export const AUTH_TOKEN_KEY = "authToken";
const LEGACY_AUTH_TOKEN_KEY = "googleIdToken";

export function getAuthToken(): string | null {
  const current = window.localStorage.getItem(AUTH_TOKEN_KEY);
  if (current) return current;

  // Backward compat for older builds that stored Google ID tokens under a different key.
  const legacy = window.localStorage.getItem(LEGACY_AUTH_TOKEN_KEY);
  if (legacy) {
    window.localStorage.setItem(AUTH_TOKEN_KEY, legacy);
    window.localStorage.removeItem(LEGACY_AUTH_TOKEN_KEY);
    return legacy;
  }

  return null;
}

export function setAuthToken(token: string) {
  window.localStorage.setItem(AUTH_TOKEN_KEY, token);
}

export function clearAuthToken() {
  window.localStorage.removeItem(AUTH_TOKEN_KEY);
}

export function decodeJwtPayload(token: string): any {
  try {
    const parts = token.split(".");
    if (parts.length < 2) return null;
    const base64 = parts[1].replaceAll("-", "+").replaceAll("_", "/");
    const json = atob(base64);
    return JSON.parse(json);
  } catch {
    return null;
  }
}