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));
  }
}