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}){
	////?????
	//ОДИН ПРОМИС:
	//состояние: PENDING/FULFILLED/REJECTED
	//результат
	//ошибка:
	//{status, payload, error}
	//{
	//       name1:{status, payload, error}
	//       name2:{status, payload, error}
	//       name3:{status, payload, error}
	//}
	if (type === 'PROMISE'){
		return {
			...state,
			[name]:{status, payload, error}
		}
	}
	return state
}

const actionPending   = (name) => ({type: 'PROMISE', status: 'PENDING', name})
const actionFulfilled = (name, payload) => ({type: 'PROMISE', status: 'FULFILLED', name, payload})
const actionRejected  = (name, error) => ({type: 'PROMISE', status: 'REJECTED', name, error})

const actionPromise   = (name, promise) =>
	async dispatch => {
		try {
			dispatch(actionPending(name))
			let payload = await promise
			dispatch(actionFulfilled(name, payload))
			return payload
		}
		catch(e){
			dispatch(actionRejected(name, e))
		}
	}

const goToMainPage = () => location.href = location.href.split("#")[0];

const checkAuthToken = () => {
	const headers = {
		"Content-Type": "application/json",
		"Accept": "application/json",
	}
	if(localStorage.getItem('authToken')) {
		return {
			...headers,
			"Authorization": `Bearer ${localStorage.getItem('authToken')}`
		}
	} else {
		return headers;
	}
}

const getGQL = url =>
	(query, variables= {}) =>
		fetch(url, {
			method: 'POST',
			headers: checkAuthToken(),
			body:JSON.stringify({query, variables})
		}).then(res => res.json())
			.then(data => {
				try {
					if(!data.data && data.errors) {
						throw new SyntaxError(`SyntaxError - ${JSON.stringify(Object.values(data.errors)[0])}`);
					}
					return Object.values(data.data)[0];
				} catch (e) {
					console.error(e);
				}
			});

function jwtDecode(token){
	try {
		return JSON.parse(atob(token.split('.')[1]))
	}
	catch(e){
	}
}


function authReducer(state={}, {type, token}){
	//{
	//  token,payload (раскодированный токен)
	//} или, если не залогинены
	//{
	// нихрена, т. .е. пустой объект
	//}
	if (type === 'AUTH_LOGIN'){ //то мы логинимся
		const payload = jwtDecode(token)
		if (payload){
			return {
				token,
				payload
			}
		}
	}
	if (type === 'AUTH_LOGOUT'){ //мы разлогиниваемся
		return {}
	}
	return state
}

const actionAuthLogout = () =>
	dispatch => {
		dispatch({type: 'AUTH_LOGOUT'});
		localStorage.removeItem('authToken');
		goToMainPage()
	}

const actionAuthLogin = (token) =>
	(dispatch, getState) => {
		const oldState = getState()
		dispatch({type: 'AUTH_LOGIN', token})
		const newState = getState()
		if (oldState !== newState)
			localStorage.setItem('authToken', token)
	}

function cartReducer(state={}, {type, amount=1, good}){
	/*
	{
		id1: {amount, good: {объект с бэка с _id, description, name, price}},
		id2: {amount, good: {объект с бэка с _id, description, name, price}},
		id3: {amount, good: {объект с бэка с _id, description, name, price}}
	}
	*/

	if (type === 'CART_ADD'){
		return {
			...state,
			[good._id]: {good, amount: (state[good._id]?.amount || 0) + amount }
		}
	}
	if (type === 'CART_SET'){
		return {
			...state,
			[good._id]: {good, amount}
		}
	}
	if (type === 'CART_DELETE'){
		const {[good._id]: skip,...newState} = state
		//const newState = { ...state }
		//delete newState[good._id]
		return newState
	}
	if (type === 'CART_CLEAR'){
		return {}
	}
	//if (type === ''){

	//}

	return state
}

const actionCartAdd    = (good, amount=1) => ({type: 'CART_ADD', good, amount})
const actionCartSet    = (good, amount=1) => ({type: 'CART_SET', good, amount})
const actionCartClear  = ()               => ({type: 'CART_CLEAR'})
const actionCartDelete = (good)           => ({type: 'CART_DELETE', good})



function combineReducers(reducers){
	function totalReducer(state={}, action){
		//{
		//promise:{
		//name1:{status, payload, error},
		//name2:{status, payload, error}
		//},
		//auth: {
		//token, payload
		//}
		//}
		const newTotalState = {}
		for (const [reducerName, reducer] of Object.entries(reducers)){
			const newSubState = reducer(state[reducerName], action)
			if (newSubState !== state[reducerName]){
				newTotalState[reducerName] = newSubState
			}
		}
		if (Object.keys(newTotalState).length){
			return {...state, ...newTotalState}
		}

		return state
	}

	return totalReducer
}

function localStoredReducer(reducer, localStorageKey){
	function wrapperReducer(state, action){
		if (state === undefined){ //если загрузка сайта
			try {
				return JSON.parse(localStorage[localStorageKey]) //пытаемся распарсить сохраненный
				//в localStorage state и подсунуть его вместо результата редьюсера
			}
			catch(e){ } //если распарсить не выйдет, то код пойдет как обычно:
		}
		const newState = reducer(state, action)
		localStorage.setItem(localStorageKey, JSON.stringify(newState)) //сохраняем состояние в localStorage
		return newState
	}
	return wrapperReducer
}


const reducers = {
	auth: authReducer,
	cart: localStoredReducer(cartReducer, 'cart'), //в localStorage должен появится ключ cart с JSON стейта корзины
	promise: localStoredReducer(promiseReducer, 'promise'),
}

const totalReducer = combineReducers(reducers)


const store = createStore(totalReducer) //не забудьте combineReducers если он у вас уже есть
store.subscribe(() => console.log(store.getState()))


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

const gql = getGQL(backendURL + 'graphql')

const rootCategories = () =>
	gql(`query cadz($q:String) {
        CategoryFind(query:$q){
            _id name
        }
    }`, {q: JSON.stringify([{parent: null}])})

const actionRootCategories = () =>
	actionPromise('rootCategories', rootCategories())

const categoryById = _id => //добавьте сюда подкатегории и родителя - пригодятся
	gql(`query catById($qCat:String){
              CategoryFindOne(query:$qCat){
                _id name
                parent {
                  _id name
                }
                subCategories {
                  name _id parent {
                    _id name
                  }
                }
                goods{
                  _id name price images{
                    url
                  } 
                }
              }  
            }`, {qCat: JSON.stringify([{_id}])})

const actionCategoryById = _id =>
	actionPromise('catById', categoryById(_id))

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

const actionGoodById = _id =>
	actionPromise('goodById', goodById(_id));

const actionOrder = () =>
	async (dispatch, getState) => {
		const order = Object.values(getState().cart).map(orderGoods => ({good: {_id: orderGoods.good._id}, count: orderGoods.amount}));
		const myOrder = await dispatch(actionPromise('myOrder', gql(`mutation myOrder($order:OrderInput) {
														  OrderUpsert(order:$order) {
														    _id createdAt total
														  }
														}`, {order: {orderGoods: order}})));
		if(myOrder) {
			dispatch(actionCartClear());
		}
	}

const orders = () =>
	gql(`query myOrders {
				  OrderFind(query:"[{}]"){
				    _id total orderGoods{
				      price count total good{
				        _id name images{
				          url
				        }
				      }
				    }
				  }
				}`, {})

const actionOrders = () =>
	actionPromise('myOrders', orders())

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

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

const actionFullLogin = (login, password) =>
	async dispatch => {
		const token = await dispatch(actionLogin(login, password))
		if (token){
			dispatch(actionAuthLogin(token));
			goToMainPage()
		}
	}

const actionFullRegister = (login, password) =>
	async dispatch => {
		const user = await dispatch(actionRegister(login, password))
		if(user) {
			dispatch(actionFullLogin(login, password))
		}
	}

const actionFullOrders = () =>
	async dispatch => {
		await dispatch(actionOrders());
		if(Object.keys(store.getState().auth).length === 0) {
			goToMainPage()
		}
	}

function Password(parent, open) {

	const input = document.createElement('input');
	input.id = 'password'
	input.type = 'password';
	parent.appendChild(input);

	const button = document.createElement('button');
	button.type = 'button';
	button.textContent = 'показать';
	parent.appendChild(button);

	button.addEventListener('click', () => {
		this.setOpen(open !== true);
	});

	this.setValue = newValue => input.value = newValue;

	this.getValue = () => input.value;

	this.setOpen = openUpdate => {
		open = openUpdate;
		if(typeof this.onOpenChange === 'function') {
			this.onOpenChange(openUpdate);
		}
		button.textContent = (openUpdate) ? 'показать' : 'скрыть';
		input.type = (openUpdate) ? 'password' : 'text';
	}

	this.getOpen = () => open;

	input.addEventListener('input', event => {
		if (typeof this.onChange === 'function'){
			this.onChange(event.target.value);
		}
	});
}

function LoginForm(parent) {

	const createDivider = () => parent.appendChild(document.createElement('br'));

	const input = document.createElement('input');
	input.id = 'login';
	input.type = 'text';
	parent.appendChild(input);

	const button = document.createElement('button');
	button.type = 'button';
	button.textContent = 'Логин';
	button.disabled = true;

	input.addEventListener('input', event => {
		if (typeof this.onChange === 'function'){
			this.onChange(event.target.value);
		}
	});

	button.addEventListener('click', event => {
		if (typeof this.onLogin === 'function') {
			this.onLogin(event.target);
		}
	});

	this.getLogin = () => input.value;

	createDivider();
	const password = new Password(parent, true);

	const getPassword = () => password.getValue();

	createDivider();
	parent.appendChild(button);

	const isDisabled = () => button.disabled = (!(getPassword() !== '' && this.getLogin() !== ''));

	password.onChange = () => isDisabled();

	this.onChange = () => isDisabled();

	this.setButtonText = newText => button.textContent = newText;
}

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

store.subscribe(() => {
	const catById = store.getState().promise.catById?.payload
	const [,route] = location.hash.split('/')
	if (catById && route === 'category'){
		const {name, goods, parent, subCategories} = catById;
		main.innerHTML = `<h1>${name}</h1>`;

		if(parent) {
			const {_id, name} = parent;
			const breadcrumbs = document.createElement('a');
			breadcrumbs.innerText = name;
			breadcrumbs.href = `#/category/${_id}`;
			main.prepend(breadcrumbs);
		}

		if(subCategories) {
			const listSubCategories = document.createElement('ul');
			for (let {_id, name} of subCategories) {
				listSubCategories.innerHTML += `
					<li>
						<a href="#/category/${_id}">${name}</a>
					</li>
				`;
			}
			main.append(listSubCategories);
		}

		for (let good of goods){
			const {_id, name, price, images} = good
			const a = document.createElement('a')
			a.classList.add('card')
			a.innerHTML = `
                <div>
                    <img class="card__image" alt="${name}" src="${backendURL + images[0]?.url}" />
                    <h2>${name}</h2>
                    <strong>${price}</strong>
                </div>
            `
			a.href      = `#/good/${_id}`

			const button = document.createElement('button')
			button.type = 'button';
			button.innerText = 'добавить в корзину'
			button.onclick = () => {
				store.dispatch(actionCartAdd(good))
			}
			main.append(a)
			main.append(button)
		}
	}
})

store.subscribe(() => {
	const goodById = store.getState().promise.goodById?.payload
	const [,route] = location.hash.split('/')
	if (goodById && route === 'good'){
		const {name, description, price, images} = goodById
		main.innerHTML = `
			<div>
				<h1>${name}</h1>
				<p>${description}</p>
				<strong>${price}</strong>
			</div>
		`;
		const button = document.createElement('button')
		button.type = 'button';
		button.innerText = 'добавить в корзину'
		button.onclick = () => {
			store.dispatch(actionCartAdd(goodById))
		}
		main.append(button);
		let imageGroup = document.createElement('div');
		imageGroup.classList.add('good-images')
		for (const img in images) {
			imageGroup.innerHTML += `
				<div>
					<img class="good-images__element" src="${backendURL + images[img]?.url}" alt="${name} photo-${img}">
				</div>
			`
		}
		main.append(imageGroup)
	}
})

const drawCart = () => {
	const cart = store.getState().cart;
	const [,route] = location.hash.split('/');
	if (cart && route === 'cart'){
		if(Object.keys(cart).length === 0) {
			main.innerHTML = '<h1>Корзина пустая</h1>';
		} else {
			main.innerHTML = '';
			const cartBlock = document.createElement('div');
			cartBlock.classList.add('cart');
			const totalAmountByPosition = [];
			for (const good of Object.values(cart)) {
				const {_id, name, price, images} = good.good;
				totalAmountByPosition.push(price * good.amount);
				const cartElement = document.createElement('div');
				cartElement.classList.add('cart__element')
				cartElement.innerHTML = `
					<figure class="cart__figure">
						<a class="cart__image-link" href="#/good/${_id}">
							<img class="cart__image" src="${backendURL + images[0]?.url}" alt="${name}">
						</a>
						<figcaption class="cart__caption">
							<a href="#/good/${_id}" class="cart__name">${name}</a>
							<strong class="cart__price">Цена - ${price}</strong>
							<p class="cart__amount">Количество - ${good.amount} шт.</p>
							<p class="cart__amount-total">Итого по позиции - ${price * good.amount}</p>
						</figcaption>
					</figure>
				`;
				const cartQuantity = document.createElement('fieldset');
				cartQuantity.classList.add('cart__quantity');
				const cartQuantityAmount = document.createElement('span');
				const incDecButton = (text, classStr, incDec) => {
					const button = document.createElement('button');
					button.type = 'button';
					button.id = `${(incDec ? 'decrease' : 'increase')}`
					button.innerText = text;
					button.classList.add('cart__quantity-button', `cart__quantity-button--${classStr}`);
					button.onclick = () => {
						store.dispatch(actionCartAdd(good.good, (incDec ? -1 : +1)));
						if(cart[_id].amount > 1 && button.id === 'decrease') {
							button.disabled = false
						}
					}
					if(cart[_id].amount === 1 && button.id === 'decrease') {
						button.disabled = true;
					}
					return button;
				}
				cartQuantityAmount.classList.add('cart__quantity-amount');
				cartQuantityAmount.innerText = good.amount;
				cartElement.append(cartQuantity);
				cartQuantity.append(incDecButton('-', 'decrease', true));
				cartQuantity.append(cartQuantityAmount);
				cartQuantity.append(incDecButton('+', 'increase', false));
				const deleteButton = document.createElement('button');
				deleteButton.type = 'button'
				deleteButton.innerText = 'Удалить товар'
				deleteButton.classList.add('cart__delete-button')
				deleteButton.onclick = () => {
					store.dispatch(actionCartDelete(good.good))
				}
				cartElement.append(deleteButton);
				cartBlock.append(cartElement);
			}
			main.append(cartBlock)
			const totalPrice = document.createElement('p');
			totalPrice.innerHTML = `Итого - <b>${totalAmountByPosition.reduce((a, b) => a + b, 0)}</b>`;
			main.append(totalPrice);
			const makeOrderButton = document.createElement('button');
			makeOrderButton.type = 'button';
			makeOrderButton.innerText = 'Оформить заказ';
			makeOrderButton.classList.add('cart-button');
			makeOrderButton.onclick = () => {
				store.dispatch(actionOrder());
			}
			main.append(makeOrderButton)
		}
	}
}

store.subscribe(drawCart);

store.subscribe(() => {
	const orders = store.getState().promise.myOrders?.payload;
	const [,route] = location.hash.split('/')
	if(orders && route === 'orderhistory') {
		main.innerHTML = '<h1>Мои заказы</h1>';
		const orderCartGroup = document.createElement('div');
		orderCartGroup.classList.add('order-cart-group');
		for (const [index, value] of Object.entries(orders)) {
			const orderCartGroupElement = document.createElement('div');
			orderCartGroupElement.classList.add('order-cart-group__element')
			orderCartGroupElement.innerHTML = `<h2>Заказ №${+index+1} (ID заказа - ${value._id})</h2>`;
			const orderCartElements = document.createElement('div');
			orderCartElements.classList.add('order-cart__elements');
			const totalAll = document.createElement('p');
			totalAll.innerHTML = `<p>Итого - <b>${value.total}</b></p>`;
			for (const goodElement of Object.values(value.orderGoods)) {
				const {price, count, total, good} = goodElement;
				const orderCartElement = document.createElement('div');
				orderCartElement.classList.add('order-cart__element');
				orderCartElement.innerHTML = `
					<figure class="order-cart__figure">
						<a class="order-cart__image-link"
					       href="#/good/${good._id}"
				        >
							<img class="order-cart__image"
								 src="${backendURL + good.images[0]?.url}"
								 alt="${good.name}"
						    >
						</a>
						<figcaption class="order-cart__caption">
							<a class="order-cart__headline-link"
						       href="#/good/${good._id}"
					        >
								<h3 class="order-cart__headline">${good.name}</h3>
							</a>
							
							<p>Цена - ${price}</p>
							<p>Количество - ${count}</p>
							<p>Итого по позиции - ${total}</p>
						</figcaption>
					</figure>
				`;
				orderCartElement.classList.add('order-cart__element');
				orderCartElements.append(orderCartElement)
			}
			orderCartGroupElement.append(orderCartElements);
			orderCartGroupElement.append(totalAll);
			orderCartGroup.append(orderCartGroupElement)
		}
		main.append(orderCartGroup)
	}
})

const drawUserName = () => {
	const buttonLogout = '<button onclick="store.dispatch(actionAuthLogout())" type="button">Выйти</button>';
	const buttonLogin = '<a href="#/login/">Войти</a>';
	const buttonRegister = '<a href="#/register/">Регистрация</a>';

	authSection.innerHTML = store.getState().auth.token ? `Пользователь - <a href="#/orderhistory">${store.getState().auth.payload.sub.login}</a><div>${buttonLogout}</div>` :`Пользователь - <i>anon</i> <div>${buttonLogin}  ${buttonRegister}</div>`;
}
drawUserName() //работаем безусловно при перезагрузке страницы
store.subscribe(drawUserName) //а так же при обновлении redux

// честно стырил отсюда - https://gist.github.com/realmyst/1262561?permalink_comment_id=2299442#gistcomment-2299442
const declOfNum = (n, titles) => titles[(n % 10 === 1 && n % 100 !== 11) ? 0 : n % 10 >= 2 && n % 10 <= 4 && (n % 100 < 10 || n % 100 >= 20) ? 1 : 2];

const drawCardAmount = () => {
	if(store.getState().cart && store.getState().auth.token) {
		let totalAmount = Object.values(store.getState().cart).reduce((a, b) => a + b.amount, 0);
		cartIcon.innerHTML = `<a href="#/cart">Корзина</a> - <b>${totalAmount}</b> ${declOfNum(totalAmount, ['товар', 'товара', 'товаров'])}`;
	}
}
drawCardAmount()
store.subscribe(drawCardAmount)

store.dispatch(actionAuthLogin(localStorage.authToken))
store.dispatch(actionRootCategories())

//#/category/АЙДИШНИК
//#/good/АЙДИШНИК
window.onhashchange = () => {
	const [,route, _id] = location.hash.split('/')

	const routes = {
		category() {
			store.dispatch(actionCategoryById(_id))
		},
		good(){
			store.dispatch(actionGoodById(_id))
		},
		login(){
			main.innerHTML = '';
			const loginForm = new LoginForm(main);
			loginForm.onLogin = () => store.dispatch(actionFullLogin(login.value, password.value))
		},
		register(){
			main.innerHTML = '';
			const registerForm = new LoginForm(main);
			registerForm.setButtonText('Регистрация');
			registerForm.onLogin = () => store.dispatch(actionFullRegister(login.value, password.value));
		},
		cart(){
			drawCart();
		},
		orderhistory(){
			store.dispatch(actionFullOrders())
		}
	}

	if (route in routes){
		routes[route]()
	}
}

window.onhashchange()