/**
 * Renders every public playlist, `/playlists`, and those of one playlist
 * category, `/playlists/:categorySlug`, in the order `?sort=` names, or with
 * `?mine=1` the signed-in user's own. The header's link and the avatar
 * menu's lead here.
 *
 * @module
 */

import { useCallback } from "react";
import {
  Navigate,
  useLocation,
  useNavigate,
  useParams,
  useSearchParams,
} from "react-router";
import { t } from "@lingui/core/macro";
import { Trans } from "@lingui/react/macro";
import { API_URL } from "../config/api.ts";
import { type Playlist, PLAYLIST_SORTS } from "../../shared/playlist.ts";
import {
  parsePlaylistsTab,
  PLAYLISTS_TABS,
  playlistSortQuery,
  playlistsPath,
  type PlaylistsTab,
} from "../../shared/paths.ts";
import { loginPath } from "../utils/auth/next.ts";
import { userApiUrl } from "../utils/shared/urls.ts";
import { canLoadMore, pageUrl, readPage } from "../utils/feed/pagedList.ts";
import {
  deserializePlaylist,
  hydratePlaylist,
} from "../utils/shared/deserialize.ts";
import { useAuth } from "../hooks/auth/useAuth.ts";
import { useCategories } from "../hooks/category/useCategories.ts";
import { useCategoryFilter } from "../hooks/category/useCategoryFilter.ts";
import { useDocumentTitle } from "../hooks/shared/useDocumentTitle.ts";
import { useFeedCache } from "../hooks/feed/useFeedCache.ts";
import { usePagedList } from "../hooks/feed/usePagedList.ts";
import { useInfiniteScroll } from "../hooks/feed/useInfiniteScroll.ts";
import {
  useScrollRestore,
  useScrollSave,
} from "../hooks/feed/useScrollSave.ts";
import { usePlaylistListSync } from "../hooks/playlist/usePlaylistListSync.ts";
import { useOnReconnect } from "../hooks/ws/useWS.ts";
import { PageShell } from "../components/layout/PageShell.tsx";
import { PageHeader } from "../components/layout/PageHeader.tsx";
import { CategorySwitcher } from "../components/category/CategorySwitcher.tsx";
import { PlaylistCardList } from "../components/playlist/PlaylistCardList.tsx";
import { PlaylistSortTabs } from "../components/playlist/PlaylistSortTabs.tsx";
import { FeedFooter } from "../components/feed/FeedFooter.tsx";
import { ListState } from "../components/shared/ListState.tsx";
import { NotFound } from "./NotFound.tsx";

/**
 * Renders the list for the route's category, or every public playlist
 * without one, on the tab the URL's query names. Each category's list on
 * each tab is another, which the page mounts afresh. A slug that names no
 * playlist category, once the categories have loaded, is a page not found.
 */
export function Playlists(): React.JSX.Element {
  const { categorySlug } = useParams();
  const [params] = useSearchParams();
  const location = useLocation();
  const { user } = useAuth();
  const tab = parsePlaylistsTab(params);
  const { categories, isLoaded } = useCategories("playlist");
  const category = categorySlug
    ? categories.find((c) => c.slug === categorySlug)
    : undefined;
  useDocumentTitle(category ? category.name : t`Playlists`);

  if (categorySlug && isLoaded && !category) return <NotFound />;
  // A guest isn't offered the tab of their own playlists, so only a link
  // leads one there, or signing out on it.
  if (tab === "mine" && !user) {
    return (
      <Navigate to={loginPath(location.pathname + location.search)} replace />
    );
  }
  return (
    <PlaylistsList
      key={`${categorySlug ?? ""}:${tab}`}
      categorySlug={categorySlug}
      categoryId={category?.id}
      tab={tab}
    />
  );
}

/**
 * Renders the public playlists, from `GET /api/playlists`, as a grid of
 * covers, a page at a time as the list scrolls; with `categorySlug`, only
 * those in that playlist category, which the menu before the tabs switches,
 * keeping the tab, while a tab changes the order in place of the current
 * history entry, as a feed's tabs do. A signed-in user's last tab lists
 * their own instead, the private ones too, from
 * `GET /api/users/:userId/playlists` in the default order. The socket keeps
 * them live, a reconnection fetches the pages loaded again, and going back
 * restores the list and the scroll.
 */
function PlaylistsList(
  { categorySlug, categoryId, tab }: {
    categorySlug?: string;
    categoryId?: string;
    tab: PlaylistsTab;
  },
) {
  const navigate = useNavigate();
  const { user, authFetch } = useAuth();
  // `Playlists` shows the tab to no guest.
  const owner = tab === "mine" && user ? user : undefined;
  const sort = tab === "mine" ? PLAYLIST_SORTS[0] : tab;
  const { cached, saveState } = useFeedCache<Playlist>(
    `feed:playlists:${categorySlug ?? "all"}:${tab}`,
    hydratePlaylist,
  );
  const url = `${
    owner ? userApiUrl(owner, "playlists") : `${API_URL}/api/playlists`
  }${
    playlistSortQuery(
      sort,
      new URLSearchParams(categorySlug ? { category: categorySlug } : {}),
    )
  }`;
  const { state, setItems: setAllItems, loadMore, resync } = usePagedList<
    Playlist
  >(
    `${url}:${user?.id ?? "guest"}`,
    useCallback(
      (page: number, signal?: AbortSignal) =>
        authFetch(pageUrl(url, page), { signal })
          .then((res) => readPage(res, deserializePlaylist)),
      [authFetch, url],
    ),
    cached,
  );
  const loaded = state.status === "loaded" ? state.data : null;
  usePlaylistListSync(
    loaded?.items ?? [],
    useCategoryFilter(setAllItems, categoryId),
    { sort, isOwner: !!owner, ownerId: owner?.id },
  );
  useOnReconnect(resync);

  const sentinelRef = useInfiniteScroll(loadMore, canLoadMore(loaded));
  useScrollSave(
    !!loaded,
    useCallback((y) => {
      if (loaded) saveState(loaded, y);
    }, [loaded, saveState]),
  );
  useScrollRestore(cached?.scrollY, !!loaded);

  return (
    <PageShell>
      <PageHeader icon="📋" title={<Trans>Playlists</Trans>}>
        <PlaylistSortTabs
          tabs={user ? PLAYLISTS_TABS : PLAYLIST_SORTS}
          sort={tab}
          onChange={(next) =>
            navigate(playlistsPath(categorySlug, next), { replace: true })}
          leading={
            <CategorySwitcher
              kind="playlist"
              categorySlug={categorySlug}
              onSelect={(slug) => navigate(playlistsPath(slug, tab))}
            />
          }
        />
      </PageHeader>
      <ListState
        state={state}
        isEmpty={({ data }) => data.items.length === 0}
        empty={
          <p className="empty-state">
            <Trans>No playlists yet.</Trans>
          </p>
        }
      >
        {({ data }) => (
          <>
            <PlaylistCardList playlists={data.items} grid privateBadgeOnly />
            <FeedFooter
              hasMore={data.hasMore}
              loadingMore={data.loadingMore}
              sentinelRef={sentinelRef}
            />
          </>
        )}
      </ListState>
    </PageShell>
  );
}