Function mergeMangaData

Source

export function mergeMangaData(
  previousManga: NormalizedMangaItem[],
  normalizedManga: NormalizedMangaItem[],
): { mergedManga: NormalizedMangaItem[]; results: ImportResults } {
  console.debug(
    `[MangaImport] Merging ${normalizedManga.length} new items with ${previousManga.length} existing items`,
  );

  const mergedManga = [...previousManga];
  const previousTitles = new Set(
    previousManga.map((m) => m.title.toLowerCase()),
  );
  const previousIds = new Set(
    previousManga.map((m) => m.id?.toString()).filter(Boolean),
  );

  let newMangaCount = 0;
  let updatedMangaCount = 0;

  for (const manga of normalizedManga) {
    const idMatch = manga.id && previousIds.has(manga.id.toString());
    const titleMatch = previousTitles.has(manga.title.toLowerCase());

    if (idMatch || titleMatch) {
      // Update existing manga
      const existingIndex = mergedManga.findIndex(
        (existing) =>
          existing.id?.toString() === manga.id.toString() ||
          existing.title.toLowerCase() === manga.title.toLowerCase(),
      );

      if (existingIndex !== -1) {
        const existing = mergedManga[existingIndex];
        mergedManga[existingIndex] = {
          ...existing,
          ...manga,
        };
        updatedMangaCount++;
      }
    } else {
      // Add new manga
      mergedManga.push(manga);
      newMangaCount++;
      previousTitles.add(manga.title.toLowerCase());
      if (manga.id) {
        previousIds.add(manga.id.toString());
      }
    }
  }

  console.info(
    `[MangaImport] ✅ Merge complete: ${newMangaCount} new, ${updatedMangaCount} updated, ${mergedManga.length} total`,
  );

  return {
    mergedManga,
    results: {
      newMangaCount,
      updatedMangaCount,
      totalManga: mergedManga.length,
    },
  };
}
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