<?php
/**
 * Auth & session helper
 */

require_once __DIR__ . '/security-headers.php';
send_security_headers();

if (session_status() === PHP_SESSION_NONE) {
    // Configure secure session cookie defaults. 'secure' follows the
    // request scheme so local dev over plain HTTP (including the phone on
    // the LAN) can still log in; in production it's always HTTPS.
    session_set_cookie_params([
        'lifetime' => 86400 * 7, // 7 days
        'path' => '/',
        'secure' => request_is_https(),
        'httponly' => true,
        'samesite' => 'Lax'
    ]);
    session_start();
}

require_once __DIR__ . '/db.php';

function is_authenticated(): bool {
    return !empty($_SESSION['admin_user_id']);
}

function require_auth(): void {
    if (!is_authenticated()) {
        header('Location: login.php');
        exit;
    }

    // A user disabled or re-roled mid-session should be affected
    // immediately rather than when their session expires — re-check against
    // the DB instead of trusting the session's now-possibly-stale copy.
    $pdo = get_db();
    $stmt = $pdo->prepare("SELECT is_enabled, role FROM users WHERE id = ?");
    $stmt->execute([$_SESSION['admin_user_id']]);
    $row = $stmt->fetch();
    if ($row === false || (int) $row['is_enabled'] !== 1) {
        logout_user();
        header('Location: login.php');
        exit;
    }
    $_SESSION['admin_role'] = $row['role'];
}

/**
 * Like require_auth(), but also requires a specific role. Checked against
 * the role require_auth() just re-read from the DB, not the login-time copy.
 */
function require_role(string $role): void {
    require_auth();
    if (($_SESSION['admin_role'] ?? '') !== $role) {
        http_response_code(403);
        exit('Forbidden');
    }
}

function get_logged_in_user(): ?array {
    if (!is_authenticated()) {
        return null;
    }
    return [
        'id' => $_SESSION['admin_user_id'],
        'username' => $_SESSION['admin_username'] ?? 'admin',
        'role' => $_SESSION['admin_role'] ?? 'admin'
    ];
}

function authenticate_user(string $username, string $password): bool {
    $pdo = get_db();
    $stmt = $pdo->prepare("SELECT * FROM users WHERE username = ?");
    $stmt->execute([trim($username)]);
    $user = $stmt->fetch();

    if ($user && (int) $user['is_enabled'] === 1 && password_verify($password, $user['password_hash'])) {
        session_regenerate_id(true);
        $_SESSION['admin_user_id'] = $user['id'];
        $_SESSION['admin_username'] = $user['username'];
        $_SESSION['admin_role'] = $user['role'];
        return true;
    }

    return false;
}

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"],
            $params["secure"], $params["httponly"]
        );
    }
    session_destroy();
}

function get_csrf_token(): string {
    if (empty($_SESSION['csrf_token'])) {
        $_SESSION['csrf_token'] = bin2hex(random_bytes(32));
    }
    return $_SESSION['csrf_token'];
}

function verify_csrf_token(?string $token): bool {
    if (empty($_SESSION['csrf_token']) || empty($token)) {
        return false;
    }
    return hash_equals($_SESSION['csrf_token'], $token);
}