Bay Area Commute Time Tracking

const functions = require('@google-cloud/functions-framework');
const { Storage } = require('@google-cloud/storage');
const https = require('https');
const { parse } = require('csv-parse/sync');
const { stringify } = require('csv-stringify/sync');

const storage = new Storage();
const BUCKET_NAME = 'maps-commute-data';

const MAPS_API_KEY = '<insert>';
const MODE = 'driving';
const TRAFFIC_MODEL = "best_guess";

function getRequestURL(key, origin, destination, mode, trafficModel) {
	return "https://maps.googleapis.com/maps/api/directions/json" + 
		"?origin=" + encodeURI(origin) + 
		"&destination=" + encodeURI(destination) + 
		"&mode=" + encodeURI(mode) + 
		"&trafficModel=" + encodeURI(trafficModel) + 
		"&departure_time=now" + 
		"&key=" + key;
}

function getShortestDuration(responseBody) {
  console.info(responseBody);
	if (responseBody.routes.length == 0) return NaN;
	let shortest = responseBody.routes[0].legs[0].duration_in_traffic.value;
	for (let i = 1; i < responseBody.routes.length; i++) {
		shortest = Math.min(shortest, responseBody.routes[i].legs[0].duration_in_traffic.value);
	}
	return shortest;
}

function appendLogToCSV(fileName, duration, callback) {
  const bucket = storage.bucket(BUCKET_NAME);
  const file = bucket.file(fileName);
  
  file.download((err, data) => {
    let csvContent;
    if (err) {
      if (err.code === 404) {
        csvContent = [];
      } else {
        return callback(err);
      }
    } else {
      csvContent = parse(data.toString(), {
        columns: true,
        skip_empty_lines: true
      });
    }

    csvContent.push({ timestamp: new Date().toISOString(), duration: duration });
    const updatedCSV = stringify(csvContent, { header: true });
    file.save(updatedCSV, callback);
  });
}

function formatForFileName(str) {
    str = str.toLowerCase();
    str = str.replace(/[\s]/g, '_');
    str = str.replace(/[^a-z0-9_]/g, '');
    if (str.length > 40) {
        str = str.substring(0, 30) + str.substring(str.length - 10, str.length);
    }
    return str;
}

functions.http('callMapsAndLog', (cloudFnReq, cloudFnRes) => {
  const origin = cloudFnReq.headers.origin;
  const destination = cloudFnReq.headers.destination;

  const logfileName = `log-origin-${formatForFileName(origin)}-to-${formatForFileName(destination)}.csv`

  let url = getRequestURL(MAPS_API_KEY, origin, destination, MODE, TRAFFIC_MODEL);
  https.get(url, (res) => {
    let data = "";
    res.on('data', (d) => { data += d; });

	res.on('end', () => {
		let duration = getShortestDuration(JSON.parse(data));
		appendLogToCSV(logfileName, duration, (err) => {
		if (err) {
			cloudFnRes.status(500).send('Error writing to CSV: ' + err.message);
		} else {
			cloudFnRes.send(`Shortest duration from ${origin} to ${destination} is ${duration}s.`);
		}
		});
	});
  }).on('error', (e) => {
    cloudFnRes.send(e);
  });
});

{
  "dependencies": {
    "@google-cloud/functions-framework": "^3.0.0",
    "@google-cloud/storage": "^7.7.0",
    "csv-parse": "^5.5.3",
    "csv-stringify": "^6.4.5"
  }
}