import { Injectable } from '@angular/core';
import { Observable, Subject, Subscription } from 'rxjs';
import { webSocket, WebSocketSubject } from 'rxjs/webSocket';
import { filter, map } from 'rxjs/operators';
import { WebSocketMessage } from '../message-types/websocket-message';

export enum Scope {
  ZMQ = 'zmq',
  WEBSOCKET = 'websocket'
}

export enum Intent {
  CONTROL = 'control',
  EVENT = 'event'
}

@Injectable()
export class WebSocketService {
  private ws: WebSocketSubject<WebSocketMessage>;
  private subject: Subject<WebSocketMessage> = new Subject<WebSocketMessage>();
  private subscription: Subscription;

  constructor() {}

  public connect() {
    if (!this.ws) {
      if (this.subscription) {
        this.subscription.unsubscribe();
      }
      const wsproto = (location.protocol === 'https:') ? 'wss://' : 'ws://';
      const connAddr = wsproto + window.location.host + '/ws';
      this.ws = webSocket<WebSocketMessage>({
        url: connAddr,
        closeObserver: {
            next: closeEvent => {
                this.ws = null;
                this.connect();
            }
          }
      });
      this.subscription = this.ws.subscribe(msg => this.subject.next(msg));
    }
  }

  public observeControl<T extends WebSocketMessage>(key: string): Observable<T> {
    return this.observeAll<T>(key).pipe(
      filter(message => message.intent !== Intent.EVENT)
    );
  }

  public observeAll<T extends WebSocketMessage>(key: string): Observable<T> {
    return this.subject.pipe(
      filter(message => message.key.startsWith(key)),
      map(message => <T> message)
    );
  }

  public send(json: any) {
    this.ws.next(json);
  }
}