//
// Sample availabilities
//

[{
  userId: 1,
  startTime: new Date("2019-04-12T15:00:00-02:00"),
  durationInSec: 10800,
}, {
  userId: 2,
  startTime: new Date("2019-04-12T13:00:00-02:00"),
  durationInSec: 21600,
}, {
  userId: 3,
  startTime: new Date("2019-04-13T12:00:00-02:00"),
  durationInSec: 10800,
}, {
  userId: 4,
  startTime: new Date("2019-04-13T12:00:00-02:00"),
  durationInSec: 10800,
}, {
  userId: 5,
  startTime: new Date("2019-04-14T12:00:00-02:00"),
  durationInSec: 7200,
}, {
  userId: 3,
  startTime: new Date("2019-04-14T12:00:00-02:00"),
  durationInSec: 10800,
}]

//
// Write function:
//
function bucketAvailabilities(availabilities) {
  // returns
  // [{
  //   userId: 3,
  //   startTime: "2019-04-13T13:00:00-02:00",
  //   durationInSec: 10800,
  //   day: <day>,
  //   column: 0 | 1 | 2 | 3 | 4 . . .,
  // }]