/**
 * Created by Dell on 2020/9/21.
 */
import axios from 'axios'
import { MessageBox, Message } from 'element-ui'
import store from '@/store'
import { getToken, setToken } from '@/utils/auth'

const loginUrl = 'https://xxxxxxxx'

let isRefreshing = false  // 是否正在刷新token

let callbacks = [] // 失效后同时发送请求的容器 -- 缓存接口

// 刷新 token 后, 将缓存的接口重新请求一次
function onAccessTokenFetched(newToken) {
    callbacks.forEach(callback => {
        callback(newToken)
    })
    // 清空缓存接口
    callbacks = []
}

// 添加缓存接口
function addCallbacks(callback) {
    callbacks.push(callback)
}


// create an axios instance
const service = axios.create({
    baseURL: process.env.VUE_APP_BASE_API, // url = base url + request url
    withCredentials: true, // send cookies when cross-domain requests
    timeout: 5000 // request timeout
})

// request interceptor
service.interceptors.request.use(
    config => {
        // do something before request is sent

        if (store.getters.token) {
            // let each request carry token
            // ['X-Token'] is a custom headers key
            // please modify it according to the actual situation
            config.headers['X-Token'] = getToken()
        }
        return config
    },
    error => {
        // do something with request error
        console.log(error) // for debug
        return Promise.reject(error)
    }
)

// response interceptor
service.interceptors.response.use(
    response => {
        const res = response.data
        const options = res.options

        if (res.statusCode === 200) {
            return res
        } else if (res.statusCode === 401 && !options.url.includes(loginUrl)) { // 如果当前状态码为401并且请求的不是登陆接口
            /**
             * 将未授权接口缓存起来。retryOriginalRequest 这个 Promise 函数很关键，它一直处于等待状态。
             * 只有当token刷新成功后，onAccessTokenFetched 这个函数执行了回调函数，返回了 resolve 状态
             */
            const retryOriginalRequest = new Promise(resolve => {
                addCallbacks(newToken => {
                    // 表示用新的token去替换掉原来的token
                    options.header.Authorization = newToken
                    // 替换掉url -- 因为baseURL会扩展请求url
                    options.url = options.url.replace(process.env.VUE_APP_BASE_API, '')
                    resolve(service.request(options)) // 调用resolve请求队列里面接口
                })

                // 无感刷新Token
                if (!isRefreshing) {
                    isRefreshing = true
                    refreshToken().then(res => {  // 用rftoken获取新的token
                        const newToken = res.token
                        const newRefreshToken = res.refreshToken
                        // setToken()
                        // setRefreshToken()
                        onAccessTokenFetched(newToken)
                    }).catch(() => {
                        // 刷新token报错的话, 就需要跳转到登录页面
                        // setToken('')
                        // setRefreshToken('')
                        Message({
                            message: res.message || 'Error',
                            type: 'error',
                            duration: 5 * 1000
                        })
                        // to re-login
                        MessageBox.confirm('You have been logged out, you can cancel to stay on this page, or log in again', 'Confirm logout', {
                            confirmButtonText: 'Re-Login',
                            cancelButtonText: 'Cancel',
                            type: 'warning'
                        }).then(() => {
                            store.dispatch('user/resetToken').then(() => {
                                location.reload()
                            })
                        })
                    }).finally(() => {
                        isRefreshing = false
                    })
                }
            })
            return retryOriginalRequest // 将token过期期间请求的接口包装成promise返回，等待刷新token后重新请求
        } else {
            return Promise.reject(new Error(res.message || 'Error'))
        }
    },
    error => {
        console.log('err' + error) // for debug
        Message({
            message: error.message,
            type: 'error',
            duration: 5 * 1000
        })
        return Promise.reject(error)
    }
)

export default service