Adding a Pusher container as a middleware/dispatcher between front and back

pusher/src/Model/Group.ts

@@ -0,0 +1,138 @@
+import { ConnectCallback, DisconnectCallback } from "./PusherRoom";
+import { User } from "./User";
+import {PositionInterface} from "_Model/PositionInterface";
+import {Movable} from "_Model/Movable";
+import {PositionDispatcher} from "_Model/PositionDispatcher";
+import {gaugeManager} from "../Services/GaugeManager";
+
+export class Group implements Movable {
+    static readonly MAX_PER_GROUP = 4;
+
+    private static nextId: number = 1;
+
+    private id: number;
+    private users: Set<User>;
+    private x!: number;
+    private y!: number;
+    private hasEditedGauge: boolean = false;
+    private wasDestroyed: boolean = false;
+    private roomId: string;
+
+
+    constructor(roomId: string, users: User[], private connectCallback: ConnectCallback, private disconnectCallback: DisconnectCallback, private positionNotifier: PositionDispatcher) {
+        this.roomId = roomId;
+        this.users = new Set<User>();
+        this.id = Group.nextId;
+        Group.nextId++;
+        //we only send a event for prometheus metrics if the group lives more than 5 seconds
+        setTimeout(() => {
+            if (!this.wasDestroyed) {
+                this.hasEditedGauge = true;
+                gaugeManager.incNbGroupsPerRoomGauge(roomId);
+            }
+        }, 5000);
+
+        users.forEach((user: User) => {
+            this.join(user);
+        });
+
+        this.updatePosition();
+    }
+
+    getUsers(): User[] {
+        return Array.from(this.users.values());
+    }
+
+    getId() : number {
+        return this.id;
+    }
+
+    /**
+     * Returns the barycenter of all users (i.e. the center of the group)
+     */
+    getPosition(): PositionInterface {
+        return {
+            x: this.x,
+            y: this.y
+        };
+    }
+
+    /**
+     * Computes the barycenter of all users (i.e. the center of the group)
+     */
+    updatePosition(): void {
+        const oldX = this.x;
+        const oldY = this.y;
+
+        let x = 0;
+        let y = 0;
+        // Let's compute the barycenter of all users.
+        this.users.forEach((user: User) => {
+            const position = user.getPosition();
+            x += position.x;
+            y += position.y;
+        });
+        x /= this.users.size;
+        y /= this.users.size;
+        if (this.users.size === 0) {
+            throw new Error("EMPTY GROUP FOUND!!!");
+        }
+        this.x = x;
+        this.y = y;
+
+        if (oldX === undefined) {
+            this.positionNotifier.enter(this);
+        } else {
+            this.positionNotifier.updatePosition(this, {x, y}, {x: oldX, y: oldY});
+        }
+    }
+
+    isFull(): boolean {
+        return this.users.size >= Group.MAX_PER_GROUP;
+    }
+
+    isEmpty(): boolean {
+        return this.users.size <= 1;
+    }
+
+    join(user: User): void
+    {
+        // Broadcast on the right event
+        this.connectCallback(user, this);
+        this.users.add(user);
+        user.group = this;
+    }
+
+    leave(user: User): void
+    {
+        const success = this.users.delete(user);
+        if (success === false) {
+            throw new Error("Could not find user "+user.id+" in the group "+this.id);
+        }
+        user.group = undefined;
+
+        if (this.users.size !== 0) {
+            this.updatePosition();
+        }
+
+        // Broadcast on the right event
+        this.disconnectCallback(user, this);
+    }
+
+    /**
+     * Let's kick everybody out.
+     * Usually used when there is only one user left.
+     */
+    destroy(): void
+    {
+        if (this.hasEditedGauge) gaugeManager.decNbGroupsPerRoomGauge(this.roomId);
+        for (const user of this.users) {
+            this.leave(user);
+        }
+        this.wasDestroyed = true;
+    }
+
+    get getSize(){
+        return this.users.size;
+    }
+}