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 authReducer(state, { type, token }) {
  if (!state) {
    if (localStorage.authToken) {
      type = "AUTH_LOGIN";
      token = localStorage.authToken;
    } else {
      return {};
    }
  }
  if (type === "AUTH_LOGIN") {
    localStorage.authToken = token;
    let payload = jwtDecode(token);
    if (typeof payload !== "object") {
      return {};
    }
    return { token, payload };
  }
  if (type === "AUTH_LOGOUT") {
    localStorage.authToken = "";
    return {};
  }
  return state;
}

const actionAuthLogin = (token) => ({
  type: "AUTH_LOGIN",
  token,
});
const actionAuthLogout = () => ({ type: "AUTH_LOGOUT" });

function cartReducer(state = {}, { type, good = {}, count }) {
  const { _id } = good;

  const types = {
    CART_ADD() {
      count = +count;
      if (!count) {
        return state;
      }
      return {
        ...state,
        [_id]: { good, count: count + (state[_id]?.count || 0) },
      };
    },
    CART_CHANGE() {
      count = +count;
      if (!count) {
        return state;
      }
      return {
        ...state,
        [_id]: { good, count },
      };
    },
    CART_REMOVE() {
      let { [_id]: remove, ...goods } = state;
      return goods;
    },
    CART_CLEAR() {
      return {};
    },
    CART_SHOW() {
      state = JSON.parse(localStorage.cart);
      return state;
    },
  };
  if (type in types) {
    return types[type]();
  }
  return state;
}

function promiseReducer(state = {}, { type, status, payload, errors, name }) {
  if (!state) {
    return {};
  }
  if (type === "PROMISE") {
    return {
      ...state,
      [name]: { status, payload, errors },
    };
  }
  return state;
}
const actionPending = (name) => ({ type: "PROMISE", status: "PENDING", name });
const actionResolved = (name, payload) => ({
  type: "PROMISE",
  status: "RESOLVED",
  name,
  payload,
});
const actionRejected = (name, errors) => ({
  type: "PROMISE",
  status: "REJECTED",
  name,
  errors,
});
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));
  }
};

function combineReducers(reducers) {
  return (state = {}, action) => {
    const newState = {};
    let newSubState;
    for (const [reducerName, reducer] of Object.entries(reducers)) {
      newSubState = reducer(state[reducerName], action);
      if (state[reducerName] !== newSubState) {
        newState[reducerName] = newSubState;
      }
    }
    if (Object.keys(newState).length !== 0) {
      return { ...state, ...newState };
    } else {
      return state;
    }
  };
}

const combinedReducer = combineReducers({
  promise: promiseReducer,
  auth: authReducer,
  cart: cartReducer,
});
const store = createStore(combinedReducer);

const actionCartAdd = (good, count) => ({
  type: "CART_ADD",
  good,
  count,
});
const actionCartChange = (good, count) => ({
  type: "CART_CHANGE",
  good,
  count,
});
const actionCartRemove = (good) => ({ type: "CART_REMOVE", good });
const actionCartClear = () => ({ type: "CART_CLEAR" });
const actionCartShow = () => ({ type: "CART_SHOW" });

const actionOrder = () => async (dispatch, getState) => {
  let { cart } = getState();
  const orderGoods = Object.entries(cart).map(([_id, { count }]) => ({
    good: { _id },
    count,
  }));
  let result = await dispatch(
    actionPromise(
      "order",
      gql(
        `
                    mutation newOrder($order:OrderInput){
                      OrderUpsert(order:$order)
                        { _id total }
                    }
            `,
        { order: { orderGoods } }
      )
    )
  );

  if (result?._id) {
    dispatch(actionCleanCart());
  }
};

const getGQL =
  (url) =>
  async (query, variables = {}) => {
    let obj = await fetch(url, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      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 }]) }
    )
  );

const actionLogin = (login, password) =>
  actionPromise(
    "login",
    gql(
      `query log($login: String, $password: String) {
      login(login: $login, password: $password)
  }`,
      { login: login, password: password }
    )
  );

const actionFullLogin = (login, password) => async (dispatch) => {
  console.log(login, password);
  let token = await dispatch(actionLogin(login, password));
  console.log(token);
  if (token) {
    dispatch(actionAuthLogin(token));
  }
};

const actionRegister = (login, password) =>
  actionPromise(
    "registration",
    gql(
      `mutation reg2($user:UserInput) {
      UserUpsert(user:$user) {
      _id login
      }
  }
  `,
      { user: { login: login, password: password } }
    )
  );

const actionFullRegister = (login, password) => async (dispatch) => {
  console.log(login, password);
  let check = await dispatch(actionRegister(login, password));
  console.log(check);
  if (check) {
    dispatch(actionFullLogin(login, password));
  }
};

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

store.subscribe(() => {
  const { promise } = store.getState();
  if (promise?.rootCats?.payload) {
    asideList.innerHTML = "";
    let count = -1;
    for (const { _id, name } of promise.rootCats.payload) {
      count++;
      const link = document.createElement("a");
      link.href = `#/category/${_id}`;
      link.innerText = name;
      link.className = "nav-link";
      link.id = `rootCat${count}`;
      asideList.appendChild(link);
    }
  }
});

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

  if (route === "cart") {
    main.innerHTML = "";
    const { cart } = store.getState();

    for (let good in cart) {
      let {
        good: {
          _id: id,
          name: name,
          price: price,
          images: [{ url }],
        },
        count,
      } = cart[good];

      let cardMain = document.createElement("div");
      cardMain.id = "cardMain";
      let goodImgBlock = document.createElement("div");
      goodImgBlock.innerHTML = `
          <img src="${backURL}/${url}" width="400" height="200"/>
      `;
      cardMain.appendChild(goodImgBlock);
      let goodInfoBlock = document.createElement("div");
      let goodName = document.createElement("h2");
      goodName.innerText = `${name}`;
      let goodPrice = document.createElement("p");
      goodPrice.innerText = `${price * count}$`;
      let goodCount = document.createElement("p");
      goodCount.innerText = `${count} шт.`;
      goodInfoBlock.appendChild(goodName);
      goodInfoBlock.appendChild(goodPrice);
      goodInfoBlock.appendChild(goodCount);
      cardMain.appendChild(goodInfoBlock);

      let br = document.createElement("br");
      let goodEditBlock = document.createElement("div");
      goodEditBlock.className = "form-outline";
      let deleteBtn = document.createElement("button");
      deleteBtn.innerText = "Delete";
      deleteBtn.id = "deleteBtn";
      deleteBtn.type = "button";
      deleteBtn.className = "btn btn-danger";
      goodEditBlock.appendChild(deleteBtn);
      goodEditBlock.appendChild(br);
      deleteBtn.onclick = () => {
        store.dispatch(actionCartRemove(cart[good].good));
        cardMain.remove();
        console.log(store.getState());
      };

      let countLabel = document.createElement("label");
      countLabel.className = "form-label";
      countLabel.htmlFor = "countField";
      countLabel.innerText = "Change count";
      let countField = document.createElement("input");
      countField.type = "number";
      countField.value = cart[good].count;
      countField.min = "1";
      countField.id = "countField";
      countField.className = "form-control";
      goodEditBlock.appendChild(countLabel);
      goodEditBlock.appendChild(countField);
      countField.oninput = () => {
        goodPrice.innerText = `${price * +countField.value}$`;
        goodCount.innerText = `${countField.value} шт.`;
        store.dispatch(actionCartChange(cart[good].good, countField.value));
      };
      cardMain.appendChild(goodEditBlock);
      main.appendChild(cardMain);
    }
    let clearBtn = document.createElement("button");
    clearBtn.innerText = "Clear Cart";
    clearBtn.id = "clearBtn";
    clearBtn.type = "button";
    clearBtn.className = "btn btn-dark";

    let makeOrder = document.createElement("button");
    makeOrder.innerText = "Make Order";
    makeOrder.id = "makeOrder";
    makeOrder.type = "button";
    makeOrder.className = "btn btn-success";

    if (Object.keys(cart).length !== 0) {
      main.appendChild(makeOrder);
      main.appendChild(clearBtn);
    } else {
      main.innerHTML = "<h2>Your cart is empty!</h2>";
    }

    makeOrder.onclick = () => {
      store.dispatch(actionOrder());
      alert("Thanks for your order!");
      store.dispatch(actionCartClear());
      document.location.reload();
    };

    clearBtn.onclick = () => {
      store.dispatch(actionCartClear());
      document.location.reload();
    };
  }
};

window.onhashchange = () => {
  const [, route, _id] = location.hash.split("/");
  let signOut = document.createElement("button");
  signOut.innerText = "Sign Out";
  signOut.id = "signoutBtn";
  signOut.className = "btn btn-secondary";
  const routes = {
    category() {
      store.dispatch(actionCatById(_id));
    },
    good() {
      store.dispatch(actionGoodById(_id));
    },
    login() {
      let loginInput = document.getElementById("loginInput");
      let passwordInput = document.getElementById("pass1Input");
      if (
        loginInput &&
        passwordInput &&
        loginInput.value &&
        passwordInput.value
      ) {
        store.dispatch(
          actionFullLogin(
            loginInput.value.slice(0, loginInput.value.indexOf("@")),
            passwordInput.value
          )
        );
      } else {
        throw new Error("Error login");
      }
    },
    register() {
      let regInput = document.getElementById("regInput");
      let passwordInput = document.getElementById("pass2Input");
      if (regInput && passwordInput && regInput.value && passwordInput.value) {
        store.dispatch(
          actionFullRegister(
            regInput.value.slice(0, regInput.value.indexOf("@")),
            passwordInput.value
          )
        );
      } else {
        throw new Error("Error register");
      }
    },
    cart() {
      openCart();
    },
  };
  if (route in routes) routes[route]();
};

window.onhashchange();

store.subscribe(() => {
  const [, route] = location.hash.split("/");
  const { cart } = store.getState();
  if (Object.keys(cart).length === 0 && route === "cart") {
    let makeOrderBtn = document.getElementById("makeOrder");
    let clearCartBtn = document.getElementById("clearBtn");
    if (makeOrderBtn) {
      makeOrderBtn.remove();
    }
    if (clearCartBtn) {
      clearCartBtn.remove();
    }
    localStorage.cart = "";
    main.innerHTML = "<h2>Your cart is empty!</h2>";
  } else if (Object.keys(cart).length !== 0) {
    let cartStr = JSON.stringify(cart);
    localStorage.cart = cartStr;
  }
});

window.onunload = () => {
  if (localStorage.cart !== "") {
    store.dispatch(actionCartShow());
    openCart();
  }
};

window.onunload();

store.subscribe(() => {
  const { promise } = store.getState();
  const [, route, _id] = location.hash.split("/");
  if (promise?.catById?.payload && route === "category") {
    const { name } = promise.catById.payload;
    main.innerHTML = `<h1>${name}</h1>`;
    if (promise.catById.payload?.subCategories) {
      for (const { _id, name } of promise.catById.payload.subCategories) {
        const rootCat = document.querySelector(
          `a[href="#/category/${promise.catById.payload._id}"]`
        );
        const subNav = document.createElement("nav");
        subNav.className = "nav nav-pills flex-column";
        const link = document.createElement("a");
        link.href = `#/category/${_id}`;
        link.innerText = name;
        link.className = "nav-link ms-3 my-1";
        subNav.appendChild(link);
        rootCat.appendChild(subNav);
      }
    }
    if (promise.catById.payload?.goods) {
      for (const good of promise.catById.payload.goods) {
        const { _id, name, price, images } = good;
        const card = document.createElement("div");
        const link = document.createElement("a");
        card.innerHTML = `<h2>${name}</h2>
                            <img src="${backURL}/${images[0].url}" width="400" height="200"/><br/>
                            <strong>${price}$</strong><br/>
                              `;
        link.innerText = name;
        link.href = `#/good/${_id}`;
        card.appendChild(link);

        let buyBtn = document.createElement("button");
        buyBtn.className = "btn btn-success";
        buyBtn.textContent = "Buy";
        buyBtn.onclick = () => {
          store.dispatch(actionCartAdd(good, 1));
        };
        card.appendChild(buyBtn);
        main.append(card);
      }
    }
  }
});

store.subscribe(() => {
  const { cart } = store.getState();

  let countGoods = 0;

  for (let good of Object.keys(cart)) {
    countGoods += cart[good].count;
  }
  cartIcon.innerText = `Товаров в корзине: ${countGoods}`;

  cartIcon.onclick = () => {
    window.location.href = "#/cart";
  };
});

store.subscribe(() => {
  const { promise } = store.getState();
  const [, route, _id] = location.hash.split("/");
  if (promise?.goodById?.payload && route === "good") {
    main.innerHTML = "";
    const { name, description, price, images } = promise.goodById.payload;
    main.innerHTML = `
    <div>
        <div>
            <img src="${backURL}/${images[0].url}" width="400" height="200"/>
        </div>
        <div>
            <h2>${name}</h2>
            <p><strong>${price}$</strong></p>
            <p><span>${description}</span></p>
        </div>
    </div>`;
  }
});

store.subscribe(() => console.log(store.getState()));

function jwtDecode(token) {
  try {
    return JSON.parse(atob(token.split(".")[1]));
  } catch (error) {
    console.log(error);
  }
}

store.subscribe(async () => {
  const { promise } = store.getState();

  let signinBtn = document.getElementById("signinBtn");
  let signupBtn = document.getElementById("signupBtn");

  if (promise?.rootCats?.payload && !signinBtn && !signupBtn) {
    let signIn = document.createElement("button");
    signIn.innerText = "Sign In";
    signIn.id = "signinBtn";
    signIn.type = "button";
    signIn.className = "btn btn-light";
    let signUp = document.createElement("button");
    signUp.innerText = "Sign Up";
    signUp.id = "signupBtn";
    signUp.type = "button";
    signUp.className = "btn btn-light";
    let authBlock = document.createElement("div");
    authBlock.id = "authBlock";
    authBlock.appendChild(signIn);
    authBlock.appendChild(signUp);
    authnav.appendChild(authBlock);
  }
});

store.subscribe(async () => {
  let signinBtn = document.getElementById("signinBtn");
  if (signinBtn) {
    signinBtn.onclick = () => {
      try {
        let registerFields = document.getElementById("registerFields");
        if (registerFields !== null) {
          registerFields.style.display = "none";
        }
        signinBtn.style.display = "none";
        signupBtn.style.display = "inline";

        let fieldsBlock = document.createElement("div");
        fieldsBlock.className = "fields";
        fieldsBlock.id = "loginFields";
        let email = document.createElement("input");
        email.type = "email";
        email.placeholder = "Enter your email";
        email.className = "form-control";
        email.id = "loginInput";
        let password = document.createElement("input");
        password.type = "password";
        password.placeholder = "Enter your password";
        password.className = "form-control";
        password.id = "pass1Input";
        let login = document.createElement("button");
        login.innerText = "Login";
        login.id = "loginBtn";
        login.className = "btn btn-primary";
        fieldsBlock.appendChild(email);
        fieldsBlock.appendChild(password);
        fieldsBlock.appendChild(login);
        authBlock.prepend(fieldsBlock);

        loginBtn.onclick = () => {
          window.location.href = "#/login";
          console.log(store.getState());
        };
      } catch (error) {
        console.log(error);
      }
    };
  }
});

store.subscribe(async () => {
  let signupBtn = document.getElementById("signupBtn");
  if (signupBtn) {
    signupBtn.onclick = () => {
      try {
        let loginFields = document.getElementById("loginFields");
        if (loginFields !== null) {
          loginFields.style.display = "none";
        }
        signinBtn.style.display = "inline";
        signupBtn.style.display = "none";

        let fieldsBlock = document.createElement("div");
        fieldsBlock.className = "fields";
        fieldsBlock.id = "registerFields";
        let email = document.createElement("input");
        email.type = "email";
        email.placeholder = "Enter your email";
        email.className = "form-control";
        email.id = "regInput";
        let password = document.createElement("input");
        password.type = "password";
        password.placeholder = "Enter your password";
        password.className = "form-control";
        password.id = "pass2Input";
        let register = document.createElement("button");
        register.innerText = "Register";
        register.id = "regBtn";
        register.className = "btn btn-primary";
        fieldsBlock.appendChild(email);
        fieldsBlock.appendChild(password);
        fieldsBlock.appendChild(register);
        authBlock.prepend(fieldsBlock);

        regBtn.onclick = () => {
          window.location.href = "#/register";
          console.log(store.getState());
        };
      } catch (error) {
        console.log(error);
      }
    };
  }
});

store.subscribe(async () => {
  const { promise, auth } = store.getState();
  let accountLink = document.getElementById("accountLink");
  let signoutBtn = document.getElementById("signoutBtn");
  let signinBtn = document.getElementById("signinBtn");
  let signupBtn = document.getElementById("signupBtn");

  if (auth?.token && !signoutBtn && !accountLink) {
    signinBtn.style.display = "none";
    signupBtn.style.display = "none";

    if (promise?.register?.status === "RESOLVED") {
      let registerBlock = document.getElementById("registerFields");
      registerBlock.style.display = "none";
      signupBtn.style.display = "none";
      window.location.href = window.location.href.replace("#/register", "");
      console.log(store.getState());
    }
    if (promise?.login?.status === "RESOLVED") {
      let loginBlock = document.getElementById("loginFields");
      loginBlock.style.display = "none";
      signinBtn.style.display = "none";
      window.location.href = window.location.href.replace("#/login", "");
      console.log(store.getState());
    }
    let signOut = document.createElement("button");
    signOut.innerText = "Sign Out";
    signOut.id = "signoutBtn";
    signOut.className = "btn btn-secondary";
    let authBlock = document.createElement("div");
    authBlock.id = "authBlock";
    authBlock.appendChild(signOut);
    let nickname = auth.payload.sub.login;
    let account = document.createElement("button");
    account.textContent = nickname;
    account.type = "button";
    account.id = "accountLink";
    account.className = "btn btn-success";
    authBlock.prepend(account);
    authnav.appendChild(authBlock);
    signOut.onclick = () => {
      signOut.style.display = "none";
      store.dispatch(actionAuthLogout());
      signinBtn.style.display = "inline";
      signupBtn.style.display = "inline";
      account.remove();
    };
  }
});