s', '<em>$1</em>', $escaped);
    return $escaped;
}

function renderFaqMarkdown(string $markdown): string {
    $normalized = str_replace(["\r\n", "\r"], "\n", $markdown);
    $lines = explode("\n", $normalized);
    $htmlParts = [];
    $paragraphLines = [];
    $listType = '';

    $flushParagraph = function () use (&$paragraphLines, &$htmlParts): void {
        if (empty($paragraphLines)) {
            return;
        }

        $rendered = [];
        foreach ($paragraphLines as $line) {
            $rendered[] = renderFaqInlineMarkdown($line);
        }

        $htmlParts[] = '<p>' . implode("<br>\n", $rendered) . '</p>';
        $paragraphLines = [];
    };

    $closeList = function () use (&$listType, &$htmlParts): void {
        if ($listType !== '') {
            $htmlParts[] = '</' . $listType . '>';
            $listType = '';
        }
    };

    foreach ($lines as $line) {
        $line = rtrim($line);
        $trimmed = trim($line);

        if ($trimmed === '') {
            $flushParagraph();
            $closeList();
            continue;
        }

        if (preg_match('/^(#{1,3})\s+(.+)$/', $trimmed, $matches) === 1) {
            $flushParagraph();
            $closeList();
            $level = strlen($matches[1]);
            $htmlParts[] = '<h' . $level . '>' . renderFaqInlineMarkdown($matches[2]) . '</h' . $level . '>';
            continue;
        }

        if (preg_match('/^\s*[-*]\s+(.+)$/', $line, $matches) === 1) {
            $flushParagraph();
            if ($listType !== 'ul') {
                $closeList();
                $listType = 'ul';
                $htmlParts[] = '<ul>';
            }
            $htmlParts[] = '<li>' . renderFaqInlineMarkdown($matches[1]) . '</li>';
            continue;
        }

        if (preg_match('/^\s*\d+\.\s+(.+)$/', $line, $matches) === 1) {
            $flushParagraph();
            if ($listType !== 'ol') {
                $closeList();
                $listType = 'ol';
                $htmlParts[] = '<ol>';
            }
            $htmlParts[] = '<li>' . renderFaqInlineMarkdown($matches[1]) . '</li>';
            continue;
        }

        $closeList();
        $paragraphLines[] = $trimmed;
    }

    $flushParagraph();
    $closeList();

    return empty($htmlParts) ? '<p>Keine FAQ-Inhalte vorhanden.</p>' : implode("\n", $htmlParts);
}

function getDefaultOrganizations() {
    return [
        [
            'id' => 'feuerwehr-freising',
            'label' => 'Amt 32 - Feuerwehr Freising',
            'sort_order' => 10,
            'active' => true,
        ],
    ];
}

function normalizeOrganizationId($id) {
    return normalizeCategoryId($id);
}

function normalizeOrganizationLabel($label) {
    return trim((string) $label);
}

function isValidOrganizationLabel($label) {
    $label = normalizeOrganizationLabel($label);
    if ($label === '') {
        return false;
    }

    $length = function_exists('mb_strlen') ? mb_strlen($label) : strlen($label);
    return $length <= 120;
}

function normalizeOrganizations($organizations) {
    $normalized = [];
    if (!is_array($organizations)) {
        $organizations = [];
    }

    foreach ($organizations as $organization) {
        if (!is_array($organization)) {
            continue;
        }

        $id = normalizeOrganizationId($organization['id'] ?? '');
        $label = normalizeOrganizationLabel($organization['label'] ?? '');
        if ($id === '' || !isValidOrganizationLabel($label)) {
            continue;
        }

        $sortOrder = isset($organization['sort_order']) ? (int) $organization['sort_order'] : 0;
        $active = !isset($organization['active']) || (bool) $organization['active'];

        $normalized[$id] = [
            'id' => $id,
            'label' => $label,
            'sort_order' => $sortOrder,
            'active' => $active,
        ];
    }

    if (empty($normalized)) {
        foreach (getDefaultOrganizations() as $organization) {
            $normalized[$organization['id']] = $organization;
        }
    }

    uasort($normalized, function ($left, $right) {
        if ($left['sort_order'] === $right['sort_order']) {
            return strcasecmp($left['label'], $right['label']);
        }
        return $left['sort_order'] <=> $right['sort_order'];
    });

    return array_values($normalized);
}

function getOrganizations($onlyActive = false) {
    $data = readJsonFile(ORGANIZATIONS_FILE);
    $organizations = normalizeOrganizations($data['organizations'] ?? []);

    if ($onlyActive) {
        $organizations = array_values(array_filter($organizations, function ($organization) {
            return !empty($organization['active']);
        }));
    }

    return $organizations;
}

function saveOrganizations($organizations) {
    writeJsonFile(ORGANIZATIONS_FILE, ['organizations' => normalizeOrganizations($organizations)]);
}

function getOrganizationById($organizationId) {
    $organizationId = normalizeOrganizationId($organizationId);
    foreach (getOrganizations(false) as $organization) {
        if ($organization['id'] === $organizationId) {
            return $organization;
        }
    }
    return null;
}

function generateOrganizationIdFromLabel($label, $existingOrganizations = []) {
    $baseId = normalizeOrganizationId($label);
    if ($baseId === '') {
        $baseId = 'organization';
    }

    $used = [];
    foreach (normalizeOrganizations($existingOrganizations) as $organization) {
        $used[$organization['id']] = true;
    }

    $candidate = $baseId;
    $counter = 2;
    while (isset($used[$candidate])) {
        $candidate = $baseId . '-' . $counter;
        $counter++;
    }

    return $candidate;
}

function getDefaultSystemSettings() {
    return [
        'order_recipient_email' => defined('ORDER_RECIPIENT_EMAIL') ? ORDER_RECIPIENT_EMAIL : getDefaultAdminEmail(),
        'order_confirmation_required' => defined('ORDER_CONFIRMATION_REQUIRED') ? (bool) ORDER_CONFIRMATION_REQUIRED : false,
        'order_confirmation_expiry_days' => defined('ORDER_CONFIRMATION_EXPIRY_DAYS') ? (int) ORDER_CONFIRMATION_EXPIRY_DAYS : 7,
        'attach_order_pdf_to_admin_email' => defined('ATTACH_ORDER_PDF_TO_ADMIN_EMAIL') ? (bool) ATTACH_ORDER_PDF_TO_ADMIN_EMAIL : true,
    ];
}

function normalizeSystemSettings($settings) {
    $defaults = getDefaultSystemSettings();
    if (!is_array($settings)) {
        $settings = [];
    }

    $recipientEmail = normalizeAdminEmail($settings['order_recipient_email'] ?? $defaults['order_recipient_email']);
    if (!isValidAdminEmail($recipientEmail)) {
        $recipientEmail = $defaults['order_recipient_email'];
    }

    $expiryDays = isset($settings['order_confirmation_expiry_days']) ? (int) $settings['order_confirmation_expiry_days'] : $defaults['order_confirmation_expiry_days'];
    if ($expiryDays < 1) {
        $expiryDays = 7;
    }

    return [
        'order_recipient_email' => $recipientEmail,
        'order_confirmation_required' => !empty($settings['order_confirmation_required']),
        'order_confirmation_expiry_days' => $expiryDays,
        'attach_order_pdf_to_admin_email' => !empty($settings['attach_order_pdf_to_admin_email']),
    ];
}

function getSystemSettings() {
    $data = readJsonFile(SETTINGS_FILE);
    return normalizeSystemSettings($data['settings'] ?? []);
}

function saveSystemSettings($settings) {
    writeJsonFile(SETTINGS_FILE, ['settings' => normalizeSystemSettings($settings)]);
}

function getOrderRecipientEmail() {
    $settings = getSystemSettings();
    return $settings['order_recipient_email'];
}

function isOrderConfirmationRequired() {
    $settings = getSystemSettings();
    return !empty($settings['order_confirmation_required']);
}

function getOrderConfirmationExpiryDays() {
    $settings = getSystemSettings();
    return max(1, (int) $settings['order_confirmation_expiry_days']);
}

function shouldAttachOrderPdfToAdminEmail() {
    $settings = getSystemSettings();
    return !empty($settings['attach_order_pdf_to_admin_email']);
}

function normalizeOrderItem($item) {
    if (!is_array($item)) {
        return null;
    }

    $productId = isset($item['product_id']) ? (int) $item['product_id'] : 0;
    if ($productId <= 0) {
        return null;
    }

    $product = getProductById($productId);
    if ($product === null) {
        return null;
    }

    $size = trim((string) ($item['size'] ?? ''));
    $sizes = getProductSizes($product);
    if (!empty($sizes)) {
        if ($size === '' || !in_array($size, $sizes, true)) {
            return null;
        }
    } else {
        $size = '';
    }

    return [
        'product_id' => $productId,
        'product_name' => $product['name'],
        'size' => $size,
        'availability_label' => $size !== '' ? getAvailabilityLabel($product, $size) : '',
        'is_processed' => !empty($item['is_processed']),
    ];
}

function normalizeOrderItems($items) {
    $normalized = [];
    $seen = [];

    if (!is_array($items)) {
        return [];
    }

    foreach ($items as $item) {
        $record = normalizeOrderItem($item);
        if ($record === null) {
            continue;
        }

        $key = $record['product_id'] . '|' . $record['size'];
        if (isset($seen[$key])) {
            continue;
        }

        $seen[$key] = true;
        $normalized[] = $record;
    }

    return array_values($normalized);
}

function getOrders() {
    $data = readJsonFile(ORDERS_FILE);
    $orders = isset($data['orders']) && is_array($data['orders']) ? $data['orders'] : [];
    $normalized = [];

    foreach ($orders as $order) {
        $record = normalizeOrderRecord($order);
        if ($record !== null) {
            $normalized[] = $record;
        }
    }

    return $normalized;
}

function saveOrders($orders) {
    $normalized = [];
    foreach ($orders as $order) {
        $record = normalizeOrderRecord($order);
        if ($record !== null) {
            $normalized[] = $record;
        }
    }

    writeJsonFile(ORDERS_FILE, ['orders' => array_values($normalized)]);
}

function generateOrderId() {
    $orders = getOrders();
    $year = date('Y');
    $prefix = defined('ORDER_PREFIX') ? ORDER_PREFIX : 'ORD';
    $max = 0;
    $pattern = '/^' . preg_quote($prefix, '/') . '-\d{4}-(\d+)$/';

    foreach ($orders as $order) {
        if (preg_match($pattern, (string) $order['id'], $matches) === 1) {
            $number = (int) $matches[1];
            if ($number > $max) {
                $max = $number;
            }
        }
    }

    return sprintf('%s-%s-%03d', $prefix, $year, $max + 1);
}

function normalizeOrderRecord($order) {
    if (!is_array($order)) {
        return null;
    }

    $id = trim((string) ($order['id'] ?? ''));
    $customerName = trim((string) ($order['customer_name'] ?? ''));
    $customerEmail = normalizeAdminEmail($order['customer_email'] ?? '');
    $organizationId = normalizeOrganizationId($order['organization_id'] ?? '');
    $organizationLabel = trim((string) ($order['organization_label'] ?? ''));
    $items = normalizeOrderItems($order['items'] ?? []);

    if ($id === '' || $customerName === '' || !isValidAdminEmail($customerEmail) || $organizationId === '' || $organizationLabel === '' || empty($items)) {
        return null;
    }

    $createdAt = trim((string) ($order['created_at'] ?? ''));
    if ($createdAt === '') {
        $createdAt = date('Y-m-d H:i:s');
    }

    $confirmationStatus = trim((string) ($order['confirmation_status'] ?? 'confirmed'));
    $allowedConfirmationStatuses = ['not_required', 'pending', 'confirmed', 'expired'];
    if (!in_array($confirmationStatus, $allowedConfirmationStatuses, true)) {
        $confirmationStatus = 'confirmed';
    }

    $status = trim((string) ($order['status'] ?? 'open'));
    $allowedStatuses = ['open', 'partial', 'processed', 'cancelled'];
    if (!in_array($status, $allowedStatuses, true)) {
        $status = 'open';
    }

    $normalized = [
        'id' => $id,
        'customer_name' => $customerName,
        'customer_email' => $customerEmail,
        'organization_id' => $organizationId,
        'organization_label' => $organizationLabel,
        'comment' => trim((string) ($order['comment'] ?? '')),
        'items' => $items,
        'status' => $status,
        'confirmation_status' => $confirmationStatus,
        'confirmation_token' => trim((string) ($order['confirmation_token'] ?? '')),
        'confirmation_expires_at' => trim((string) ($order['confirmation_expires_at'] ?? '')),
        'confirmed_at' => trim((string) ($order['confirmed_at'] ?? '')),
        'created_at' => $createdAt,
        'updated_at' => trim((string) ($order['updated_at'] ?? $createdAt)),
        'cancelled_at' => trim((string) ($order['cancelled_at'] ?? '')),
        'cancelled_by' => trim((string) ($order['cancelled_by'] ?? '')),
        'cancellation_reason' => trim((string) ($order['cancellation_reason'] ?? '')),
        'admin_notified_at' => trim((string) ($order['admin_notified_at'] ?? '')),
    ];

    return refreshOrderState($normalized);
}

function refreshOrderState($order) {
    if (!is_array($order)) {
        return null;
    }

    if (($order['status'] ?? '') === 'cancelled') {
        return $order;
    }

    if (($order['confirmation_status'] ?? '') === 'pending' && !empty($order['confirmation_expires_at'])) {
        $expiresAt = strtotime((string) $order['confirmation_expires_at']);
        if ($expiresAt !== false && time() > $expiresAt) {
            $order['confirmation_status'] = 'expired';
        }
    }

    $processedCount = 0;
    foreach ($order['items'] as $item) {
        if (!empty($item['is_processed'])) {
            $processedCount++;
        }
    }

    if ($processedCount <= 0) {
        $order['status'] = 'open';
    } elseif ($processedCount >= count($order['items'])) {
        $order['status'] = 'processed';
    } else {
        $order['status'] = 'partial';
    }

    return $order;
}

function expirePendingOrders() {
    $orders = getOrders();
    $changed = false;

    foreach ($orders as &$order) {
        $updated = refreshOrderState($order);
        if ($updated !== $order) {
            $order = $updated;
            $changed = true;
        }
    }
    unset($order);

    if ($changed) {
        saveOrders($orders);
    }
}

function getOrderById($orderId) {
    $orderId = trim((string) $orderId);
    if ($orderId === '') {
        return null;
    }

    foreach (getOrders() as $order) {
        if ($order['id'] === $orderId) {
            return $order;
        }
    }

    return null;
}

function findOrderByConfirmationToken($token) {
    $token = trim((string) $token);
    if ($token === '') {
        return null;
    }

    foreach (getOrders() as $order) {
        if (($order['confirmation_token'] ?? '') === $token) {
            return $order;
        }
    }

    return null;
}

function buildOrderConfirmationUrl($token) {
    $path = '/order-confirm.php?token=' . urlencode($token);
    return buildAbsoluteUrl($path);
}

function buildAbsoluteUrl($path) {
    $path = '/' . ltrim((string) $path, '/');
    $siteUrl = defined('SITE_URL') ? trim((string) SITE_URL) : '';

    if (strpos($siteUrl, '://') !== false) {
        return rtrim($siteUrl, '/') . $path;
    }

    $basePath = trim($siteUrl);
    if ($basePath !== '' && $basePath !== '/') {
        $path = '/' . trim($basePath, '/') . $path;
    }

    $scheme = isHttpsRequest() ? 'https' : 'http';
    $host = $_SERVER['HTTP_HOST'] ?? '';
    if ($host === '') {
        return $path;
    }

    return $scheme . '://' . $host . $path;
}

function isHttpsRequest(): bool {
    if (!empty($_SERVER['HTTPS']) && strtolower((string) $_SERVER['HTTPS']) !== 'off') {
        return true;
    }
    if (!empty($_SERVER['HTTP_X_FORWARDED_PROTO']) && strtolower((string) $_SERVER['HTTP_X_FORWARDED_PROTO']) === 'https') {
        return true;
    }
    if (!empty($_SERVER['SERVER_PORT']) && (int) $_SERVER['SERVER_PORT'] === 443) {
        return true;
    }
    return false;
}

function createOrder($customerName, $customerEmail, $organizationId, $comment, $items) {
    $customerName = sanitize($customerName);
    $customerEmail = normalizeAdminEmail($customerEmail);
    $organizationId = normalizeOrganizationId($organizationId);
    $comment = trim((string) $comment);
    $items = normalizeOrderItems($items);

    if ($customerName === '') {
        return ['success' => false, 'message' => 'Bitte geben Sie einen Namen ein.'];
    }
    if (!isValidAdminEmail($customerEmail)) {
        return ['success' => false, 'message' => 'Bitte geben Sie eine gültige E-Mail-Adresse ein.'];
    }
    if (empty($items)) {
        return ['success' => false, 'message' => 'Der Warenkorb ist leer oder enthält ungültige Positionen.'];
    }

    $organization = getOrganizationById($organizationId);
    if ($organization === null || empty($organization['active'])) {
        return ['success' => false, 'message' => 'Bitte wählen Sie eine gültige Organisation aus.'];
    }

    $now = date('Y-m-d H:i:s');
    $requiresConfirmation = isOrderConfirmationRequired();
    $confirmationToken = $requiresConfirmation ? bin2hex(random_bytes(24)) : '';
    $confirmationExpiresAt = '';
    if ($requiresConfirmation) {
        $expires = new DateTimeImmutable();
        $expires = $expires->modify('+' . getOrderConfirmationExpiryDays() . ' days');
        $confirmationExpiresAt = $expires->format('Y-m-d H:i:s');
    }

    $order = [
        'id' => generateOrderId(),
        'customer_name' => $customerName,
        'customer_email' => $customerEmail,
        'organization_id' => $organization['id'],
        'organization_label' => $organization['label'],
        'comment' => $comment,
        'items' => $items,
        'status' => 'open',
        'confirmation_status' => $requiresConfirmation ? 'pending' : 'not_required',
        'confirmation_token' => $confirmationToken,
        'confirmation_expires_at' => $confirmationExpiresAt,
        'confirmed_at' => $requiresConfirmation ? '' : $now,
        'created_at' => $now,
        'updated_at' => $now,
        'cancelled_at' => '',
        'cancelled_by' => '',
        'cancellation_reason' => '',
        'admin_notified_at' => '',
    ];

    $orders = getOrders();
    $orders[] = $order;
    saveOrders($orders);

    if ($requiresConfirmation) {
        sendOrderConfirmationRequestEmail($order);
    } else {
        $result = sendConfirmedOrderAdminNotification($order);
        if ($result) {
            markOrderAdminNotified($order['id']);
            $order = getOrderById($order['id']);
        }
        sendOrderCreatedCustomerEmail($order);
    }

    return ['success' => true, 'order' => $order];
}

function markOrderAdminNotified($orderId) {
    $orders = getOrders();
    foreach ($orders as &$order) {
        if ($order['id'] !== $orderId) {
            continue;
        }

        $order['admin_notified_at'] = date('Y-m-d H:i:s');
        $order['updated_at'] = date('Y-m-d H:i:s');
        break;
    }
    unset($order);

    saveOrders($orders);
}

function confirmOrderByToken($token) {
    $orders = getOrders();
    $now = date('Y-m-d H:i:s');

    foreach ($orders as &$order) {
        if (($order['confirmation_token'] ?? '') !== $token) {
            continue;
        }

        $order = refreshOrderState($order);

        if ($order['status'] === 'cancelled') {
            return ['success' => false, 'message' => 'Diese Bestellung wurde storniert und kann nicht mehr bestätigt werden.'];
        }
        if ($order['confirmation_status'] === 'confirmed') {
            return ['success' => false, 'message' => 'Diese Bestellung wurde bereits bestätigt.'];
        }
        if ($order['confirmation_status'] === 'expired') {
            return ['success' => false, 'message' => 'Der Bestätigungslink ist abgelaufen.'];
        }
        if ($order['confirmation_status'] !== 'pending') {
            return ['success' => false, 'message' => 'Für diese Bestellung ist keine Bestätigung erforderlich.'];
        }

        $expiresAt = strtotime((string) $order['confirmation_expires_at']);
        if ($expiresAt !== false && time() > $expiresAt) {
            $order['confirmation_status'] = 'expired';
            $order['updated_at'] = $now;
            saveOrders($orders);
            return ['success' => false, 'message' => 'Der Bestätigungslink ist abgelaufen.'];
        }

        $order['confirmation_status'] = 'confirmed';
        $order['confirmed_at'] = $now;
        $order['updated_at'] = $now;
        saveOrders($orders);

        $sent = sendConfirmedOrderAdminNotification($order);
        if ($sent) {
            markOrderAdminNotified($order['id']);
        }
        sendOrderConfirmedCustomerEmail(getOrderById($order['id']));

        return ['success' => true, 'order' => getOrderById($order['id'])];
    }
    unset($order);

    return ['success' => false, 'message' => 'Bestellung nicht gefunden.'];
}

function toggleOrderItemProcessed($orderId, $itemIndex) {
    $orders = getOrders();
    $now = date('Y-m-d H:i:s');

    foreach ($orders as &$order) {
        if ($order['id'] !== $orderId) {
            continue;
        }

        if ($order['status'] === 'cancelled') {
            return ['success' => false, 'message' => 'Stornierte Bestellungen können nicht mehr bearbeitet werden.'];
        }
        if (($order['confirmation_status'] ?? '') === 'pending') {
            return ['success' => false, 'message' => 'Unbestätigte Bestellungen können noch nicht bearbeitet werden.'];
        }
        if (($order['confirmation_status'] ?? '') === 'expired') {
            return ['success' => false, 'message' => 'Abgelaufene unbestätigte Bestellungen können nicht bearbeitet werden.'];
        }
        if (!isset($order['items'][$itemIndex])) {
            return ['success' => false, 'message' => 'Position nicht gefunden.'];
        }

        $order['items'][$itemIndex]['is_processed'] = empty($order['items'][$itemIndex]['is_processed']);
        $order['updated_at'] = $now;
        $order = refreshOrderState($order);
        saveOrders($orders);

        return ['success' => true, 'order' => $order];
    }
    unset($order);

    return ['success' => false, 'message' => 'Bestellung nicht gefunden.'];
}

function cancelOrder($orderId, $adminUsername, $reason = '') {
    $orders = getOrders();
    $now = date('Y-m-d H:i:s');
    $adminUsername = normalizeAdminUsername($adminUsername);
    $reason = trim((string) $reason);

    foreach ($orders as &$order) {
        if ($order['id'] !== $orderId) {
            continue;
        }

        if ($order['status'] === 'cancelled') {
            return ['success' => false, 'message' => 'Die Bestellung ist bereits storniert.'];
        }

        $order['status'] = 'cancelled';
        $order['cancelled_at'] = $now;
        $order['cancelled_by'] = $adminUsername;
        $order['cancellation_reason'] = $reason;
        $order['updated_at'] = $now;
        saveOrders($orders);

        return ['success' => true, 'order' => $order];
    }
    unset($order);

    return ['success' => false, 'message' => 'Bestellung nicht gefunden.'];
}

function getOrderStatusLabel($order) {
    if (($order['status'] ?? '') === 'cancelled') {
        return 'Storniert';
    }
    if (($order['confirmation_status'] ?? '') === 'pending') {
        return 'Unbestätigt';
    }
    if (($order['confirmation_status'] ?? '') === 'expired') {
        return 'Bestätigung abgelaufen';
    }
    if (($order['status'] ?? '') === 'processed') {
        return 'Bearbeitet';
    }
    if (($order['status'] ?? '') === 'partial') {
        return 'Teilweise bearbeitet';
    }
    return 'Offen';
}

function getOrderStatusClass($order) {
    if (($order['status'] ?? '') === 'cancelled') {
        return 'status-cancelled';
    }
    if (($order['confirmation_status'] ?? '') === 'pending') {
        return 'status-unconfirmed';
    }
    if (($order['confirmation_status'] ?? '') === 'expired') {
        return 'status-expired';
    }
    if (($order['status'] ?? '') === 'processed') {
        return 'status-processed';
    }
    if (($order['status'] ?? '') === 'partial') {
        return 'status-partial';
    }
    return 'status-open';
}

function formatDate($dateString) {
    $dateString = trim((string) $dateString);
    if ($dateString === '') {
        return '-';
    }

    try {
        $date = new DateTimeImmutable($dateString);
        return $date->format('d.m.Y H:i');
    } catch (Exception $exception) {
        return $dateString;
    }
}

function getCart() {
    $cart = $_SESSION['cart'] ?? [];
    if (!is_array($cart)) {
        $cart = [];
    }

    $normalized = [];

    foreach ($cart as $item) {
        $productId = isset($item['product_id']) ? (int) $item['product_id'] : 0;
        $size = trim((string) ($item['size'] ?? ''));
        $product = getProductById($productId);
        if ($product === null) {
            continue;
        }

        $sizes = getProductSizes($product);
        if (!empty($sizes)) {
            if ($size === '' || !in_array($size, $sizes, true)) {
                continue;
            }
        } else {
            $size = '';
        }

        if (isset($normalized[$productId])) {
            unset($normalized[$productId]);
        }

        $normalized[$productId] = [
            'product_id' => $productId,
            'size' => $size,
        ];
    }

    $_SESSION['cart'] = array_values($normalized);
    return $_SESSION['cart'];
}

function addCartItem($productId, $size = '') {
    $productId = (int) $productId;
    $size = trim((string) $size);
    $product = getProductById($productId);
    if ($product === null) {
        return [
            'success' => false,
            'status' => 'error',
        ];
    }

    $sizes = getProductSizes($product);
    if (!empty($sizes)) {
        if ($size === '' || !in_array($size, $sizes, true)) {
            return [
                'success' => false,
                'status' => 'error',
            ];
        }
    } else {
        $size = '';
    }

    $cart = getCart();
    foreach ($cart as $index => $item) {
        if ((int) $item['product_id'] !== $productId) {
            continue;
        }

        $existingSize = trim((string) ($item['size'] ?? ''));
        if ($existingSize === $size) {
            return [
                'success' => true,
                'status' => 'unchanged',
                'size' => $size,
            ];
        }

        $cart[$index]['size'] = $size;
        $_SESSION['cart'] = array_values($cart);

        return [
            'success' => true,
            'status' => 'replaced',
            'size' => $size,
            'previous_size' => $existingSize,
        ];
    }

    $cart[] = [
        'product_id' => $productId,
        'size' => $size,
    ];

    $_SESSION['cart'] = array_values($cart);
    return [
        'success' => true,
        'status' => 'added',
        'size' => $size,
    ];
}

function removeCartItemByIndex($index) {
    $cart = getCart();
    if (isset($cart[$index])) {
        unset($cart[$index]);
        $_SESSION['cart'] = array_values($cart);
    }
}

function clearCart() {
    $_SESSION['cart'] = [];
}

function getCartItemsDetailed() {
    $items = [];
    foreach (getCart() as $index => $cartItem) {
        $product = getProductById($cartItem['product_id']);
        if ($product === null) {
            continue;
        }

        $size = trim((string) ($cartItem['size'] ?? ''));
        $items[] = [
            'cart_index' => $index,
            'product' => $product,
            'size' => $size,
            'availability_label' => $size !== '' ? getAvailabilityLabel($product, $size) : '',
        ];
    }

    return $items;
}

function buildOrderItemsFromCart() {
    $items = [];
    foreach (getCart() as $cartItem) {
        $product = getProductById($cartItem['product_id']);
        if ($product === null) {
            continue;
        }

        $size = trim((string) ($cartItem['size'] ?? ''));
        $items[] = [
            'product_id' => $product['id'],
            'size' => $size,
            'is_processed' => false,
        ];
    }

    return normalizeOrderItems($items);
}

function buildOrderItemsHtml($order) {
    $parts = [];
    foreach ($order['items'] as $item) {
        $label = '<strong>' . escape($item['product_name']) . '</strong>';
        if ($item['size'] !== '') {
            $label .= ' - Größe: ' . escape($item['size']);
        }
        if (!empty($item['availability_label'])) {
            $label .= '<br><small>' . nl2br(escape($item['availability_label'])) . '</small>';
        }
        $parts[] = '<li style="margin: 0 0 0.75rem 0; padding: 0.9rem 1rem; background: #f8f4e7; border: 1px solid #d7ceb5; border-radius: 18px; color: #111111;">' . $label . '</li>';
    }

    return '<ul style="list-style: none; margin: 0; padding: 0;">' . implode('', $parts) . '</ul>';
}

function buildOrderSummaryHtml($order, $title, $introHtml, $extraHtml = '') {
    $itemsHtml = buildOrderItemsHtml($order);

    return '
    <html>
    <head>
        <meta charset="UTF-8">
    </head>
    <body style="font-family: \'Freising Sans\', Arial, sans-serif; line-height: 1.6; color: #111111; background: #f4efe1; padding: 1.5rem;">
        <div style="max-width: 720px; margin: 0 auto; background: #ffffff; padding: 2rem; border-radius: 28px; border: 1px solid #d7ceb5; box-shadow: 0 18px 40px rgba(16, 16, 16, 0.08);">
            <p style="margin: 0 0 0.5rem; font-size: 0.8rem; letter-spacing: 0.08em; text-transform: uppercase; color: #5e5a4d;">' . escape(SITE_DEPARTMENT_NAME) . '</p>
            <h1 style="margin: 0; font-size: 1.75rem; line-height: 1.2; color: #111111;">' . escape(SITE_NAME) . '</h1>
            <p style="margin: 0.25rem 0 1.5rem; font-size: 1rem; color: #5e5a4d;">' . escape(SITE_SERVICE_HEADER) . '</p>
            <div style="width: 80px; height: 6px; border-radius: 999px; background: #ffd71c; margin-bottom: 1.5rem;"></div>
            <h2 style="color: #111111; margin-top: 0;">' . escape($title) . '</h2>
            ' . $introHtml . '
            <div style="background: #f8f4e7; border: 2px solid #ffd71c; padding: 1.5rem; margin: 1.5rem 0; border-radius: 20px;">
                <h3 style="margin-top: 0;">Bestellnummer</h3>
                <p style="margin: 0; color: #111111; font-family: monospace; font-size: 1.05rem;">' . escape($order['id']) . '</p>
            </div>
            <p><strong>Name:</strong> ' . escape($order['customer_name']) . '</p>
            <p><strong>E-Mail:</strong> ' . escape($order['customer_email']) . '</p>
            <p><strong>Organisation:</strong> ' . escape($order['organization_label']) . '</p>
            <p><strong>Erstellt am:</strong> ' . escape(formatDate($order['created_at'])) . '</p>
            <h3>Bestellte Artikel</h3>
            <div style="background: #fffdf6; border: 1px solid #d7ceb5; border-left: 6px solid #ffd71c; border-radius: 20px; padding: 1rem;">' . $itemsHtml . '</div>
            <p><strong>Kommentar:</strong><br>' . ($order['comment'] !== '' ? nl2br(escape($order['comment'])) : 'Kein Kommentar') . '</p>
            ' . $extraHtml . '
            <p style="margin: 2rem 0 0; color: #5e5a4d; font-size: 0.9rem;">' . escape(SITE_NAME) . ' | ' . escape(SITE_DEPARTMENT_NAME) . '<br>' . escape(SITE_ADDRESS_LINE) . '</p>
        </div>
    </body>
    </html>';
}

function sendOrderConfirmationRequestEmail($order) {
    $subject = SITE_SERVICE_NAME . ': Bestellung bestätigen - ' . $order['id'];
    $link = buildOrderConfirmationUrl($order['confirmation_token']);
    $expiryText = formatDate($order['confirmation_expires_at']);
    $intro = '<p>Guten Tag ' . escape($order['customer_name']) . ',</p><p>bitte bestätigen Sie Ihre Bestellung im ' . escape(SITE_SERVICE_NAME) . ' der Stadt Freising über den folgenden Link.</p>';
    $extra = '
        <p><a href="' . escape($link) . '" style="display: inline-block; padding: 0.75rem 1.5rem; background: #ffd71c; color: #111111; text-decoration: none; border: 2px solid #ffd71c; border-radius: 14px; font-weight: 700;">Bestellung bestätigen</a></p>
        <p>Der Link ist gültig bis: <strong>' . escape($expiryText) . '</strong></p>
        <p>Falls der Button nicht funktioniert, verwenden Sie bitte diesen Link:<br>' . escape($link) . '</p>';
    $message = buildOrderSummaryHtml($order, 'Bestellung bestätigen', $intro, $extra);

    return sendEmail($order['customer_email'], $subject, $message);
}

function sendOrderCreatedCustomerEmail($order) {
    $subject = SITE_SERVICE_NAME . ': Ihre Bestellung - ' . $order['id'];
    $intro = '<p>Guten Tag ' . escape($order['customer_name']) . ',</p><p>Ihre Bestellung wurde erfasst und an ' . escape(SITE_DEPARTMENT_NAME) . ' weitergeleitet.</p>';
    $message = buildOrderSummaryHtml($order, 'Bestellung eingegangen', $intro);

    return sendEmail($order['customer_email'], $subject, $message);
}

function sendOrderConfirmedCustomerEmail($order) {
    $subject = SITE_SERVICE_NAME . ': Bestellung bestätigt - ' . $order['id'];
    $intro = '<p>Guten Tag ' . escape($order['customer_name']) . ',</p><p>Ihre Bestellung wurde bestätigt und an ' . escape(SITE_DEPARTMENT_NAME) . ' weitergeleitet.</p>';
    $message = buildOrderSummaryHtml($order, 'Bestellung bestätigt', $intro);

    return sendEmail($order['customer_email'], $subject, $message);
}

function sendConfirmedOrderAdminNotification($order) {
    $recipient = getOrderRecipientEmail();
    if (!isValidAdminEmail($recipient)) {
        return false;
    }

    $subject = SITE_SERVICE_NAME . ': Neue Bestellung - ' . $order['id'];
    $intro = '<p>Eine neue Bestellung im ' . escape(SITE_SERVICE_NAME) . ' der Stadt Freising wurde freigegeben und muss bearbeitet werden.</p>';
    $message = buildOrderSummaryHtml($order, 'Neue PSA-Bestellung', $intro);

    $attachments = [];
    if (shouldAttachOrderPdfToAdminEmail()) {
        $attachments[] = [
            'filename' => 'bestellung-' . strtolower($order['id']) . '.pdf',
            'content_type' => 'application/pdf',
            'content' => generateOrderPdf($order),
        ];
    }

    return sendEmail($recipient, $subject, $message, true, $attachments);
}

function sendEmail($to, $subject, $message, $isHtml = true, $attachments = []) {
    $headers = [];
    $headers[] = 'From: ' . FROM_NAME . ' <' . FROM_EMAIL . '>';
    $headers[] = 'Reply-To: ' . FROM_EMAIL;
    $headers[] = 'X-Mailer: PHP/' . phpversion();

    if (empty($attachments)) {
        if ($isHtml) {
            $headers[] = 'MIME-Version: 1.0';
            $headers[] = 'Content-Type: text/html; charset=UTF-8';
        } else {
            $headers[] = 'Content-Type: text/plain; charset=UTF-8';
        }

        return mail($to, $subject, $message, implode("\r\n", $headers));
    }

    $boundary = '=_Boundary_' . bin2hex(random_bytes(8));
    $headers[] = 'MIME-Version: 1.0';
    $headers[] = 'Content-Type: multipart/mixed; boundary="' . $boundary . '"';

    $body = [];
    $body[] = '--' . $boundary;
    $body[] = 'Content-Type: ' . ($isHtml ? 'text/html' : 'text/plain') . '; charset=UTF-8';
    $body[] = 'Content-Transfer-Encoding: 8bit';
    $body[] = '';
    $body[] = $message;

    foreach ($attachments as $attachment) {
        if (!is_array($attachment)) {
            continue;
        }

        $filename = trim((string) ($attachment['filename'] ?? 'attachment.bin'));
        $contentType = trim((string) ($attachment['content_type'] ?? 'application/octet-stream'));
        $content = isset($attachment['content']) ? (string) $attachment['content'] : '';

        $body[] = '--' . $boundary;
        $body[] = 'Content-Type: ' . $contentType . '; name="' . $filename . '"';
        $body[] = 'Content-Transfer-Encoding: base64';
        $body[] = 'Content-Disposition: attachment; filename="' . $filename . '"';
        $body[] = '';
        $body[] = chunk_split(base64_encode($content));
    }

    $body[] = '--' . $boundary . '--';
    $body[] = '';

    return mail($to, $subject, implode("\r\n", $body), implode("\r\n", $headers));
}

function buildOrderPdfLines($order) {
    $lines = [
        SITE_FULL_NAME,
        SITE_DEPARTMENT_NAME,
        '',
        SITE_SERVICE_HEADER,
        'Bestellnummer: ' . $order['id'],
        'Erstellt am: ' . formatDate($order['created_at']),
        'Name: ' . $order['customer_name'],
        'E-Mail: ' . $order['customer_email'],
        'Organisation: ' . $order['organization_label'],
        '',
        'Artikel:',
    ];

    foreach ($order['items'] as $item) {
        $line = '- ' . $item['product_name'];
        if ($item['size'] !== '') {
            $line .= ' | Größe: ' . $item['size'];
        }
        if ($item['availability_label'] !== '') {
            $line .= ' | Hinweis: ' . preg_replace('/\s+/', ' ', $item['availability_label']);
        }
        $lines[] = $line;
    }

    $lines[] = '';
    $lines[] = 'Kommentar:';
    if ($order['comment'] !== '') {
        foreach (preg_split('/\r\n|\r|\n/', $order['comment']) as $commentLine) {
            $lines[] = $commentLine;
        }
    } else {
        $lines[] = 'Kein Kommentar';
    }

    return $lines;
}

function pdfEscapeText($text) {
    $text = str_replace('\\', '\\\\', $text);
    $text = str_replace('(', '\(', $text);
    $text = str_replace(')', '\)', $text);
    $text = str_replace("\r", '', $text);

    if (function_exists('iconv')) {
        $converted = @iconv('UTF-8', 'Windows-1252//TRANSLIT//IGNORE', $text);
        if (is_string($converted)) {
            $text = $converted;
        }
    }

    return $text;
}

function generateOrderPdf($order) {
    $lines = buildOrderPdfLines($order);
    $content = "BT\n/F1 12 Tf\n14 TL\n50 790 Td\n";
    $first = true;

    foreach ($lines as $line) {
        if (!$first) {
            $content .= "T*\n";
        }
        $first = false;
        $content .= '(' . pdfEscapeText($line) . ") Tj\n";
    }

    $content .= "ET";
    $length = strlen($content);

    $objects = [];
    $objects[] = "1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n";
    $objects[] = "2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n";
    $objects[] = "3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 595 842] /Contents 4 0 R /Resources << /Font << /F1 5 0 R >> >> >>\nendobj\n";
    $objects[] = "4 0 obj\n<< /Length " . $length . " >>\nstream\n" . $content . "\nendstream\nendobj\n";
    $objects[] = "5 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>\nendobj\n";

    $pdf = "%PDF-1.4\n";
    $offsets = [0];
    foreach ($objects as $object) {
        $offsets[] = strlen($pdf);
        $pdf .= $object;
    }

    $xrefOffset = strlen($pdf);
    $pdf .= "xref\n0 " . (count($objects) + 1) . "\n";
    $pdf .= "0000000000 65535 f \n";

    for ($i = 1; $i <= count($objects); $i++) {
        $pdf .= sprintf("%010d 00000 n \n", $offsets[$i]);
    }

    $pdf .= "trailer\n<< /Size " . (count($objects) + 1) . " /Root 1 0 R >>\n";
    $pdf .= "startxref\n" . $xrefOffset . "\n%%EOF";

    return $pdf;
}