comments implement

src/modules/comment/application/use-cases/watch-issue-comments/watch-issue-comments.use-case.ts

@@ -0,0 +1,28 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { filter, type Observable } from 'rxjs';
+import { ISSUE_REPOSITORY, type IIssueRepository } from '../../../../issue/domain/repositories/issue.repository.interface.js';
+import { IssueNotFoundException } from '../../../../issue/domain/exceptions/issue-not-found.exception.js';
+import { WatchIssueCommentsQuery } from './watch-issue-comments.query.js';
+import { type CommentEvent, CommentEventsService } from '../../services/comment-events.service.js';
+
+/**
+ * Поток событий комментариев одной задачи для SSE. Доступ к задаче
+ * проверяется один раз — при подключении.
+ */
+@Injectable()
+export class WatchIssueCommentsUseCase {
+  constructor(
+    @Inject(ISSUE_REPOSITORY)
+    private readonly issueRepository: IIssueRepository,
+    private readonly commentEventsService: CommentEventsService,
+  ) {}
+
+  async execute(query: WatchIssueCommentsQuery): Promise<Observable<CommentEvent>> {
+    const issue = await this.issueRepository.findById(query.issueId, query.userId);
+    if (!issue) {
+      throw new IssueNotFoundException(query.issueId);
+    }
+
+    return this.commentEventsService.onEvents().pipe(filter((event) => event.comment.issueId === query.issueId));
+  }
+}