import { useCallback, useMemo, useState, type ReactNode } from "react";
import { LS, setAccountRaw } from "../lib/storage";
import { useUrlMirror } from "../lib/useUrlMirror";
import { useNavigation } from "./navigationContext";
import { readSelectedId } from "./playlistsInit";
import {
  PlaylistsActionsContext,
  PlaylistsStateContext,
  type PlaylistsActions,
  type PlaylistsState,
} from "./playlistsContext";

// Owns the Playlists module's shared local state — the rail's name filter and the selected playlist
// — lifted out of the App god component so the header search box, the PlaylistsRail, and the
// Playlists detail pane read it via hooks instead of prop-drilling through App. Mirrors
// FeedFiltersProvider / NavigationProvider (split State + Actions contexts, one-line hooks; composed
// in main.tsx around <App/>).
//
// The `search` term is ephemeral (resets on reload, like the other list filters); the selected
// playlist is per-account persisted (LS.playlist) so a reload returns you to it. Neither is
// server-synced, and an account switch does a full reload, so init-from-storage is all the
// hydration these need — no per-account load effect (unlike the server-backed feed filters).
//
// The contexts + hooks live in playlistsContext.ts.

export function PlaylistsProvider({ children }: { children: ReactNode }) {
  const [search, setSearchState] = useState("");
  const [selectedId, setSelectedIdState] = useState<number | null>(readSelectedId);

  const setSearch = useCallback((q: string) => setSearchState(q), []);
  const setSelectedId = useCallback((id: number | null) => {
    setSelectedIdState(id);
    if (id != null) setAccountRaw(LS.playlist, String(id));
  }, []);

  // Mirror the selected playlist to ?pl on the Playlists page so it's bookmarkable; clear it elsewhere
  // (the localStorage copy still restores it on return). useUrlMirror keeps ?page and the other nav
  // params intact.
  const { page } = useNavigation();
  useUrlMirror({ pl: page === "playlists" && selectedId != null ? String(selectedId) : null });

  const state = useMemo<PlaylistsState>(() => ({ search, selectedId }), [search, selectedId]);
  const actions = useMemo<PlaylistsActions>(
    () => ({ setSearch, setSelectedId }),
    [setSearch, setSelectedId],
  );

  return (
    <PlaylistsActionsContext.Provider value={actions}>
      <PlaylistsStateContext.Provider value={state}>{children}</PlaylistsStateContext.Provider>
    </PlaylistsActionsContext.Provider>
  );
}