/* global Counter:true */

Counter = function (name, cursor, interval) {
  this.name = name;
  this.cursor = cursor;
  this.interval = interval || 1000 * 10;
  this._collectionName = 'counters-collection';
};

// every cursor must provide a collection name via this method
Counter.prototype._getCollectionName = function () {
  return `counter-${this.name}`;
};

// the api to publish (async: Meteor 3 awaits _publishCursor)
Counter.prototype._publishCursor = async function (sub) {
  const self = this;

  sub.added(self._collectionName, self.name, { count: await self.cursor.countAsync() });

  const handler = Meteor.setInterval(async () => {
    try {
      const count = await self.cursor.countAsync();
      sub.changed(self._collectionName, self.name, { count });
    } catch (e) {
      // transient db error: retry on the next tick
    }
  }, this.interval);

  sub.onStop(() => {
    Meteor.clearInterval(handler);
  });

  return {
    stop: sub.onStop.bind(sub)
  };
};