IFTTT Filter to search for a 1-hour slot in Google Calendar to schedule our event in

ifttt-filter-find-calendar-slot.js

/*
 * Author: Mike Lopez <e@mikelopez.com>
 * Description: Find a 1-hour slot in Google Calendar to schedule our event in
 */

// sort events by start date (because nope, they're not sorted)
GoogleCalendar.listEventsForDateRange.sort(function(a, b) {
  if (moment(a.Start).isSame(b.Start)) {
    return 0;
  }
  return moment(a.Start).isBefore(b.Start) ? -1 : 1;
});

// initialize start date
var eventStart = window_hours(moment(Meta.currentUserTime).utc());

// find a slot
var gEvent;
while (gEvent = GoogleCalendar.listEventsForDateRange.shift()) {
  // slot has to be >= 60 minutes
  if (moment(gEvent.Start).diff(eventStart, 'minutes') >= 60) {
    // found a slot, stop the loop
    break;
  }

  // set eventStart to end of current event
  eventStart = window_hours(moment(gEvent.End));
}

// set start time
GoogleCalendar.addDetailedEvent.setStartTime(
  moment(eventStart).add(
    Math.floor(Math.random() * 11), // add some randomness to start time
    'minutes'
  ).format()
);

// set end time
GoogleCalendar.addDetailedEvent.setEndTime(
  moment(eventStart).add(1, 'hour').format()
);

/**
 * Adjust eventStart to within window hours
 * 
 * @param  moment eventStart Moment object
 * @return moment
 */
function window_hours(eventStart: any) {
  // window hours 9am-4pm +8GMT Mondays to Saturdays only
  if (eventStart.hour() < 1) {
    // too early, advance to 9am +8GMT
    eventStart.hour(1).minute(0);
  }
  if (eventStart.hour() > 8) {
    // too late, advance hour to 9am +8GMT tomorrow
    eventStart.add(1, 'day').hour(1).minute(0);
  }
  if (eventStart.day() == 0) {
    // sunday, advanced to Monday
    eventStart.add(1, 'day');
  }
  return eventStart;
}