import { IPhotoItem } from './reportTypes';
import { REPORT_TEXTS } from './texts';

function readFile<T extends ArrayBuffer | string>(file: File, read: (reader: FileReader) => void): Promise<T> {
  return new Promise<T>((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = () => resolve(reader.result as T);
    reader.onerror = () => reject(new Error(REPORT_TEXTS.photos.readError(file.name)));
    read(reader);
  });
}

/** Выбранные фото: содержимое для загрузки и data: URL для превью. Файлы читаются по очереди. */
export async function readPhotoFiles(files: File[]): Promise<IPhotoItem[]> {
  const photos: IPhotoItem[] = [];
  for (const file of files) {
    const buffer = await readFile<ArrayBuffer>(file, (reader) => reader.readAsArrayBuffer(file));
    const preview = await readFile<string>(file, (reader) => reader.readAsDataURL(file));
    photos.push({ name: file.name, preview, buffer });
  }
  return photos;
}