'use strict'

const isObj = require('lodash/isObject')
const sortBy = require('lodash/sortBy')
const pRetry = require('p-retry')
const omit = require('lodash/omit')

const defaultProfile = require('./lib/default-profile')
const validateProfile = require('./lib/validate-profile')
const {INVALID_REQUEST} = require('./lib/errors')
const sliceLeg = require('./lib/slice-leg')

const isNonEmptyString = str => 'string' === typeof str && str.length > 0

const validateLocation = (loc, name = 'location') => {
	if (!isObj(loc)) {
		throw new TypeError(name + ' must be an object.')
	} else if (loc.type !== 'location') {
		throw new TypeError('invalid location object.')
	} else if ('number' !== typeof loc.latitude) {
		throw new TypeError(name + '.latitude must be a number.')
	} else if ('number' !== typeof loc.longitude) {
		throw new TypeError(name + '.longitude must be a number.')
	}
}

const validateWhen = (when, name = 'when') => {
	if (Number.isNaN(+when)) {
		throw new TypeError(name + ' is invalid')
	}
}

const createClient = (profile, userAgent, opt = {}) => {
	profile = Object.assign({}, defaultProfile, profile)
	validateProfile(profile)

	if ('string' !== typeof userAgent) {
		throw new TypeError('userAgent must be a string');
	}

	const _stationBoard = (station, type, parse, opt = {}) => {
		if (isObj(station)) station = profile.formatStation(station.id)
		else if ('string' === typeof station) station = profile.formatStation(station)
		else throw new TypeError('station must be an object or a string.')

		if ('string' !== typeof type || !type) {
			throw new TypeError('type must be a non-empty string.')
		}

		if (!profile.departuresGetPasslist && ('stopovers' in opt)) {
			throw new Error('opt.stopovers is not supported by this endpoint')
		}
		if (!profile.departuresStbFltrEquiv && ('includeRelatedStations' in opt)) {
			throw new Error('opt.includeRelatedStations is not supported by this endpoint')
		}

		opt = Object.assign({
			// todo: for arrivals(), this is actually a station it *has already* stopped by
			direction: null, // only show departures stopping by this station
			line: null, // filter by line ID
			duration: 10, // show departures for the next n minutes
			results: null, // max. number of results; `null` means "whatever HAFAS wants"
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			linesOfStops: false, // parse & expose lines at the stop/station?
			remarks: true, // parse & expose hints & warnings?
			stopovers: false, // fetch & parse previous/next stopovers?
			// departures at related stations
			// e.g. those that belong together on the metro map.
			includeRelatedStations: true
		}, opt)
		opt.when = new Date(opt.when || Date.now())
		if (Number.isNaN(+opt.when)) throw new Error('opt.when is invalid')

		const req = profile.formatStationBoardReq({profile, opt}, station, type)

		// todo [breaking]: return object with realtimeDataUpdatedAt
		return profile.request({profile, opt}, userAgent, req)
		.then(({res, common}) => {
			if (!Array.isArray(res.jnyL)) return []

			const ctx = {profile, opt, common, res}
			return res.jnyL.map(res => parse(ctx, res))
			.sort((a, b) => new Date(a.when) - new Date(b.when)) // todo
		})
	}

	const departures = (station, opt = {}) => {
		return _stationBoard(station, 'DEP', profile.parseDeparture, opt)
	}
	const arrivals = (station, opt = {}) => {
		return _stationBoard(station, 'ARR', profile.parseArrival, opt)
	}

	const journeys = (from, to, opt = {}) => {
		from = profile.formatLocation(profile, from, 'from')
		to = profile.formatLocation(profile, to, 'to')

		if (('earlierThan' in opt) && ('laterThan' in opt)) {
			throw new TypeError('opt.earlierThan and opt.laterThan are mutually exclusive.')
		}
		if (('departure' in opt) && ('arrival' in opt)) {
			throw new TypeError('opt.departure and opt.arrival are mutually exclusive.')
		}
		let journeysRef = null
		if ('earlierThan' in opt) {
			if (!isNonEmptyString(opt.earlierThan)) {
				throw new TypeError('opt.earlierThan must be a non-empty string.')
			}
			if (('departure' in opt) || ('arrival' in opt)) {
				throw new TypeError('opt.earlierThan and opt.departure/opt.arrival are mutually exclusive.')
			}
			journeysRef = opt.earlierThan
		}
		if ('laterThan' in opt) {
			if (!isNonEmptyString(opt.laterThan)) {
				throw new TypeError('opt.laterThan must be a non-empty string.')
			}
			if (('departure' in opt) || ('arrival' in opt)) {
				throw new TypeError('opt.laterThan and opt.departure/opt.arrival are mutually exclusive.')
			}
			journeysRef = opt.laterThan
		}

		opt = Object.assign({
			results: null, // number of journeys – `null` means "whatever HAFAS returns"
			via: null, // let journeys pass this station?
			stopovers: false, // return stations on the way?
			transfers: -1, // maximum nr of transfers
			transferTime: 0, // minimum time for a single transfer in minutes
			// todo: does this work with every endpoint?
			accessibility: 'none', // 'none', 'partial' or 'complete'
			bike: false, // only bike-friendly journeys
			walkingSpeed: 'normal', // 'slow', 'normal', 'fast'
			// Consider walking to nearby stations at the beginning of a journey?
			startWithWalking: true,
			tickets: false, // return tickets?
			polylines: false, // return leg shapes?
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			remarks: true, // parse & expose hints & warnings?
			scheduledDays: false
		}, opt)
		if (opt.via) opt.via = profile.formatLocation(profile, opt.via, 'opt.via')

		if (opt.when !== undefined) {
			throw new Error('opt.when is not supported anymore. Use opt.departure/opt.arrival.')
		}
		let when = new Date(), outFrwd = true
		if (opt.departure !== undefined && opt.departure !== null) {
			when = new Date(opt.departure)
			if (Number.isNaN(+when)) throw new TypeError('opt.departure is invalid')
		} else if (opt.arrival !== undefined && opt.arrival !== null) {
			if (!profile.journeysOutFrwd) {
				throw new Error('opt.arrival is unsupported')
			}
			when = new Date(opt.arrival)
			if (Number.isNaN(+when)) throw new TypeError('opt.arrival is invalid')
			outFrwd = false
		}

		const filters = [
			profile.formatProductsFilter({profile}, opt.products || {})
		]
		if (
			opt.accessibility &&
			profile.filters &&
			profile.filters.accessibility &&
			profile.filters.accessibility[opt.accessibility]
		) {
			filters.push(profile.filters.accessibility[opt.accessibility])
		}

		if (!['slow','normal','fast'].includes(opt.walkingSpeed)) {
			throw new Error('opt.walkingSpeed must be one of these values: "slow", "normal", "fast".')
		}
		const gisFltrL = []
		if (profile.journeysWalkingSpeed) {
			gisFltrL.push({
				meta: 'foot_speed_' + opt.walkingSpeed,
				mode: 'FB',
				type: 'M'
			})
		}

		const query = {
			getPasslist: !!opt.stopovers,
			maxChg: opt.transfers,
			minChgTime: opt.transferTime,
			depLocL: [from],
			viaLocL: opt.via ? [{loc: opt.via}] : [],
			arrLocL: [to],
			jnyFltrL: filters,
			gisFltrL,
			getTariff: !!opt.tickets,
			// todo: this is actually "take additional stations nearby the given start and destination station into account"
			// see rest.exe docs
			ushrp: !!opt.startWithWalking,

			getPT: true, // todo: what is this?
			getIV: false, // todo: walk & bike as alternatives?
			getPolyline: !!opt.polylines
			// todo: `getConGroups: false` what is this?
			// todo: what is getEco, fwrd?
		}
		if (journeysRef) query.ctxScr = journeysRef
		else {
			query.outDate = profile.formatDate(profile, when)
			query.outTime = profile.formatTime(profile, when)
		}
		if (opt.results !== null) query.numF = opt.results
		if (profile.journeysOutFrwd) query.outFrwd = outFrwd

		return profile.request({profile, opt}, userAgent, {
			cfg: {polyEnc: 'GPA'},
			meth: 'TripSearch',
			req: profile.transformJourneysQuery({profile, opt}, query)
		})
		.then(({res, common}) => {
			if (!Array.isArray(res.outConL)) return []
			// todo: outConGrpL

			const ctx = {profile, opt, common, res}
			const journeys = res.outConL
			.map(j => profile.parseJourney(ctx, j))

			return {
				earlierRef: res.outCtxScrB,
				laterRef: res.outCtxScrF,
				journeys,
				// todo [breaking]: rename to realtimeDataUpdatedAt
				realtimeDataFrom: res.planrtTS ? parseInt(res.planrtTS) : null,
			}
		})
	}

	const refreshJourney = (refreshToken, opt = {}) => {
		if ('string' !== typeof refreshToken || !refreshToken) {
			throw new TypeError('refreshToken must be a non-empty string.')
		}

		opt = Object.assign({
			stopovers: false, // return stations on the way?
			tickets: false, // return tickets?
			polylines: false, // return leg shapes? (not supported by all endpoints)
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			remarks: true // parse & expose hints & warnings?
		}, opt)

		const req = profile.formatRefreshJourneyReq({profile, opt}, refreshToken)

		return profile.request({profile, opt}, userAgent, req)
		.then(({res, common}) => {
			if (!Array.isArray(res.outConL) || !res.outConL[0]) {
				const err = new Error('invalid response')
				// technically this is not a HAFAS error
				// todo: find a different flag with decent DX
				err.isHafasError = true
				throw err
			}

			const ctx = {profile, opt, common, res}
			return {
				// todo [breaking]: rename to realtimeDataUpdatedAt
				realtimeDataFrom: res.planrtTS ? parseInt(res.planrtTS) : null,
				...profile.parseJourney(ctx, res.outConL[0])
			}
		})
	}

	// Although the DB Navigator app passes the *first* stopover of the trip
	// (instead of the previous one), it seems to work with the previous one as well.
	const journeysFromTrip = async (fromTripId, previousStopover, to, opt = {}) => {
		if (!isNonEmptyString(fromTripId)) {
			throw new Error('fromTripId must be a non-empty string.')
		}

		if ('string' === typeof to) {
			to = profile.formatStation(to)
		} else if (isObj(to) && (to.type === 'station' || to.type === 'stop')) {
			to = profile.formatStation(to.id)
		} else throw new Error('to must be a valid stop or station.')

		if (!isObj(previousStopover)) throw new Error('previousStopover must be an object.')

		let prevStop = previousStopover.stop
		if (isObj(prevStop)) {
			prevStop = profile.formatStation(prevStop.id)
		} else if ('string' === typeof prevStop) {
			prevStop = profile.formatStation(prevStop)
		} else throw new Error('previousStopover.stop must be a valid stop or station.')

		let depAtPrevStop = previousStopover.departure || previousStopover.plannedDeparture
		if (!isNonEmptyString(depAtPrevStop)) {
			throw new Error('previousStopover.(planned)departure must be a string')
		}
		depAtPrevStop = Date.parse(depAtPrevStop)
		if (Number.isNaN(depAtPrevStop)) {
			throw new Error('previousStopover.(planned)departure is invalid')
		}
		if (depAtPrevStop > Date.now()) {
			throw new Error('previousStopover.(planned)departure must be in the past')
		}

		opt = Object.assign({
			stopovers: false, // return stations on the way?
			transferTime: 0, // minimum time for a single transfer in minutes
			accessibility: 'none', // 'none', 'partial' or 'complete'
			tickets: false, // return tickets?
			polylines: false, // return leg shapes?
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			remarks: true, // parse & expose hints & warnings?
		}, opt)

		// make clear that `departure`/`arrival`/`when` are not supported
		if (opt.departure) throw new Error('journeysFromTrip + opt.departure is not supported by HAFAS.')
		if (opt.arrival) throw new Error('journeysFromTrip + opt.arrival is not supported by HAFAS.')
		if (opt.when) throw new Error('journeysFromTrip + opt.when is not supported by HAFAS.')

		const filters = [
			profile.formatProductsFilter({profile}, opt.products || {})
		]
		if (
			opt.accessibility &&
			profile.filters &&
			profile.filters.accessibility &&
			profile.filters.accessibility[opt.accessibility]
		) {
			filters.push(profile.filters.accessibility[opt.accessibility])
		}
		// todo: support walking speed filter

		// todo: are these supported?
		// - getPT
		// - getIV
		// - trfReq
		// features from `journeys()` not supported here:
		// - `maxChg`: maximum nr of transfers
		// - `bike`: only bike-friendly journeys
		// - `numF`: how many journeys?
		// - `via`: let journeys pass this station
		// todo: find a way to support them

		const query = {
			// https://github.com/marudor/BahnhofsAbfahrten/blob/49ebf8b36576547112e61a6273bee770f0769660/packages/types/HAFAS/SearchOnTrip.ts#L16-L30
			// todo: support search by `journey.refreshToken` (a.k.a. `ctxRecon`) via `sotMode: RC`?
			sotMode: 'JI', // seach by trip ID (a.k.a. "JID")
			jid: fromTripId,
			locData: { // when & where the trip has been entered
				loc: prevStop,
				type: 'DEP', // todo: are there other values?
				date: profile.formatDate(profile, depAtPrevStop),
				time: profile.formatTime(profile, depAtPrevStop)
			},
			arrLocL: [to],
			jnyFltrL: filters,
			getPasslist: !!opt.stopovers,
			getPolyline: !!opt.polylines,
			minChgTime: opt.transferTime,
			getTariff: !!opt.tickets,
		}

		const {res, common} = await profile.request({profile, opt}, userAgent, {
			cfg: {polyEnc: 'GPA'},
			meth: 'SearchOnTrip',
			req: query,
		})
		if (!Array.isArray(res.outConL)) return []

		const ctx = {profile, opt, common, res}
		// todo [breaking]: return object with realtimeDataUpdatedAt
		return res.outConL
		.map(rawJourney => profile.parseJourney(ctx, rawJourney))
		.map((journey) => {
			// For the first (transit) leg, HAFAS sometimes returns *all* past
			// stopovers of the trip, even though it should only return stopovers
			// between the specified `depAtPrevStop` and the arrival at the
			// interchange station. We slice the leg accordingly.
			const fromLegI = journey.legs.findIndex(l => l.tripId === fromTripId)
			if (fromLegI < 0) return journey
			const fromLeg = journey.legs[fromLegI]
			return {
				...journey,
				legs: [
					...journey.legs.slice(0, fromLegI),
					sliceLeg(fromLeg, previousStopover.stop, fromLeg.destination),
					...journey.legs.slice(fromLegI + 2),
				],
			}
		})
	}

	const locations = (query, opt = {}) => {
		if (!isNonEmptyString(query)) {
			throw new TypeError('query must be a non-empty string.')
		}
		opt = Object.assign({
			fuzzy: true, // find only exact matches?
			results: 5, // how many search results?
			stops: true, // return stops/stations?
			addresses: true,
			poi: true, // points of interest
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			linesOfStops: false // parse & expose lines at each stop/station?
		}, opt)

		const req = profile.formatLocationsReq({profile, opt}, query)

		return profile.request({profile, opt}, userAgent, req)
		.then(({res, common}) => {
			if (!res.match || !Array.isArray(res.match.locL)) return []

			const ctx = {profile, opt, common, res}
			return res.match.locL.map(loc => profile.parseLocation(ctx, loc))
		})
	}

	const stop = (stop, opt = {}) => {
		if ('object' === typeof stop) stop = profile.formatStation(stop.id)
		else if ('string' === typeof stop) stop = profile.formatStation(stop)
		else throw new TypeError('stop must be an object or a string.')

		opt = Object.assign({
			linesOfStops: false, // parse & expose lines at the stop/station?
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			remarks: true, // parse & expose hints & warnings?
		}, opt)

		const req = profile.formatStopReq({profile, opt}, stop)

		return profile.request({profile, opt}, userAgent, req)
		.then(({res, common}) => {
			if (!res || !Array.isArray(res.locL) || !res.locL[0]) {
				// todo: proper stack trace?
				// todo: DRY with lib/request.js
				const err = new Error('response has no stop')
				// technically this is not a HAFAS error
				// todo: find a different flag with decent DX
				err.isHafasError = true
				err.code = INVALID_REQUEST
				throw err
			}

			const ctx = {profile, opt, res, common}
			return profile.parseLocation(ctx, res.locL[0])
		})
	}

	const nearby = (location, opt = {}) => {
		validateLocation(location, 'location')

		opt = Object.assign({
			results: 8, // maximum number of results
			distance: null, // maximum walking distance in meters
			poi: false, // return points of interest?
			stops: true, // return stops/stations?
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			linesOfStops: false // parse & expose lines at each stop/station?
		}, opt)

		const req = profile.formatNearbyReq({profile, opt}, location)

		return profile.request({profile, opt}, userAgent, req)
		.then(({common, res}) => {
			if (!Array.isArray(res.locL)) return []

			// todo: parse `.dur` – walking duration?
			const ctx = {profile, opt, common, res}
			const results = res.locL.map(loc => profile.parseNearby(ctx, loc))
			return Number.isInteger(opt.results) ? results.slice(0, opt.results) : results
		})
	}

	const trip = (id, lineName, opt = {}) => {
		if (!isNonEmptyString(id)) {
			throw new TypeError('id must be a non-empty string.')
		}
		if (!isNonEmptyString(lineName)) {
			throw new TypeError('lineName must be a non-empty string.')
		}
		opt = Object.assign({
			stopovers: true, // return stations on the way?
			polyline: false, // return a track shape?
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			remarks: true // parse & expose hints & warnings?
		}, opt)

		const req = profile.formatTripReq({profile, opt}, id, lineName)

		// todo [breaking]: return object with realtimeDataUpdatedAt
		return profile.request({profile, opt}, userAgent, req)
		.then(({common, res}) => {
			const ctx = {profile, opt, common, res}
			return profile.parseTrip(ctx, res.journey)
		})
	}

	// todo [breaking]: rename to trips()?
	const tripsByName = (lineNameOrFahrtNr = '*', opt = {}) => {
		if (!isNonEmptyString(lineNameOrFahrtNr)) {
			throw new TypeError('lineNameOrFahrtNr must be a non-empty string.')
		}
		opt = Object.assign({
			when: null,
			fromWhen: null, untilWhen: null,
			onlyCurrentlyRunning: true,
			products: {},
			currentlyStoppingAt: null,
			lineName: null,
			operatorNames: null,
			additionalFilters: [], // undocumented
		}, opt)

		const req = {
			// fields: https://github.com/marudor/BahnhofsAbfahrten/blob/f619e754f212980261eb7e2b151cd73ba0213da8/packages/types/HAFAS/JourneyMatch.ts#L4-L23
			input: lineNameOrFahrtNr,
			onlyCR: opt.onlyCurrentlyRunning,
			jnyFltrL: [
				profile.formatProductsFilter({profile}, opt.products),
			],
			// todo: passing `tripId` yields a `CGI_READ_FAILED` error
			// todo: passing a stop ID as `extId` yields a `PARAMETER` error
			// todo: `onlyRT: true` reduces the number of results, but filters recent trips 🤔
			// todo: `onlyTN: true` yields a `NO_MATCH` error
			// todo: useAeqi
		}
		if (opt.when !== null) {
			req.date = profile.formatDate(profile, new Date(opt.when))
			req.time = profile.formatTime(profile, new Date(opt.when))
		}
		// todo: fromWhen doesn't work yet, but untilWhen does
		if (opt.fromWhen !== null) {
			req.dateB = profile.formatDate(profile, new Date(opt.fromWhen))
			req.timeB = profile.formatTime(profile, new Date(opt.fromWhen))
		}
		if (opt.untilWhen !== null) {
			req.dateE = profile.formatDate(profile, new Date(opt.untilWhen))
			req.timeE = profile.formatTime(profile, new Date(opt.untilWhen))
		}
		const filter = (mode, type, value) => ({mode, type, value})
		if (opt.currentlyStoppingAt !== null) {
			if (!isNonEmptyString(opt.currentlyStoppingAt)) {
				throw new TypeError('opt.currentlyStoppingAt must be a non-empty string.')
			}
			req.jnyFltrL.push(filter('INC', 'STATIONS', opt.currentlyStoppingAt))
		}
		if (opt.lineName !== null) {
			if (!isNonEmptyString(opt.lineName)) {
				throw new TypeError('opt.lineName must be a non-empty string.')
			}
			// todo: does this target `line` or `lineId`?
			req.jnyFltrL.push(filter('INC', 'LINE', opt.lineName))
		}
		if (opt.operatorNames !== null) {
			if (
				!Array.isArray(opt.operatorNames)
				|| opt.operatorNames.length === 0
				|| !opt.operatorNames.every(isNonEmptyString)
			) {
				throw new TypeError('opt.operatorNames must be an array of non-empty strings.')
			}
			// todo: is the an escaping mechanism for ","
			req.jnyFltrL.push(filter('INC', 'OP', opt.operatorNames.join(',')))
		}
		req.jnyFltrL = [...req.jnyFltrL, ...opt.additionalFilters]

		// todo [breaking]: return object with realtimeDataUpdatedAt
		return profile.request({profile, opt}, userAgent, {
			cfg: {polyEnc: 'GPA'},
			meth: 'JourneyMatch',
			req,
		})
		// todo [breaking]: catch `NO_MATCH` errors, return []
		.then(({res, common}) => {
			const ctx = {profile, opt, common, res}
			return res.jnyL.map(t => profile.parseTrip(ctx, t))
		})
	}

	const radar = ({north, west, south, east}, opt) => {
		if ('number' !== typeof north) throw new TypeError('north must be a number.')
		if ('number' !== typeof west) throw new TypeError('west must be a number.')
		if ('number' !== typeof south) throw new TypeError('south must be a number.')
		if ('number' !== typeof east) throw new TypeError('east must be a number.')
		if (north <= south) throw new Error('north must be larger than south.')
		if (east <= west) throw new Error('east must be larger than west.')

		opt = Object.assign({
			results: 256, // maximum number of vehicles
			duration: 30, // compute frames for the next n seconds
			// todo: what happens with `frames: 0`?
			frames: 3, // nr of frames to compute
			products: null, // optionally an object of booleans
			polylines: true, // return a track shape for each vehicle?
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
		}, opt || {})
		opt.when = new Date(opt.when || Date.now())
		if (Number.isNaN(+opt.when)) throw new TypeError('opt.when is invalid')

		const req = profile.formatRadarReq({profile, opt}, north, west, south, east)

		// todo [breaking]: return object with realtimeDataUpdatedAt
		return profile.request({profile, opt}, userAgent, req)
		.then(({res, common}) => {
			if (!Array.isArray(res.jnyL)) return []

			const ctx = {profile, opt, common, res}
			return res.jnyL.map(m => profile.parseMovement(ctx, m))
		})
	}

	const reachableFrom = (address, opt = {}) => {
		validateLocation(address, 'address')

		opt = Object.assign({
			when: Date.now(),
			maxTransfers: 5, // maximum of 5 transfers
			maxDuration: 20, // maximum travel duration in minutes, pass `null` for infinite
			products: {},
			subStops: true, // parse & expose sub-stops of stations?
			entrances: true, // parse & expose entrances of stops/stations?
			polylines: false, // return leg shapes?
		}, opt)
		if (Number.isNaN(+opt.when)) throw new TypeError('opt.when is invalid')

		const req = profile.formatReachableFromReq({profile, opt}, address)

		const refetch = () => {
			return profile.request({profile, opt}, userAgent, req)
			.then(({res, common}) => {
				if (!Array.isArray(res.posL)) {
					const err = new Error('invalid response')
					err.shouldRetry = true
					throw err
				}

				const byDuration = []
				let i = 0, lastDuration = NaN
				for (const pos of sortBy(res.posL, 'dur')) {
					const loc = common.locations[pos.locX]
					if (!loc) continue
					if (pos.dur !== lastDuration) {
						lastDuration = pos.dur
						i = byDuration.length
						byDuration.push({
							duration: pos.dur,
							stations: [loc]
						})
					} else {
						byDuration[i].stations.push(loc)
					}
				}
				// todo [breaking]: return object with realtimeDataUpdatedAt
				return byDuration
			})
		}

		return pRetry(refetch, {
			retries: 3,
			factor: 2,
			minTimeout: 2 * 1000
		})
	}

	const remarks = async (opt = {}) => {
		opt = {
			results: 100, // maximum number of remarks
			// filter by time
			from: Date.now(),
			to: null,
			products: null, // filter by affected products
			polylines: false, // return leg shapes? (not supported by all endpoints)
			...opt
		}

		if (opt.from !== null) {
			opt.from = new Date(opt.from)
			validateWhen(opt.from, 'opt.from')
		}
		if (opt.to !== null) {
			opt.to = new Date(opt.to)
			validateWhen(opt.to, 'opt.to')
		}

		const req = profile.formatRemarksReq({profile, opt})
		const {
			res, common,
		} = await profile.request({profile, opt}, userAgent, req)

		// todo [breaking]: return object with realtimeDataUpdatedAt
		const ctx = {profile, opt, common, res}
		return (res.msgL || [])
		.map(w => profile.parseWarning(ctx, w))
	}

	const lines = async (query, opt = {}) => {
		if (!isNonEmptyString(query)) {
			throw new TypeError('query must be a non-empty string.')
		}

		const req = profile.formatLinesReq({profile, opt}, query)
		const {
			res, common,
		} = await profile.request({profile, opt}, userAgent, req)

		// todo [breaking]: return object with realtimeDataUpdatedAt
		if (!Array.isArray(res.lineL)) return []
		const ctx = {profile, opt, common, res}
		return res.lineL.map(l => {
			const parseDirRef = i => (res.common.dirL[i] || {}).txt || null
			return {
				...omit(l.line, ['id', 'fahrtNr']),
				id: l.lineId,
				// todo: what is locX?
				directions: Array.isArray(l.dirRefL)
					? l.dirRefL.map(parseDirRef)
					: null,
				trips: Array.isArray(l.jnyL)
					? l.jnyL.map(t => profile.parseTrip(ctx, t))
					: null,
			}
		})
	}

	const serverInfo = async (opt = {}) => {
		const {res, common} = await profile.request({profile, opt}, userAgent, {
			meth: 'ServerInfo',
			req: {}
		})

		const ctx = {profile, opt, common, res}
		return {
			timetableStart: res.fpB || null,
			timetableEnd: res.fpE || null,
			serverTime: res.sD && res.sT
				? profile.parseDateTime(ctx, res.sD, res.sT)
				: null,
			realtimeDataUpdatedAt: res.planrtTS
				? parseInt(res.planrtTS)
				: null,
		}
	}

	const client = {
		departures,
		arrivals,
		journeys,
		locations,
		stop,
		nearby,
		serverInfo,
	}
	if (profile.trip) client.trip = trip
	if (profile.radar) client.radar = radar
	if (profile.refreshJourney) client.refreshJourney = refreshJourney
	if (profile.journeysFromTrip) client.journeysFromTrip = journeysFromTrip
	if (profile.reachableFrom) client.reachableFrom = reachableFrom
	if (profile.tripsByName) client.tripsByName = tripsByName
	if (profile.remarks !== false) client.remarks = remarks
	if (profile.lines !== false) client.lines = lines
	Object.defineProperty(client, 'profile', {value: profile})
	return client
}

module.exports = createClient