import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { useClient } from 'hooks/useClient';

const KEY = ['soulseek', 'favorites'] as const;
const EMPTY: string[] = [];

/**
 * The owner's favourited Soulseek peers, backed by the officer-slskd sidecar's own `/_officer/favorites`
 * route (slskd has no favourites API — Officer owns that data). One shared react-query cache, so every
 * star in the workspace reflects the same state; toggling is optimistic and rolls back on failure.
 */
export function useSoulseekFavorites() {
  const { get, post, delete: del } = useClient();
  const qc = useQueryClient();

  const { data } = useQuery({
    queryKey: KEY,
    queryFn: () => get<string[]>('/soulseek/_officer/favorites'),
    staleTime: 60_000,
  });

  const mutation = useMutation({
    mutationFn: ({ on, username }: { on: boolean; username: string }) =>
      on
        ? post('/soulseek/_officer/favorites', { username })
        : del(`/soulseek/_officer/favorites?username=${encodeURIComponent(username)}`),
    onMutate: async ({ on, username }) => {
      await qc.cancelQueries({ queryKey: KEY });
      const prev = qc.getQueryData<string[]>(KEY) ?? EMPTY;
      const next = on ? [...prev, username].sort((a, b) => a.localeCompare(b)) : prev.filter((u) => u !== username);
      qc.setQueryData<string[]>(KEY, next);
      return { prev };
    },
    onError: (_err, _vars, ctx) => {
      if (ctx?.prev) qc.setQueryData(KEY, ctx.prev);
    },
  });

  const favorites = data ?? EMPTY;
  const isFavorite = (username: string) => favorites.includes(username);
  const toggle = (username: string) => {
    if (!username) return;
    mutation.mutate({ on: !isFavorite(username), username });
  };

  return { favorites, isFavorite, toggle };
}