immich/web/src/lib/utils/duplicate-utils.ts

import { getExifCount } from '$lib/utils/exif-utils';
import type { AssetResponseDto } from '@immich/sdk';
import { sortBy } from 'lodash-es';

/**
 * Suggests the best duplicate asset to keep from a list of duplicates.
 *
 * The best asset is determined by the following criteria:
 *  - Largest image file size in bytes
 *  - Largest count of exif data
 *
 * @param assets List of duplicate assets
 * @returns The best asset to keep
 */
export const suggestDuplicate = (assets: AssetResponseDto[]): AssetResponseDto | undefined => {
  let duplicateAssets = sortBy(assets, (asset) => asset.exifInfo?.fileSizeInByte ?? 0);

  // Update the list to only include assets with the largest file size
  duplicateAssets = duplicateAssets.filter(
    (asset) => asset.exifInfo?.fileSizeInByte === duplicateAssets.at(-1)?.exifInfo?.fileSizeInByte,
  );

  // If there are multiple assets with the same file size, sort the list by the count of exif data
  if (duplicateAssets.length >= 2) {
    duplicateAssets = sortBy(duplicateAssets, getExifCount);
  }

  // Return the last asset in the list
  return duplicateAssets.pop();
};