import { useMemo, useState } from "react";
import { useTranslation } from "react-i18next";
import type { TFunction } from "i18next";
import { useQuery, useQueryClient } from "@tanstack/react-query";
import { Check, ListMusic, Lock, Plus, Search, X } from "lucide-react";
import { qk } from "../lib/queryKeys";
import { api, isIntrinsicReadOnly, type PlexCard, type PlexCollection } from "../lib/api";
import { formatRuntime } from "../lib/format";
import { notifyActionError } from "../lib/actionErrors";
import { useDebounced } from "../lib/useDebounced";
import { LoadingState, StateMessage } from "./ui/QueryState";
import PosterTile from "./PosterTile";
import PlexLibraryPicker from "./PlexLibraryPicker";
import NavGrid from "./ui/NavGrid";
import { Button } from "./ui/Button";
import { IconButton } from "./ui/IconButton";
import { Input } from "./ui/Input";
import { SURFACE } from "./ui/surfaces";

// A collection tile's sub-line: item count · total runtime (each dropped when unknown, e.g. show-only
// collections have no movie runtime).
function collectionMeta(c: PlexCollection, t: TFunction, lang: string): string {
  const parts: string[] = [];
  if (c.child_count != null) parts.push(t("plex.browse.items", { count: c.child_count }));
  const rt = formatRuntime(c.total_runtime_s, lang);
  if (rt) parts.push(rt);
  return parts.join(" · ");
}

// The Playlist / Collection browse surfaces reached from the header pill (Piece 2): a grid of tiles,
// each a way INTO that area — a playlist tile opens the playlist view, a collection tile filters the
// title grid by that collection. Both reuse the existing list endpoints (plexPlaylists / plexCollections
// union), so this is a pure front-end surface. Collection tiles show a poster collage of their top
// films (PosterTile), falling back to a title-hash colour; playlists have no server art yet, so they
// take the colour fallback.

const GRID = "grid grid-cols-2 gap-3 sm:grid-cols-3 md:grid-cols-4 lg:grid-cols-5 xl:grid-cols-6";

// A grid of the user's Plex playlists; a tile opens that playlist's view.
export function PlexPlaylistsBrowse({ onOpen }: { onOpen: (id: number) => void }) {
  const { t } = useTranslation();
  const q = useQuery({ queryKey: qk.plexPlaylists(), queryFn: () => api.plexPlaylists() });
  const playlists = q.data?.playlists ?? [];

  if (q.isError && !q.data) {
    return (
      <StateMessage tone="error" onRetry={() => q.refetch()}>
        {t("common.loadError")}
      </StateMessage>
    );
  }
  if (q.isLoading) return <LoadingState shape="poster" label={t("plex.loading")} />;
  if (playlists.length === 0)
    return <p className="text-muted text-sm">{t("plex.playlist.none")}</p>;

  return (
    <NavGrid className={GRID}>
      {playlists.map((p, i) => (
        <PosterTile
          key={p.id}
          navIndex={i}
          title={p.title}
          subtitle={t("plex.browse.items", { count: p.item_count })}
          topRight={<ListMusic className="h-4 w-4 text-white/80 drop-shadow" />}
          onClick={() => onOpen(p.id)}
          className="h-28"
        />
      ))}
    </NavGrid>
  );
}

// The "New collection" panel (admin, ask B-route): name (rejected if it duplicates an existing one —
// Plex conflates same-named collections) + a search to pick the FIRST title, since Plex can't create an
// empty collection. Creating opens the new collection's detail page (onCreated → onPick).
function NewCollectionPanel({
  existingNames,
  onCreated,
  onClose,
}: {
  existingNames: Set<string>;
  onCreated: (rk: string) => void;
  onClose: () => void;
}) {
  const { t } = useTranslation();
  const [name, setName] = useState("");
  const [term, setTerm] = useState("");
  const [busy, setBusy] = useState(false);
  const trimmed = name.trim();
  // Advisory only: `existingNames` is the search-scoped, all-library collection union, whereas the
  // backend enforces uniqueness PER library (Plex only conflates same-named collections within one
  // section). So a match here is a hint, not a hard block — it must not gate creation, or a valid
  // same-name collection in another library would be un-creatable. The backend's 409 is authoritative.
  const dupHint = trimmed.length > 0 && existingNames.has(trimmed.toLowerCase());
  const nameOk = trimmed.length > 0;

  async function create(card: PlexCard) {
    if (!nameOk || busy) return;
    setBusy(true);
    try {
      const col = await api.plexCreateCollection("", trimmed, card.id); // backend derives the library
      onCreated(col.id);
    } catch (e) {
      // The backend is authoritative on per-library name uniqueness — a taken name comes back
      // structured, and so localized (see localizeDetail).
      notifyActionError(e, t("plex.collection.editFailed"));
      setBusy(false);
    }
  }

  return (
    <div className={`${SURFACE.panel} mb-6 p-4`}>
      <div className="mb-2 flex items-center justify-between gap-2">
        <h3 className="text-sm font-semibold">{t("plex.collection.newCollectionTitle")}</h3>
        <IconButton size="md" onClick={onClose} label={t("common.close")}>
          <X />
        </IconButton>
      </div>
      <Input
        className="w-full"
        autoFocus
        value={name}
        onChange={(e) => setName(e.target.value)}
        placeholder={t("plex.collection.namePlaceholder")}
        aria-label={t("plex.collection.newCollection")}
      />
      {dupHint ? (
        <p className="mt-1 mb-2 text-xs text-muted">{t("plex.collection.nameMaybeTaken")}</p>
      ) : (
        <p className="mt-1 mb-2 text-xs text-muted">{t("plex.collection.newHint")}</p>
      )}
      <div className="mb-3 flex items-center gap-2">
        <Search className="h-4 w-4 shrink-0 text-muted" />
        <Input
          className="flex-1"
          value={term}
          onChange={(e) => setTerm(e.target.value)}
          disabled={!nameOk}
          placeholder={t("plex.collection.addSearch")}
          aria-label={t("plex.collection.addSearch")}
        />
      </div>
      <PlexLibraryPicker
        scope="both"
        term={term}
        enabled={nameOk}
        renderAction={(c) => (
          <Button
            variant="glass"
            size="xs"
            icon={<Check />}
            onClick={() => create(c)}
            loading={busy}
          >
            {t("plex.collection.createWith")}
          </Button>
        )}
      />
    </div>
  );
}

// A grid of Plex collections (searchable — the union can run to hundreds); a tile opens its info page.
export function PlexCollectionsBrowse({ onPick }: { onPick: (id: string, title: string) => void }) {
  const { t, i18n } = useTranslation();
  const qc = useQueryClient();
  const isAdmin = qc.getQueryData<{ role?: string }>(qk.me())?.role === "admin";
  const [search, setSearch] = useState("");
  const [creating, setCreating] = useState(false);
  const searchDeb = useDebounced(search.trim(), 300);
  const q = useQuery({
    queryKey: qk.plexCollections("union", searchDeb),
    queryFn: () => api.plexCollections(undefined, searchDeb || undefined),
  });
  const collections = useMemo(() => q.data?.collections ?? [], [q.data?.collections]);
  const existingNames = useMemo(
    () => new Set(collections.map((c) => c.title.trim().toLowerCase())),
    [collections],
  );

  return (
    <div>
      <div className="mb-4 flex flex-wrap items-center gap-2">
        <Input
          className="w-full max-w-sm"
          size="sm"
          pill
          type="search"
          value={search}
          onChange={(e) => setSearch(e.target.value)}
          placeholder={t("plex.filter.collectionSearch")}
          aria-label={t("plex.filter.collectionSearch")}
        />
        {isAdmin && !creating && (
          <Button variant="glass" size="sm" icon={<Plus />} onClick={() => setCreating(true)}>
            {t("plex.collection.newCollection")}
          </Button>
        )}
      </div>
      {creating && (
        <NewCollectionPanel
          existingNames={existingNames}
          onCreated={(rk) => {
            setCreating(false);
            onPick(rk, "");
          }}
          onClose={() => setCreating(false)}
        />
      )}
      {q.isError && !q.data ? (
        <StateMessage tone="error" onRetry={() => q.refetch()}>
          {t("common.loadError")}
        </StateMessage>
      ) : q.isLoading ? (
        <LoadingState shape="poster" label={t("plex.loading")} />
      ) : collections.length === 0 ? (
        <p className="text-muted text-sm">{t("plex.filter.collectionEmpty")}</p>
      ) : (
        <NavGrid className={GRID}>
          {collections.map((c, i) => (
            <PosterTile
              key={c.id}
              navIndex={i}
              title={c.title}
              art={c.art}
              subtitle={collectionMeta(c, t, i18n.language)}
              topRight={
                isIntrinsicReadOnly(c) ? (
                  <Lock
                    className="h-3.5 w-3.5 text-white/80 drop-shadow"
                    aria-label={t("plex.collection.readOnly")}
                  />
                ) : undefined
              }
              onClick={() => onPick(c.id, c.title)}
              className="h-28"
            />
          ))}
        </NavGrid>
      )}
    </div>
  );
}