import { Injectable } from '@nestjs/common';
import { IssueAttachment } from '../../domain/entities/issue-attachment.entity.js';
import { IssueAttachmentDto } from '../dto/issue-attachment.dto.js';
import { GetFilesUseCase } from '../../../file/application/use-cases/get-files/get-files.use-case.js';
import { GetFilesQuery } from '../../../file/application/use-cases/get-files/get-files.query.js';

/** Раскрывает вложения в метаданные файлов из file-модуля */
@Injectable()
export class IssueAttachmentExpanderService {
  constructor(private readonly getFilesUseCase: GetFilesUseCase) {}

  async expandAll(attachments: IssueAttachment[]): Promise<IssueAttachmentDto[]> {
    if (attachments.length === 0) return [];

    const files = await this.getFilesUseCase.execute(new GetFilesQuery(attachments.map((a) => a.fileId)));
    const filesById = new Map(files.map((file) => [file.id, file]));

    // Файл могли удалить между запросами — такое вложение просто не показываем
    return attachments.flatMap((attachment) => {
      const file = filesById.get(attachment.fileId);
      return file ? [{ issueId: attachment.issueId, file, attachedAt: attachment.createdAt }] : [];
    });
  }
}