task-stream/libs/api/tracker/application/src/lib/commands/attach-file.command-handler.ts

import { randomUUID } from 'node:crypto';
import { CommandHandler, ICommandHandler } from '@nestjs/cqrs';
import { BusinessRuleError } from '@task-stream/api/shared/domain';
import { AttachmentStorage, attachmentKey } from '../ports/attachment-storage';
import { AttachFileCommand, AttachmentResult } from './attach-file.command';
import { ack } from './command-result';
import { WriteAccess } from './write-access';

/**
 * Stores the bytes first and records them on the ticket after: a file with no
 * record is cleaned up here, never a record with no file.
 */
@CommandHandler(AttachFileCommand)
export class AttachFileCommandHandler
  implements ICommandHandler<AttachFileCommand>
{
  constructor(
    private readonly access: WriteAccess,
    private readonly storage: AttachmentStorage,
  ) {}

  async execute(command: AttachFileCommand): Promise<AttachmentResult> {
    const { issue } = await this.access.issueForReporter(
      command.issueId,
      command.actorId,
    );
    if (command.commentId) {
      const comment = await this.access.comment(command.commentId);
      if (comment.issueId !== issue.id) {
        throw new BusinessRuleError(
          `That comment belongs to another ticket, not ${issue.key}`,
        );
      }
    }

    const id = randomUUID();
    const key = attachmentKey(issue.projectId, issue.id, id);
    issue.attach(command.actorId, {
      id,
      fileName: command.file.fileName,
      mimeType: command.file.mimeType,
      size: command.file.content.length,
      uploadedBy: command.actorId,
      uploadedAt: new Date().toISOString(),
      commentId: command.commentId,
    });

    await this.storage.put(key, command.file.content);
    try {
      await issue.commitAndWait();
    } catch (error) {
      await this.storage.remove(key);
      throw error;
    }
    // The id lets a client point at the file, e.g. an image inside a comment.
    return { ...ack(issue), attachmentId: id };
  }
}