// функция createStore

function createStore(reducer) {
    let state = reducer(undefined, {})
    let cbs = []

    function dispatch(action) {
        if (typeof action === 'function') {
            return action(dispatch)
        }

        const newState = reducer(state, action)
        if (newState !== state) {
            state = newState
            for (let cb of cbs)
                cb()
        }
    }
    
    return {
        dispatch,
        getState() {
            return state
        },
        subscribe(cb) {
            cbs.push(cb)
            return () => cbs = cbs.filter(c => c !== cb)
        }
    }
}

// функция promiseReducer

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

    return state
}

const store = createStore(promiseReducer)

// actions

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 payload = await promise
            dispatch(actionResolved(name, payload)) 
            return payload
        }
        catch(error){
             dispatch(actionRejected(name, error))
        }
    }

// функция cartReducer

function cartReducer(state = {}, { type, count = 1, _id, name }) {
    if (type === "CART_ADD") {
        return {
            ...state,
            [_id]: {
                name: name,
                count: state[_id] ? state[_id].count + count : count
            }
        }
    }

    if (type === "CART_CHANGE") {
        return {
            ...state,
            [_id]: {
                name: name,
                count: count
            }
        }
    }

    if (type === 'CART_REMOVE') {
        let { [_id]: count, ...copyWithout } = state
        return copyWithout
    }

    if (type === 'CART_CLEAR') {
        return {}
    }

    return state
}

//  reducers 

let reducers = {
    promise: promiseReducer,
    cart: cartReducer
}

// функция combineReducers

function combineReducers(reducers) {
    function commonReducer(state = {}, action) {
        let newState = {}

        for (let key in reducers) {
            let innerState = reducers[key](state[key], action)

            innerState === state[key] ? newState[key] = state[key] : newState[key] = innerState
        }

        return newState
    }

    return commonReducer
}

// запросы

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())

let shopGQL = getGQL("http://shop-roles.asmer.fs.a-level.com.ua/graphql")

const actionRootCategories = () =>
    actionPromise('rootCategories', shopGQL(`query cats($query:String) {
        CategoryFind(query:$query) {
            _id name 
        }
    }`, {query: JSON.stringify([{parent:null}])}))

store.dispatch(actionRootCategories())

const actionCategoryById = (_id) => 
    actionPromise('catById', shopGQL(`query catById($query:String) {
        CategoryFindOne(query:$query) {
            _id name goods {
                _id name price description images {
                    url
                }
            }
        }
    }`, {query: JSON.stringify([{_id}])}))

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


window.onhashchange = () => {
    let { 1: route, 2: id } = location.hash.split('/')
    if (route === 'categories') {
        store.dispatch(actionCategoryById(id))
    }

    if (route === 'good') {
        store.dispatch(actionGoodById(id))
    }
}

function drawMainMenu() {
    let cats = store.getState().rootCategories.payload
    if (cats) {
        aside.innerText = ''
        for (let { _id, name } of cats.data.CategoryFind) {
            let catA = document.createElement('a')
            catA.href = `#/categories/${_id}`
            catA.innerText = name
            aside.append(catA)
        }
    }
}

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

store.subscribe(() => {
    const { 1: route, 2: id } = location.hash.split('/')
    if (route === 'categories') {
        const catById = store.getState().catById?.payload
        if (catById) {
            aside.innerText = ''
            let cats = document.createElement('p')
            cats.innerText = "Вы в категории ==>" + " " + catById.data.CategoryFindOne.name
            mainMenu = document.createElement('a')
            mainMenu.innerText = "Назад в главное меню"
            mainMenu.onclick = () => {
                main.innerText = ''
                drawMainMenu()
            }
            aside.append(mainMenu, cats)

            let goods = catById.data.CategoryFindOne.goods
            for (let {_id, name, price, description, images} of goods) {
                let div = document.createElement('div')
                div.className = 'goods'
                let btnCart = document.createElement('btn')
                let btn = document.createElement('button')
                btn.textContent = "Добавить в карзину"
                let img = document.createElement('img')
                img.style.width ='400px'
                img.src = `http://shop-roles.asmer.fs.a-level.com.ua/${images[0].url}`
                let prices = document.createElement('span')
                let descriptions = document.createElement('p')
                prices.innerText = `Цена: ${price} грн`
                descriptions.innerText = `Описание: ${description}`
                let goodA = document.createElement('a')
                goodA.href = `#/good/${_id}`
                goodA.innerText = name
                main.append(div)
                btnCart.append(btn)
                div.append(goodA, img, prices, descriptions, btnCart)
            }
        }
    }
    if (route === 'good') {
        const goodById = store.getState().goodById?.payload
        const catById = store.getState().catById?.payload
        if (goodById) {
            aside.innerText = ''
            main.innerText = ''
            let cats = document.createElement('p')
            cats.innerText = "Вы в категории ==>" + " " + catById.data.CategoryFindOne.name
            menuGoods = document.createElement('a')
            menuGoods.innerText = catById.data.CategoryFindOne.name  + " " + "<== Назад в список товаров"
            mainMenu = document.createElement('a')
            mainMenu.innerText = "Назад в главное меню"
            mainMenu.onclick = () => {
                main.innerText = ''
                drawMainMenu()
            }
            aside.append(mainMenu, cats)

            let good = goodById.data.GoodFind
            for (let {name, price, description, images} of good) {
                let div = document.createElement('div')
                div.className = 'good'
                let btn = document.createElement('button')
                btn.textContent = "Добавить в карзину"
                let img = document.createElement('img')
                img.style.width ='400px'
                img.src = `http://shop-roles.asmer.fs.a-level.com.ua/${images[0].url}`
                let prices = document.createElement('span')
                let descriptions = document.createElement('p')
                prices.innerText = `Цена: ${price} грн`
                descriptions.innerText = `Описание: ${description}`
                let goodA = document.createElement('a')
                goodA.innerText = name
                main.append(div)
                div.append(goodA, img, prices, descriptions, btn)
            }
        }
    }
})