index.js

var googleAuth = (function () {

    function installClient() {
        var apiUrl = 'https://apis.google.com/js/api.js'
        return new Promise((resolve) => {
            var script = document.createElement('script')
            script.src = apiUrl
            script.onreadystatechange = script.onload = function () {
                if (!script.readyState || /loaded|complete/.test(script.readyState)) {
                    setTimeout(function () {
                        resolve()
                    }, 500)
                }
            }
            document.getElementsByTagName('head')[0].appendChild(script)
        })
    }

    function initClient(config) {
        return new Promise((resolve) => {
            window.gapi.load('auth2', () => {
                window.gapi.auth2.init(config)
                    .then(() => {
                        resolve(window.gapi)
                    })
            })
        })

    }

    function Auth() {
        if (!(this instanceof Auth))
            return new Auth()
        this.GoogleAuth = null /* window.gapi.auth2.getAuthInstance() */
        this.isAuthorized = false
        this.isInit = false
        this.prompt = null
        this.config = {}

        this.isLoaded = function () {
            /* eslint-disable */
            console.warn('isLoaded() will be deprecated. You can use "this.$gAuth.isInit"')
            return !!this.GoogleAuth
        };

        this.init = (config, prompt) => {
            this.prompt = prompt
            this.config = config
            if(config.autoload) {
                this.load()
            }
        }

        this.load = () => {
            installClient()
                .then(() => {
                    return initClient(this.config)
                })
                .then((gapi) => {
                    this.GoogleAuth = gapi.auth2.getAuthInstance()
                    this.isInit = true
                    this.isAuthorized = this.GoogleAuth.isSignedIn.get()
                })
        };

        this.signIn = (successCallback, errorCallback) => {
            return new Promise((resolve, reject) => {
                if (!this.GoogleAuth) {
                    if (typeof errorCallback === 'function') errorCallback(false)
                    reject(false)
                    return
                }
                this.GoogleAuth.signIn()
                    .then(googleUser => {
                        if (typeof successCallback === 'function') successCallback(googleUser)
                        this.isAuthorized = this.GoogleAuth.isSignedIn.get()
                        resolve(googleUser)
                    })
                    .catch(error => {
                        if (typeof errorCallback === 'function') errorCallback(error)
                        reject(error)
                    })
            })
        };

        this.getAuthCode = (successCallback, errorCallback) => {
            return new Promise((resolve, reject) => {
                if (!this.GoogleAuth) {
                    if (typeof errorCallback === 'function') errorCallback(false)
                    reject(false)
                    return
                }
                this.GoogleAuth.grantOfflineAccess({ prompt: this.prompt })
                    .then(function (resp) {
                        if (typeof successCallback === 'function') successCallback(resp.code)
                        resolve(resp.code)
                    })
                    .catch(function (error) {
                        if (typeof errorCallback === 'function') errorCallback(error)
                        reject(error)
                    })
            })
        };

        this.signOut = (successCallback, errorCallback) => {
            return new Promise((resolve, reject) => {
                if (!this.GoogleAuth) {
                    if (typeof errorCallback === 'function') errorCallback(false)
                    reject(false)
                    return
                }
                this.GoogleAuth.signOut()
                    .then(() => {
                        if (typeof successCallback === 'function') successCallback()
                        this.isAuthorized = false
                        resolve(true)
                    })
                    .catch(error => {
                        if (typeof errorCallback === 'function') errorCallback(error)
                        reject(error)
                    })
            })
        };
    }

    return new Auth()
})();




function installGoogleAuthPlugin(Vue, options) {
    /* eslint-disable */
    //set config
    let GoogleAuthConfig = null
    let GoogleAuthDefaultConfig = { scope: 'profile email', discoveryDocs: ['https://www.googleapis.com/discovery/v1/apis/drive/v3/rest'], autoload: true }
    let prompt = 'select_account'
    if (typeof options === 'object') {
        GoogleAuthConfig = Object.assign(GoogleAuthDefaultConfig, options)
        if (options.scope) GoogleAuthConfig.scope = options.scope
        if (options.prompt) prompt = options.prompt
        if (!options.clientId) {
            console.warn('clientId is required')
        }
    } else {
        console.warn('invalid option type. Object type accepted only')
    }

    //Install Vue plugin
    Vue.gAuth = googleAuth
    Object.defineProperties(Vue.prototype, {
        $gAuth: {
            get: function () {
                return Vue.gAuth
            }
        }
    })
    Vue.gAuth.init(GoogleAuthConfig, prompt)
}

export default installGoogleAuthPlugin