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

'use strict';

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

const mailgun = require('mailgun-js');

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_MAILGUN_ENABLED === 'enabled') {
      this.mg = mailgun({
        apiKey: process.env.MAILGUN_API_KEY,
        domain: process.env.MAILGUN_DOMAIN,
      });
    }

    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) {
    return new Promise((resolve, reject) => {
      this.log.info('sending email', { to: message.to, subject: message.subject });
      this.mg.messages().send(message, async (error, body) => {
        if (error) {
          return reject(error);
        }
        resolve(body);
      });
    });
  }

  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);
  },
};