import { Injectable } from '@angular/core';
import { Subject, BehaviorSubject, Observable } from 'rxjs';
import { filter } from 'rxjs/operators';

@Injectable({
  providedIn: 'root'
})
export class MessageLiveDataSourceService {

  private messageSubject: Subject<any> = new Subject<any>();
  private isPaused: BehaviorSubject<boolean> = new BehaviorSubject<boolean>(false);
  private messageBuffer: any[] = []; // Buffer to store messages when paused
  private authentication!: string

  constructor() { }

  handleMessage(event: any) {
    const data: any  = event.data || MessageEvent;

    if (this.isPaused.getValue()) {
      this.messageBuffer.push({}); // Buffer the message if paused
    } else {
      this.messageSubject.next({} as any);
    }
  }


  pauseBroadcast() {
    this.isPaused.next(true);
  }

  resumeBroadcast() {
    this.isPaused.next(false);
    this.flushMessageBuffer(); // Emit all buffered messages
  }

  private flushMessageBuffer() {
    while (this.messageBuffer.length > 0) {
      const bufferedMessage = this.messageBuffer.shift();
      this.messageSubject.next(bufferedMessage);
    }
  }

  subscribe(endpoint: any): Observable<any>  {
    return this.messageSubject.pipe(
      filter(message =>
        message &&
        message.endpoint === endpoint &&
        message.authentication == this.authentication
      )
    )
  }
}