export type WishlistSort = 'title' | 'author'

type ListedBook = Pick<WishlistBook, 'title' | 'authors'>

/** "Last, First" -> "First Last" */
export function wishlistAuthorName(author: string): string {
  const [last, first] = author.split(/,\s*/, 2)
  return first ? `${first} ${last}` : author
}

function searchableText(book: ListedBook): string {
  const authors = book.authors.flatMap(author => [author, wishlistAuthorName(author)])
  return [book.title, ...authors].join(' ').toLowerCase()
}

const collator = new Intl.Collator('de', { sensitivity: 'base', numeric: true })

function compare(sort: WishlistSort) {
  const byTitle = (a: ListedBook, b: ListedBook) => collator.compare(a.title, b.title)
  const byAuthor = (a: ListedBook, b: ListedBook) => collator.compare(a.authors[0] ?? '', b.authors[0] ?? '')
  return sort === 'title'
    ? (a: ListedBook, b: ListedBook) => byTitle(a, b) || byAuthor(a, b)
    : (a: ListedBook, b: ListedBook) => byAuthor(a, b) || byTitle(a, b)
}

function searchAndSort<Book extends ListedBook>(books: Book[], search: string, sort: WishlistSort): Book[] {
  const terms = search.trim().toLowerCase().split(/\s+/).filter(Boolean)
  return books
    .filter((book) => {
      const text = searchableText(book)
      return terms.every(term => text.includes(term))
    })
    .toSorted(compare(sort))
}

export function useWishlist(search: Ref<string>, sort: Ref<WishlistSort>) {
  const { data, error, status } = useFetch<WishlistBook[]>('/api/wishlist/books', { key: 'wishlist-books', default: () => [] })
  const { data: reading } = useFetch<WishlistShelfBook[]>('/api/wishlist/reading', { key: 'wishlist-reading', default: () => [] })
  const { data: read } = useFetch<WishlistShelfBook[]>('/api/wishlist/read', { key: 'wishlist-read', default: () => [] })

  return {
    books: computed(() => searchAndSort(data.value, search.value, sort.value)),
    total: computed(() => data.value.length),
    readingBooks: computed(() => searchAndSort(reading.value, search.value, sort.value)),
    readingTotal: computed(() => reading.value.length),
    readBooks: computed(() => searchAndSort(read.value, search.value, sort.value)),
    readTotal: computed(() => read.value.length),
    error,
    status
  }
}