export class AppState {
  constructor(initialState = {}) {
    this._state = { ...initialState };
    this._listeners = new Set();
  }

  get(key) {
    return this._state[key];
  }

  getAll() {
    return { ...this._state };
  }

  set(patch) {
    this._state = { ...this._state, ...patch };
    for (const listener of this._listeners) {
      listener(this.getAll());
    }
  }

  subscribe(listener) {
    this._listeners.add(listener);
    return () => this._listeners.delete(listener);
  }
}