SkateSpots/src/hooks/useSasquatchPro.ts

/**
 * useSasquatchPro — is the logged-in user a current Pro supporter?
 * ─────────────────────────────────────────────────────────────────────────────
 * Verifies Pro access two ways, strongest first:
 *
 *   1. ZAP RECEIPT (NIP-57, kind 9735): the platform's Lightning provider
 *      publishes a receipt when the user zaps the platform. The receipt's zap
 *      request (kind 9734) is signed by the USER's npub and tags the SkateSpots
 *      Pro address, so it cryptographically binds payment → identity. A user
 *      cannot forge this. We read the tier/expiry from the zap request's
 *      `pro-tier` / `pro-expiry` tags (added at purchase time).
 *
 *   2. SELF-SIGNED RECEIPT (kind 32671): fallback for providers that don't emit
 *      zap receipts. Signed by the user, references the payment. Weaker (a
 *      technical user could self-issue), but never locks a paying user out.
 *
 * Access = the max unexpired expiry found across either source.
 */

import { useMemo } from 'react';
import { useQuery } from '@tanstack/react-query';
import { useNostr } from '@nostrify/react';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { PLATFORM_OWNER_PUBKEYS } from '@/hooks/useListingRestrictions';
import { SASQUATCH_PRO_KIND } from '@/lib/types';
import type { NostrEvent } from '@nostrify/nostrify';

export interface ProStatus {
  /** True if the user currently has active Pro access. */
  isPro: boolean;
  /** Unix seconds when access expires (max across sources), or null. */
  expiresAt: number | null;
  /** How access was granted. */
  source: 'owner' | 'zap' | 'self' | null;
  isLoading: boolean;
}

function tagVal(tags: string[][], name: string): string | undefined {
  return tags.find((t) => t[0] === name)?.[1];
}

/** Extract an expiry (unix seconds) from a Pro-bearing event, if valid & ours. */
function expiryFromSelfReceipt(event: NostrEvent, userPubkey: string): number | null {
  if (event.pubkey !== userPubkey) return null;
  const exp = Number(tagVal(event.tags, 'expiry'));
  return Number.isFinite(exp) && exp > 0 ? exp : null;
}

/** Extract expiry from a zap receipt whose zap-request is signed by the user. */
function expiryFromZapReceipt(receipt: NostrEvent, userPubkey: string): number | null {
  // The 9735 receipt embeds the original 9734 zap request as a `description` tag.
  const desc = tagVal(receipt.tags, 'description');
  if (!desc) return null;
  try {
    const zapReq = JSON.parse(desc) as NostrEvent;
    if (zapReq.pubkey !== userPubkey) return null; // must be signed by the user
    const exp = Number(tagVal(zapReq.tags, 'pro-expiry'));
    return Number.isFinite(exp) && exp > 0 ? exp : null;
  } catch {
    return null;
  }
}

export function useSasquatchPro(): ProStatus {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();
  const pubkey = user?.pubkey;

  // Platform owners always have Pro.
  const isOwner = !!pubkey && PLATFORM_OWNER_PUBKEYS.includes(pubkey);

  const { data, isLoading } = useQuery({
    queryKey: ['sasquatch-pro', pubkey],
    enabled: !!pubkey && !isOwner,
    staleTime: 60_000,
    queryFn: async (c): Promise<{ expiresAt: number | null; source: ProStatus['source'] }> => {
      if (!pubkey) return { expiresAt: null, source: null };
      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(6000)]);

      // Fetch both sources in one round-trip:
      //  • self-signed receipts authored by the user (kind 32671)
      //  • zap receipts (9735) tagging the user as the zapper (#P)
      const events = await nostr.query(
        [
          { kinds: [SASQUATCH_PRO_KIND], authors: [pubkey], limit: 10 },
          { kinds: [9735], '#P': [pubkey], limit: 50 },
        ],
        { signal },
      );

      let best = 0;
      let source: ProStatus['source'] = null;

      for (const ev of events) {
        if (ev.kind === SASQUATCH_PRO_KIND) {
          const exp = expiryFromSelfReceipt(ev, pubkey);
          if (exp && exp > best) { best = exp; source = 'self'; }
        } else if (ev.kind === 9735) {
          const exp = expiryFromZapReceipt(ev, pubkey);
          // Zap receipts are the stronger source — prefer them on ties.
          if (exp && exp >= best) { best = exp; source = 'zap'; }
        }
      }

      return { expiresAt: best || null, source: best ? source : null };
    },
  });

  return useMemo<ProStatus>(() => {
    if (isOwner) {
      return { isPro: true, expiresAt: null, source: 'owner', isLoading: false };
    }
    const now = Math.floor(Date.now() / 1000);
    const expiresAt = data?.expiresAt ?? null;
    const isPro = !!expiresAt && expiresAt > now;
    return {
      isPro,
      expiresAt,
      source: isPro ? data?.source ?? null : null,
      isLoading,
    };
  }, [isOwner, data, isLoading]);
}