first commit

apps/twitch-extension-panel/src/app/services/pubsub.service.ts

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+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;
+    });
+  }
+}