const moment = require('moment');
const uuid = require('uuid/v4');
const { DOWNLOAD_LINK_SUBJECT } = require('./constants');

async function sendDownloadLink({
  user,
  loaders: { Settings },
  connectors: {
    errors,
    secrets,
    services: { Users, I18n, Limit },
    models: { User },
  },
}) {
  // downloadLinkLimiter can be used to limit downloads for the user's data to
  // once every 7 days.
  const downloadLinkLimiter = new Limit('profileDataDownloadLimiter', 1, '7d');

  // Check that the user has not already requested a download within the last
  // 7 days.
  const attempts = await downloadLinkLimiter.get(user.id);
  if (attempts && attempts >= 1) {
    throw errors.ErrMaxRateLimit;
  }

  // Check if the lastAccountDownload time is within 7 days.
  if (
    user.lastAccountDownload &&
    moment(user.lastAccountDownload)
      .add(7, 'days')
      .isAfter(moment())
  ) {
    throw errors.ErrMaxRateLimit;
  }

  // The account currently does not have a download link, let's record the
  // download. This will throw an error if a race ocurred and we should stop
  // now.
  await downloadLinkLimiter.test(user.id);

  // Generate a token for the download link.
  const token = await secrets.jwt.sign(
    { user: user.id },
    { jwtid: uuid.v4(), expiresIn: '1d', subject: DOWNLOAD_LINK_SUBJECT }
  );

  const now = new Date();

  const { organizationName } = await Settings.load('organizationName');

  // Send the download link via the user's attached email account.
  await Users.sendEmail(user, {
    template: 'download',
    locals: {
      token,
      organizationName,
      now,
    },
    subject: I18n.t('email.download.subject', organizationName),
  });

  // Amend the lastAccountDownload on the user.
  await User.update(
    { id: user.id },
    { $set: { 'metadata.lastAccountDownload': now } }
  );
}

module.exports = ctx => ({
  User: {
    requestDownloadLink: () => sendDownloadLink(ctx),
  },
});