<?php
if (session_status() === PHP_SESSION_NONE) {
    session_start();
}

require_once __DIR__ . '/db.php';
require_once __DIR__ . '/functions.php';

function current_user(): ?array {
    if (empty($_SESSION['user_id'])) {
        return null;
    }
    static $cached = null;
    if ($cached && (int)$cached['id'] === (int)$_SESSION['user_id']) {
        return $cached;
    }
    $stmt = db()->prepare('SELECT * FROM users WHERE id = ? LIMIT 1');
    $stmt->execute([(int)$_SESSION['user_id']]);
    $user = $stmt->fetch();
    if (!$user) {
        logout_user();
        return null;
    }
    $cached = $user;
    return $cached;
}

function require_login(): array {
    $user = current_user();
    if (!$user) {
        header('Location: login.php');
        exit;
    }
    return $user;
}

function login_user(array $user): void {
    $_SESSION['user_id'] = (int)$user['id'];
    $_SESSION['last_ping_ts'] = time();
    db()->prepare('UPDATE users SET last_login_at = NOW(), last_seen_at = NOW() WHERE id = ?')->execute([(int)$user['id']]);
}

function logout_user(): void {
    $_SESSION = [];
    if (ini_get('session.use_cookies')) {
        $params = session_get_cookie_params();
        setcookie(session_name(), '', time() - 42000, $params['path'], $params['domain'], (bool)$params['secure'], (bool)$params['httponly']);
    }
    session_destroy();
}