tracktracker/back/data/realtime.js

const axios = require('axios');
const csv = require('csv-parse');

const network = require('./network');
const {TAM_REALTIME} = require('./endpoints');

const sortByFirstKey = (a, b) => a[0] - b[0];

const fetchRealtime = () => new Promise((res, rej) =>
{
    const stream = axios.get(TAM_REALTIME, {
        responseType: 'stream'
    }).then(stream =>
    {
        const parser = csv({
            delimiter: ';',
        });

        const courses = {};
        stream.pipe(parser);

        stream.on('readable', () =>
        {
            let row;

            while (row = stream.read())
            {
                if (row.length === 0 || row[0] === 'course')
                {
                    // Ignore les lignes invalides et l’en-tête
                    continue;
                }

                const course = row[0];
                const stopRef = row[2];
                const lineRef = row[4];
                const eta = row[9];
                const destinationRef = row[10];

                if (!(course in courses))
                {
                    courses[course] = {
                        lineRef,
                        destinationRef,
                        stops: [],
                    };
                }

                courses[course].stops.push([parseInt(eta, 10), stopRef]);
                courses[course].stops.sort(sortByFirstKey);
            }
        });

        stream.on('end', () => res(courses));
        stream.on('error', err => rej(err));
    });
});

const updateVehicles = async (lines, vehicles) =>
{
    const courses = await fetchRealtime();
    const currentTime = Math.floor(Date.now() / 1000);

    for (let [courseRef, course] of Object.entries(courses))
    {
        if (course.lineRef in lines)
        {
            if (!(courseRef in vehicles))
            {
                // New vehicle: identify which route it pertains to
                const line = lines[course.lineRef];
                let routeIndex = null;

                for (let [index, route] of Object.entries(line.routes))
                {
                    const destRef = route.stops[route.stops.length - 1].ref;

                    if (destRef === course.destinationRef)
                    {
                        routeIndex = index;
                    }
                }

                if (routeIndex !== null)
                {
                    const route = line.routes[routeIndex];

                    // Convert ETAs to absolute times
                    const nextStops = course.stops.map(([eta, ref]) => [
                        eta + currentTime,
                        ref
                    ]);

                    // Convert stop refs to indices
                    const stopIndices = course.stops.map(([eta, ref]) => [
                        eta,
                    ]);

                    // Find the preceding stop from which the vehicle is coming
                    const arrivingStop = stopIndices[0][1];
                    const arrivingStopIndex = route.stops.findIndex(
                        stop => stop.ref === arrivingStop
                    );

                    const leavingStop = arrivingStopIndex === 0
                        ? route.stops[0]
                        : route.stops[arrivingStopIndex - 1];

                    if (nextStop === 0)
                    {
                        // Vehicle at starting point
                        vehicles[courseRef] = {
                            lineRef: course.lineRef,
                            stopRef

                            stopIndex: 0,
                            nextStops: stopIndices,

                            distance: 0,
                            speed: 0,
                        };
                    }
                    else
                    {
                        // Vehicle in transit between two stops
                        vehicles[courseRef] = {
                            lineRef: course.lineRef,
                            routeIndex,

                            stopIndex: nextStop - 1,
                            nextStops: stopIndices,

                            distance: 0,
                            speed: route.distances[nextStop - 1] / eta,
                        };
                    }
                }
            }
            else
            {
                // Existing vehicle: update information
                const vehicle = vehicles[courseRef];

                const line = lines[vehicle.lineRef];
                const route = line.routes[vehicle.routeIndex];

                // Convert stop refs to indices
                const stopIndices = course.stops.map(([eta, ref]) => [
                    eta,
                    route.stops.findIndex(stop => stop.ref === ref),
                ]);

                console.log(stopIndices);
                console.log(vehicle);
                console.log(course);
                console.log('---');
            }
        }
    }
};

const sleep = time => new Promise(res => setTimeout(res, time));

const updateLoop = async (lines, vehicles = {}) =>
{
    await updateVehicles(lines, vehicles);
    await sleep(30000);
    return updateLoop(lines, vehicles);
};

(async () =>
{
    const lines = {'1': await network.fetchLineData('1')};
    updateLoop(lines);

    // console.log(require('util').inspect(vehicles, true, 10));
})();