import java.util.Properties;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.activation.DataHandler;
import java.io.File;

public class SendFileAttachmentOAuth2 {
    public static void main(String[] args) {
        // Email configuration
        final String username = "ShunYCheung@gmail.com"; // Your Gmail address
        
        // OAuth2 token (you'll need to obtain this separately through the Google OAuth flow)
        // This is not your password, but an access token obtained through OAuth2 authentication
        final String oauth2Token = "wijs04heid"; 
        
        // Recipient email
        String toEmail = "cheung@emory.edu"; // Replace with recipient email
        
        // SMTP properties
        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "587");
        props.put("mail.smtp.auth.mechanisms", "XOAUTH2");
        props.put("mail.smtp.auth.login.disable", "true");
        props.put("mail.smtp.auth.plain.disable", "true");
        
        // Create a custom authenticator for XOAUTH2
        Authenticator authenticator = new Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, oauth2Token);
            }
        };
        
        // Create session with OAuth2 authentication
        Session session = Session.getInstance(props, authenticator);
        
        try {
            // Create message
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(username));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(toEmail));
            message.setSubject("File Attachment");
            
            // Create the message body part
            BodyPart messageBodyPart = new MimeBodyPart();
            messageBodyPart.setText("Please find the attached file.");
            
            // Create multipart message
            Multipart multipart = new MimeMultipart();
            multipart.addBodyPart(messageBodyPart);
            
            // File attachment part
            messageBodyPart = new MimeBodyPart();
            String filename = "x"; // The name of the file to attach
            File file = new File(filename);
            
            if (!file.exists()) {
                System.out.println("File does not exist: " + filename);
                return;
            }
            
            DataSource source = new FileDataSource(file);
            messageBodyPart.setDataHandler(new DataHandler(source));
            messageBodyPart.setFileName(filename);
            multipart.addBodyPart(messageBodyPart);
            
            // Set the complete message parts
            message.setContent(multipart);
            
            // Send message
            System.out.println("Sending email with attachment...");
            Transport.send(message);
            System.out.println("Email sent successfully!");
            
        } catch (MessagingException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }
}