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, name, status, payload, error }) {
    if (type === 'PROMISE') {
        return {
            ...state,
            [name]: { status, payload, error }
        }
    }
    return state
}

const jwtDecode = token => {
    try {
        let [, payload] = token.split(".");
        let payloadParsed = JSON.parse(atob(payload));
        return payloadParsed;
    }
    catch (e) {
        console.log(e);
    }
}

function authReducer(state, { type, token }) {
    if (state === undefined) {
        if (localStorage.authToken) {
            type = "AUTH_LOGIN";
            token = localStorage.authToken;
        } else {
            return {};
        }
    }
    if (type === 'AUTH_LOGIN') {
        let payload = jwtDecode(token);
        if (payload) {
            localStorage.authToken = token;
            return { token, payload };
        }
    }
    if (type === 'AUTH_LOGOUT') {
        localStorage.authToken = "";
        return {};
    }
    return state;
}

function combineReducers(reducers) {
    return (state = {}, action) => {
        const newState = {}
        for (const [reducerName, reducer] of Object.entries(reducers)) {
            let newSubState = reducer(state[reducerName], action)

            if (newSubState !== state[reducerName]) {
                newState[reducerName] = newSubState
            }
        }

        if (Object.keys(newState).length !== 0) {
            return { ...state, ...newState }
        } else {
            return state
        }
    }
}

function cartReducer(state = {}, { type, good = {}, count = 1 }) {
    //каков state
    //{
    //  _id1: {count:1, good: {_id1, name, price, images}}
    //  _id2: {count:1, good: {_id1, name, prica, images}}
    //}
    //
    const { _id } = good;
    if (type === 'CART_ADD') {
        return {
            ...state,
            [_id]: { count: (state[_id] ? (state[_id].count += count) : count), good: good }
        }
    }
    if (type === 'CART_CHANGE') {
        return {
            ...state,
            [_id]: { count: count, good: good }
        }
    }
    if (type === 'CART_DELETE') {
        let newState = { ...state };
        delete newState[_id];
        // const {_id, ...newState} = state; 
        return {
            ...newState,
        }
    }
    if (type === 'CART_CLEAR') {
        return {}
    }


    return state;
}

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


const actionCartAdd = (good, count = 1) => ({ type: 'CART_ADD', good, count });
const actionCartChange = (good, count = 1) => ({ type: 'CART_CHANGE', good, count });
const actionCartDelete = (good) => ({ type: 'CART_DELETE', good });
const actionCartClear = () => ({ type: 'CART_CLEAR' });

const cartEl = document.getElementsByClassName("cartN")[0];
let username;
const loginEl = document.getElementsByClassName("loginQ")[0];
const logoEl = document.getElementById("logo");

// const store = createStore(promiseReducer) //не забудьте combineReducers если он у вас уже есть

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


const actionPending = name => ({ type: 'PROMISE', name, status: 'PENDING' });
const actionFulfilled = (name, payload) => ({ type: 'PROMISE', name, status: 'FULFILLED', payload });
const actionRejected = (name, error) => ({ type: 'PROMISE', name, status: 'REJECTED', error });
const actionAuthLogin = (token) => ({ type: 'AUTH_LOGIN', token });
const actionAuthLogout = () => ({ type: 'AUTH_LOGOUT' });
const actionPromise = (name, promise) =>
    async dispatch => {
        dispatch(actionPending(name))
        try {
            let payload = await promise
            dispatch(actionFulfilled(name, payload))
            return payload
        }
        catch (error) {
            dispatch(actionRejected(name, error))
        }
    }

const getGQL = url =>
    (query, variables) => fetch(url, {
        method: 'POST',
        headers: {
            "Content-Type": "application/json",
            ...(localStorage.authToken ? { "Authorization": "Bearer " + localStorage.authToken } : {})
        },
        body: JSON.stringify({ query, variables })
    }).then(res => res.json())
        .then(data => {
            if (data.data) {
                return Object.values(data.data)[0]
            }
            else throw new Error(JSON.stringify(data.errors))
        })

const backendURL = "http://shop-roles.node.ed.asmer.org.ua";

const gql = getGQL(backendURL + '/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){
            subCategories{
            name _id goods {
                _id
                name
            }
            }
            _id name goods {
                _id name price images {
                    url
                }
            }
        }
    }`, { q: JSON.stringify([{ _id }]) }));


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


const orderHistory = () =>
    actionPromise(
        'history',
        gql(` query OrderFind{
        OrderFind(query:"[{}]"){
            _id total createdAt orderGoods{
                count good{
                    _id name price images{
                        url
                    }
                }
                owner{
                    _id login 
                }
            }
        }
    }
    `));

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

const actionRegister = (login, password) =>
    actionPromise(
        'register',
        gql(
            `mutation register ($login:String, $password:String){
    UserUpsert(user:{login:$login, password:$password}){
	_id login
    }
}`,
            { login: login, password: password }
        )
    );

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(actionCartClear());
        document.location.hash = "#/cart/";
        alert("Поздравляем, вы оформили заказ!");
    }
};


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

store.dispatch(actionRootCats());

store.subscribe(() => {
    const { rootCats } = store.getState().promise
    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() {
            // console.log("good")
            //задиспатчить actionGoodById
            // console.log('ТОВАРОСТРАНИЦА')
            store.dispatch(actionGoodById(_id));
        },
        login() {
            main.innerHTML = `<h2>Для осуществления заказов:<br>если вы зарегистрированы,
            введите логин и пароль и нажмите Войти;<br>если не зарегистрированы - нужно зарегистрироваться</h2>`;
            const formEl = document.createElement("div");
            const p1el = document.createElement("p");
            const p2el = document.createElement("p");
            const p3el = document.createElement("p");
            const br1El = document.createElement("br");
            const br2El = document.createElement("br");
            const br3El = document.createElement("br");
            const input1El = document.createElement("input");
            const input2El = document.createElement("input");
            const buttonLogEl = document.createElement("button");
            const buttonRegEl = document.createElement("button");
            const buttonLogOutEl = document.createElement("button");
            p1el.innerText = "Введите логин:";
            p2el.innerText = "Введите пароль:";
            input1El.id = "inputLogin";
            input2El.id = "inputPassword";
            input2El.type = "password";
            buttonLogEl.innerText = "Войти";
            buttonRegEl.innerText = "Зарегистрироваться";
            buttonLogOutEl.innerText = "Выйти";
            if (username) {
                buttonLogEl.disabled = true;
                buttonRegEl.disabled = true;
            }
            buttonLogEl.onclick = () => {
                store.dispatch(actionFullLogin(input1El.value, input2El.value));
                // if (username) location.hash = "#/goods";
            }
            buttonRegEl.onclick = () => {
                store.dispatch(actionFullRegister(input1El.value, input2El.value));
            }
            buttonLogOutEl.onclick = () => {
                store.dispatch(actionAuthLogout());
                username = "";
                document.location.hash = "#/login/";
            }
            formEl.append(p1el, input1El, p2el, input2El, br1El, br2El, buttonLogEl, buttonLogOutEl, buttonRegEl);
            main.append(formEl);
            //по кнопке - store.dispatch(actionFullLogin(login, password))
        },
        register() {
            //отрисовка тут
            //по кнопке - store.dispatch(actionFullRegister(login, password))
        },
        dashboard() {
            store.dispatch(orderHistory());

        },
        cart() {
            const cart = store.getState().cart;
            if (Object.entries(cart).length > 0) {
                main.innerHTML = `<h2>Содержимое вашей корзины</h2>`;
                const { cart } = store.getState();
                let totalScore = 0;
                let totalCount = 0;
                const tableCartEl = document.createElement("table");
                const trEl = document.createElement("tr");
                const td1El = document.createElement("td");
                const td2El = document.createElement("td");
                const td3El = document.createElement("td");
                const td4El = document.createElement("td");
                const td5El = document.createElement("td");
                td1El.innerText = "Удалить";
                td2El.innerText = "Наименование товара";
                td3El.innerText = "Цена";
                td4El.innerText = "Количество";
                td5El.innerText = "Изменить";
                trEl.append(td1El, td2El, td3El, td4El, td5El);
                tableCartEl.append(trEl);

                if (Object.entries(cart).length > 0) {
                    for (let [key, value] of Object.entries(cart)) {
                        const { count, good } = value;
                        const { name, _id, price } = good;
                        const buttonDel = document.createElement("button");
                        const buttonMinus = document.createElement("button");
                        const buttonPlus = document.createElement("button");
                        buttonMinus.innerText = "-";
                        buttonPlus.innerText = "+";
                        buttonDel.innerText = "Удалить";


                        buttonMinus.onclick = () => {
                            if (count == 1) {
                                store.dispatch(actionCartDelete({ _id, name, price }));
                            } else {
                                store.dispatch(actionCartChange({ _id, name, price }, count - 1));
                            }
                            document.location.hash = `#/cart/${_id}/${count}`
                        }
                        buttonPlus.onclick = () => {
                            store.dispatch(actionCartChange({ _id, name, price }, count + 1));
                            document.location.hash = `#/cart/${_id}/${count}`
                        }
                        buttonDel.onclick = () => {
                            store.dispatch(actionCartDelete({ _id, name, price }));
                            document.location.hash = `#/cart/${_id}`;
                        }

                        const trEl = document.createElement("tr");
                        const td1El = document.createElement("td");
                        const td2El = document.createElement("td");
                        const td3El = document.createElement("td");
                        const td4El = document.createElement("td");
                        const td5El = document.createElement("td");
                        td1El.append(buttonDel);
                        td2El.innerText = name;
                        td3El.innerText = price;
                        td4El.innerText = count;
                        td5El.append(buttonMinus, buttonPlus);
                        trEl.append(td1El, td2El, td3El, td4El, td5El);
                        tableCartEl.append(trEl);

                        totalScore += price * count;
                        totalCount += count;

                    }
                    const trEl = document.createElement("tr");
                    const td1El = document.createElement("td");
                    const td2El = document.createElement("td");
                    const td3El = document.createElement("td");
                    const td4El = document.createElement("td");
                    const td5El = document.createElement("td");
                    td1El.innerText = "";
                    td2El.innerText = "";
                    td3El.innerText = totalScore;
                    td4El.innerText = totalCount;
                    td5El.innerText = "";
                    trEl.append(td1El, td2El, td3El, td4El, td5El);
                    tableCartEl.append(trEl);

                }

                main.append(tableCartEl);

                const buttonCartClear = document.createElement("button");
                const buttonSend = document.createElement("button");
                const buttonHistory = document.createElement("button");
                buttonSend.innerText = "Отправить заказ";
                buttonCartClear.innerText = "Очистить корзину";
                buttonHistory.innerText = "История заказов";
                buttonSend.onclick = () => {
                    store.dispatch(actionOrder());

                }
                buttonCartClear.onclick = () => {
                    store.dispatch(actionCartClear());
                    document.location.hash = "#/cart/";
                }
                buttonHistory.onclick = () => {
                    document.location.hash = "#/dashboard";
                }

                main.append(buttonSend, buttonCartClear, buttonHistory);
            } else {
                main.innerHTML = `<h2>Ваша корзина пуста...</h2><a href="#/dashboard">история заказов</a>`;
            }

        },
    }
    if (route in routes)
        routes[route]()
}
window.onhashchange()


store.subscribe(() => {
    const { catById } = store.getState().promise;
    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 card = document.createElement('div')
                card.innerHTML = `<a href="#/category/${_id}"><h2>${name}</h2></a>`;
                main.append(card);
            }
        }
        for (const { _id, name, price, images } of catById.payload.goods) {
            const card = document.createElement('div')
            card.innerHTML = `<h2>${name}</h2>
                            <img src="${backendURL}/${images[0].url}" /><br>
                            <strong>Цена: ${price} грн</strong><br>
                            <button onclick="store.dispatch(actionCartAdd({_id: '${_id}',
                                        name: '${name}', price: '${price}'}))">Купить</button>
                            <a href="#/good/${_id}">описание товара</a>`
            main.append(card)
        }

    }
})

store.subscribe(() => {
    const { goodById } = store.getState().promise;
    const [, route, _id] = location.hash.split('/');
    //ТУТ ДОЛЖНА БЫТЬ ПРОВЕРКА НА НАЛИЧИЕ goodById в редакс
    //и проверка на то, что сейчас в адресной строке адрес ВИДА #/good/АЙДИ
    //в таком случае очищаем main и рисуем информацию про товар с подробностями
    if (goodById?.payload && route === 'good') {
        const { _id, name, price, description, images } = goodById.payload;
        main.innerHTML = `<h2>${name}</h2>`;
        const card = document.createElement('div');
        card.innerHTML = `<img src="${backendURL}/${images[0].url}" /><br>
                                <strong>Цена: ${price} грн</strong><br>
                                <button onclick="store.dispatch(actionCartAdd({_id: '${_id}',
                                            name: '${name}', price: '${price}'}))">Купить</button>
                                <p>Описание товара:</p>
                                <p>${description}</p>
                                `
        main.append(card);
    }
})

store.subscribe(() => {
    const { cart } = store.getState();
    // console.log(cart);
    let numInCart = 0;
    if (Object.entries(cart).length > 0) {
        for (let [key, value] of Object.entries(cart)) {
            const { count } = value;
            numInCart += count;
        }
    }
    cartEl.innerText = numInCart;
    //достаем всю корзину
    //считаем общее количество всех позиций (3 айфона + 7 пицц = 10)
    //выводим число в кошик на странице через его HTML id
});

store.subscribe(() => {
    const { auth } = store.getState();
    // const [,route,] = location.hash.split('/');
    if (Object.keys(auth).length !== 0) {
        username = auth?.payload.sub.login;
    }
    if (localStorage.authToken) {
        // console.log("login");
        loginEl.innerText = "";
        logoEl.innerHTML = `\n                <h1>${username}, добро пожаловать в интернет магазин NotРОЗЕТКА</h1>\n            `
    } else {
        // console.log("logout");
        loginEl.innerText = "?";
        logoEl.innerHTML = `\n                <h1>Добро пожаловать в интернет магазин</h1>\n            `
    }
});

//store.dispatch(actionPromise('delay1000', delay(1000)))
//store.dispatch(actionPromise('delay2000', delay(2000)))
//store.dispatch(actionPromise('failedfetch', fetch('https://swapi.dev/api/people/1/')
//.then(res => res.json())))

store.subscribe(() => {
    const { history } = store.getState().promise;
    const [, route] = location.hash.split('/');

    if (history?.payload && route === 'dashboard') {

        main.innerHTML = "<p><b>История ваших заказов:</b></p>";
        const card = document.createElement('div');

        for (let [key, value] of Object.entries(history.payload)) {
            const { _id, createdAt, total, orderGoods } = value;
            const p1El = document.createElement("p");
            const dateOfOrder = new Date(+createdAt);
            p1El.innerHTML = `${dateOfOrder.toLocaleDateString()} ${dateOfOrder.toLocaleTimeString()}
                            Заказ ID: ${_id} от , c ${orderGoods.length} товарами на сумму ${total} грн`;
            card.append(p1El);
        }

        if (Object.keys(history.payload).length == 0) {
            const p1El = document.createElement("p");
            p1El.innerHTML = "<p>Вы раньше еще ничего не заказывали</p>";
            card.append(p1El);
        }
        main.append(card);

    }

});

function alerting() {
    const { auth } = store.getState();
    if (Object.keys(auth).length !== 0) {
        username = auth?.payload.sub.login;
    }
    if (username) {
        alert(`${username}, вы успешно зашли на сайт!`);
        document.location.hash = "#/category/5dc49f4d5df9d670df48cc64";

    } else {
        alert("Вы ввели неправильно логин или пароль!");
    }
}

function alertingReg(id, login) {
    if (id) {
        alert(`Вы успешно зарегистрировались с логином ${login}`);
    } else {
        alert(`Логин ${login} уже занят, прыдумайте другой!`);
    }
}