processing.js

const _ = require('lodash');

const send = require('./send');

let waitUserId = null;
const couples = []; // [['id', 'id'], ['id', 'id']]

module.exports = async ({ user_id: userId, body: text, payload }) => {
  userId = +userId;
  const index = _.findIndex(couples, arr => _.indexOf(arr, userId) !== -1);

  if (index === -1) {
    if (!waitUserId || waitUserId === userId) {
      waitUserId = userId;
      await send(userId, 'Ждём собеседника...');
      return;
    } else {
      couples.push([userId, waitUserId]);
      const text = 'Поприветствуйте собеседника.';
      await send(userId, text);
      await send(waitUserId, text);
      waitUserId = null;
      return;
    }
  } else {
    const couple = couples[index];
    const to = _.indexOf(couple, userId) === 0 ? couple[1] : couple[0];

    let button;
    try {
      button = +JSON.parse(payload).button;
    } catch (error) {} // eslint-disable-line

    if (button === 1) {
      couples.splice(index, 1);

      await send(to, 'Собеседник отключился.');
      await send(userId, 'Чат остановлен');
      return;
    }

    await send(to, text);
  }
};