first commit

libs/api/tracker/application/src/lib/changes.service.ts

@@ -0,0 +1,77 @@
+import { Injectable } from '@nestjs/common';
+import { QueryBus } from '@nestjs/cqrs';
+import { NotFoundError } from '@task-stream/api/shared/domain';
+import { ActivityReadModel } from '@task-stream/api/tracker/domain';
+import {
+  ChangeFeed,
+  CommentChange,
+  IssueChange,
+  ProjectChange,
+  ReleaseChange,
+} from './ports/change-feed';
+import { CanViewProjectQuery } from './queries/can-view-project.query';
+import { GetIssueQuery } from './queries/get-issue.query';
+
+/** Realtime subscriptions, authorised at subscribe time. */
+@Injectable()
+export class ChangesService {
+  constructor(
+    private readonly queryBus: QueryBus,
+    private readonly changeFeed: ChangeFeed,
+  ) {}
+
+  async watchIssues(
+    viewerId: string,
+    projectId: string,
+  ): Promise<AsyncIterableIterator<IssueChange>> {
+    await this.assertCanView(viewerId, projectId);
+    return this.changeFeed.issues(projectId);
+  }
+
+  async watchComments(
+    viewerId: string,
+    issueId: string,
+  ): Promise<AsyncIterableIterator<CommentChange>> {
+    await this.queryBus.execute(new GetIssueQuery(viewerId, issueId)); // access check
+    return this.changeFeed.comments(issueId);
+  }
+
+  async watchActivity(
+    viewerId: string,
+    projectId: string,
+  ): Promise<AsyncIterableIterator<ActivityReadModel>> {
+    await this.assertCanView(viewerId, projectId);
+    return this.changeFeed.activity(projectId);
+  }
+
+  async watchReleases(
+    viewerId: string,
+    projectId: string,
+  ): Promise<AsyncIterableIterator<ReleaseChange>> {
+    await this.assertCanView(viewerId, projectId);
+    return this.changeFeed.releases(projectId);
+  }
+
+  async watchProject(
+    viewerId: string,
+    projectId: string,
+  ): Promise<AsyncIterableIterator<ProjectChange>> {
+    await this.assertCanView(viewerId, projectId);
+    return this.changeFeed.project(projectId);
+  }
+
+  /** Projects the viewer is added to or removed from. */
+  watchMyProjects(viewerId: string): AsyncIterableIterator<ProjectChange> {
+    return this.changeFeed.userProjects(viewerId);
+  }
+
+  private async assertCanView(
+    viewerId: string,
+    projectId: string,
+  ): Promise<void> {
+    const allowed = await this.queryBus.execute(
+      new CanViewProjectQuery(viewerId, projectId),
+    );
+    if (!allowed) throw new NotFoundError('Project', projectId);
+  }
+}