import { Injectable } from '@angular/core';

import { MissionSnapshot } from '@fog-explorer/api-interfaces';

import { MissionStateStore } from './mission-state.store';
import { TwitchAuthService } from './twitch-auth.service';

interface MissionDeltaMessage {
  sequence: number;
  missionId: string;
  state: string;
  recentLog: MissionSnapshot['recentLog'];
}

@Injectable({ providedIn: 'root' })
export class PubSubService {
  private lastSequence = 0;

  constructor(
    private readonly auth: TwitchAuthService,
    private readonly store: MissionStateStore
  ) {}

  subscribeToMissionUpdates(topic: string, fullRefetch: () => Promise<void>): void {
    this.auth.onPubSub(topic, async (_target, _contentType, message) => {
      const parsed = JSON.parse(message) as MissionDeltaMessage;
      if (parsed.sequence !== this.lastSequence + 1 && this.lastSequence !== 0) {
        await fullRefetch();
      } else {
        const current = this.store.mission();
        if (current && current.id === parsed.missionId) {
          this.store.setMission({
            ...current,
            state: parsed.state as MissionSnapshot['state'],
            recentLog: parsed.recentLog.slice(-15),
            tickIndex: parsed.sequence
          });
        }
      }
      this.lastSequence = parsed.sequence;
    });
  }
}