tracktracker/back/data/endpoints.js

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const unzip = require('unzip-stream');
const csv = require('csv-parse');
const request = require('request');
const requestp = require('request-promise-native');
const overpassEndpoint = 'https://lz4.overpass-api.de/api/interpreter';
/**
* Submit an Overpass query.
*
* @async
* @param query Query in Overpass QL.
* @return Results as provided by the endpoint.
*/
const queryOverpass = query => requestp.post(
overpassEndpoint,
{form: 'data=' + query}
);
exports.queryOverpass = queryOverpass;
/**
* Process a CSV stream to extract passings.
*
* @private
* @param csvStream Stream containing CSV data.
* @param callback See fetchTamRealtime for a description of the callback.
*/
const processTamPassingStream = (csvStream, callback) =>
{
const parser = csv({
delimiter: ';',
});
const rowStream = csvStream.pipe(parser);
rowStream.on('readable', () =>
{
let row;
while (row = rowStream.read())
{
if (row.length === 0 || row[0] === 'course')
{
// Ignore les lignes invalides et len-tête
continue;
}
callback(null, {
course: row[0],
stopCode: row[1],
stopId: row[2],
stopName: row[3],
routeShortName: row[4],
tripHeadsign: row[5],
directionId: row[6],
departureTime: row[7],
isTheorical: row[8],
delaySec: row[9],
destArCode: row[10],
});
}
});
rowStream.on('end', () => callback(null, null));
rowStream.on('error', err => callback(err));
};
const tamRealtimeEndpoint = 'http://data.montpellier3m.fr/node/10732/download';
/**
* Fetch realtime passings for the current day across the network.
*
* @param callback Called for each passing during parsing. First argument will
* be non-null only if an error occurred. Second argument will contain passings
* or be null if the end was reached.
*/
const fetchTamRealtime = (callback) =>
{
const csvStream = request(tamRealtimeEndpoint);
processTamPassingStream(csvStream, callback);
};
exports.fetchTamRealtime = fetchTamRealtime;
const tamTheoreticalEndpoint =
'http://data.montpellier3m.fr/node/10731/download';
const tamTheoreticalFileName = 'offre_du_jour.csv';
/**
* Fetch theoretical passings for the current day across the network.
*
* @param callback Called for each passing during parsing. First argument will
* be non-null only if an error occurred. Second argument will contain passings
* or be null if the end was reached.
*/
const fetchTamTheoretical = (callback) =>
{
const fileStream = request(tamTheoreticalEndpoint).pipe(unzip.Parse());
fileStream.on('entry', entry =>
{
if (entry.type !== 'File' || entry.path !== tamTheoreticalFileName)
{
entry.autodrain();
return;
}
processTamPassingStream(entry, callback);
});
fileStream.on('error', err => callback(err));
};
exports.fetchTamTheoretical = fetchTamTheoretical;