const { ipcMain } = require('electron');
const { ImapFlow } = require('imapflow');

ipcMain.on('imap:listTree:from', listTreeFrom);
ipcMain.on('imap:listTree:to', listTreeTo);
ipcMain.on('imap:migrate', migrate);

async function connect (options) {
  const client = new ImapFlow({
    host: options.server,
    port: options.port,
    auth: {
      user: options.username,
      pass: options.password,
    },
  });

  await client.connect();

  return client;
}

async function listTreeFrom (event, options) {
  const client = await connect(options);

  event.reply('imap:listTree:from:reply', await client.listTree());
  await client.logout();
}

async function listTreeTo (event, options) {
  const client = await connect(options);

  event.reply('imap:listTree:to:reply', await client.listTree());
  await client.logout();
}

async function migrate (event, { from, to }) {
  const fromClient = await connect(from);
  const toClient = await connect(to);

  const fromFolders = (await fromClient.list()).filter((folder) => folder.subscribed);
  for (const fromFolder of fromFolders) {
    try {
      await toClient.mailboxCreate(fromFolder.path);
    } catch (e) {}

    const fromMailbox = await fromClient.getMailboxLock(fromFolder.path);
    const toMailbox = await toClient.getMailboxLock(fromFolder.path);
    try {
      const toMsgsGenerator = await toClient.fetch('1:*', { flags: true, envelope: true, source: true });
      const toMsgs = [];
      for await (const toMsg of toMsgsGenerator) {
        toMsgs.push(toMsg);
      }
      const fromMsgsGenerator = await fromClient.fetch('1:*', { flags: true, envelope: true, source: true });

      for await (const fromMsg of fromMsgsGenerator) {
        if (toMsgs.some((toMsg) => Buffer.compare(toMsg.source, fromMsg.source) === 0)) {
          continue;
        }

        await toClient.append(fromFolder.path, fromMsg.source, Array.from(fromMsg.flags), fromMsg.envelope.date);
      }
    } finally {
      fromMailbox.release();
      toMailbox.release();
    }
  }

  await fromClient.logout();
  await toClient.logout();
}