export const AUTH_TOKEN_KEY = "authToken";
export const AUTH_USER_KEY = "authUser";

function decodeJwtPayload(token) {
  try {
    const parts = token.split(".");
    if (parts.length < 2) return null;
    const base64 = parts[1].replace(/-/g, "+").replace(/_/g, "/");
    const normalized = base64.padEnd(Math.ceil(base64.length / 4) * 4, "=");
    const json = atob(normalized);
    return JSON.parse(json);
  } catch {
    return null;
  }
}

export function isTokenExpired(token) {
  if (!token) return true;
  const payload = decodeJwtPayload(token);
  if (!payload || typeof payload.exp !== "number") return true;
  return payload.exp * 1000 <= Date.now();
}

export function getAuthToken() {
  return localStorage.getItem(AUTH_TOKEN_KEY);
}

export function clearAuthSession() {
  localStorage.removeItem(AUTH_TOKEN_KEY);
  localStorage.removeItem(AUTH_USER_KEY);
}

export function logoutAndRedirect(path = "/dashboard") {
  clearAuthSession();
  window.location.assign(path);
}