// email.js
// Copyright (C) 2021 Digital Telepresence, LLC
// License: Apache-2.0

'use strict';

const path = require('path');
const pug = require('pug');

const nodemailer = require('nodemailer');

const mongoose = require('mongoose');
const EmailBlacklist = mongoose.model('EmailBlacklist');

const disposableEmailDomains = require('disposable-email-provider-domains');
const emailValidator = require('email-validator');
const emailDomainCheck = require('email-domain-check');

const { SiteService } = require('../../lib/site-lib');

class EmailService extends SiteService {

  constructor (dtp) {
    super(dtp, module.exports);
  }

  async start ( ) {
    await super.start();

    if (process.env.DTP_EMAIL_ENABLED !== 'enabled') {
      return;
    }

    const SMTP_PORT = parseInt(process.env.DTP_EMAIL_SMTP_PORT || '587', 10);
    this.log.info('creating SMTP transport', {
      host: process.env.DTP_EMAIL_SMTP_HOST,
      port: SMTP_PORT,
    });
    this.transport = nodemailer.createTransport({
      host: process.env.DTP_EMAIL_SMTP_HOST,
      port: SMTP_PORT,
      secure: process.env.DTP_EMAIL_SMTP_SECURE === 'enabled',
      auth: {
        user: process.env.DTP_EMAIL_SMTP_USER,
        pass: process.env.DTP_EMAIL_SMTP_PASS,
      },
      pool: true,
      maxConnections: parseInt(process.env.DTP_EMAIL_SMTP_POOL_MAX_CONN || '5', 10),
      maxMessages: parseInt(process.env.DTP_EMAIL_SMTP_POOL_MAX_MSGS || '5', 10),
    });

    this.templates = {
      html: {
        welcome: pug.compileFile(path.join(this.dtp.config.root, 'app', 'templates', 'html', 'welcome.pug')),
      },
      text: {
        welcome: pug.compileFile(path.join(this.dtp.config.root, 'app', 'templates', 'text', 'welcome.pug')),
      },
    };
  }

  async send (message) {
    this.log.info('sending email', { to: message.to, subject: message.subject });
    await this.transport.sendMail(message);
  }

  async checkEmailAddress (emailAddress) {
    this.log.debug('validating email address', { emailAddress });
    if (!emailValidator.validate(emailAddress)) {
      throw new Error('Email address is invalid');
    }

    const domainCheck = await emailDomainCheck(emailAddress);
    this.log.debug('email domain check', { domainCheck });
    if (!domainCheck) {
      throw new Error('Email address is invalid');
    }

    await this.isEmailBlacklisted(emailAddress);
  }

  async isEmailBlacklisted (emailAddress) {
    emailAddress = emailAddress.toLowerCase().trim();

    const domain = emailAddress.split('@')[1];
    this.log.debug('checking email domain for blacklist', { domain });
    if (disposableEmailDomains.domains.includes(domain)) {
      this.log.alert('blacklisted email domain blocked', { emailAddress, domain });
      throw new Error('Invalid email address');
    }

    const blacklistRecord = await EmailBlacklist.findOne({ email: emailAddress });
    if (blacklistRecord) {
      throw new Error('Email address has requested to not receive emails', { blacklistRecord });
    }

    return false;
  }

  async renderTemplate (templateId, templateType, message) {
    return this.templates[templateType][templateId](message);
  }
}

module.exports = {
  slug: 'email',
  name: 'email',
  create: (dtp) => {
    return new EmailService(dtp);
  },
};