OpenSlides/client/src/app/core/services/websocket.service.ts

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import { Injectable } from '@angular/core';
import { Router } from '@angular/router';
import { webSocket, WebSocketSubject } from 'rxjs/webSocket';
import { Observable, Subject } from 'rxjs';
interface WebsocketMessage {
type: string;
content: any;
id: string;
}
/**
* Service that handles WebSocket connections.
*
* Creates or returns already created WebSockets.
*/
@Injectable({
providedIn: 'root'
})
export class WebsocketService {
/**
* Constructor that handles the router
* @param router the URL Router
*/
constructor(private router: Router) {}
/**
* Observable subject that might be `any` for simplicity, `MessageEvent` or something appropriate
*/
private _websocketSubject: WebSocketSubject<WebsocketMessage>;
/**
* Subjects for types of websocket messages. A subscriber can get an Observable by {@function getOberservable}.
*/
private _subjects: { [type: string]: Subject<any> } = {};
/**
* Creates a new WebSocket connection as WebSocketSubject
*
* Can return old Subjects to prevent multiple WebSocket connections.
*/
public connect(): void {
const socketProtocol = this.getWebSocketProtocol();
const socketPath = this.getWebSocketPath();
const socketServer = window.location.hostname + ':' + window.location.port;
if (!this._websocketSubject) {
this._websocketSubject = webSocket(socketProtocol + socketServer + socketPath);
// directly subscribe. The messages are distributes below
this._websocketSubject.subscribe(message => {
const type: string = message.type;
if (type === 'error') {
console.error('Websocket error', message.content);
} else if (this._subjects[type]) {
this._subjects[type].next(message.content);
} else {
console.log(`Got unknown websocket message type "${type}" with content`, message.content);
}
});
}
}
/**
* Returns an observable for messages of the given type.
* @param type the message type
*/
public getOberservable<T>(type: string): Observable<T> {
if (!this._subjects[type]) {
this._subjects[type] = new Subject<T>();
}
return this._subjects[type].asObservable();
}
/**
* Sends a message to the server with the content and the given type.
*
* @param type the message type
* @param content the actual content
*/
public send<T>(type: string, content: T): void {
if (!this._websocketSubject) {
return;
}
const message: WebsocketMessage = {
type: type,
content: content,
id: ''
};
const possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
for (let i = 0; i < 8; i++) {
message.id += possible.charAt(Math.floor(Math.random() * possible.length));
}
this._websocketSubject.next(message);
}
/**
* Delegates to socket-path for either the side or projector websocket.
*/
private getWebSocketPath(): string {
//currentRoute does not end with '/'
const currentRoute = this.router.url;
if (currentRoute.includes('/projector') || currentRoute.includes('/real-projector')) {
return '/ws/projector';
} else {
return '/ws/site/';
}
}
/**
* returns the desired websocket protocol
*
* TODO: HTTPS is not yet tested
*/
private getWebSocketProtocol(): string {
if (location.protocol === 'https') {
return 'wss://';
} else {
return 'ws://';
}
}
}