// =============================================================================
// Email Helper Functions
// (c) Mathigon
// =============================================================================


import path from 'path';
import {compileFile} from 'pug';
import Sendgrid from '@sendgrid/mail';

import {UserDocument} from '../models/user';
import {CONFIG} from './utilities';


if (CONFIG.accounts.sendgridKey) Sendgrid.setApiKey(CONFIG.accounts.sendgridKey);

function loadEmailTemplate(name: string) {
  const prefix = path.join(__dirname, '../templates/emails/');
  const html = compileFile(`${prefix}/${name}.pug`);
  const text = compileFile(`${prefix}/${name}-simple.pug`);
  return [html, text];
}

type MailData = Omit<Sendgrid.MailDataRequired, 'from'|'to'> & {from?: string, to?: string, user?: UserDocument};

export async function sendEmail(options: MailData) {
  if (!options.from) options.from = `${CONFIG.siteName} <no_reply@${CONFIG.domain}>`;
  if (options.user && !options.to) options.to = `${options.user.fullName} <${options.user.email}>`;

  try {
    return await Sendgrid.send(options as Sendgrid.MailDataRequired);
  } catch (error) {
    console.error(`Failed to send email to`, options.to, error);
  }
}

// -----------------------------------------------------------------------------

const WELCOME = loadEmailTemplate('welcome');
export function sendWelcomeEmail(user: UserDocument) {
  return sendEmail({
    subject: 'Welcome to Mathigon!',
    html: WELCOME[0]({user, config: CONFIG}),
    text: WELCOME[1]({user, config: CONFIG}),
    user
  });
}

const RESET = loadEmailTemplate('reset');
export function sendPasswordResetEmail(user: UserDocument, token: string) {
  return sendEmail({
    subject: 'Mathigon Password Reset',
    html: RESET[0]({user, token, config: CONFIG}),
    text: RESET[1]({user, token, config: CONFIG}),
    user
  });
}

const PASSWORD = loadEmailTemplate('password');
export function sendPasswordChangedEmail(user: UserDocument) {
  return sendEmail({
    subject: 'Mathigon Password Change Notification',
    html: PASSWORD[0]({user, config: CONFIG}),
    text: PASSWORD[1]({user, config: CONFIG}),
    user
  });
}

const CHANGE_EMAIL = loadEmailTemplate('change-email');
export function sendChangeEmailConfirmation(user: UserDocument) {
  return sendEmail({
    subject: 'Confirm your new email address for Mathigon',
    html: CHANGE_EMAIL[0]({user, config: CONFIG}),
    text: CHANGE_EMAIL[1]({user, config: CONFIG}),
    user
  });
}