Chris Chen
69 lines
2.4 KiB
TypeScript
69 lines
2.4 KiB
TypeScript
import { Injectable } from '@angular/core';
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import { BehaviorSubject, Observable } from 'rxjs';
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import {
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HubConnection, HubConnectionBuilder, HubConnectionState, LogLevel,
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} from '@microsoft/signalr';
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import { environment } from '../../../../environments/environment';
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import { AttendanceCounts, AttendanceCategory } from '../models/attendance.model';
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/**
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* Thin wrapper around the AttendanceHub SignalR connection. Exposes the latest
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* authoritative counts as an observable and a fire-and-forget increment() that
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* sends a batched delta to the server. The server broadcasts the new totals
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* back to every connected client.
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*/
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@Injectable({ providedIn: 'root' })
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export class AttendanceSignalrService {
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// Hub lives at the host root; environment.apiUrl is e.g. http://localhost:42019/api
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private readonly hubUrl = environment.apiUrl.replace(/\/api\/?$/, '') + '/hubs/attendance';
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private connection?: HubConnection;
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private readonly counts$$ = new BehaviorSubject<AttendanceCounts | null>(null);
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/** Latest authoritative counts pushed by the server (null until first message). */
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get counts$(): Observable<AttendanceCounts | null> {
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return this.counts$$.asObservable();
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}
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async start(): Promise<void> {
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if (this.connection) {
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return;
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}
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this.connection = new HubConnectionBuilder()
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.withUrl(this.hubUrl)
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.withAutomaticReconnect()
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.configureLogging(LogLevel.Warning)
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.build();
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this.connection.on('ReceiveCounts', (counts: AttendanceCounts) => {
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this.counts$$.next(counts);
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});
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await this.connection.start();
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}
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async stop(): Promise<void> {
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if (this.connection) {
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await this.connection.stop();
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this.connection = undefined;
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}
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}
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/** Send a batched delta (may be negative) for one age group. */
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async increment(category: AttendanceCategory, delta: number): Promise<void> {
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if (delta === 0 || this.connection?.state !== HubConnectionState.Connected) {
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return;
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}
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await this.connection.invoke('Increment', category, delta);
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}
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/** Overwrite one age group with an absolute value (clamped at zero server-side). */
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async setCount(category: AttendanceCategory, value: number): Promise<void> {
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if (this.connection?.state !== HubConnectionState.Connected) {
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throw new Error('Not connected to the attendance hub.');
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}
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await this.connection.invoke('SetCount', category, value);
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}
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}
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