const csv = require("csv-parse");
const axios = require("axios");
const { snakeToCamelCase, unzipFile } = require("../../util");

/**
 * Data available for each passing of a vehicle at a station.
 *
 * See also <http://data.montpellier3m.fr/node/10733/download>.
 * @typedef {Object} Passing
 * @property {string} course Identifier of the overall trip of the same vehicle
 * from one end of the route to another (unique for the day).
 * @property {string} stopCode Unused internal stop identifier.
 * @property {string} stopId Unique network identifier for the station at
 * which the vehicle will pass (same id as in GTFS).
 * @property {string} routeShortName Transport line number.
 * @property {string} tripHeadsign Name of the final stop of this trip.
 * @property {string} directionId Route identifier inside the line.
 * @property {string} departureTime Theoretical time at which the
 * vehicle will depart the stop (HH:MM:SS format).
 * @property {string} isTheorical (sic) Whether the arrival time is only
 * a theoretical information.
 * @property {string} delaySec Number of seconds before the vehicle arrives
 * at the station.
 * @property {string} destArCode Unique network identifier for the final
 * stop of this trip.
 */

const realtimeEndpoint = "http://data.montpellier3m.fr/node/10732/download";

/**
 * Fetch real time passings of vehicles across the network.
 * @yields {{{lastUpdate: number, nextUpdate: number}|Passing}} First value
 * is an object containing the time of last update and the time of next
 * update of this information. Next values are informations about each vehicle
 * passing.
 */
const fetchRealtime = async function *() {
    const res = await axios.get(realtimeEndpoint, {
        responseType: "stream"
    });

    const lastUpdate = new Date(res.headers["last-modified"]).getTime();
    const nextUpdate = lastUpdate + 65 * 1000;

    yield { lastUpdate, nextUpdate };

    const parser = res.data.pipe(csv({
        delimiter: ";",
        columns: header => header.map(snakeToCamelCase)
    }));

    for await (const passing of parser) {
        yield passing;
    }
};

exports.fetchRealtime = fetchRealtime;

const theoreticalEndpoint = "http://data.montpellier3m.fr/node/10731/download";

/**
 * Fetch theoretical passings for the current day across the network.
 * @yields {{{lastUpdate: number, nextUpdate: number}|Passing}} First value
 * is an object containing the time of last update and the time of next
 * update of this information. Next values are informations about each vehicle
 * passing.
 */
const fetchTheoretical = async function *() {
    const res = await axios.get(theoreticalEndpoint, {
        responseType: "stream"
    });

    const lastUpdate = new Date();

    if (lastUpdate.getHours() < 4) {
        lastUpdate.setDate(lastUpdate.getDate() - 1);
    }

    lastUpdate.setHours(4);
    lastUpdate.setMinutes(0);
    lastUpdate.setSeconds(0);
    lastUpdate.setMilliseconds(0);

    const nextUpdate = new Date(lastUpdate);

    nextUpdate.setDate(nextUpdate.getDate() + 1);

    yield {
        lastUpdate: lastUpdate.getTime(),
        nextUpdate: nextUpdate.getTime()
    };

    const stream = await unzipFile(res.data, "offre_du_jour.csv");
    const parser = stream.pipe(csv({
        delimiter: ";",
        columns: header => header.map(snakeToCamelCase)
    }));

    for await (const passing of parser) {
        yield passing;
    }
};

exports.fetchTheoretical = fetchTheoretical;