{-# LANGUAGE DataKinds         #-}
{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE DeriveAnyClass    #-}
{-# LANGUAGE LambdaCase        #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes       #-}
{-# LANGUAGE RecordWildCards   #-}
{-# LANGUAGE TemplateHaskell   #-}
{-# LANGUAGE TypeFamilies      #-}

module Server.ControlRoom (ControlRoom(..)) where

import           Config                    (ServerConfig (..), UffdConfig (..))
import           Control.Monad             (forM, forM_, join)
import           Control.Monad.Extra       (maybeM)
import           Control.Monad.IO.Class    (MonadIO (liftIO))
import qualified Data.Aeson                as A
import qualified Data.ByteString.Char8     as C8
import qualified Data.ByteString.Lazy      as LB
import           Data.Coerce               (coerce)
import           Data.Function             (on, (&))
import           Data.Functor              ((<&>))
import           Data.List                 (lookup, nubBy)
import           Data.List.NonEmpty        (nonEmpty)
import           Data.Map                  (Map)
import qualified Data.Map                  as M
import           Data.Maybe                (catMaybes, fromJust, isJust)
import           Data.Pool                 (Pool)
import           Data.Text                 (Text)
import qualified Data.Text                 as T
import           Data.Time                 (UTCTime (..), addDays,
                                            getCurrentTime, utctDay)
import           Data.Time.Calendar        (Day)
import           Data.Time.Format.ISO8601  (iso8601Show)
import           Data.UUID                 (UUID)
import qualified Data.UUID                 as UUID
import qualified Data.Vector               as V
import           Database.Persist          (Entity (..), delete, entityVal, get,
                                            insert, selectList, (==.))
import           Database.Persist.Sql      (PersistFieldSql, SqlBackend,
                                            runSqlPool)
import           Extrapolation             (Extrapolator (..),
                                            LinearExtrapolator (..))
import           Fmt                       ((+|), (|+))
import           GHC.Float                 (int2Double)
import           GHC.Generics              (Generic)
import qualified GTFS
import           Numeric                   (showFFloat)
import           Persist
import           Server.Util               (Service, secondsNow)
import           Text.Blaze.Html           (ToMarkup (..))
import           Text.Blaze.Internal       (MarkupM (Empty))
import           Text.Read                 (readMaybe)
import           Text.Shakespeare.Text
import           Yesod
import           Yesod.Auth
import           Yesod.Auth.OAuth2.Prelude
import           Yesod.Auth.OpenId         (IdentifierType (..), authOpenId)
import           Yesod.Auth.Uffd           (UffdUser (..), uffdClient)
import           Yesod.Form
import           Yesod.Orphans             ()


data ControlRoom = ControlRoom
  { getGtfs     :: GTFS.GTFS
  , getPool     :: Pool SqlBackend
  , getSettings :: ServerConfig
  }

mkMessage "ControlRoom" "messages" "en"

mkYesod "ControlRoom" [parseRoutes|
/ RootR GET
/auth AuthR Auth getAuth

/tickets TicketsR GET
/ticket/#UUID TicketViewR GET
/ticket/map/#UUID TicketMapViewR GET
/ticket/announce/#UUID AnnounceR POST
/ticket/del-announce/#UUID DelAnnounceR GET

/token/block/#Token TokenBlock GET

/gtfs/trips GtfsTripsViewR GET
/gtfs/trip/#GTFS.TripId GtfsTripViewR GET
/gtfs/import/#Day GtfsTicketImportR POST

/obu OnboardUnitMenuR GET
/obu/#UUID OnboardUnitR GET
/tracker OnboardTrackerR GET
|]

emptyMarkup :: MarkupM a -> Bool
emptyMarkup (Empty _) = True
emptyMarkup _         = False

instance Yesod ControlRoom where
  authRoute _ = Just $ AuthR LoginR
  isAuthorized OnboardUnitMenuR _ = pure Authorized
  isAuthorized (OnboardUnitR _) _ = pure Authorized
  isAuthorized OnboardTrackerR _ = pure Authorized
  isAuthorized (AuthR _) _ = pure Authorized
  isAuthorized _ _ = do
    UffdConfig{..} <- getYesod <&> serverConfigLogin . getSettings
    if uffdConfigEnable then maybeAuthId >>= \case
      Just _  -> pure Authorized
      Nothing -> pure AuthenticationRequired
    else pure Authorized


  defaultLayout w = do
      PageContent{..} <- widgetToPageContent w
      msgs <- getMessages

      withUrlRenderer [hamlet|
        $newline never
        $doctype 5
        <html>
          <head>
            <title>
              $if emptyMarkup pageTitle
                Tracktrain
              $else
                #{pageTitle}
            $maybe description <- pageDescription
              <meta name="description" content="#{description}">
            ^{pageHead}
            <link rel="stylesheet" href="/assets/style.css">
            <meta name="viewport" content="width=device-width, initial-scale=1">
          <body>
            $forall (status, msg) <- msgs
              <!--  <p class="message #{status}">#{msg} -->
            ^{pageBody}
        |]


instance RenderMessage ControlRoom FormMessage where
  renderMessage _ _ = defaultFormMessage

instance YesodPersist ControlRoom where
  type YesodPersistBackend ControlRoom = SqlBackend
  runDB action = do
    pool <- getYesod <&> getPool
    runSqlPool action pool


-- this instance is only slightly cursed (it keeps login information
-- as json in a session cookie and hopes nothing will ever go wrong)
instance YesodAuth ControlRoom where
  type AuthId ControlRoom = UffdUser

  authPlugins cr = case config of
    UffdConfig {..} -> if uffdConfigEnable
      then [ uffdClient uffdConfigUrl uffdConfigClientName uffdConfigClientSecret ]
      else []
    where config = serverConfigLogin (getSettings cr)

  maybeAuthId = do
    e <- lookupSession "json"
    pure $ case e of
      Nothing    -> Nothing
      Just extra -> A.decode (LB.fromStrict $ C8.pack $ T.unpack extra)

  authenticate creds = do
    forM_ (credsExtra creds) (uncurry setSession)
    -- extra <- lookupSession "extra"
    -- pure (Authenticated ( undefined))
    e <- lookupSession "json"
    case e of
      Nothing -> error "no session information"
      Just extra -> case A.decode (LB.fromStrict $ C8.pack $ T.unpack extra) of
        Nothing   -> error "malformed session information"
        Just user -> pure $ Authenticated user

  loginDest _ = RootR
  logoutDest _ = RootR
  -- hardcode redirecting to uffd directly; showing the normal login
  -- screen is kinda pointless when there's only one option
  loginHandler = do
    redirect ("/auth/page/uffd/forward" :: Text)
  onLogout = do
    clearSession




getRootR :: Handler Html
getRootR = redirect TicketsR

getTicketsR :: Handler Html
getTicketsR = do
  req <- getRequest
  let maybeDay = lookup "day" (reqGetParams req) >>= (readMaybe . T.unpack)
  mdisplayname <- maybeAuthId <&> fmap uffdDisplayName

  (day, isToday) <- liftIO $ getCurrentTime <&> utctDay <&> \today ->
    case maybeDay of
      Just day -> (day, day == today)
      Nothing  -> (today, True)

  let prevday = (T.pack . iso8601Show . addDays (-1))  day
  let nextday = (T.pack . iso8601Show . addDays 1) day
  gtfs <- getYesod <&> getGtfs

  -- TODO: tickets should have all trip information saved
  tickets <- runDB $ selectList [ TicketDay ==. day ] [ Asc TicketTripName ] >>= mapM (\ticket -> do
    stops <- selectList [ StopTicket ==. entityKey ticket ] []
    startStation <- getJust (stopStation $ entityVal $ head stops)
    pure (ticket, startStation, fmap entityVal stops))

  let trips = GTFS.tripsOnDay gtfs day

  (widget, enctype) <- generateFormPost (tripImportForm (fmap (,day) (M.elems trips)))
  defaultLayout $ do
    [whamlet|
<h1> _{MsgTrainsOnDay (iso8601Show day)}
$maybe name <- mdisplayname
  <p>_{MsgLoggedInAs name} - <a href="@{AuthR LogoutR}">_{MsgLogout}</a>
<nav>
  <a class="nav-left" href="@?{(TicketsR, [("day", prevday)])}">← #{prevday}
  $if isToday
    _{Msgtoday}
  $else
    <a href="@{TicketsR}">_{Msgtoday}
  <a class="nav-right" href="@?{(TicketsR, [("day", nextday)])}">#{nextday} →
<section>
  <h2>_{MsgTickets}
  <ol>
   $forall (Entity (TicketKey ticketId) Ticket{..}, startStation, stops) <- tickets
    <li><a href="@{TicketViewR ticketId}">_{MsgTrip} #{ticketTripName}</a>
         : _{Msgdep} #{stopDeparture (head stops)} #{stationName startStation} → #{ticketHeadsign}
   $if null tickets
     <li style="text-align: center"><em>(_{MsgNone})</em>
<section>
  <h2>_{MsgAccordingToGtfs}
  <form method=post action="@{GtfsTicketImportR day}" enctype=#{enctype}>
    ^{widget}
    <button>_{MsgImportTrips}
   $if null trips
     <li style="text-align: center"><em>(_{MsgNone})
|]


-- TODO: this function should probably look for duplicate imports
postGtfsTicketImportR :: Day -> Handler Html
postGtfsTicketImportR day = do
  gtfs <- getYesod <&> getGtfs
  let trips = GTFS.tripsOnDay gtfs day
  ((result, widget), enctype) <- runFormPost (tripImportForm (fmap (,day) (M.elems trips)))
  case result of
    FormSuccess selected -> do
      now <- liftIO getCurrentTime

      shapeMap <- selected
        <&> (\(trip@GTFS.Trip{..}, _) -> (GTFS.shapeId tripShape, tripShape))
        & nubBy ((==) `on` fst)
        & mapM (\(shapeId, shape) -> runDB $ do
           key <- insert Shape
           insertMany
             $ shape
             & GTFS.shapePoints
             & V.indexed
             & V.toList
             <&> \(idx, pos) -> ShapePoint (Geopos pos) idx key
           pure (shapeId, key))
        <&> M.fromList

      stationMap <- selected
        <&> (\(trip@GTFS.Trip{..}, _) -> V.toList (tripStops <&> GTFS.stopStation))
        & concat
        & nubBy ((==) `on` GTFS.stationId)
        & mapM (\GTFS.Station{..} -> runDB $ do
            maybeExists <- selectFirst [ StationShortName ==. stationId ] []
            case maybeExists of
              Nothing -> do
                key <- insert Station
                  { stationGeopos = Geopos (stationLat, stationLon)
                  , stationShortName = stationId , stationName }
                pure (stationId, key)
              Just (Entity key _) -> pure (stationId, key))
        <&> M.fromList

      selected
        <&> (\(trip@GTFS.Trip{..}, day) ->
            let
              ticket = Ticket
                   { ticketTripName = tripTripId, ticketDay = day, ticketImported = now
                   , ticketSchedule_version = Nothing, ticketVehicle = Nothing
                   , ticketCompleted = False, ticketHeadsign = gtfsHeadsign trip
                   , ticketShape = fromJust (M.lookup (GTFS.shapeId tripShape) shapeMap)}
              stops = V.toList tripStops <&> \GTFS.Stop{..} ticketId -> Stop
                   { stopTicket = ticketId
                   , stopStation = fromJust (M.lookup (GTFS.stationId stopStation) stationMap)
                   , stopArrival, stopDeparture, stopSequence}
            in (ticket, stops))
        & unzip
        & \(tickets, stops) -> runDB $ do
            ticketIds <- insertMany tickets
            forM (zip ticketIds stops) $ \(ticketId, unfinishedStops) ->
              insertMany (fmap (\s -> s ticketId) unfinishedStops)

      redirect (TicketsR, [("day", T.pack (iso8601Show day))])

    FormFailure _ -> defaultLayout [whamlet|
<section>
  <h2>_{MsgAccordingToGtfs}
  <form method=post action="@{GtfsTicketImportR day}" enctype=#{enctype}>
    ^{widget}
    <button>_{MsgImportTrips}
|]

getTicketViewR :: UUID -> Handler Html
getTicketViewR ticketId = do
  let ticketKey = TicketKey ticketId
  Ticket{..} <- runDB $ get ticketKey
     >>= \case {Nothing -> notFound; Just a -> pure a}

  stops <- runDB $ selectList [StopTicket ==. ticketKey] [] >>= mapM (\stop -> do
    station <- getJust (stopStation (entityVal stop))
    pure (entityVal stop, station))

  anns <- runDB $ selectList [ AnnouncementTicket ==. ticketKey ] []
  joins <- runDB $ selectList [ TrackerTicketTicket ==. ticketKey ] []
    <&> fmap (trackerTicketTracker . entityVal)
  trackers <- runDB $ selectList
    ([ TrackerId <-. joins ] ||. [ TrackerCurrentTicket ==. Just ticketKey ])
    [Asc TrackerExpires]
  lastPing <- runDB $ selectFirst [ TrainPingToken <-. fmap entityKey trackers ] [Desc TrainPingTimestamp]
  anchors <- runDB $ selectList [ TrainAnchorTicket ==. ticketKey ] []
    <&> nonEmpty . fmap entityVal

  (widget, enctype) <- generateFormPost (announceForm ticketId)

  nowSeconds <- secondsNow ticketDay
  defaultLayout $ do
    mr <- getMessageRender
    setTitle (toHtml (""+|mr MsgTrip|+" "+|ticketTripName|+" "+|mr Msgon|+" "+|ticketDay|+"" :: Text))
    [whamlet|
<h1>_{MsgTrip} #
  <a href="@{GtfsTripViewR ticketTripName}">#{ticketTripName}
  _{Msgon}
  <a href="@?{(TicketsR, [("day", T.pack (iso8601Show ticketDay))])}">#{ticketDay}
<section>
  <h2>_{MsgLive}
  <p><strong>_{MsgLastPing}: </strong>
    $maybe Entity _ TrainPing{..} <- lastPing
      _{MsgTrainPing (latitude trainPingGeopos) (longitude trainPingGeopos) trainPingTimestamp}
      (<a href="/api/debug/pings/#{UUID.toString ticketId}/#{ticketDay}">_{Msgraw}</a>)
    $nothing
      <em>(_{MsgNoTrainPing})
  <p><strong>_{MsgEstimatedDelay}</strong>:
    $maybe history <- anchors
      $maybe TrainAnchor{..} <- guessAtSeconds history nowSeconds
        \ #{trainAnchorDelay} (_{MsgOnStationSequence (showFFloat (Just 3) trainAnchorSequence "")})
    $nothing
      <em> (_{MsgNone})
  <p><a href="@{TicketMapViewR ticketId}">_{MsgMap}</a>
<section>
  <h2>_{MsgStops}
  <ol>
    $forall (Stop{..}, Station{..}) <- stops
      <li value="#{stopSequence}"> #{stopArrival} #{stationName}
        $maybe history <- anchors
          $maybe delay <- guessDelay history (int2Double stopSequence)
            \ (#{delay})
<section>
  <h2>_{MsgAnnouncements}
  <ul>
    $forall Entity (AnnouncementKey uuid) Announcement{..} <- anns
      <li><em>#{announcementHeader}: #{announcementMessage}</em> <a href="@{DelAnnounceR uuid}">_{Msgdelete}</a>
    $if null anns
      <li><em>(_{MsgNone})</em>
  <h3>_{MsgNewAnnouncement}
  <form method=post action=@{AnnounceR ticketId} enctype=#{enctype}>
    ^{widget}
    <button>_{MsgSubmit}
<section>
  <h2>_{MsgTokens}
  <table>
    <tr><th style="width: 20%">_{MsgAgent}</th><th style="width: 50%">_{MsgToken}</th><th>_{MsgExpires}</th><th>_{MsgStatus}</th>
    $if null trackers
      <tr><td></td><td style="text-align:center"><em>(_{MsgNone})
    $forall Entity (TrackerKey key) Tracker{..} <- trackers
      <tr :trackerBlocked:.blocked>
        <td title="#{trackerAgent}">#{trackerAgent}
        <td title="#{key}">#{key}
        <td title="#{trackerExpires}">#{trackerExpires}
        $if trackerBlocked
          <td title="_{MsgUnblockToken}"><a href="@?{(TokenBlock key, [("unblock", "true")])}">_{MsgUnblockToken}</a>
        $else
          <td title="_{MsgBlockToken}"><a href="@{TokenBlock key}">_{MsgBlockToken}</a>
|]
          where guessDelay history = fmap trainAnchorDelay . extrapolateAtPosition LinearExtrapolator history
                guessAtSeconds = extrapolateAtSeconds LinearExtrapolator


getTicketMapViewR :: UUID -> Handler Html
getTicketMapViewR ticketId = do
  Ticket{..} <- runDB $ get (TicketKey ticketId)
    >>= \case { Nothing -> notFound ; Just ticket -> pure ticket }

  stops <- runDB $ selectList [StopTicket ==. TicketKey ticketId] [] >>= mapM (\stop -> do
    station <- getJust (stopStation (entityVal stop))
    pure (entityVal stop, station))

  (widget, enctype) <- generateFormPost (announceForm ticketId)

  defaultLayout [whamlet|
<h1>_{MsgTrip} <a href="@{TicketViewR ticketId}">#{ticketTripName} _{Msgon} #{ticketDay}</a>
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.3/dist/leaflet.css"
     integrity="sha256-kLaT2GOSpHechhsozzB+flnD+zUyjE2LlfWPgU04xyI="
     crossorigin=""/>
<script src="https://unpkg.com/leaflet@1.9.3/dist/leaflet.js"
     integrity="sha256-WBkoXOwTeyKclOHuWtc+i2uENFpDZ9YPdf5Hf+D7ewM="
     crossorigin=""></script>
<div id="map">
<p id="status">
<script>
  let map = L.map('map');

  L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
      attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
  }).addTo(map);

  ws = new WebSocket((location.protocol == "http:" ? "ws" : "wss") + "://" + location.host + "/api/train/subscribe/#{UUID.toText ticketId}");

  var marker = null;

  ws.onmessage = (msg) => {
    let json = JSON.parse(msg.data);
    if (marker === null) {
      marker = L.marker([json.lat, json.long]);
      marker.addTo(map);
    } else {
      marker.setLatLng([json.lat, json.long]);
    }
    map.setView([json.lat, json.long], 13);
    document.getElementById("status").innerText = "_{MsgLastPing}: "+json.lat+","+json.long+" ("+json.timestamp+")";
  }
|]



getGtfsTripsViewR :: Handler Html
getGtfsTripsViewR = do
  GTFS.GTFS{..} <- getYesod <&> getGtfs
  defaultLayout $ do
    setTitle "List of Trips"
    [whamlet|
<h1>List of Trips
<section><ul>
  $forall trip@GTFS.Trip{..} <- trips
    <li><a href="@{GtfsTripViewR tripTripId}">#{GTFS.tripName trip}</a>
      : #{GTFS.stopDeparture (V.head tripStops)} #{GTFS.stationName (GTFS.stopStation (V.head tripStops))}
|]


getGtfsTripViewR :: GTFS.TripId -> Handler Html
getGtfsTripViewR tripId = do
  GTFS.GTFS{..} <- getYesod <&> getGtfs
  case M.lookup tripId trips of
    Nothing -> notFound
    Just trip@GTFS.Trip{..} -> defaultLayout [whamlet|
<h1>_{MsgTrip} #{GTFS.tripName trip}
<section>
  <h2>_{MsgInfo}
  <p><strong>_{MsgtripId}:</strong> #{tripTripId}
  <p><strong>_{MsgtripHeadsign}:</strong> #{mightbe tripHeadsign}
  <p><strong>_{MsgtripShortname}:</strong> #{mightbe tripShortName}
<section>
  <h2>_{MsgStops}
  <ol>
    $forall GTFS.Stop{..} <- tripStops
      <div>(#{stopSequence}) #{stopArrival} #{GTFS.stationName stopStation}
<section>
  <h2>Dates
  <ul>
    TODO!
|]


postAnnounceR :: UUID -> Handler Html
postAnnounceR ticketId = do
    ((result, widget), enctype) <- runFormPost (announceForm ticketId)
    case result of
        FormSuccess ann -> do
          runDB $ insert ann
          redirect RootR -- (TicketViewR trip day)
        _ -> defaultLayout
            [whamlet|
                <p>_{MsgInvalidInput}.
                <form method=post action=@{AnnounceR ticketId} enctype=#{enctype}>
                    ^{widget}
                    <button>_{MsgSubmit}
            |]

getDelAnnounceR :: UUID -> Handler Html
getDelAnnounceR uuid = do
  ann <- runDB $ do
    a <- get (AnnouncementKey uuid)
    delete (AnnouncementKey uuid)
    pure a
  case ann of
    Nothing -> notFound
    Just Announcement{..} ->
      let (TicketKey ticketId) = announcementTicket
      in redirect (TicketViewR ticketId)

getTokenBlock :: Token -> Handler Html
getTokenBlock token = do
  YesodRequest{..} <- getRequest
  let blocked = lookup "unblock" reqGetParams /= Just "true"
  maybe <- runDB $ do
    update (TrackerKey token) [ TrackerBlocked =. blocked ]
    get (TrackerKey token)
  case maybe of
    Just r@Tracker{..} -> do
      liftIO $ print r
      redirect $ case trackerCurrentTicket of
        Just ticket -> TicketViewR (coerce ticket)
        Nothing     -> RootR
    Nothing -> notFound

getOnboardUnitMenuR :: Handler Html
getOnboardUnitMenuR = do
  day <- liftIO getCurrentTime <&> utctDay

  tickets <-
    runDB $ selectList [ TicketCompleted ==. False, TicketDay ==. day ] [] >>= mapM (\ticket -> do
      firstStop <- selectFirst [StopTicket ==. entityKey ticket] [ Asc StopDeparture ]
      pure (ticket, entityVal $ fromJust firstStop))

  defaultLayout $ do
    [whamlet|
      <h1>_{MsgOBU}
      <section>
       _{MsgChooseTrain}
       $forall (Entity (TicketKey ticketId) Ticket{..}, firstStop) <- tickets
         <hr>
         <a href="@{OnboardUnitR ticketId}">
          #{ticketTripName}: #{ticketHeadsign} #{stopDeparture firstStop}
      <section>
        <a href="@{OnboardTrackerR}">_{MsgStartTracking}
    |]

getOnboardUnitR :: UUID -> Handler Html
getOnboardUnitR ticketId = do
  Ticket{..} <- runDB $ get (TicketKey ticketId) >>= \case
    Nothing -> notFound
    Just ticket -> pure ticket
  defaultLayout $(whamletFile "site/obu.hamlet")

getOnboardTrackerR :: Handler Html
getOnboardTrackerR = do
  defaultLayout
    $( whamletFile "site/tracker.hamlet")


announceForm :: UUID -> Html -> MForm Handler (FormResult Announcement, Widget)
announceForm ticketId = renderDivs $ Announcement
  <$> pure (TicketKey ticketId)
  <*> areq textField (fieldSettingsLabel MsgHeader) Nothing
  <*> areq textField (fieldSettingsLabel MsgText) Nothing
  <*> aopt urlField (fieldSettingsLabel MsgMaybeWeblink) Nothing
  <*> lift (liftIO getCurrentTime <&> Just)



tripImportForm
  :: [(GTFS.Trip GTFS.Deep GTFS.Deep, Day)]
  -> Html
  -> MForm Handler (FormResult [(GTFS.Trip GTFS.Deep GTFS.Deep, Day)], Widget)
tripImportForm trips extra = do
  forms <- forM trips $ \(trip, day) -> do
    (aRes, aView) <- mreq checkBoxField "import" Nothing
    let dings = fmap (\res -> if res then Just (trip, day) else Nothing) aRes
    pure (trip, day, dings, aView)

  let widget = toWidget [whamlet|
     #{extra}
     <ol>
       $forall (trip@GTFS.Trip{..}, day, res, view) <- forms
         <li>
           ^{fvInput view}
           <label for="^{fvId view}">
             _{MsgTrip} #{GTFS.tripName trip}
               : _{Msgdep} #{GTFS.stopDeparture (V.head tripStops)} #{GTFS.stationName (GTFS.stopStation (V.head tripStops))} → #{gtfsHeadsign trip}
  |]

  let (a :: FormResult [Maybe (GTFS.Trip GTFS.Deep GTFS.Deep, Day)]) =
        sequenceA (fmap (\(_,_,res,_) -> res) forms)

  pure (fmap catMaybes a, widget)


mightbe :: Maybe Text -> Text
mightbe (Just a) = a
mightbe Nothing  = ""


gtfsHeadsign :: GTFS.Trip GTFS.Deep GTFS.Deep -> Text
gtfsHeadsign GTFS.Trip{..} =
  case tripHeadsign of
    Just headsign -> headsign
    Nothing       -> GTFS.stationName (GTFS.stopStation (V.last tripStops))