packages/core/src/parser/merge.ts

import { ParsedFile } from '../db/schemas.js';

/**
 * Merges two arrays, deduplicating the result.
 */
export function arrayMerge<T>(
  arr1: T[] | undefined,
  arr2: T[] | undefined
): T[] {
  return Array.from(new Set([...(arr1 ?? []), ...(arr2 ?? [])]));
}

function richerParsedFile(
  fileParsed: ParsedFile | undefined,
  folderParsed: ParsedFile | undefined
): ParsedFile | undefined {
  if (!fileParsed) return folderParsed;
  if (!folderParsed) return fileParsed;

  // determine a parsed files richness by counting how many of the important fields are filled out.
  const importantFields: (keyof ParsedFile)[] = [
    'title',
    'year',
    'seasons',
    'episodes',
    'resolution',
    'quality',
    'encode',
    'releaseGroup',
    'editions',
    'regraded',
    'repack',
    'uncensored',
    'unrated',
    'upscaled',
    'network',
    'container',
    'extension',
    'visualTags',
    'audioTags',
    'audioChannels',
    'languages',
    'subtitles',
    'seasonPack',
  ];
  const fileParsedRichness = importantFields.reduce(
    (count, field) => count + (fileParsed[field] ? 1 : 0),
    0
  );
  const folderParsedRichness = importantFields.reduce(
    (count, field) => count + (folderParsed[field] ? 1 : 0),
    0
  );

  return fileParsedRichness >= folderParsedRichness ? fileParsed : folderParsed;
}

/**
 * Merges two ParsedFile objects (typically from folder and file parsing),
 * combining arrays and falling back between scalar fields.
 * The `overrides` parameter allows callers to override specific fields
 * (e.g. resolution, releaseGroup, languages) after the merge.
 */
export function mergeParsedFiles(
  fileParsed: ParsedFile | undefined,
  folderParsed: ParsedFile | undefined,
  overrides?: Partial<ParsedFile>
): ParsedFile | undefined {
  if (!fileParsed && !folderParsed) return undefined;

  /**
   * Returns the first non-empty array from the given arguments, or undefined if none.
   */
  function arrayFallback<T>(...arrs: (T[] | undefined)[]): T[] | undefined {
    for (const arr of arrs) {
      if (arr && arr.length > 0) {
        return arr;
      }
    }
  }

  let seasonPack = folderParsed?.seasonPack || fileParsed?.seasonPack;
  let episodes = arrayFallback(fileParsed?.episodes, folderParsed?.episodes);
  let seasons = arrayFallback(fileParsed?.seasons, folderParsed?.seasons);
  const richest = richerParsedFile(fileParsed, folderParsed);

  return {
    title: richest?.title || folderParsed?.title || fileParsed?.title,
    year: fileParsed?.year || folderParsed?.year,
    folderSeasons:
      seasons !== folderParsed?.seasons ? folderParsed?.seasons : undefined,
    folderEpisodes:
      episodes !== folderParsed?.episodes ? folderParsed?.episodes : undefined,
    seasons,
    episodes,
    date: fileParsed?.date || folderParsed?.date,
    resolution: fileParsed?.resolution || folderParsed?.resolution,
    quality: fileParsed?.quality || folderParsed?.quality,
    encode: fileParsed?.encode || folderParsed?.encode,
    releaseGroup: fileParsed?.releaseGroup || folderParsed?.releaseGroup,
    editions: arrayMerge(folderParsed?.editions, fileParsed?.editions),
    regraded: fileParsed?.regraded || folderParsed?.regraded,
    repack: fileParsed?.repack || folderParsed?.repack,
    uncensored: fileParsed?.uncensored || folderParsed?.uncensored,
    unrated: fileParsed?.unrated || folderParsed?.unrated,
    upscaled: fileParsed?.upscaled || folderParsed?.upscaled,
    network: fileParsed?.network || folderParsed?.network,
    container: fileParsed?.container || folderParsed?.container,
    extension: fileParsed?.extension || folderParsed?.extension,
    visualTags: arrayMerge(folderParsed?.visualTags, fileParsed?.visualTags),
    audioTags: arrayMerge(folderParsed?.audioTags, fileParsed?.audioTags),
    audioChannels: arrayMerge(
      folderParsed?.audioChannels,
      fileParsed?.audioChannels
    ),
    languages: arrayMerge(folderParsed?.languages, fileParsed?.languages),
    subtitles: arrayMerge(folderParsed?.subtitles, fileParsed?.subtitles),
    subbed: fileParsed?.subbed || folderParsed?.subbed || false,
    dubbed: fileParsed?.dubbed || folderParsed?.dubbed || false,
    seasonPack,
    ...overrides,
  };
}