routes.js

var dbOperations = require('./db-operations');
function initialize(app, db, socket, io) {

  //A GET request to /cops should return back the nearest cops in the vicinity.
  app.get('/cops', function (req, res) {
    var latitude = Number(req.query.lat);
    var longitude = Number(req.query.long);

    dbOperations.fetchNearestCops(db, [longitude, latitude], function (results) {
      res.json({ cops: results });
    });
  });

  app.get('/cops/info', function (req, res) {
    var userId = req.query.userId;
    dbOperations.fetchCopDetails(db, userId, function (results) {
      res.json({
        copDetails: results,
      });
    });
  });

  app.get('/requests/info', function (req, res) {
    dbOperations.fetchRequests(db, function (results) {
      var features = results.map(function (row) {
        return {
          type: 'Feature',
          geometry: {
            type: 'Point',
            coordinates: row.location.coordinates
          },
          properties: {
            status: row.status,
            requestTime: row.requestTime,
            address: row.location.address
          }
        };
      });
      var geoJsonData = {
        type: 'FeatureCollection',
        features: features
      }

      res.json(geoJsonData);
    })
  });

  //Listen to a 'request-for-help' event from connected citizens
  socket.on('request-for-help', function (eventData) {
    /*
        eventData contains userId and location
        1. First save the request details inside a table requestsData
        2. AFTER saving, fetch nearby cops from citizen’s location
        3. Fire a request-for-help event to each of the cop’s room
    */

    var requestTime = new Date(); //Time of the request

    var ObjectID = require('mongodb').ObjectID;
    var requestId = new ObjectID; //Generate unique ID for the request

    //1. First save the request details inside a table requestsData.
    //Convert latitude and longitude to [longitude, latitude]
    var location = {
      coordinates: [
        eventData.location.longitude,
        eventData.location.latitude
      ],
      address: eventData.location.address
    };
    dbOperations.saveRequest(db, requestId, requestTime, location, eventData.citizenId, 'waiting', function (results) {

      //2. AFTER saving, fetch nearby cops from citizen’s location
      dbOperations.fetchNearestCops(db, location.coordinates, function (results) {
        eventData.requestId = requestId;
        //3. After fetching nearest cops, fire a 'request-for-help' event to each of them
        for (var i = 0; i < results.length; i++) {
          io.sockets.in(results[i].userId).emit('request-for-help', eventData);
        }
      });
    });
  });

  //Listen to a 'request-accepted' event from connected cops
  socket.on('request-accepted', function (eventData) {
    //Convert string to MongoDb's ObjectId data-type
    var ObjectID = require('mongodb').ObjectID;
    var requestId = new ObjectID(eventData.requestDetails.requestId);

    //For the request with requestId, update request details
    dbOperations.updateRequest(db, requestId, eventData.copDetails.copId, 'engaged', function (results) {
      //Fire a 'request-accepted' event to the citizen and send cop details
      io.sockets.in(eventData.requestDetails.citizenId).emit('request-accepted', eventData.copDetails);
    });
  });
}

exports.initialize = initialize;