import {inject, Injectable, OnDestroy} from '@angular/core';
import {Subject} from 'rxjs';
import {AuthService} from '@services/auth.service';
import {EventSourcePolyfill} from 'event-source-polyfill';

export interface ChatEvent {
  type: string;
  data: any;
}

interface SsePayloadEvent {
  data: string;
}

@Injectable({providedIn: 'root'})
export class ChatService implements OnDestroy {
  private eventSource?: EventSourcePolyfill;
  private events$ = new Subject<ChatEvent>();
  private readonly authService: AuthService = inject(AuthService)

  connect() {
    if (this.eventSource) {
      return; // already connected
    }

    const jwt = this.authService.getJwt();
    if (!jwt) {
      //TODO [Stijn] [2026-07-18]: Error when no JWT available (log in?)
      return;
    }

    const source = new EventSourcePolyfill('/api/chat/read/subscribe', {
      headers: {
        Authorization: `Bearer ${jwt}`
      },
      heartbeatTimeout: 60000
    });

    this.eventSource = source;

    this.on(source, 'connected', (event) => {
      console.log('SSE connected:', event.data);
    });

    this.on(source, 'chat-message', (event) => {
      this.events$.next({type: 'chat-message', data: JSON.parse(event.data)});
    });

    source.onerror = (err) => {
      console.error('SSE error, polyfill will auto-reconnect:', err);
    };
  }

  // single, deliberate escape hatch from the broken DOM/polyfill type overlap —
  // everything else in this file stays fully typed
  private on(source: EventSourcePolyfill, eventName: string, handler: (event: SsePayloadEvent) => void): void {
    (source as unknown as { addEventListener: (type: string, listener: (event: SsePayloadEvent) => void) => void })
      .addEventListener(eventName, handler);
  }


  onEvent() {
    return this.events$.asObservable();
  }

  disconnect(): void {
    this.eventSource?.close();
    this.eventSource = undefined;
  }

  ngOnDestroy(): void {
    this.disconnect();
  }
}