Merge pull request #5174 from HSLdevcom/shift-nontransit-legs

Reconstruct itinerary after realtime modifications

app/component/itinerary/navigator/hooks/useRealtimeLegs.js

@@ -2,6 +2,89 @@ import { useCallback, useEffect, useState } from 'react';
 import { fetchQuery } from 'react-relay';
 import { checkPositioningPermission } from '../../../../action/PositionActions';
 import { legQuery } from '../../queries/LegQuery';
+import { legTime } from '../../../../util/legUtils';
+import { epochToIso } from '../../../../util/timeUtils';
+
+function nextTransitIndex(legs, i) {
+  for (let j = i; j < legs.length; j++) {
+    if (legs[j].transitLeg) {
+      return j;
+    }
+  }
+  // negative indicates not found
+  return -1;
+}
+
+function getLegGap(legs, index) {
+  return legTime(legs[index + 1].start) - legTime(legs[index].end);
+}
+
+// change non-transit legs' scheduled times
+function shiftLegs(legs, i1, i2, gap) {
+  for (let j = i1; j <= i2; j++) {
+    const leg = legs[j];
+    leg.start.scheduledTime = epochToIso(legTime(leg.start) + gap);
+    leg.end.scheduledTime = epochToIso(legTime(leg.end) + gap);
+  }
+}
+
+// scale non-transit legs' scheduled times
+function scaleLegs(legs, i1, i2, k) {
+  const base = legTime(legs[i1].start);
+  for (let j = i1; j <= i2; j++) {
+    const leg = legs[j];
+    const s = legTime(leg.start);
+    const e = legTime(leg.end);
+    leg.start.scheduledTime = epochToIso(s + k * (s - base));
+    leg.end.scheduledTime = epochToIso(e + k * (e - base));
+  }
+}
+
+function matchLegEnds(legs) {
+  if (legs.length < 2) {
+    return;
+  }
+  let transit;
+  let gap;
+
+  // shift first legs to match transit start
+  transit = nextTransitIndex(legs, 0);
+  if (transit > 0) {
+    gap = getLegGap(legs, transit - 1);
+    if (gap) {
+      shiftLegs(legs, 0, transit - 1, gap);
+    }
+  }
+
+  // shift transfers and legs after transit end
+  while (transit > 0) {
+    const walk = transit + 1; // first leg after transit
+    const nextTransit = nextTransitIndex(legs, walk);
+    const shiftEnd = nextTransit > 0 ? nextTransit - 1 : legs.length - 1;
+    if (shiftEnd > transit) {
+      gap = getLegGap(legs, transit);
+      if (gap) {
+        shiftLegs(legs, walk, shiftEnd, -gap);
+      }
+    }
+    if (nextTransit > walk) {
+      // check if transfer needs scaling
+      gap = getLegGap(legs, nextTransit - 1);
+      if (gap < 0) {
+        // transfer overlaps next transit leg, so we must make it shorter
+        const transferDuration =
+          legTime(legs[shiftEnd].end) - legTime(legs[walk].start);
+        scaleLegs(
+          legs,
+          walk,
+          shiftEnd,
+          (transferDuration + gap) / transferDuration,
+        );
+      }
+    }
+    transit = nextTransit;
+  }
+}
 
 const useRealtimeLegs = (initialLegs, mapRef, relayEnvironment) => {
   const [isPositioningAllowed, setPositioningAllowed] = useState(false);
@@ -60,8 +143,10 @@ const useRealtimeLegs = (initialLegs, mapRef, relayEnvironment) => {
           },
         };
       }
-      return { ...l };
+      return { ...l, start: { ...l.start }, end: { ...l.end } };
     });
+    // shift non-transit-legs to match possibly changed transit legs
+    matchLegEnds(rtLegs);
     setRealTimeLegs(rtLegs);
   }, [initialLegs, queryAndMapRealtimeLegs]);
 

app/util/legUtils.js

@@ -21,6 +21,15 @@ export function legTimeStr(lt) {
   return `${time[0]}:${time[1]}`;
 }
 
+/**
+ * Get time as 'hh:mm:ss'
+ */
+export function legTimeAcc(lt) {
+  const t = lt.estimated?.time || lt.scheduledTime;
+  const parts = t.split('T')[1].split('+');
+  return parts[0];
+}
+
 function filterLegStops(leg, filter) {
   if (leg.from.stop && leg.to.stop && leg.trip) {
     const stops = [leg.from.stop.gtfsId, leg.to.stop.gtfsId];

app/util/timeUtils.js

@@ -161,3 +161,10 @@ export function timeStr(dateTime) {
   const time = parts[1].split(':');
   return `${time[0]}:${time[1]}`;
 }
+
+/**
+ * Epoch ms to ISO-8601/RFC3339 datetime str
+ */
+export function epochToIso(ms) {
+  return moment(ms).format();
+}