import { IQueryHandler, QueryHandler } from '@nestjs/cqrs';
import { NotFoundError } from '@task-stream/api/shared/domain';
import { AttachmentStorage, attachmentKey } from '../ports/attachment-storage';
import { FindIssuesRepository } from '../ports/find-issues.repository';
import { AttachmentDownload, GetAttachmentQuery } from './get-attachment.query';
import { ReadAccess } from './read-access';

@QueryHandler(GetAttachmentQuery)
export class GetAttachmentQueryHandler
  implements IQueryHandler<GetAttachmentQuery, AttachmentDownload>
{
  constructor(
    private readonly findIssues: FindIssuesRepository,
    private readonly storage: AttachmentStorage,
    private readonly access: ReadAccess,
  ) {}

  async execute(query: GetAttachmentQuery): Promise<AttachmentDownload> {
    const issue = this.access.assertFound(
      await this.findIssues.findById(query.issueId),
      'Attachment',
      query.attachmentId,
    );
    await this.access.assertCanView(issue.projectId, query.viewerId, {
      entity: 'Attachment',
      ref: query.attachmentId,
    });
    const attachment = (issue.attachments ?? []).find(
      (a) => a.id === query.attachmentId,
    );
    if (!attachment) throw new NotFoundError('Attachment', query.attachmentId);
    return {
      attachment,
      content: await this.storage.read(
        attachmentKey(issue.projectId, issue.id, attachment.id),
      ),
    };
  }
}