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 combineReducers(reducers) {
    return (state={}, action) => {
        const newState = {}
        // перебрать все редьюсеры
        if (reducers) {
            for (const [reducerName, reducer] of Object.entries(reducers)) {
                const newSubState = reducer(state[reducerName], action)
                if (newSubState !== state[reducerName]) {
                    newState[reducerName] = newSubState
                }
            }
            // если newState не пустой, то вернуть стейт в 
            if (Object.keys(newState).length !== 0) {
                return {...state, ...newState}
            } else {
                return state
            }
        }

    }
}
const combinedReducer = combineReducers({promise: promiseReducer, auth: authReducer})
const store = createStore(combinedReducer)
// console.log(store.getState()) // {promise: {}, auth: {}}




function jwtDecode(token) {
    try {
        let decoded = JSON.parse(atob(token.split('.')[1])) 
        return decoded
    } catch (err) {
        console.log(err)
    }
}

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

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

// const loginStore = createStore(authReducer)
store.subscribe(() => console.log(store.getState()))


// const inputToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOnsiaWQiOiI2MWE0ZGIyOWM3NTBjMTJiYTZiYTQwMjIiLCJsb2dpbiI6ImVxd2VxZXdldyIsImFjbCI6WyI2MWE0ZGIyOWM3NTBjMTJiYTZiYTQwMjIiLCJ1c2VyIl19LCJpYXQiOjE2MzgxOTQ1NzZ9.Pi1GO6x7wdNrIrUKCQT-32-SsqmgFY-oFDrrXmw74-8'

// loginStore.dispatch(actionAuthLogin(inputToken))
// loginStore.dispatch(actionAuthLogout())
// console.log(store.getState())







function promiseReducer(state={}, {type, status, payload, error, name}) {
    if (!state) {
        return {}
    }
    if (type === 'PROMISE') {         
        return {
            ...state,
            [name]: {
                status: status,
                payload : payload,
                error: 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 promiceStore = createStore(promiseReducer)
// store.subscribe(() => console.log(store.getState()))


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

// // store.dispatch(actionPending('delay1000'))
// // delay(1000).then(data => store.dispatch(actionResolved('delay1000', data)),
// //                  error => store.dispatch(actionRejected('delay1000', error)))

// // store.dispatch(actionPending('delay2000'))
// // delay(2000).then(data => store.dispatch(actionResolved('delay2000', data)),
// //                  error => store.dispatch(actionRejected('delay2000', 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 getGQL = url =>
  async (query, variables={}) => {
    // try {
      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))
      } else {
          return a.data[Object.keys(a.data)[0]]
      }      
    // }
    // catch (error) {
    //   console.log('Что-то не так, Бро ' + error);
    // }
  }

  const backURL = 'http://shop-roles.asmer.fs.a-level.com.ua/'
  const gql = getGQL(backURL + 'graphql');




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

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


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

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


// regBtn.onclick = () => {
//     store.dispatch(actionFullRegister(loginReg.value, passReg.value))
// }


// loginBtn.onclick = () => {
//     store.dispatch(actionFullLogin(loginInput.value, passInput.value))
// }

// logoutBtn.onclick = () => {
//     store.dispatch(actionAuthLogout())
// }




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

const actionCatById = (_id) => ( //добавить подкатегории
    actionPromise('catById', gql(`query catById($q: String){
        CategoryFindOne(query: $q){
            _id name goods {
                _id name price images {
                    url
                }
            }
            subCategories {
                _id name 
            }
        }
    }`, {q: JSON.stringify([{_id}])}))
)
// actionGoodById по аналогии

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

const actionGoodsByUser = () => (
actionPromise('goodByUser', gql(`query oUser($query: String) {
    OrderFind(query:$query){
       _id orderGoods{
            price count total good{
                _id name categories{
                name
                }
                images {
                    url
                }
            }
        } 
        owner {
           _id login
          }
    }
  }`, 
   {query: JSON.stringify([{}])}))
)

  
store.dispatch(actionRootCats())

store.subscribe(() => {
    const {promise} = store.getState()
    const {rootCats} = promise
    if (rootCats?.payload) {

        aside.innerHTML = ''

        const regBtn = document.createElement('a')
        regBtn.href = `#/register`
        regBtn.innerText = 'Register'

        const loginBtn = document.createElement('a')
        loginBtn.href = `#/login`
        loginBtn.innerText = 'Login'

        const logoutBtn = document.createElement('button')
        logoutBtn.innerText = 'Logout'
        aside.append(regBtn, loginBtn, logoutBtn)

        logoutBtn.onclick = () => {
            store.dispatch(actionAuthLogout())
        }

        for (const {_id, name} of rootCats?.payload) {
            const link = document.createElement('a')
            link.href = `#/category/${_id}`
            link.innerText = name
            aside.append(link)
        }
    }
})


// location.hash - адресная строка после решетки
window.onhashchange = () => {
    const [,route, _id] = location.hash.split('/')

    const routes = {
        category(){
            store.dispatch(actionCatById(_id))
            console.log('страница категорий')           
        },
        good(){ //задиспатчить actionGoodById
            store.dispatch(actionGoodById(_id))
            console.log('страница товара')                
        },
        register(){
            let goRegister = createForm(main, 'Register', actionFullRegister)
            goRegister()
        },
        login(){
            let goLogin = createForm(main, 'Login', actionFullLogin)
            goLogin()
        },
        orders(){
            store.dispatch(actionGoodsByUser())
        }        
    }
    if (route in routes) {
        routes[route]()
    }
}


function createForm(parent, type, callback) {
    parent.innerHTML = ` 
    <input id="login${type}" type="text"/>
    <input id="pass${type}" type="password"/>
    <button id="btn${type}">${type}</button>
    `
    return () => window[`btn${type}`].onclick = () => {
                    store.dispatch(callback(window[`login${type}`].value, window[`pass${type}`].value))
                    window[`pass${type}`].value = ''
                }
}

window.onhashchange()

store.subscribe(() => {
    const {promise} = store.getState()
    const {catById} = 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 link      = document.createElement('a');
                link.href       = `#/category/${_id}`;
                link.innerText  = name;
                main.append(link);
            }
        }
        
        if (catById.payload.goods) {
            for (const {_id, name, price, images} of catById.payload.goods){
                const card      = document.createElement('div')
                card.innerHTML = `<h2>${name}</h2>
                                  <img src="${backURL}/${images[0].url}" />
                                  <strong>${price}</strong>
                                  <br>
                                  <a href="#/good/${_id}">Перейти на страницу товара</a>
                                `
                main.append(card)
            }
        }
    }
})

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


store.subscribe(() => {
    const {auth} = store.getState()
    const {payload} = auth
    if (payload?.sub ) {
        topContaner.innerHTML = ''
        const {id, login}  = payload.sub
        const name = document.createElement('div')
        name.innerText = `ПРИВЕТ ${login}`
        topContaner.append(name)
        const myOrders = document.createElement('a')
        myOrders.innerText = 'Мои заказы'
        myOrders.href       = `#/orders/${id}`
        topContaner.append(myOrders)
    } else {
        topContaner.innerHTML = ''
    }
})



store.subscribe(() => {
    const {promise} = store.getState()
    const {goodByUser} = promise
    const [,route] = location.hash.split('/')
    if (goodByUser?.payload && route === 'orders'){

        main.innerHTML = ''   

        if (goodByUser.payload) {
            let totalMoney = 0

            for (const order of goodByUser.payload) {

                if (order.orderGoods) {
                    for (const {price, count, total, good} of order.orderGoods) {
                        if (price !== null && count !== null && total !== null && good !== null) {
                            totalMoney += total                            
                            const {_id, name, images} = good                            

                            const card      = document.createElement('div')
                            card.innerHTML  = `<h2>${name}</h2>
                                                 <img src="${backURL}/${images[0].url}" />
                                                 <strong>Куплено ${count} по ${price} грн. Итого:${total}</strong>
                                                 <br>
                                                 <a href="#/good/${_id}">Перейти на страницу товара</a>
                                             `
                            main.append(card)
                        }
                    }
                }

            }
            const totalBlock = document.createElement('b')
            totalBlock.innerText = 'Итого потрачено: ' + totalMoney + ' грн'
            main.append(totalBlock)
        }
    }
})

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