// Same vanilla store contract used by Zustand, without a React dependency on
// the dedicated server. Each arena operation restores its own saved state.
export function create<T>(initialize: (set: any, get: () => T, api: any) => T) {
  let state: T;
  const listeners = new Set<(state: T, previous: T) => void>();
  const api = {
    getState: () => state,
    setState(update: any, replace = false) {
      const previous = state;
      const patch = typeof update === "function" ? update(state) : update;
      state = replace ? patch : Object.assign({}, state, patch);
      if (state !== previous) for (const listener of listeners) listener(state, previous);
    },
    subscribe(listener: (state: T, previous: T) => void) { listeners.add(listener); return () => listeners.delete(listener); },
  };
  state = initialize(api.setState, api.getState, api);
  return api;
}