import type { Readable } from 'node:stream';
import { Inject, Injectable } from '@nestjs/common';
import { FILE_STORAGE, type IFileStorage } from '../../../domain/ports/file-storage.port.js';
import { DownloadFileQuery } from './download-file.query.js';
import { FileDto } from '../../dto/file.dto.js';
import { FileApplicationMapper } from '../../mappers/file-application.mapper.js';
import { FileAccessService } from '../../services/file-access.service.js';

export interface DownloadFileResult {
  file: FileDto;
  /** Можно ли показывать в браузере inline, иначе — только скачивание */
  inline: boolean;
  stream: Readable;
}

@Injectable()
export class DownloadFileUseCase {
  constructor(
    @Inject(FILE_STORAGE)
    private readonly fileStorage: IFileStorage,
    private readonly fileAccess: FileAccessService,
  ) {}

  async execute(query: DownloadFileQuery): Promise<DownloadFileResult> {
    const file = await this.fileAccess.getVisibleFile(query.id, query.userId);
    const stream = await this.fileStorage.get(file.storageKey);

    return {
      file: FileApplicationMapper.toDto(file),
      inline: file.isInlineViewable,
      stream,
    };
  }
}