import { Injectable } from '@angular/core';
import { BehaviorSubject, Observable, Subject } from 'rxjs/Rx';
import * as Stomp from '@stomp/stompjs';
import * as SockJS from 'sockjs-client';
import { ApiWorkerService } from '../api/api-worker.service';
import { filter, map } from 'rxjs/operators';

@Injectable({
    providedIn: 'root'
})
export class WebSocketService {
    private messageSubject: Subject<{ code: string, body: any }> = new Subject<{ code: string, body: any }>();
    private state: BehaviorSubject<boolean> = new BehaviorSubject<boolean>(false);
    private readonly ws: WebSocket;
    private readonly client: Stomp.Client;

    constructor(private api: ApiWorkerService) {
        this.ws = new SockJS(this.api.prepareUrl('ws'));
        this.client = Stomp.over(this.ws);
        this.client.connect({}, () => {
            this.state.next(true);
            this.client.subscribe('/subscribe', message => {
                this.messageSubject.next({
                    code: message.headers['code'],
                    body: message.body
                });
            });
        }, () => {
            console.error('WebSocket connection error');
            this.state.next(false);
        });
    }

    public getObservable<T>(code: string): Observable<T> {
        return this.messageSubject.asObservable().pipe(
            filter(data => {
                return data.code === code;
            }),
            map(data => {
                return data.body as T;
            })
        );
    }
}