index.js

module.exports = function scheduler(conn, opt) {
  opt = opt || {};
  opt.separator = opt.separator || '.';
  opt.prefix = opt.prefix || 'schedule';
  opt.threshold = opt.threshold || 10000;
  opt.round = opt.round || 1000;
  return function publish(exchange, route, message, delay, options, fn) {
    if(delay instanceof Date) {
      delay = delay.getTime() - Date.now();
    }
    delay = Math.round(delay/opt.round)*opt.round;
    var ttl = delay;
    var time = { ms: 1000, s: 60, m: 60, h: 24, d: 30, mo: 12, y: 999999 };
    delay = Object.keys(time).map(function(unit, i, keys) {
      var mod = delay%time[unit];
      delay = Math.floor(delay/time[unit]);
      if(!mod) {
        return '';
      }
      return mod + unit;
    }).reverse().join('');
    var name = opt.prefix + opt.separator + [exchange, route, delay].join(opt.separator);
    var queue = conn.queue(name, {
      durable: true,
      autoDelete: true,
      arguments: {
        'x-dead-letter-exchange': exchange,
        'x-dead-letter-routing-key': route,
        'x-message-ttl': ttl,
        'x-expires': ttl + opt.threshold
      }
    }, function() {
      conn.publish(name, message, options, fn);
    });
  };
};