email_API4.js

const { google } = require('googleapis');
const express = require('express');
const xlsx = require('xlsx'); // Importing xlsx to handle Excel files
const app = express();
const emailValidator = require('email-validator'); // Ensure to install this package using npm
const { SMTPClient } = require('smtp-client'); // For SMTP verification
const dns = require('dns');
require('dotenv').config();

const CLIENT_ID = process.env.CLIENT_ID;
const CLIENT_SECRET = process.env.CLIENT_SECRET;
const REDIRECT_URI = process.env.REDIRECT_URI;

const oauth2Client = new google.auth.OAuth2(
    CLIENT_ID,
    CLIENT_SECRET,
    REDIRECT_URI
);

// Function to fetch recipients from Excel file
function getRecipientsFromExcel(filePath) {
    const workbook = xlsx.readFile(filePath);
    const sheetName = workbook.SheetNames[0]; // Assuming data is in the first sheet
    const worksheet = workbook.Sheets[sheetName];

    const recipients = xlsx.utils.sheet_to_json(worksheet, { header: 1 }) // Get data as an array
        .slice(1) // Skip header row
        .map(row => ({
            name: row[0], // Assuming Name is in the first column
            email: row[1] // Assuming Email is in the second column
        }));

    return recipients;
}

async function getMXServer(domain) {
    return new Promise((resolve, reject) => {
        dns.resolveMx(domain, (err, addresses) => {
            if (err || !addresses || addresses.length === 0) {
                reject(new Error(`MX record lookup failed for domain: ${domain}`));
            } else {
                // Sort by priority to pick the most preferred mail server
                const sortedAddresses = addresses.sort((a, b) => a.priority - b.priority);
                resolve(sortedAddresses[0].exchange);
            }
        });
    });
}

async function verifyEmailSMTP(email) {
    const domain = email.split('@')[1];

    try {
        const mxServer = await getMXServer(domain);
        const client = new SMTPClient({
            host: mxServer,
            port: 25,
            tls: false
        });

        await client.connect();
        await client.greet({ hostname: 'localhost' });
        await client.mail({ from: 'mounika.aeleshwaram@poulimainfo.tech' });
        await client.rcpt({ to: email });
        await client.quit();
        return true; // Email exists
    } catch (error) {
        console.log(`SMTP check failed for ${email}: ${error.message}`);
        return false; // Email does not exist or server rejected the query
    }
}

const recipients = getRecipientsFromExcel('email-api.xlsx'); // Path to your Excel file

// Delay function to pause for 5 seconds
const delay = (ms) => new Promise(resolve => setTimeout(resolve, ms));

app.get('/oauth2callback', async (req, res) => {
    const code = req.query.code;

    if (code) {
        try {
            const { tokens } = await oauth2Client.getToken(code);
            oauth2Client.setCredentials(tokens);

            const gmail = google.gmail({ version: 'v1', auth: oauth2Client });

            // Function to send email with personalized content and HTML signature
            const sendEmail = async (recipient) => {
                const mailOptions = {
                    from: '"Mounika" <mounika.aeleshwaram@poulimainfo.tech>',
                    to: recipient.email,
                    cc: 'saheli.samanta@poulimainfo.tech', // Add CC emails here
                    subject: `Re: Hire skilled Full Stack developers at affordable prices!`,
                    text: `Hi ${recipient.name}, just following up on my previous email regarding skilled developers. Please refer to the quoted message below.`, // Text version for non-HTML email clients
                    html: `
                    <p>Hi ${recipient.name},</p>
                    <p>I hope this message finds you well! I wanted to follow up on my previous email about our skilled Full Stack developers available at Poulima Infotech.</p>
                    <p>If you’re interested in exploring further, please feel free to reach out. I’d be happy to discuss your requirements and share relevant developer profiles with you.</p>
                    <p>Looking forward to your response!</p>
                
                    <p>Thanks & Regards,</p>
                
                    <table style="width: 100%; max-width: 500px; border-collapse: collapse;">
                        <tr style="height: 100px;">
                            <td style="padding: 10px; width: 42%; vertical-align: middle; text-align: center; box-shadow: 10px 0 10px -10px rgba(0, 0, 0, 0.3);">
                                <img src="https://www.poulimainfo.tech/wp-content/uploads/2022/04/Poulima-Infotech-Color-Logo.png" alt="logo" style="width: 100%; max-width: 150px; height: auto;" />
                            </td>
                            <td style="padding: 10px; width: 58%; vertical-align: middle; font-family: Arial, sans-serif;">
                                <p style="font-weight: bold; margin: 0;">Mounika Aeleshwaram</p>
                                <p style="font-weight: bold; margin: 0;">Business Development Executive</p>
                                <p style="margin: 0;"><b>T:</b> +91 (912) 120-2538</p>
                                <p style="margin: 0;"><b>E:</b> <a href="mailto:mounika.aeleshwaram@poulimainfo.tech">mounika.aeleshwaram@poulimainfo.tech</a> | <a href="https://www.poulimainfo.tech/">www.poulimainfo.tech</a></p>
                                <p style="margin: 0;">Whitefield, Bangalore | 560066, India</p>
                            </td>
                        </tr>
                    </table>
                
                    <hr style="border: none; border-top: 1px solid #ddd; margin: 20px 0;">
                    
                    <p style="color: #500050;"><strong>On Sun, 10 Nov 2024 at 20:00, Mounika &lt;mounika.aeleshwaram@poulimainfo.tech&gt; wrote:</strong></p>
                    
                    <blockquote style="border-left: 1px solid #CCCCCC; padding-left: 1ex; color: #500050;">
                        <p>Hi Team,</p>
                        <p>Greetings! My name is Mounika, and I represent the On-Demand Software Developers Team at Poulima Infotech.</p>
                        <p>Poulima Infotech is an India-based, ISO 9001:2015 Certified company recognized by DPIIT. We offer highly skilled React, React Native developers and programmers for hire on a contract basis.</p>
                        <p>If you are interested, I would be happy to share our developer profiles with you.</p>
                        <p>Thank you for considering us. We look forward to the possibility of working together and meeting your requirements.</p>
                        <p>For instant communication, please WhatsApp us at +91 9121202538.</p>
                        <p>Looking forward to hearing from you soon!</p>
                        <p>Thanks & Regards,</p>
                        
                        <table style="width: 100%; max-width: 500px; border-collapse: collapse;">
                            <tr style="height: 100px;">
                                <td style="padding: 10px; width: 42%; vertical-align: middle; text-align: center; box-shadow: 10px 0 10px -10px rgba(0, 0, 0, 0.3);">
                                    <img src="https://www.poulimainfo.tech/wp-content/uploads/2022/04/Poulima-Infotech-Color-Logo.png" alt="logo" style="width: 100%; max-width: 150px; height: auto;" />
                                </td>
                                <td style="padding: 10px; width: 58%; vertical-align: middle; font-family: Arial, sans-serif;">
                                    <p style="font-weight: bold; margin: 0;">Mounika Aeleshwaram</p>
                                    <p style="font-weight: bold; margin: 0;">Business Development Executive</p>
                                    <p style="margin: 0;"><b>T:</b> +91 (912) 120-2538</p>
                                    <p style="margin: 0;"><b>E:</b> <a href="mailto:mounika.aeleshwaram@poulimainfo.tech">mounika.aeleshwaram@poulimainfo.tech</a> | <a href="https://www.poulimainfo.tech/">www.poulimainfo.tech</a></p>
                                    <p style="margin: 0;">Whitefield, Bangalore | 560066, India</p>
                                </td>
                            </tr>
                        </table>
                    </blockquote>
                    `
                };
                

                // const mailOptions = {
                //     from: '"Mounika" <mounika.aeleshwaram@poulimainfo.tech>',
                //     to: recipient.email,
                //     subject: `Hire skilled Full Stack developers at affordable prices!`,
                //     text: `Hi ${recipient.name}, this is your personalized message!`,
                //     html: `
                //     <p>Hi Team,</p>
                //     <p>Greetings! My name is Naveena, and I represent the On-Demand Software Developers Team at Poulima Infotech.</p>
                //     <p>Poulima Infotech is an India-based, ISO 9001:2015 Certified company recognized by DPIIT. We offer highly skilled React, React Native developers and programmers for hire on a contract basis.</p>
                //     <p>If you are interested, I would be happy to share our developer profiles with you.</p>
                //     <p>Thank you for considering us. We look forward to the possibility of working together and meeting your requirements.</p>
                //     <p>For instant communication, please WhatsApp us at +91 6304116234.</p>
                //     <p>Looking forward to hearing from you soon!</p>
                //     <p>Thanks & Regards,</p>
                //     <table style="width: 100%; max-width: 500px; border-collapse: collapse;">
                //     <tr style="height: 100px;">
                //         <td style="padding: 10px; width: 42%; vertical-align: middle; text-align: center; box-shadow: 10px 0 10px -10px rgba(0, 0, 0, 0.3);">
                //             <img src="https://www.poulimainfo.tech/wp-content/uploads/2022/04/Poulima-Infotech-Color-Logo.png" alt="logo" style="width: 100%; max-width: 150px; height: auto;" />
                //         </td>
                //         <td style="padding: 10px; width: 58%; vertical-align: middle; font-family: Arial, sans-serif;">
                //             <p style="font-weight: bold; margin: 0;">Pavan Kalyan</p>
                //             <p style="font-weight: bold; margin: 0;">Business Development Manager</p>
                //             <p style="margin: 0;"><b>T:</b> +91 (630) 411-6234</p>
                //             <p style="margin: 0;"><b>E:</b> <a href="mailto:kalyan@poulimainfo.tech">kalyan@poulimainfo.tech</a> | <a href="https://www.poulimainfo.tech/">www.poulimainfo.tech</a></p>
                //             <p style="margin: 0;">Whitefield, Bangalore | 560066, India</p>
                //         </td>
                //     </tr>
                //     </table>
                //     `
                // };

                const encodedEmail = Buffer.from([
                    `From: ${mailOptions.from}`,
                    `To: ${mailOptions.to}`,
                    `Subject: ${mailOptions.subject}`,
                    `MIME-Version: 1.0`,
                    `Content-Type: text/html; charset=UTF-8`,
                    '',
                    mailOptions.html
                ].join('\n')).toString('base64')
                    .replace(/\+/g, '-')
                    .replace(/\//g, '_')
                    .replace(/=+$/, '');

                return await gmail.users.messages.send({
                    userId: 'me',
                    requestBody: {
                        raw: encodedEmail,
                    },
                });
            };

            // Send emails to all recipients with a 5-second delay between each
            for (let i = 0; i < recipients.length; i++) {
                const recipient = recipients[i];
                
                // Step 1: Syntax validation
                // if (!emailValidator.validate(recipient.email)) {
                //     console.log(`Skipping invalid email: ${recipient.email}`);
                //     continue;
                // }

                // Step 2: SMTP validation
                // try {
                //     const isEmailValid = await verifyEmailSMTP(recipient.email);
                //     if (!isEmailValid) {
                //         console.log(`Skipping non-existent email: ${recipient.email}`);
                //         continue;
                //     }
                // } catch (verificationError) {
                //     console.log(`Verification failed for ${recipient.email}: ${verificationError.message}`);
                //     continue; // Skip to the next email if verification fails
                // }

                // Step 3: Send email
                try {
                    await sendEmail(recipient);
                    console.log(`${i + 1}/${recipients.length} emails sent to ${recipient.email}`);
                } catch (sendingError) {
                    console.log(`Error sending email to ${recipient.email}: ${sendingError.message}`);
                    // Continue to next email if an error occurs
                }

                await delay(5000); // 5-second delay between emails
            }

            res.send('All emails processed successfully!');
        } catch (error) {
            res.status(500).send('Error sending email: ' + error.message);
        }
    } else {
        res.status(400).send('No authorization code provided.');
    }
});

app.listen(3000, () => {
    console.log('Server is running on http://localhost:3000');
});