import isObj from 'lodash/isObject.js';
import sortBy from 'lodash/sortBy.js';
import omit from 'lodash/omit.js';
import distance from 'gps-distance';

import {defaultProfile} from './lib/default-profile.js';
import {validateProfile} from './lib/validate-profile.js';
import {INVALID_REQUEST} from './lib/errors.js';
import {sliceLeg} from './lib/slice-leg.js';
import {HafasError} from './lib/errors.js';

// background info: https://github.com/public-transport/hafas-client/issues/286
const FORBIDDEN_USER_AGENTS = [
	'my-awesome-program', // previously used in readme.md, p/*/readme.md & docs/*.md
	'hafas-client-example', // previously used in p/*/example.js
	'link-to-your-project-or-email', // now used throughout
];

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(Number(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');
	}
	if (FORBIDDEN_USER_AGENTS.includes(userAgent.toLowerCase())) {
		throw new TypeError(`userAgent should tell the API operators how to contact you. If you have copied "${userAgent}" value from the documentation, please adapt it.`);
	}

	const _stationBoard = async (station, type, resultsField, parse, opt = {}) => {
		if (isObj(station) && station.id) {
			station = station.id;
		} else if ('string' !== typeof station) {
			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(Number(opt.when))) {
			throw new Error('opt.when is invalid');
		}

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

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

		const ctx = {profile, opt, common, res};
		const results = (res[resultsField] || res.items).map(res => parse(ctx, res)); // todo sort?

		return {
			[resultsField]: results,
			realtimeDataUpdatedAt: null, // TODO
		};
	};

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

	const journeys = async (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: null, // 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, // parse & expose dates each journey is valid on?
		}, 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(Number(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(Number(when))) {
				throw new TypeError('opt.arrival is invalid');
			}
			outFrwd = false;
		}

		const filters = profile.formatProductsFilter({profile}, opt.products || {});
		// TODO opt.accessibility

		const query = {
			maxUmstiege: opt.transfers,
			minUmstiegszeit: opt.transferTime,
			deutschlandTicketVorhanden: false,
			nurDeutschlandTicketVerbindungen: false,
			reservierungsKontingenteVorhanden: false,
			schnelleVerbindungen: true,
			sitzplatzOnly: false,
			abfahrtsHalt: from.lid,
			zwischenhalte: opt.via
				? [{id: opt.via.lid}]
				: null,
			ankunftsHalt: to.lid,
			produktgattungen: filters,
			bikeCarriage: opt.bike,
			// TODO
			// todo: this is actually "take additional stations nearby the given start and destination station into account"
			// see rest.exe docs
			// ushrp: Boolean(opt.startWithWalking),
		};
		query.anfrageZeitpunkt = profile.formatTime(profile, when);
		if (journeysRef) {
			query.pagingReference = journeysRef;
		}
		query.ankunftSuche = outFrwd ? 'ABFAHRT' : 'ANKUNFT';
		if (opt.results !== null) {
			// TODO query.numF = opt.results;
		}
		const req = profile.transformJourneysQuery({profile, opt}, query);
		const {res, common} = await profile.request({profile, opt}, userAgent, req);
		const ctx = {profile, opt, common, res};
		const verbindungen = opt.results ? res.verbindungen.slice(0, opt.results) : res.verbindungen;
		const journeys = verbindungen
			.map(j => profile.parseJourney(ctx, j));

		return {
			earlierRef: res.verbindungReference?.earlier || null,
			laterRef: res.verbindungReference?.later || null,
			journeys,
			realtimeDataUpdatedAt: null, // TODO
		};
	};

	const refreshJourney = async (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?
			scheduledDays: false, // parse & expose dates the journey is valid on?
		}, opt);

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

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

		return {
			journey: profile.parseJourney(ctx, res.verbindungen[0]),
			realtimeDataUpdatedAt: null, // TODO
		};
	};

	// 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: Boolean(opt.stopovers),
			getPolyline: Boolean(opt.polylines),
			minChgTime: opt.transferTime,
			getTariff: Boolean(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};
		const journeys = 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),
					],
				};
			});

		return {
			journeys,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? parseInt(res.planrtTS)
				: null,
		};
	};

	const locations = async (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);

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


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

	const stop = async (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);

		const {res, common} = await profile.request({profile, opt}, userAgent, req);
		if (!res || !Array.isArray(res.locL) || !res.locL[0]) {
			throw new HafasError('invalid response, expected locL[0]', null, {
				// This problem occurs on invalid input. 🙄
				code: INVALID_REQUEST,
			});
		}

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

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

		const ctx = {profile, opt, common, res};
		const results = res.map(loc => {
			const res = profile.parseLocation(ctx, loc);
			if (res.latitude || res.location?.latitude) {
				res.distance = Math.round(distance(location.latitude, location.longitude, res.latitude || res.location?.latitude, res.longitude || res.location?.longitude) * 1000);
			}
			return res;
		});

		return Number.isInteger(opt.results)
			? results.slice(0, opt.results)
			: results;
	};

	const trip = async (id, opt = {}) => {
		if (!isNonEmptyString(id)) {
			throw new TypeError('id 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?
			scheduledDays: false, // parse & expose dates trip is valid on?
		}, opt);

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

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

		const trip = profile.parseTrip(ctx, res.journey);

		return {
			trip,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? parseInt(res.planrtTS)
				: null,
		};
	};

	// todo [breaking]: rename to trips()?
	const tripsByName = async (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];

		const {res, common} = await profile.request({profile, opt}, userAgent, {
			cfg: {polyEnc: 'GPA'},
			meth: 'JourneyMatch',
			req,
		});
		// todo [breaking]: catch `NO_MATCH` errors, return []
		const ctx = {profile, opt, common, res};

		const trips = res.jnyL.map(t => profile.parseTrip(ctx, t));

		return {
			trips,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? parseInt(res.planrtTS)
				: null,
		};
	};

	const radar = async ({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.');
		}
		// With a bounding box across the antimeridian, east (e.g. -175) might be smaller than west (e.g. 175).
		// Likewise, across the north/south poles, north (e.g. -85) might be smaller than south (e.g. 85).
		// In these cases, the terms north/south & east/west become rather arbitrary of couse.
		// see also https://antimeridian.readthedocs.io/en/stable/
		// todo: how does HAFAS handle this?
		if (north === south) {
			throw new Error('bbox.north must not be equal to bbox.south.');
		}
		if (east === west) {
			throw new Error('bbox.east must not be equal to bbox.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(Number(opt.when))) {
			throw new TypeError('opt.when is invalid');
		}

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

		const {res, common} = await profile.request({profile, opt}, userAgent, req);
		if (!Array.isArray(res.jnyL)) {
			return [];
		}
		const ctx = {profile, opt, common, res};

		const movements = res.jnyL.map(m => profile.parseMovement(ctx, m));

		return {
			movements,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? parseInt(res.planrtTS)
				: null,
		};
	};

	const reachableFrom = async (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(Number(opt.when))) {
			throw new TypeError('opt.when is invalid');
		}

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

		const {res, common} = await profile.request({profile, opt}, userAgent, req);
		if (!Array.isArray(res.posL)) {
			throw new HafasError('invalid response, expected posL[0]', null, {
				shouldRetry: true,
			});
		}

		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);
			}
		}

		return {
			reachable: byDuration,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? parseInt(res.planrtTS)
				: null,
		};
	};

	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);

		const ctx = {profile, opt, common, res};
		const remarks = (res.msgL || [])
			.map(w => profile.parseWarning(ctx, w));

		return {
			remarks,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? parseInt(res.planrtTS)
				: null,
		};
	};

	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);

		if (!Array.isArray(res.lineL)) {
			return [];
		}
		const ctx = {profile, opt, common, res};
		const lines = 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,
			};
		});

		return {
			lines,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? parseInt(res.planrtTS)
				: null,
		};
	};

	const serverInfo = async (opt = {}) => {
		opt = {
			versionInfo: true, // query HAFAS versions?
			...opt,
		};

		const {res, common} = await profile.request({profile, opt}, userAgent, {
			meth: 'ServerInfo',
			req: {
				getVersionInfo: opt.versionInfo,
			},
		});

		const ctx = {profile, opt, common, res};
		return {
			// todo: what are .serverVersion & .clientVersion?
			hciVersion: res.hciVersion || null,
			timetableStart: res.fpB || null,
			timetableEnd: res.fpE || null,
			serverTime: res.sD && res.sT
				? profile.parseDateTime(ctx, res.sD, res.sT)
				: null,
			realtimeDataUpdatedAt: res.planrtTS && res.planrtTS !== '0'
				? 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;
};

export {
	createClient,
};