import { useQuery } from '@tanstack/react-query';
import { useSkateRelays } from '@/hooks/useSkateRelays';
import { ADMIN_PUBKEYS } from '@/lib/admins';
import {
  MODERATION_LABEL_NAMESPACE,
  MODERATION_LABEL_HIDDEN,
  MODERATION_LABEL_VERIFIED,
  MODERATION_LABEL_CLEARED,
} from '@/lib/types';
import { getLocalVerdicts, type LocalVerdict } from '@/lib/localModeration';
import { getLocalDeletions } from '@/lib/localDeletions';
import { useMuteList } from '@/hooks/useMuteList';

/**
 * App-wide admin moderation layer.
 *
 * SkateSpots admins (see src/lib/admins.ts) can take down ANY listing (spot,
 * crew, tour, event, shop, Lab profile, …). Because a NIP-09 deletion request
 * signed by a non-author is not honored by most relays, admin takedowns also
 * publish a NIP-32 kind:1985 `hidden` label referencing the target. This hook
 * fetches those admin labels so the client can hide the content everywhere,
 * reliably, regardless of relay NIP-09 behavior.
 *
 * Security: only labels authored by a hardcoded ADMIN pubkey are honored, so a
 * random user cannot hide someone else's listing. The label authorship is the
 * trust boundary (see .agents/skills/nostr-security §3).
 */
export interface AdminHiddenSet {
  /** Hidden addressable coordinates `kind:pubkey:d`. */
  coords: Set<string>;
  /** Hidden concrete event ids. */
  ids: Set<string>;
  /** True if either set contains anything (cheap guard for callers). */
  has: (opts: { coord?: string; id?: string }) => boolean;
  /**
   * Admin-VOUCHED targets (the positive label). Used to promote a spot out of
   * the review queue and to show a "Verified" badge.
   */
  verifiedCoords: Set<string>;
  verifiedIds: Set<string>;
  isVerified: (opts: { coord?: string; id?: string }) => boolean;
  /** Authors the viewer muted (NIP-51 kind 10000 + optimistic). */
  mutedPubkeys: Set<string>;
}

const EMPTY_PUBKEYS = new Set<string>();

const EMPTY: AdminHiddenSet = {
  coords: new Set(),
  ids: new Set(),
  has: () => false,
  verifiedCoords: new Set(),
  verifiedIds: new Set(),
  isVerified: () => false,
  mutedPubkeys: EMPTY_PUBKEYS,
};

/**
 * Drop admin-hidden entities from a parsed list. Works for any entity that
 * carries `{ id, pubkey, identifier }` (spots, crews, tours, shops, events, …).
 * `kind` is the entity's Nostr kind, used to build the `a` coordinate.
 */
export function filterAdminHidden<
  T extends { id: string; pubkey: string; identifier: string },
>(items: T[], kind: number, hidden: AdminHiddenSet): T[] {
  const deleted = getLocalDeletions();
  if (hidden.coords.size === 0 && hidden.ids.size === 0 && deleted.size === 0 && hidden.mutedPubkeys.size === 0) return items;
  return items.filter((it) => {
    // Muted authors are dropped everywhere this filter is used (NIP-51 mute).
    if (hidden.mutedPubkeys.has(it.pubkey)) return false;
    const coord = `${kind}:${it.pubkey}:${it.identifier}`;
    if (hidden.has({ coord, id: it.id })) return false;
    // Locally-deleted (NIP-09 pending): drop immediately so a deleted item can
    // never flash back from the persistence/offline cache on refresh.
    if (deleted.has(coord) || deleted.has(`e:${it.id}`)) return false;
    return true;
  });
}

/**
 * Like `filterAdminHidden`, but for a mixed-kind list where each item carries
 * its own source `event` (e.g. Lab profiles, which span 10 different kinds).
 * The kind is read from `it.event.kind`.
 */
export function filterAdminHiddenMixed<
  T extends {
    id: string;
    pubkey: string;
    identifier: string;
    event: { kind: number };
  },
>(items: T[], hidden: AdminHiddenSet): T[] {
  const deleted = getLocalDeletions();
  if (hidden.coords.size === 0 && hidden.ids.size === 0 && deleted.size === 0 && hidden.mutedPubkeys.size === 0) return items;
  return items.filter((it) => {
    if (hidden.mutedPubkeys.has(it.pubkey)) return false;
    const coord = `${it.event.kind}:${it.pubkey}:${it.identifier}`;
    if (hidden.has({ coord, id: it.id })) return false;
    if (deleted.has(coord) || deleted.has(`e:${it.id}`)) return false;
    return true;
  });
}

export function useAdminModeration() {
  const { querySkateContent, getQueryKeySuffix } = useSkateRelays();

  const query = useQuery({
    queryKey: ['admin-moderation', getQueryKeySuffix()],
    queryFn: async (): Promise<AdminHiddenSet> => {
      const signal = AbortSignal.timeout(8000);

      const events = await querySkateContent(
        [
          {
            kinds: [1985],
            authors: ADMIN_PUBKEYS,
            // One request for ALL admin verdicts: hidden, verified and cleared.
            // `cleared` (undo) MUST be included or a hidden item can never be
            // un-hidden on another device — it is the newest-wins retraction.
            '#l': [MODERATION_LABEL_HIDDEN, MODERATION_LABEL_VERIFIED, MODERATION_LABEL_CLEARED],
            limit: 1000,
          },
        ],
        { signal },
      );

      const adminSet = new Set(ADMIN_PUBKEYS.map((p) => p.toLowerCase()));

      // NEWEST VERDICT PER TARGET WINS. Kind 1985 is a regular event, so there
      // can be several labels for one target; the latest one is the current
      // truth. That is what makes a verdict reversible: an undo publishes
      // `cleared`, which supersedes an earlier `hidden`/`verified`.
      const verdicts = new Map<string, { verdict: LocalVerdict; at: number }>();

      for (const ev of events) {
        // Defense in depth: re-verify author + namespace + label client-side.
        if (!adminSet.has(ev.pubkey.toLowerCase())) continue;
        const hasNamespace = ev.tags.some(
          ([n, v]) => n === 'L' && v === MODERATION_LABEL_NAMESPACE,
        );
        if (!hasNamespace) continue;

        const labelOf = (want: string) =>
          ev.tags.some(([n, v]) => n === 'l' && v === want);
        const verdict: LocalVerdict | null = labelOf(MODERATION_LABEL_HIDDEN)
          ? 'hidden'
          : labelOf(MODERATION_LABEL_VERIFIED)
            ? 'verified'
            : labelOf(MODERATION_LABEL_CLEARED)
              ? 'cleared'
              : null;
        if (!verdict) continue;

        for (const [n, v] of ev.tags) {
          const key = n === 'a' ? v : n === 'e' ? `e:${v}` : null;
          if (!key) continue;
          const current = verdicts.get(key);
          if (!current || ev.created_at > current.at) {
            verdicts.set(key, { verdict, at: ev.created_at });
          }
        }
      }

      // Overlay this device's OPTIMISTIC verdicts (just-made ones win until the
      // relay catches up, and an undo written locally replaces the old verdict).
      for (const [key, entry] of getLocalVerdicts()) {
        const current = verdicts.get(key);
        if (!current || entry.at >= current.at) verdicts.set(key, entry);
      }

      const coords = new Set<string>();
      const ids = new Set<string>();
      const verifiedCoords = new Set<string>();
      const verifiedIds = new Set<string>();

      for (const [key, { verdict }] of verdicts) {
        const isId = key.startsWith('e:');
        const value = isId ? key.slice(2) : key;
        if (verdict === 'hidden') (isId ? ids : coords).add(value);
        else if (verdict === 'verified') (isId ? verifiedIds : verifiedCoords).add(value);
        // `cleared` adds nothing — the target is simply neutral again.
      }

      return {
        coords,
        ids,
        has: ({ coord, id }) =>
          (!!coord && coords.has(coord)) || (!!id && ids.has(id)),
        verifiedCoords,
        verifiedIds,
        isVerified: ({ coord, id }) =>
          (!!coord && verifiedCoords.has(coord)) || (!!id && verifiedIds.has(id)),
        mutedPubkeys: EMPTY_PUBKEYS,
      };
    },
    staleTime: 60 * 1000,
    gcTime: 10 * 60 * 1000,
    refetchOnMount: true,
  });

  const mutes = useMuteList();
  const mutedPubkeys = mutes.data ?? EMPTY_PUBKEYS;

  // Even if the relay query is still loading/empty, honor local optimistic
  // hides so the takedown is reflected immediately on this device.
  if (!query.data) {
    const coords = new Set<string>();
    const ids = new Set<string>();
    const verifiedCoords = new Set<string>();
    const verifiedIds = new Set<string>();

    for (const [key, entry] of getLocalVerdicts()) {
      const isId = key.startsWith('e:');
      const value = isId ? key.slice(2) : key;
      if (entry.verdict === 'hidden') (isId ? ids : coords).add(value);
      else if (entry.verdict === 'verified') (isId ? verifiedIds : verifiedCoords).add(value);
    }

    if (coords.size === 0 && ids.size === 0 && verifiedCoords.size === 0 && verifiedIds.size === 0) {
      return { ...EMPTY, mutedPubkeys };
    }

    return {
      coords,
      ids,
      has: ({ coord, id }) =>
        (!!coord && coords.has(coord)) || (!!id && ids.has(id)),
      verifiedCoords,
      verifiedIds,
      isVerified: ({ coord, id }) =>
        (!!coord && verifiedCoords.has(coord)) || (!!id && verifiedIds.has(id)),
      mutedPubkeys,
    };
  }

  return { ...query.data, mutedPubkeys };
}