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{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE ConstrainedClassMethods #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE RecordWildCards #-}
module Extrapolation (Extrapolator(..), LinearExtrapolator, linearDelay, distanceAlongLine) where
import Data.Foldable (maximumBy, minimumBy)
import Data.Function (on)
import Data.List.NonEmpty (NonEmpty)
import qualified Data.List.NonEmpty as NE
import qualified Data.Map as M
import Data.Time (Day, UTCTime (UTCTime, utctDay),
diffUTCTime, getCurrentTime,
nominalDiffTimeToSeconds)
import qualified Data.Vector as V
import GHC.Float (int2Double)
import GHC.IO (unsafePerformIO)
import Conduit (MonadIO (liftIO))
import Data.List (sortBy)
import GTFS (Depth (Deep), GTFS (..), Seconds (..),
Shape (..), Station (stationName),
Stop (..), Time, Trip (..), seconds2Double,
stationGeopos, toSeconds)
import Persist (Running (..), TrainAnchor (..),
TrainPing (..))
import Server.Util (utcToSeconds)
class Extrapolator a where
-- | here's a position ping, guess things from that!
extrapolateAnchorFromPing :: GTFS -> Running -> TrainPing -> TrainAnchor
-- | extrapolate status at some time (i.e. "how much delay does the train have *now*?")
extrapolateAtSeconds :: NonEmpty TrainAnchor -> Seconds -> Maybe TrainAnchor
-- | extrapolate status at some places (i.e. "how much delay will it have at the next station?")
extrapolateAtPosition :: NonEmpty TrainAnchor -> Double -> Maybe TrainAnchor
data LinearExtrapolator
instance Extrapolator LinearExtrapolator where
-- TODO: this kind of sorting is bullshit; should look up depending on position,
-- not time (else there's glitches)
extrapolateAtSeconds history secondsNow =
fmap (minimumBy (compare `on` difference))
$ NE.nonEmpty $ NE.filter (\a -> trainAnchorWhen a < secondsNow) history
where difference status = secondsNow - (trainAnchorWhen status)
-- note that this sorts (descending) for time first as a tie-breaker
-- (in case the train just stands still for a while, take the most recent update)
extrapolateAtPosition history positionNow =
fmap (minimumBy (compare `on` difference))
$ NE.nonEmpty $ sortBy (flippedCompare `on` trainAnchorWhen)
$ NE.filter (\a -> trainAnchorSequence a < positionNow) history
where difference status = positionNow - (trainAnchorSequence status)
flippedCompare a b = case compare a b of
LT -> GT
GT -> LT
a -> a
extrapolateAnchorFromPing gtfs@GTFS{..} Running{..} ping@TrainPing{..} = TrainAnchor
{ trainAnchorCreated = trainPingTimestamp
, trainAnchorTrip = runningTrip
, trainAnchorDay = runningDay
, trainAnchorWhen = utcToSeconds trainPingTimestamp runningDay
, trainAnchorSequence
, trainAnchorDelay
, trainAnchorMsg = Nothing
}
where Just trip = M.lookup runningTrip trips
(trainAnchorDelay, trainAnchorSequence) = linearDelay gtfs trip ping runningDay
linearDelay :: GTFS -> Trip Deep Deep -> TrainPing -> Day -> (Seconds, Double)
linearDelay GTFS{..} trip@Trip{..} TrainPing{..} runningDay = unsafePerformIO $ do
print (observedPosition, observedProgress)
print (stationName . stopStation $ lastStop, stationName . stopStation $ nextStop)
print (distanceAlongLine line (stationGeopos $ stopStation lastStop) closestPoint
, distanceAlongLine line (stationGeopos $ stopStation lastStop) (stationGeopos $ stopStation nextStop))
pure (observedDelay, observedPosition)
where closestPoint = minimumBy (compare `on` euclid (trainPingLat, trainPingLong)) line
line = shapePoints tripShape
lastStop = tripStops V.! (nextIndex - 1)
nextStop = tripStops V.! nextIndex
nextIndex = if idx' == 0
then 1 else idx'
where idx' = fst $ V.minimumBy (compare `on` snd)
$ V.filter (\(_,dist) -> dist > 0) $ V.indexed
$ fmap (distanceAlongLine line closestPoint . stationGeopos . stopStation) tripStops
expectedTravelTime =
toSeconds (stopArrival nextStop) tzseries runningDay
- toSeconds (stopDeparture lastStop) tzseries runningDay
expectedProgress = crop $
seconds2Double (utcToSeconds trainPingTimestamp runningDay
- toSeconds (stopDeparture lastStop) tzseries runningDay)
/ seconds2Double expectedTravelTime
where crop a
| a < 0 = 0
| a > 1 = 1
| otherwise = a
observedProgress =
distanceAlongLine line (stationGeopos $ stopStation lastStop) closestPoint
/ distanceAlongLine line (stationGeopos $ stopStation lastStop) (stationGeopos $ stopStation nextStop)
observedPosition =
(int2Double $ stopSequence lastStop) + observedProgress * (int2Double $ stopSequence nextStop - stopSequence lastStop)
observedDelay = Seconds $ round $
(expectedProgress - observedProgress) * int2Double (unSeconds expectedTravelTime)
-- if the hypothetical on-time train is already at (or past) the next station,
-- just add the time distance we're behind
+ if expectedProgress == 1
then seconds2Double (utcToSeconds trainPingTimestamp runningDay - toSeconds (stopArrival nextStop) tzseries runningDay)
else 0
distanceAlongLine :: V.Vector (Double, Double) -> (Double, Double) -> (Double, Double) -> Double
distanceAlongLine line p1 p2 = along2 - along1
where along1 = along p1
along2 = along p2
along p@(x,y) =
sumSegments
$ V.take (index + 1) line
where index = V.minIndexBy (compare `on` euclid p) line
sumSegments :: V.Vector (Double, Double) -> Double
sumSegments line = snd
$ foldl (\(p,a) p' -> (p', a + euclid p p')) (V.head line,0) $ line
euclid :: Floating f => (f,f) -> (f,f) -> f
euclid (x1,y1) (x2,y2) = sqrt (x*x + y*y)
where x = x1 - x2
y = y1 - y2
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