fix date of next-day DEVI leg in an overnight journey 🐛

follow-up of a2870f6
follow-up of 6e6285c
fixes #301

parse/date-time.js

@@ -1,7 +1,13 @@
 import {DateTime, FixedOffsetZone, IANAZone} from 'luxon'
 import {luxonIANAZonesByProfile as timezones} from '../lib/luxon-timezones.js'
 
-const parseDateTime = ({profile}, date, time, tzOffset = null, timestamp = false) => {
+const parseDaysOffset = (_, time) => {
+	return time.length > 6 ? parseInt(time.slice(0, -6)) : 0
+}
+
+const parseDateTime = (ctx, date, time, tzOffset = null, timestamp = false) => {
+	const {profile} = ctx
+
 	const pDate = [date.substr(-8, 4), date.substr(-4, 2), date.substr(-2, 2)]
 	if (!pDate[0] || !pDate[1] || !pDate[2]) {
 		throw new Error('invalid date format: ' + date)
@@ -12,7 +18,7 @@ const parseDateTime = ({profile}, date, time, tzOffset = null, timestamp = false
 		throw new Error('invalid time format: ' + time)
 	}
 
-	const daysOffset = time.length > 6 ? parseInt(time.slice(0, -6)) : 0
+	const daysOffset = parseDaysOffset(ctx, time)
 
 	let timezone
 	if (tzOffset !== null) {

parse/journey.js

@@ -15,7 +15,28 @@ import {findRemarks} from './find-remarks.js'
 const parseJourney = (ctx, j) => { // j = raw jouney
 	const {profile, opt} = ctx
 
-	const legs = j.secL.map(l => profile.parseJourneyLeg(ctx, l, j.date))
+	const legs = []
+	for (const l of j.secL) {
+		let date = j.date
+		// Next-day DEVI legs in an overnight journey lack both
+		// - the "01" prefix in {dep.d,arr.a}Time{S,R} and
+		// - the jny.trainStartDate field.
+		// However, we can use the previous leg's effective date.
+		const prevLeg = legs[legs.length - 1] || null
+		if (l.type === 'DEVI' && prevLeg?.arrival) {
+			// todo: parse effective date from jny.ctxRecon/gis.ctx instead?
+			// todo: prefer plannedArrival?
+			date = [
+				prevLeg.arrival.slice(0, 4), // year
+				prevLeg.arrival.slice(5, 7), // month
+				prevLeg.arrival.slice(8, 10), // day
+			].join('')
+		}
+
+		const leg = profile.parseJourneyLeg(ctx, l, date)
+		legs.push(leg)
+	}
+
 	const res = {
 		type: 'journey',
 		legs,