Switch from RabbitMQ to server-sent events

(not fully working yet)

backend/lib/eventManager.ts

@@ -0,0 +1,170 @@
+import { Response } from "express";
+import { logger } from "../app";
+import { ISeverity, NotificationType, PublicNotificationType } from "../models/notifications/notification.interface";
+import { addNotification } from "../models/notifications/notification.model";
+import { IPhone } from "../models/phone/phone.interface";
+import { IUser } from "../models/user/user.interface";
+import { User } from "../models/user/user.model";
+import { randomString } from "./crypto";
+
+/**
+ * This class stores one specific client.
+ */
+export class Client {
+    id: string;
+    userId: string;
+    stream: Response;
+
+    constructor(stream: Response, userId: string) {
+        this.id = randomString(16);
+        this.userId = userId;
+        this.stream = stream;
+    }
+
+    send(type: NotificationType, data: any) {
+        this.stream.write(`event: ${type}\ndata: ${JSON.stringify(data)}\n\n`);
+    }
+
+    async getUser() {
+        return await User.findById(this.userId);
+    }
+}
+
+export class Clients {
+    private clients: Client[];
+
+    constructor(clients: Client[]) {
+        this.clients = clients;
+    }
+
+    getClientsByUser(userId: string) {
+        const userClients = [];
+        for (let i = 0; i < this.clients.length; i++) {
+            if (this.clients[i].userId === userId) {
+                userClients.push(this.clients[i]);
+            }
+        }
+
+        return userClients;
+    }
+
+    closeAllClientsByUser(userId: string) {
+        this.getClientsByUser(userId).forEach(client => {
+            client.stream.end();
+        });
+    }
+
+    addClient(client: Client) {
+        this.clients.push(client);
+
+        return client;
+    }
+
+    getClients() {
+        return this.clients;
+    }
+}
+
+export class EventManager {
+    constructor() {
+        setInterval(() => {
+            this.broadcast('info', { message: "Test" });
+        }, 2000);
+    }
+
+    // This map stores a open data stream and it's associated room.
+    private clients: Clients = new Clients([]);
+
+    private addClient(stream: Response, userId: string) {
+        this.clients.addClient(new Client(stream, userId));
+    }
+
+    /**
+     * Add a client to a specific room
+     * @param room Used as an id for the specific room
+     * @param stream A open connection to the user
+     */
+    async join(userId: string, stream: Response) {
+        if (stream.req == undefined) {
+            stream.send(500);
+            return;
+        }
+
+        // Check user
+        const user = await User.findById(userId);
+        if (user === null) {
+            stream.send(401);
+            return;
+        }
+
+        // Make sure to keep the connection open
+        stream.writeHead(200, {
+            'Content-Type': 'text/event-stream',
+            'Cache-Control': 'no-cache',
+            'Connection': 'keep-alive'
+        });
+
+        this.addClient(stream, userId);
+        logger.debug(`Client ${stream.req.hostname} of user ${user.name} joined.`);
+    }
+
+    /**
+     * Push a new event into a specific room
+     * @param event Type of the event
+     * @param data Content of the event
+     * @param selector Room to push in. If empty then it will be a public broadcast to anyone.
+     */
+    push(type: NotificationType, data: any, user: IUser, severity = ISeverity.INFO) {
+        let clients = this.clients.getClientsByUser(user.id);
+        if (clients === undefined) return;
+
+        /* Manage notifications */
+        if (type != 'beat' && user !== undefined) {
+            if (type == 'phone_alive' || type == 'phone_dead') {
+                addNotification(type, severity, ((data as IPhone)._id), user);
+            }
+        }
+
+        data = { type, severity, ...data };
+
+        clients.forEach((client) => {
+            client.stream.write(`event: ${type}\ndata: ${JSON.stringify(data)}\n\n`);
+        });
+
+        if (user === undefined) {
+            logger.debug(`Broadcasted event ${type} to all users (${clients.length} clients affected)`);
+        } else {
+            logger.debug(`Broadcasted event ${type} to user ${user.id} (${clients.length} clients affected)`);
+        }
+    }
+
+    /**
+     * Very much like push() but it will send this message to **every connected client!**
+     */
+    broadcast(type: PublicNotificationType, data: any) {
+        this.clients.getClients().forEach(async client => {
+            console.log(`Send ${JSON.stringify(data)} (of type ${type}) to a client of user ${(await client.getUser())?.name}`);
+            client.stream.write(`event: message\ndata: ${JSON.stringify(data)}\n\n`);
+        });
+
+        logger.debug(`Broadcasted event ${type} to all users (${this.clients.getClients().length} clients affected)`);
+    }
+
+    /**
+     * End the communication with a specific client.
+     */
+    end(stream: Response, userId: string) {
+        stream.end();
+
+        logger.debug(`End connection with ${stream.req?.hostname} (user: ${userId})`);
+    }
+
+    static buildEventTypeName(type: EventType, user: IUser) {
+        return `${type}-${user}`;
+    }
+}
+
+export type EventType = 
+    | 'tracker'     // Receive just the gps location of a specific user.
+    | 'user'        // Receive user updates.
+    | 'all';        // Receive all above events.