export const CROSS_TAB_CHANNEL_NAME = 'hipctf.auth.v1';
export const CROSS_TAB_STORAGE_KEY = 'hipctf.auth.invalidate.v1';
export const CROSS_TAB_EVENT_TYPE = 'hipctf.session.invalidated';

export interface CrossTabInvalidationMessage {
  type: 'session-invalidated';
  origin: string;
  ts: number;
}

export function encodeInvalidationMessage(origin: string): CrossTabInvalidationMessage {
  return {
    type: 'session-invalidated',
    origin,
    ts: Date.now(),
  };
}

export function isCrossTabInvalidationMessage(
  value: unknown,
): value is CrossTabInvalidationMessage {
  if (!value || typeof value !== 'object') return false;
  const v = value as Record<string, unknown>;
  return (
    v['type'] === 'session-invalidated' &&
    typeof v['origin'] === 'string' &&
    typeof v['ts'] === 'number'
  );
}

export function isStorageInvalidationEvent(
  event: { key?: string | null; newValue?: string | null } | null | undefined,
): boolean {
  if (!event) return false;
  if (event.key !== CROSS_TAB_STORAGE_KEY) return false;
  if (event.newValue == null) return false;
  try {
    const parsed = JSON.parse(event.newValue) as unknown;
    return isCrossTabInvalidationMessage(parsed);
  } catch {
    return false;
  }
}