<?php
/**
 * Authentication middleware and handlers
 */

/**
 * Check if role column exists in sales_users table
 * @param mysqli $db Database connection
 * @return bool
 */
function roleColumnExists(mysqli $db): bool
{
    static $exists = null;
    if ($exists === null) {
        $result = $db->query("SHOW COLUMNS FROM sales_users LIKE 'role'");
        $exists = ($result && $result->num_rows > 0);
        
        // If column doesn't exist, try to add it
        if (!$exists) {
            $db->query("ALTER TABLE sales_users ADD COLUMN role VARCHAR(50) DEFAULT 'agent'");
            $exists = true;
        }
    }
    return $exists;
}

/**
 * Handle login action
 * @param mysqli $db Database connection
 * @return void
 */
function handleLogin(mysqli $db): void
{
    $input = json_decode(file_get_contents('php://input'), true);
    $username = $input['username'] ?? '';
    
    // Check if role column exists and use appropriate query
    $hasRoleColumn = roleColumnExists($db);
    
    if ($hasRoleColumn) {
        $stmt = $db->prepare("SELECT password, full_name, role FROM sales_users WHERE username = ?");
    } else {
        $stmt = $db->prepare("SELECT password, full_name, 'agent' as role FROM sales_users WHERE username = ?");
    }
    $stmt->bind_param("s", $username);
    $stmt->execute();
    $res = $stmt->get_result()->fetch_assoc();

    if ($res && password_verify($input['password'], $res['password'])) {
        $_SESSION['user'] = $username;
        $_SESSION['full_name'] = $res['full_name'];
        $_SESSION['role'] = $res['role'] ?? 'agent';

        // Recovery cookie payload
        $cookie_payload = base64_encode(json_encode([
            'user' => $username,
            'full_name' => $res['full_name'],
            'role' => $res['role'] ?? 'agent',
            'expires' => MIDNIGHT_TIMESTAMP
        ]));
        
        setcookie('telvero_remember', $cookie_payload, MIDNIGHT_TIMESTAMP, '/', '', isset($_SERVER['HTTPS']), true);

        echo json_encode([
            'success' => true,
            'user' => $res['full_name'],
            'role' => $res['role'] ?? 'agent'
        ]);
    } else {
        http_response_code(401);
        echo json_encode(['error' => 'Login mislukt']);
    }
}

/**
 * Handle session check action
 * @return void
 */
function handleCheckSession(): void
{
    if (isset($_SESSION['user'])) {
        echo json_encode([
            'authenticated' => true,
            'user' => $_SESSION['full_name'] ?? $_SESSION['user'],
            'role' => $_SESSION['role'] ?? 'agent'
        ]);
    } else {
        echo json_encode(['authenticated' => false]);
    }
}

/**
 * Handle logout action
 * @return void
 */
function handleLogout(): void
{
    session_destroy();
    setcookie('telvero_remember', '', time() - 3600, '/');
    echo json_encode(['success' => true]);
}

/**
 * Check if user is authenticated
 * @return bool
 */
function isAuthenticated(): bool
{
    return isset($_SESSION['user']);
}

/**
 * Check if user has administrator role
 * @return bool
 */
function isAdmin(): bool
{
    return isset($_SESSION['role']) && $_SESSION['role'] === 'administrator';
}

/**
 * Get current user's role
 * @return string
 */
function getUserRole(): string
{
    return $_SESSION['role'] ?? 'agent';
}

/**
 * Get current username
 * @return string|null
 */
function getCurrentUsername(): ?string
{
    return $_SESSION['user'] ?? null;
}

/**
 * Require authentication - exits if not authenticated
 * @return void
 */
function requireAuth(): void
{
    if (!isAuthenticated()) {
        http_response_code(403);
        echo json_encode(['error' => 'Not authenticated']);
        exit;
    }
}

/**
 * Require administrator role - exits if not admin
 * Logs unauthorized access attempts
 * @param mysqli $db Database connection for logging
 * @param string $page The page being accessed
 * @return void
 */
function requireAdmin(mysqli $db, string $page): void
{
    if (!isAuthenticated()) {
        logUnauthorizedAccess($db, null, $page, 'not_authenticated');
        http_response_code(403);
        die("Toegang geweigerd. Log eerst in.");
    }
    
    if (!isAdmin()) {
        logUnauthorizedAccess($db, getCurrentUsername(), $page, 'insufficient_permissions');
        http_response_code(403);
        die("Toegang geweigerd. U heeft geen toegang tot deze pagina.");
    }
}

/**
 * Log unauthorized access attempt to the database
 * @param mysqli $db Database connection
 * @param string|null $username The username attempting access (null if not logged in)
 * @param string $page The page being accessed
 * @param string $reason The reason for denial
 * @return void
 */
function logUnauthorizedAccess(mysqli $db, ?string $username, string $page, string $reason): void
{
    $ip = $_SERVER['REMOTE_ADDR'] ?? 'unknown';
    $userAgent = $_SERVER['HTTP_USER_AGENT'] ?? 'unknown';
    $details = json_encode([
        'page' => $page,
        'reason' => $reason,
        'ip' => $ip,
        'user_agent' => $userAgent
    ]);
    
    $stmt = $db->prepare("INSERT INTO sales_logs (username, action_type, details, created_at) VALUES (?, 'unauthorized_access', ?, NOW())");
    $usernameForLog = $username ?? 'anonymous';
    $stmt->bind_param("ss", $usernameForLog, $details);
    $stmt->execute();
}