/** 데스크톱 메인↔위젯 창 상태 동기화 (localStorage) */
export const DESKTOP_SYNC_KEY = 'gc_desktop_sync';

export interface DesktopSyncState {
  selectedMarket?: string;
  selectedStrategyId?: number | null;
  theme?: string;
  updatedAt: number;
}

export function readDesktopSync(): DesktopSyncState | null {
  try {
    const raw = localStorage.getItem(DESKTOP_SYNC_KEY);
    if (!raw) return null;
    return JSON.parse(raw) as DesktopSyncState;
  } catch {
    return null;
  }
}

export function writeDesktopSync(partial: Omit<DesktopSyncState, 'updatedAt'>): void {
  const prev = readDesktopSync() ?? { updatedAt: 0 };
  const next: DesktopSyncState = {
    ...prev,
    ...partial,
    updatedAt: Date.now(),
  };
  try {
    localStorage.setItem(DESKTOP_SYNC_KEY, JSON.stringify(next));
  } catch {
    /* ignore */
  }
}

export function subscribeDesktopSync(cb: (state: DesktopSyncState) => void): () => void {
  const onStorage = (e: StorageEvent) => {
    if (e.key !== DESKTOP_SYNC_KEY) return;
    const state = readDesktopSync();
    if (state) cb(state);
  };
  window.addEventListener('storage', onStorage);
  return () => window.removeEventListener('storage', onStorage);
}