auth.js

const { app, BrowserWindow } = require('electron');
const { google } = require('googleapis');
const settings = require('electron-settings');
const express = require('express');

async function getCredentials() {
    try {
        const credentials = await settings.get('credentials');
        return JSON.parse(credentials);
    } catch (error) {
        throw error;
    }
}

const getOAuthCodeByInteraction = async (interactionWindow, authPageURL, app) => {
    interactionWindow.loadURL(authPageURL);
    return new Promise(async (resolve, reject) => {
        const onclosed = () => {
            reject('Interaction ended intentionally ;(');
        };
        interactionWindow.on('closed', onclosed);

        app.get('/', (req, res) => {
            let code = req.query.code;
            interactionWindow.removeListener('closed', onclosed);
            interactionWindow.close()

            return resolve(code)

        });
    });
};

const authorize = async () => {
    const credentials = await getCredentials();
    const { client_secret, client_id, redirect_uris } = credentials.installed;
    const redirect_uri = `${redirect_uris[0]}:3011`
    const oauth2Client = new google.auth.OAuth2(
        client_id, client_secret, redirect_uri);

    let token = {};

    // check if we have previously stored a token
    try {
        token = JSON.parse(await settings.get('token'));
        if (!token)
            throw new Error
    } catch (err) {
        const url = oauth2Client.generateAuthUrl({
            scope: ['https://www.googleapis.com/auth/spreadsheets.readonly']
        });
        // set server:
        const app = express();
        const port = 3011;
        const server = app.listen(port)
        server;
        // Create another window and get code;
        const authWindow = new BrowserWindow({ x: 60, y: 60, useContentSize: true });
        const code = await getOAuthCodeByInteraction(authWindow, url, app);
        server.close(() => {
            console.log('server closed')
        })
        try {
            let fetchedTokens = await oauth2Client.getToken(code),
                token = fetchedTokens.tokens
            await storeToken(token)
        } catch (err) {
            console.log('Error while trying to retrieve access token')
            throw err
        }
    }
    oauth2Client.setCredentials(token);
    return oauth2Client
}

async function storeToken(token) {
    try {
        await settings.set('token', JSON.stringify(token));
    } catch (error) {
        throw error;
    }
}


async function fetchData(spreadsheetId, sheetName) {
    try {
        const auth = await authorize();
        const sheets = google.sheets('v4');
        const range = `${sheetName}`
        const response = await sheets.spreadsheets.values.get({ auth, spreadsheetId, range, valueRenderOption: 'UNFORMATTED_VALUE', dateTimeRenderOption: 'SERIAL_NUMBER' })
        const rows = response.data.values
        if (rows.length == 0) {
            console.log('No data found.')
            return
        }
        return rows;
    } catch (err) {
        console.log(`The API returned an error: ${err}`)
        return
    }
}

async function parseSpreadSheetLink({ link }) {
    try {
        const auth = await authorize();
        const pattern = /\/spreadsheets\/d\/([^\/]+)\/edit[^#]*(?:#gid=([0-9]+))?/gm
        let result = pattern.exec(link)
        const spreadsheetId = result[1];
        const tabId = Number(result[2])
        // Getting Sheet Name
        const sheets = google.sheets('v4');
        const sheetNameResponse = await sheets.spreadsheets.get({ auth, spreadsheetId });
        const spreadSheetTitle = sheetNameResponse.data.properties.title;
        const sheetData = sheetNameResponse.data.sheets.filter(item => {
            if (item.properties.sheetId == tabId)
                return item.properties.title
        })
        const sheetName = sheetData[0].properties.title;

        return { spreadSheetTitle, sheetName, spreadsheetId, tabId }
    } catch (error) {
        console.log(`The API returned an error ${error}`)
    }
}

module.exports = {
    authorize,
    parseSpreadSheetLink,
    fetchData
}