export interface JwtPayload {
  exp?: number;
  iat?: number;
  id?: number;
  email?: string;
  role?: string;
  [key: string]: unknown;
}

export function decodeToken(token: string | null): JwtPayload | null {
  if (!token) return null;
  const parts = token.split(".");
  if (parts.length !== 3) return null;
  try {
    const payload = parts[1].replace(/-/g, "+").replace(/_/g, "/");
    const padded = payload + "=".repeat((4 - (payload.length % 4)) % 4);
    const json =
      typeof atob === "function"
        ? atob(padded)
        : Buffer.from(padded, "base64").toString("utf8");
    return JSON.parse(json) as JwtPayload;
  } catch {
    return null;
  }
}

export function isTokenValid(token: string | null): boolean {
  const decoded = decodeToken(token);
  if (!decoded || !decoded.exp) return false;
  return decoded.exp * 1000 > Date.now();
}