socket-events.js

const dbOperations = require('./db/db-operations');
const mongoose = require('mongoose');

function initialize(server) {
	// Creating a new socket.io instance by passing the HTTP server object
	const io = require('socket.io')(server);

	io.on('connection', (socket) => { // Listen on the 'connection' event for incoming sockets
		console.log('A user just connected');

		socket.on('join', (data) => { // Listen to any join event from connected users
			socket.join(data.userId); // User joins a unique room/channel that's named after the userId
			console.log(`User joined room: ${data.userId}`);
		});

		// Listen to a 'request-for-help' event from connected civilians
		socket.on('request-for-help', async (eventData) => {
            /*
            	eventData contains userId and location
            	1. First save the request details in the collection requestsData
            	2. AFTER saving, fetch nearby cops from civilian’s location
            	3. Fire a request-for-help event to each of the cop’s room
            */

			// 1. First save the request details in the collection requestsData.
			const requestTime = new Date(); // Time of the request
			const requestId = mongoose.Types.ObjectId(); // Generate unique ID for the request

			const location = { // Convert latitude and longitude to [longitude, latitude]
				coordinates: [
					eventData.location.longitude,
					eventData.location.latitude
				],
				address: eventData.location.address
			};

			await dbOperations.saveRequest(requestId, requestTime, location, eventData.civilianId, 'waiting');

			// 2. AFTER saving, fetch nearby cops from civilian’s location
			const nearestCops = await dbOperations.fetchNearestCops(location.coordinates, 2000);
			eventData.requestId = requestId;

			// 3. After fetching nearest cops, fire a 'request-for-help' event to each of them
			for (let i = 0; i < nearestCops.length; i++) {
				io.sockets.in(nearestCops[i].userId).emit('request-for-help', eventData);
			}

		});

		socket.on('request-accepted', async (eventData) => { // Listen to a 'request-accepted' event from connected cops
			console.log('eventData contains: ', eventData);

			// Convert string to MongoDb's ObjectId data-type
			const requestId = mongoose.Types.ObjectId(eventData.requestDetails.requestId);

			// Then update the request in the database with the cop details for given requestId
			await dbOperations.updateRequest(requestId, eventData.copDetails.copId, 'engaged');

			// After updating the request, emit a 'request-accepted' event to the civilian and send cop details
			io.sockets.in(eventData.requestDetails.civilianId).emit('request-accepted', eventData.copDetails);
		});

	});
}

exports.initialize = initialize;