mail.js

const {google} = require('googleapis');
const mailComposer = require('nodemailer/lib/mail-composer');
const Attachments = require('./attachments.js');
const fs = require('fs');

class Mail{

  constructor(auth, contact){
    const { emailAddresses, engagementManagers, employerGroupId, companyName } = contact;
    this.gmail = google.gmail({version: 'v1', auth});
    this.auth = auth;
    this.from = 'gretchen.ziegler@sapphire-digital.com';
    this.to = emailAddresses;
    this.cc = engagementManagers;
    this.employerGroupId = employerGroupId;
    this.company = companyName;
    this.task = 'draft';
    this.subject = `November 2019 Invoice for ${companyName}`;

    try {
      this.body = fs.readFileSync('email_body.html', 'utf8');
    } catch(e) {
      throw(`Error: ${e}`);
    }
  }

  createMail(){
    // Get attachments, compile, encode, and send mail.
    let self = this;

    let attachments = new Attachments(this.employerGroupId);

    attachments.encodedList(function(encodedAttachments){
      self.composeMail(self, encodedAttachments).compile().build((err, msg) => {
        // Do not generate invoice if attachments are missing.
        if(err){
          return console.log(`Error compiling email: ${err}`);
        } else if(encodedAttachments.length < 2){
          return console.log(`Will not generate invoice: Attachments missing for ${self.company}`);
        }

        const encodedMessage = Buffer.from(msg)
          .toString('base64')
          .replace(/\+/g, '-')
          .replace(/\//g, '_')
          .replace(/=+$/, '');

        // If the task is 'mail', send automatically. Otherwise, create draft.
        if(self.task === 'mail'){
          self.sendMail(encodedMessage);
        } else {
          self.saveDraft(encodedMessage);
        }
      });
    });
  }

  // Compose mail.
  composeMail(self, attachments){
    return new mailComposer({
      to: self.to,
      cc: self.cc,
      html: self.body,
      subject: self.subject,
      textEncoding: 'base64',
      attachments: attachments
    });
  }

  // Send the message to the specified recipient.
  sendMail(encodedMessage){
    this.gmail.users.messages.send({
      userId: this.from,
      resource: {
        raw: encodedMessage
      }
    }, (err, result) => {
      if(err){
        return console.log(`The API returned an error: ${err}`);
      } else {
        console.log(`Sending email reply from server: ${result.data}`);
      }
    });
  }

  // Save a draft.
  saveDraft(encodedMessage){
    this.gmail.users.drafts.create({
      userId: this.from,
      resource: {
        message: {
          raw: encodedMessage
        }
      }
    }, (err, result) => {
      if(err){
        return console.log(`Error creating draft for ${this.company}: ${err}`);
      } else {
        console.log(`Draft created successfully for ${this.company}`);
      }
    });
  }
}

module.exports = Mail;