export interface JwtPayload {
  exp?: number;
  iat?: number;
  [key: string]: any;
}

export function base64UrlDecode(value: string) {
  let base64 = value.replace(/-/g, '+').replace(/_/g, '/');
  while (base64.length % 4 !== 0) {
    base64 += '=';
  }
  try {
    return atob(base64);
  } catch {
    return '';
  }
}

export function parseJwt(token: string): JwtPayload | null {
  if (!token) return null;
  const parts = token.split('.');
  if (parts.length < 2) return null;
  try {
    const decoded = base64UrlDecode(parts[1]);
    if (!decoded) return null;
    return JSON.parse(decoded) as JwtPayload;
  } catch {
    return null;
  }
}

export function isTokenExpired(token: string): boolean {
  const payload = parseJwt(token);
  if (!payload || typeof payload.exp !== 'number') return true;
  return Math.floor(Date.now() / 1000) >= payload.exp;
}

export function clearAuthStorage() {
  if (typeof window !== 'undefined') {
    localStorage.removeItem('token');
    localStorage.removeItem('user');
    document.cookie = 'token=; path=/; expires=Thu, 01 Jan 1970 00:00:00 GMT';
  }
}