WIP: Create busy placeholders in GCal

mark-empty-as-busy.js

function toDateRanges(items) {
  return items
    .filter(calEvent => {
      return (
        calEvent.start &&
        calEvent.start.dateTime &&
        calEvent.end &&
        calEvent.end.dateTime
      );
    })
    .map(calEvent => {
      return {
        startDate: new Date(calEvent.start.dateTime),
        endDate: new Date(calEvent.end.dateTime)
      };
    })
    .sort((a, b) => {
      if (a.startDate.valueOf() < b.startDate.valueOf()) {
        return -1;
      }
      if (a.startDate.valueOf() > b.startDate.valueOf()) {
        return 1;
      }
      return 0;
    });
}

function findGaps(ranges) {
  let holes = [];
  for (let i = 1; i < ranges.length; i++) {
    const beginningOfHole = ranges[i - 1].endDate;
    const endOfHole = ranges[i].startDate;
    if (beginningOfHole.valueOf() < endOfHole.valueOf()) {
      holes.push({ from: beginningOfHole, until: endOfHole });
    }
  }
  return holes;
}