backend/controller/authController.js

const fs = require('fs');
const { google } = require('googleapis');
require('dotenv').config();

// import the OAuth2 client
const { oAuth2Client } = require('../config/googleOAuth');

// Controller function for /auth route
const redirectToGoogleOAuth = (req, res) => {
    const authUrl = oAuth2Client.generateAuthUrl({
        access_type: 'offline', // Request offline access for refresh token
        scope: ['https://www.googleapis.com/auth/gmail.send', 'https://www.googleapis.com/auth/calendar'], // Scopes
    });
    res.redirect(authUrl); // Redirect to Google's OAuth consent page
    console.log('Redirecting for OAuth consent...');
};

// Controller function to handle OAuth callback
const handleOAuthCallback = async (req, res) => {
    const code = req.query.code;

    try {
        const { tokens } = await oAuth2Client.getToken(code); // Exchange code for tokens
        console.log('Received tokens:', tokens); // Log tokens for debugging

        // Set tokens to the OAuth2 client
        oAuth2Client.setCredentials(tokens);

        // Save tokens to the .env file
        saveTokensToEnv(tokens);

        res.send('Authorization successful! You can now send emails.');
    } catch (error) {
        console.error('Error during OAuth callback:', error);
        res.status(500).send('Failed to authenticate with Google');
    }
};

// Helper function to save tokens to .env file
const saveTokensToEnv = (tokens) => {
    const envVariables = `
ACCESS_TOKEN=${tokens.access_token}
REFRESH_TOKEN=${tokens.refresh_token || 'No refresh token available'}
    `;

    // Append tokens to the .env file
    fs.appendFileSync('.env', envVariables, 'utf8');
    console.log('Tokens saved to .env file.');
};

module.exports = { redirectToGoogleOAuth, handleOAuthCallback };