function createStore(reducer) {
  let state = reducer(undefined, {}); //стартовая инициализация состояния, запуск редьюсера со state === undefined
  let cbs = []; //массив подписчиков

  const getState = () => state; //функция, возвращающая переменную из замыкания
  const subscribe = (cb) => (
    cbs.push(cb), //запоминаем подписчиков в массиве
    () => (cbs = cbs.filter((c) => c !== cb))
  ); //возвращаем функцию unsubscribe, которая удаляет подписчика из списка

  const dispatch = (action) => {
    if (typeof action === "function") {
      //если action - не объект, а функция
      return action(dispatch, getState); //запускаем эту функцию и даем ей dispatch и getState для работы
    }
    const newState = reducer(state, action); //пробуем запустить редьюсер
    if (newState !== state) {
      //проверяем, смог ли редьюсер обработать action
      state = newState; //если смог, то обновляем state
      for (let cb of cbs) cb(); //и запускаем подписчиков
    }
  };

  return {
    getState, //добавление функции getState в результирующий объект
    dispatch,
    subscribe, //добавление subscribe в объект
  };
}

function promiseReducer(state = {}, { type, status, payload, error, name }) {
  if (type === "PROMISE") {
    return {
      ...state,
      [name]: { status, payload, error },
    };
  }
  return state;
}

const actionPending = (name) => ({ type: "PROMISE", status: "PENDING", name });
const actionResolved = (name, payload) => ({
  type: "PROMISE",
  status: "RESOLVED",
  name,
  payload,
});
const actionRejected = (name, error) => ({
  type: "PROMISE",
  status: "REJECTED",
  name,
  error,
});
const actionPromise = (name, promise) => async (dispatch) => {
  dispatch(actionPending(name));
  try {
    let data = await promise;
    dispatch(actionResolved(name, data));
    return data;
  } catch (error) {
    dispatch(actionRejected(name, error));
  }
};

const store = createStore(promiseReducer);
store.subscribe(() => console.log(store.getState()));

const delay = (ms) => new Promise((ok) => setTimeout(() => ok(ms), ms));

const getGQL =
  (url) =>
  async (query, variables = {}) => {
    let obj = await fetch(url, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        ...(localStorage.authToken
          ? { Authorization: "Bearer " + localStorage.authToken }
          : {}),
      },
      body: JSON.stringify({ query, variables }),
    });
    let a = await obj.json();
    if (!a.data && a.errors) throw new Error(JSON.stringify(a.errors));
    return a.data[Object.keys(a.data)[0]];
  };

const backURL = "http://shop-roles.asmer.fs.a-level.com.ua";

const gql = getGQL(backURL + "/graphql");

const actionRootCats = () =>
  actionPromise(
    "rootCats",
    gql(`query {
      CategoryFind(query: "[{\\"parent\\":null}]"){
          _id name
      }
  }`)
  );

const actionCatById = (_id) =>
  actionPromise(
    "catById",
    gql(
      `query catById($q: String){
      CategoryFindOne(query: $q){
          _id name,
          goods{
            _id name price images {
               url
            }
          },
          subCategories{
            name, subCategories{
              name
            }
          }
        }
  }`,
      { q: JSON.stringify([{ _id }]) }
    )
  );

const actionGoodById = (_id) =>
  actionPromise(
    "goodById",
    gql(
      `query goodById($q: String){
  GoodFindOne(query: $q){
          _id name description price images{
            url
          }
      }
  }`,
      { q: JSON.stringify([{ _id }]) }
    )
  );

store.dispatch(actionRootCats());
store.dispatch(actionGoodById());

store.subscribe(() => {
  const { rootCats } = store.getState();
  if (rootCats?.payload) {
    aside.innerHTML = "";
    for (const { _id, name } of rootCats?.payload) {
      const link = document.createElement("a");
      link.href = `#/category/${_id}`;
      link.innerText = name;
      aside.append(link);
    }
  }
});

window.onhashchange = () => {
  const [, route, _id] = location.hash.split("/");

  const routes = {
    category() {
      store.dispatch(actionCatById(_id));
    },
    good() {
      store.dispatch(actionGoodById(_id));
    },
  };
  if (route in routes) routes[route]();
};

window.onhashchange();

store.subscribe(() => {
  const { catById } = store.getState();
  const [, route, _id] = location.hash.split("/");
  if (catById?.payload && route === "category") {
    const { name } = catById.payload;
    main.innerHTML = `<h1>${name}</h1>`;
    if (catById.payload?.subCategories) {
      for (const { _id, name } of catById.payload.subCategories) {
        const link = document.createElement("a");
        link.href = `#/category/${_id}`;
        link.innerText = name;
        main.append(link);
        main.innerHTML += "<br/>";
      }
    }
    if (catById.payload?.goods) {
      for (const { _id, name, price, images } of catById.payload.goods) {
        const card = document.createElement("div");
        const link = document.createElement("a");
        card.innerHTML = `<h2>${name}</h2>
                            <img src="${backURL}/${images[0].url}" /><br/>
                            <strong>${price}$</strong><br/>
                              `;
        link.innerText = name;
        link.href = `#/good/${_id}`;
        card.appendChild(link);
        main.append(card);
      }
    }
  }
});

store.subscribe(() => {
  const { goodById } = store.getState();
  const [, route, _id] = location.hash.split("/");
  if (goodById?.payload && route === "good") {
    main.innerHTML = "";
    const { name, description, price, images } = goodById.payload;
    main.innerHTML = `
    <div>
        <div>
            <img src="${backURL}/${images[0].url}" width="400" height="400"/>
        </div>
        <div>
            <h2>${name}</h2>
            <p><strong>${price}$</strong></p>
            <p><span>${description}</span></p>
        </div>
    </div>`;
  }
});

//store.dispatch(actionPromise('', delay(1000)))
//store.dispatch(actionPromise('delay2000', delay(2000)))
//store.dispatch(actionPromise('luke', fetch('https://swapi.dev/api/people/1/').then(res => res.json())))