import type { CommandDispatcher } from "@commands/dispatcher";
import { createCommandDispatcher } from "@commands/dispatcher";
import type { CommandRegistry } from "@commands/registry";
import type { AppState } from "./state";

export type StateListener = (state: AppState) => void;

export type AppStore = {
  getState(): AppState;
  subscribe(listener: StateListener): () => void;
  dispatch: CommandDispatcher["dispatch"];
};

export function createAppStore(initialState: AppState, registry: CommandRegistry): AppStore {
  let state = initialState;
  const listeners = new Set<StateListener>();

  const emit = () => {
    for (const listener of listeners) listener(state);
  };

  const dispatcher = createCommandDispatcher({
    registry,
    getState: () => state,
    setState: (nextState) => {
      state = nextState;
      emit();
    },
  });

  return {
    getState: () => state,
    subscribe(listener) {
      listeners.add(listener);
      return () => listeners.delete(listener);
    },
    dispatch: dispatcher.dispatch,
  };
}