<?php
// Function to fetch company settings from DB
function get_company_settings() {
    static $settings = null;
    if ($settings === null) {
        try {
            if (function_exists('db')) {
                $pdo = db();
                $stmt = $pdo->query("SELECT * FROM company_settings LIMIT 1");
                $settings = $stmt->fetch(PDO::FETCH_ASSOC);
            }
        } catch (Exception $e) {
            // Log error or ignore if table doesn't exist yet
        }
        
        // Default values if no settings found
        if (!$settings) {
            $settings = [
                'company_name' => 'My Restaurant',
                'address' => '123 Food Street',
                'phone' => '555-0199',
                'email' => 'info@restaurant.com',
                'vat_rate' => 0.00,
                'currency_symbol' => '$',
                'currency_decimals' => 2,
                'currency_position' => 'before'
            ];
        }
    }
    return $settings;
}

// Function to format currency using settings
function format_currency($amount) {
    $settings = get_company_settings();
    $symbol = $settings['currency_symbol'] ?? '$';
    $decimals = (int)($settings['currency_decimals'] ?? 2);
    $position = $settings['currency_position'] ?? 'before';
    
    $formatted_number = number_format((float)$amount, $decimals);
    
    if ($position === 'after') {
        return $formatted_number . ' ' . $symbol;
    } else {
        return $symbol . $formatted_number;
    }
}

/**
 * Calculate the current price of a product considering promotions.
 * 
 * @param array|object $product The product data from DB.
 * @return float The effective price.
 */
function get_product_price($product) {
    $product = (array)$product;
    $price = (float)$product['price'];
    
    $today = date('Y-m-d');
    $promo_active = !empty($product['promo_discount_percent']) && 
                   !empty($product['promo_date_from']) && 
                   !empty($product['promo_date_to']) && 
                   $today >= $product['promo_date_from'] && 
                   $today <= $product['promo_date_to'];
                   
    if ($promo_active) {
        $discount = $price * ((float)$product['promo_discount_percent'] / 100);
        $price -= $discount;
    }
    
    return $price;
}

/**
 * Paginate a query result. 
 * 
 * @param PDO $pdo The PDO connection object.
 * @param string $query The base SQL query (without LIMIT/OFFSET).
 * @param array $params Query parameters.
 * @param int $default_limit Default items per page.
 * @return array Pagination result with keys: data, total_rows, total_pages, current_page, limit.
 */
function paginate_query($pdo, $query, $params = [], $default_limit = 20) {
    // Get current page
    $page = isset($_GET['page']) && is_numeric($_GET['page']) ? (int)$_GET['page'] : 1;
    if ($page < 1) $page = 1;

    // Get limit (allow 20, 50, 100, or -1 for all)
    $limit = isset($_GET['limit']) ? (int)$_GET['limit'] : $default_limit;
    // Validate limit
    if ($limit != -1 && !in_array($limit, [20, 50, 100])) {
         $limit = $default_limit; 
    }
    
    // If limit is -1, fetch all
    if ($limit == -1) {
         try {
             $stmt = $pdo->prepare($query);
             $stmt->execute($params);
             $data = $stmt->fetchAll();
             return [
                 'data' => $data,
                 'total_rows' => count($data),
                 'total_pages' => 1,
                 'current_page' => 1,
                 'limit' => -1
             ];
         } catch (PDOException $e) {
             die("Pagination Query Error (All): " . $e->getMessage() . "\nQuery: " . $query);
         }
    }

    // Count total rows using a subquery to handle complex queries safely
    // Strip ORDER BY from the query for the count to avoid SQL errors and improve performance
    // Use a more robust regex that handles potential trailing semicolons or whitespace
    $count_query = preg_replace('/ORDER\s+BY.*?(?=;|$)/is', '', $query);
    $count_sql = "SELECT COUNT(*) FROM ($count_query) as count_table";
    
    try {
        $stmt = $pdo->prepare($count_sql);
        $stmt->execute($params);
        $total_rows = $stmt->fetchColumn();
    } catch (PDOException $e) {
        // If stripping ORDER BY failed or caused issues, try with the original query in subquery
        try {
            $count_sql_fallback = "SELECT COUNT(*) FROM ($query) as count_table";
            $stmt = $pdo->prepare($count_sql_fallback);
            $stmt->execute($params);
            $total_rows = $stmt->fetchColumn();
        } catch (PDOException $e2) {
            die("Pagination Count Error: " . $e2->getMessage() . "\nSQL: " . $count_sql);
        }
    }
    
    $total_pages = ceil($total_rows / $limit);
    if ($page > $total_pages && $total_pages > 0) $page = $total_pages;
    
    // Calculate offset
    $offset = ($page - 1) * $limit;
    if ($offset < 0) $offset = 0;
    
    // Add LIMIT and OFFSET
    $query_with_limit = $query . " LIMIT " . (int)$limit . " OFFSET " . (int)$offset;
    
    try {
        $stmt = $pdo->prepare($query_with_limit);
        $stmt->execute($params);
        $data = $stmt->fetchAll();
    } catch (PDOException $e) {
        die("Pagination Data Error: " . $e->getMessage() . "\nSQL: " . $query_with_limit);
    }

    return [
        'data' => $data,
        'total_rows' => $total_rows,
        'total_pages' => $total_pages,
        'current_page' => $page,
        'limit' => $limit
    ];
}

/**
 * Render pagination controls and limit selector.
 * 
 * @param array $pagination The result array from paginate_query.
 * @param array $extra_params Additional GET parameters to preserve.
 */
function render_pagination_controls($pagination, $extra_params = []) {
    $page = $pagination['current_page'];
    $total_pages = $pagination['total_pages'];
    $limit = $pagination['limit'];
    
    // Build query string for limit change
    $params = array_merge($_GET, $extra_params);
    unset($params['page']); // Reset page when limit changes
    
    // Limit Selector
    $limits = [20, 50, 100, -1];
    echo '<div class="d-flex justify-content-between align-items-center mb-0 bg-white p-2 rounded flex-wrap gap-2">';
    
    echo '<div class="d-flex align-items-center flex-wrap gap-3">';
    echo '<form method="GET" class="d-flex align-items-center mb-0">';
    // Preserve other GET params
    foreach ($params as $key => $val) {
        if ($key !== 'limit') echo '<input type="hidden" name="'.htmlspecialchars((string)$key).'" value="'.htmlspecialchars((string)$val).'">';
    }
    echo '<small class="me-2 text-muted fw-bold">SHOW:</small>';
    echo '<select name="limit" class="form-select form-select-sm" style="width: auto;" onchange="this.form.submit()">';
    foreach ($limits as $l) {
        $label = $l == -1 ? 'All' : $l;
        $selected = $limit == $l ? 'selected' : '';
        echo "<option value='$l' $selected>$label</option>";
    }
    echo '</select>';
    echo '</form>';
    
    // Total Count
    echo '<span class="text-muted small border-start ps-3">Total: <strong>' . $pagination['total_rows'] . '</strong> items</span>';
    
    // Optional Total Amount (Sum)
    if (isset($pagination['total_amount_sum'])) {
        echo '<span class="text-success small border-start ps-3">Total Sum: <strong class="fs-5">' . format_currency($pagination['total_amount_sum']) . '</strong></span>';
    }

    if ($total_pages > 0) {
        echo '<span class="text-muted small border-start ps-3">Page <strong>' . $page . '</strong> of <strong>' . $total_pages . '</strong></span>';
    }
    echo '</div>';
    
    // Pagination Links
    if ($total_pages > 1) {
        echo '<nav aria-label="Page navigation">';
        echo '<ul class="pagination pagination-sm mb-0">';
        
        // Previous
        $prev_disabled = $page <= 1 ? 'disabled' : '';
        $prev_page = max(1, $page - 1);
        $url_params = array_merge($params, ['page' => $prev_page, 'limit' => $limit]);
        $prev_url = '?' . http_build_query($url_params);
        echo "<li class='page-item $prev_disabled'><a class='page-link' href='$prev_url' aria-label='Previous'><span aria-hidden='true'>&laquo;</span></a></li>";
        
        // Logic to show limited page numbers with ellipsis
        $shown_pages = [];
        $shown_pages[] = 1;
        $shown_pages[] = $total_pages;
        for ($i = $page - 3; $i <= $page + 3; $i++) {
            if ($i > 1 && $i < $total_pages) {
                $shown_pages[] = $i;
            }
        }
        sort($shown_pages);
        $shown_pages = array_unique($shown_pages);
        
        $prev_p = 0;
        foreach ($shown_pages as $p) {
            if ($prev_p > 0 && $p > $prev_p + 1) {
                echo "<li class='page-item disabled'><span class='page-link'>...</span></li>";
            }
            
            $active = $p == $page ? 'active' : '';
            $url_params = array_merge($params, ['page' => $p, 'limit' => $limit]);
            $url = '?' . http_build_query($url_params);
            echo "<li class='page-item $active'><a class='page-link' href='$url'>$p</a></li>";
            $prev_p = $p;
        }
        
        // Next
        $next_disabled = $page >= $total_pages ? 'disabled' : '';
        $next_page = min($total_pages, $page + 1);
        $url_params = array_merge($params, ['page' => $next_page, 'limit' => $limit]);
        $next_url = '?' . http_build_query($url_params);
        echo "<li class='page-item $next_disabled'><a class='page-link' href='$next_url' aria-label='Next'><span aria-hidden='true'>&raquo;</span></a></li>";
        
        echo '</ul></nav>';
    }
    echo '</div>';
}

/**
 * Get the project root URL
 */
function get_base_url() {
    $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') || ($_SERVER['SERVER_PORT'] ?? 80) == 443 || ($_SERVER['HTTP_X_FORWARDED_PROTO'] ?? "") === "https" ? "https://" : "http://";
    $host = $_SERVER['HTTP_HOST'] ?? 'localhost';
    
    $script = $_SERVER['SCRIPT_NAME'] ?? '/index.php';
    $path = dirname($script);
    $path = str_replace('\\', '/', $path); // Corrected escaping for backslash
    
    $subdirs = ['/admin', '/api', '/includes', '/db', '/mail', '/ai', '/assets'];
    foreach ($subdirs as $dir) {
        if ($path === $dir || str_ends_with($path, $dir)) {
            $path = substr($path, 0, -strlen($dir));
            break;
        }
    }
    
    if ($path === '' || $path === '.') $path = '/';
    return $protocol . $host . rtrim($path, '/') . '/';
}

if (!function_exists('str_ends_with')) {
    function str_ends_with($haystack, $needle) {
        $length = strlen($needle);
        if (!$length) return true;
        return substr($haystack, -$length) === $needle;
    }
}

/**
 * Initialize session with security and persistence improvements
 */
function init_session() {
    if (session_status() === PHP_SESSION_NONE) {
        // Set session lifetime to 1 week (604800 seconds)
        $lifetime = 604800;
        
        // Ensure gc_maxlifetime is at least as long as cookie lifetime
        ini_set('session.gc_maxlifetime', (string)$lifetime);
        
        // Set cookie parameters before session_start
        $isSecure = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') || ($_SERVER['SERVER_PORT'] ?? 80) == 443 || ($_SERVER['HTTP_X_FORWARDED_PROTO'] ?? "") === "https";
        
        session_set_cookie_params([
            'lifetime' => $lifetime,
            'path' => '/',
            'domain' => '',
            'secure' => $isSecure,
            'httponly' => true,
            'samesite' => 'Lax'
        ]);
        
        session_start();
    }
}

function login_user($username, $password) {
    $pdo = db();
    $stmt = $pdo->prepare("SELECT u.*, g.name as group_name, g.permissions 
                          FROM users u 
                          LEFT JOIN user_groups g ON u.group_id = g.id 
                          WHERE u.username = ? AND u.is_active = 1 
                          LIMIT 1");
    $stmt->execute([$username]);
    $user = $stmt->fetch(PDO::FETCH_ASSOC);

    if ($user && password_verify($password, $user['password'])) {
        init_session();
        unset($user['password']); // Don't store hash in session
        $_SESSION['user'] = $user;
        return true;
    }
    return false;
}

function logout_user() {
    init_session();
    unset($_SESSION['user']);
    session_destroy();
}

function get_logged_user() {
    init_session();
    return $_SESSION['user'] ?? null;
}

function require_login() {
    if (!get_logged_user()) {
        header('Location: ' . get_base_url() . 'login.php');
        exit;
    }
}

function has_permission($permission) {
    $user = get_logged_user();
    if (!$user) return false;

    // If permissions are missing from session (stale session), fetch from DB
    if (!isset($user['permissions'])) {
        $pdo = db();
        $stmt = $pdo->prepare("SELECT g.permissions FROM users u JOIN user_groups g ON u.group_id = g.id WHERE u.id = ?");
        $stmt->execute([$user['id']]);
        $perms = $stmt->fetchColumn();
        $_SESSION['user']['permissions'] = $perms;
        $user['permissions'] = $perms;
    }

    $userPerms = $user['permissions'] ?: '';
    
    // Admin has all permissions
    if ($userPerms === 'all') return true;
    
    $permissions = explode(',', $userPerms);
    $permissions = array_map('trim', $permissions); 
    
    return in_array('all', $permissions) || in_array($permission, $permissions);
}

function require_permission($permission) {
    require_login();
    if (!has_permission($permission)) {
        die("Access Denied: You do not have permission to view this page ($permission).");
    }
}

function get_user_outlets($userId) {
    $pdo = db();
    $stmt = $pdo->prepare("SELECT outlet_id FROM user_outlets WHERE user_id = ?");
    $stmt->execute([$userId]);
    return $stmt->fetchAll(PDO::FETCH_COLUMN);
}

function can_access_outlet($userId, $outletId) {
    if (has_permission('all')) return true;
    $outlets = get_user_outlets($userId);
    return in_array($outletId, $outlets);
}

function create_backup() {
    $backupDir = __DIR__ . '/../storage/backups/';
    if (!is_dir($backupDir)) {
        mkdir($backupDir, 0777, true);
    }
    
    $filename = 'backup_' . date('Y-m-d_H-i-s') . '.sql';
    $path = $backupDir . $filename;
    
    // We'll use the environment variables from db/config.php
    $command = sprintf(
        'mysqldump -h %s -u %s -p%s %s > %s',
        escapeshellarg(DB_HOST),
        escapeshellarg(DB_USER),
        escapeshellarg(DB_PASS),
        escapeshellarg(DB_NAME),
        escapeshellarg($path)
    );
    
    exec($command, $output, $returnVar);
    
    if ($returnVar === 0) {
        // Enforce retention: keep 5 latest
        $files = glob($backupDir . '/*.sql');
        if (count($files) > 5) {
            usort($files, function($a, $b) {
                return filemtime($a) - filemtime($b);
            });
            while (count($files) > 5) {
                $oldest = array_shift($files);
                unlink($oldest);
            }
        }
        return $filename;
    }
    return false;
}

/**
 * Trigger auto backup if enabled and 24h passed since last backup.
 * Optimized to prevent session locking and hang.
 */
function trigger_auto_backup() {
    $settings = get_company_settings();
    if (empty($settings['auto_backup_enabled'])) return;
    
    // Only Admin (with 'all' permission) should trigger backups to avoid overhead
    if (!has_permission('all')) return;
    
    $lastBackup = !empty($settings['last_auto_backup']) ? strtotime($settings['last_auto_backup']) : 0;
    $now = time();
    
    // Run once every 24 hours
    if ($now - $lastBackup > 86400) {
        // Release session lock before starting a potentially long-running backup
        if (session_status() === PHP_SESSION_ACTIVE) {
            session_write_close();
        }
        
        if (create_backup()) {
            $pdo = db();
            $stmt = $pdo->prepare("UPDATE company_settings SET last_auto_backup = NOW(), updated_at = NOW() LIMIT 1");
            $stmt->execute();
        } else {
            error_log("Auto backup failed at " . date('Y-m-d H:i:s'));
            $pdo = db();
            $stmt = $pdo->prepare("UPDATE company_settings SET last_auto_backup = NOW(), updated_at = NOW() LIMIT 1");
            $stmt->execute();
        }
    }
}