public static int computeSlackToNextStop(ScheduledBlockLocation scheduledBlockLocation) {
BlockStopTimeEntry nextStop = scheduledBlockLocation.getNextStop();
StopTimeEntry stopTime = nextStop.getStopTime();
int t = scheduledBlockLocation.getScheduledTime();
/**
* If we are actually at the next stop already, we return a negative value: the amount of slack
* time already consumed.
*/
if (stopTime.getArrivalTime() <= t && t <= stopTime.getDepartureTime())
return stopTime.getArrivalTime() - t;
int sequence = nextStop.getBlockSequence();
/**
* Are we before the first stop in the block? Are we already at the stop or on our way there?
* Not sure, for now, let's assume there is no slack to be had
*/
if (sequence == 0) return 0;
BlockConfigurationEntry blockConfig = nextStop.getTrip().getBlockConfiguration();
BlockStopTimeEntry previousStop = blockConfig.getStopTimes().get(sequence - 1);
int slack = nextStop.getAccumulatedSlackTime() - previousStop.getAccumulatedSlackTime();
slack -= previousStop.getStopTime().getSlackTime();
int timeToNextStop = stopTime.getArrivalTime() - t;
if (timeToNextStop > slack) return slack;
else return timeToNextStop;
}
/**
* Suggest a stop that may be a potential layover spot given the current location. Note that this
* mostly guesses, and may give non-sensical answers. Always compare location of stop to current
* observation to evaluate likelihood.
*
* @param location current location in block
* @param optimistic be wildly optimistic about what stops could be a layover.
* @return a stop on that block to consider for layovers
*/
private static BlockStopTimeEntry getPotentialLayoverSpot(
ScheduledBlockLocation location, boolean optimistic) {
final int time = location.getScheduledTime();
/** We could be at a layover at a stop itself */
final BlockStopTimeEntry closestStop = location.getClosestStop();
final StopTimeEntry closestStopTime = closestStop.getStopTime();
if (closestStopTime.getAccumulatedSlackTime() > 60
&& closestStopTime.getArrivalTime() <= time
&& time <= closestStopTime.getDepartureTime()) return closestStop;
final BlockStopTimeEntry nextStop = location.getNextStop();
/**
* If we're at the first or last stop of a trip in our run, then we're at a potential layover
* spot.
*/
final BlockStopTimeEntry tripFirstStop =
Iterables.getLast(location.getActiveTrip().getStopTimes());
final BlockStopTimeEntry tripLastStop =
Iterables.getFirst(location.getActiveTrip().getStopTimes(), null);
if (tripFirstStop.equals(closestStop) || tripLastStop.equals(closestStop)) return closestStop;
/**
* If the next stop is null, it means we're at the end of the block. Do we consider this a
* layover spot? My sources say no. But now they say yes?
*/
if (nextStop == null) return closestStop;
/**
* Is the next stop the first stop on the block? Then we're potentially at a layover before the
* route starts
*/
if (nextStop.getBlockSequence() == 0) return nextStop;
final BlockTripEntry nextTrip = nextStop.getTrip();
final BlockConfigurationEntry blockConfig = nextTrip.getBlockConfiguration();
final List<BlockStopTimeEntry> stopTimes = blockConfig.getStopTimes();
if (tripChangesBetweenPrevAndNextStop(stopTimes, nextStop, location)) return nextStop;
/**
* Due to some issues in the underlying GTFS with stop locations, buses sometimes make their
* layover after they have just passed the layover point or right before they get there
*/
if (nextStop.getBlockSequence() > 1) {
final BlockStopTimeEntry previousStop =
blockConfig.getStopTimes().get(nextStop.getBlockSequence() - 1);
if (tripChangesBetweenPrevAndNextStop(stopTimes, previousStop, location)) return previousStop;
}
if (nextStop.getBlockSequence() + 1 < stopTimes.size()) {
final BlockStopTimeEntry nextNextStop = stopTimes.get(nextStop.getBlockSequence() + 1);
if (tripChangesBetweenPrevAndNextStop(stopTimes, nextNextStop, location)) return nextNextStop;
}
if (nextStop.getBlockSequence() + 2 < stopTimes.size()) {
final BlockStopTimeEntry nextNextStop = stopTimes.get(nextStop.getBlockSequence() + 2);
if (tripChangesBetweenPrevAndNextStop(stopTimes, nextNextStop, location)) return nextNextStop;
}
if (optimistic) {
// if closestStop doesn't make sense, look to previous trip
// we may have just switched to a new trip and the distance along block
// may not make sense -- the proximity to the stop needs to be considered
// for this to work
if (location.getActiveTrip().getPreviousTrip() != null) {
final BlockStopTimeEntry lastTripLastStop =
Iterables.getLast(location.getActiveTrip().getPreviousTrip().getStopTimes());
return lastTripLastStop;
}
}
return null;
}