SkateSpots/src/hooks/useActivityNotifications.ts

import { useMemo } from 'react';
import { useNostr } from '@nostrify/react';
import { useQuery } from '@tanstack/react-query';
import type { NostrEvent } from '@nostrify/nostrify';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { isAdminPubkey } from '@/lib/admins';

/**
 * General, app-wide activity notifications for the logged-in user.
 * ─────────────────────────────────────────────────────────────────────────────
 * This complements the crew-specific notifications (invites / join-requests)
 * with the "social" notifications any Nostr user expects: reactions, reposts,
 * zaps, mentions and replies/comments that reference THEM.
 *
 * How it works: we do ONE combined query for events that tag the user's pubkey
 * (`#p`), across the relevant kinds, then classify them in JS. This keeps relay
 * load minimal (a single filter) per the project's query-efficiency rules.
 */

export type ActivityType = 'reaction' | 'repost' | 'zap' | 'mention' | 'reply' | 'rsvp' | 'event-update';

export interface ActivityNotification {
  id: string;
  type: ActivityType;
  /** Who triggered it (reactor / reposter / zapper / author). */
  pubkey: string;
  createdAt: number;
  /** The raw event, for rendering extra context (reaction emoji, comment text). */
  event: NostrEvent;
  /** For reactions: the emoji/content ("+", "🛹", …). */
  content?: string;
  /** The event id this activity points at (their content), if any. */
  targetEventId?: string;
  /** Sats amount for zaps, parsed from the bolt11/description when available. */
  amountSats?: number;
  /** For RSVPs: accepted / tentative / declined. */
  rsvpStatus?: 'accepted' | 'tentative' | 'declined';
}

const REACTION_KIND = 7;
const REPOST_KINDS = [6, 16];
const ZAP_RECEIPT_KIND = 9735;
const TEXT_NOTE_KIND = 1;
const COMMENT_KIND = 1111;
const RSVP_KIND = 31925;
const EVENT_UPDATE_KIND = 7103;

/** Parse the sats amount out of a zap receipt (9735) if we can. */
function parseZapAmount(event: NostrEvent): number | undefined {
  // Zap receipts embed the original zap request in a "description" tag; that
  // request usually carries an "amount" tag in millisats.
  try {
    const desc = event.tags.find(([t]) => t === 'description')?.[1];
    if (desc) {
      const req = JSON.parse(desc) as { tags?: string[][] };
      const amountMsat = req.tags?.find((t) => t[0] === 'amount')?.[1];
      if (amountMsat) {
        const msat = parseInt(amountMsat, 10);
        if (Number.isFinite(msat) && msat > 0) return Math.round(msat / 1000);
      }
    }
  } catch {
    // ignore malformed description
  }
  return undefined;
}

/** The pubkey that actually SENT a zap (the zapper), from the receipt. */
function zapSenderPubkey(event: NostrEvent): string {
  // Prefer the "P" (uppercase) tag = sender pubkey (NIP-57), then the embedded
  // request's pubkey, then fall back to the receipt author (the LN service).
  const upperP = event.tags.find(([t]) => t === 'P')?.[1];
  if (upperP) return upperP;
  try {
    const desc = event.tags.find(([t]) => t === 'description')?.[1];
    if (desc) {
      const req = JSON.parse(desc) as { pubkey?: string };
      if (req.pubkey) return req.pubkey;
    }
  } catch {
    // ignore
  }
  return event.pubkey;
}

export function useActivityNotifications() {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();

  const query = useQuery({
    queryKey: ['activity-notifications', user?.pubkey],
    enabled: !!user?.pubkey,
    // Refresh periodically so the bell stays fresh without hammering relays.
    staleTime: 60_000,
    refetchInterval: 90_000,
    queryFn: async (c) => {
      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(4000)]);
      const pubkey = user!.pubkey;

      // Single combined query: everything that tags me.
      const events = await nostr.query(
        [
          {
            kinds: [
              REACTION_KIND,
              ...REPOST_KINDS,
              ZAP_RECEIPT_KIND,
              TEXT_NOTE_KIND,
              COMMENT_KIND,
              RSVP_KIND,
              EVENT_UPDATE_KIND,
            ],
            '#p': [pubkey],
            limit: 120,
          },
        ],
        { signal },
      );

      const out: ActivityNotification[] = [];

      for (const event of events) {
        // Never notify the user about their own actions.
        if (event.pubkey === pubkey && event.kind !== ZAP_RECEIPT_KIND) continue;

        const targetEventId = event.tags.find(([t]) => t === 'e')?.[1];

        if (event.kind === REACTION_KIND) {
          out.push({
            id: event.id,
            type: 'reaction',
            pubkey: event.pubkey,
            createdAt: event.created_at,
            event,
            content: event.content || '+',
            targetEventId,
          });
        } else if (REPOST_KINDS.includes(event.kind)) {
          out.push({
            id: event.id,
            type: 'repost',
            pubkey: event.pubkey,
            createdAt: event.created_at,
            event,
            targetEventId,
          });
        } else if (event.kind === ZAP_RECEIPT_KIND) {
          const sender = zapSenderPubkey(event);
          if (sender === pubkey) continue; // don't notify on self-zaps
          out.push({
            id: event.id,
            type: 'zap',
            pubkey: sender,
            createdAt: event.created_at,
            event,
            targetEventId,
            amountSats: parseZapAmount(event),
          });
        } else if (event.kind === TEXT_NOTE_KIND) {
          // A kind-1 that p-tags me: either a reply to my note or a mention.
          const isReply = event.tags.some(([t]) => t === 'e');
          out.push({
            id: event.id,
            type: isReply ? 'reply' : 'mention',
            pubkey: event.pubkey,
            createdAt: event.created_at,
            event,
            content: event.content,
            targetEventId,
          });
        } else if (event.kind === COMMENT_KIND) {
          out.push({
            id: event.id,
            type: 'reply',
            pubkey: event.pubkey,
            createdAt: event.created_at,
            event,
            content: event.content,
            targetEventId,
          });
        } else if (event.kind === RSVP_KIND) {
          // Someone RSVP'd to an event I'm hosting (RSVP p-tags the host).
          const status = event.tags.find(([t]) => t === 'status')?.[1];
          if (status !== 'accepted' && status !== 'tentative' && status !== 'declined') continue;
          out.push({
            id: event.id,
            type: 'rsvp',
            pubkey: event.pubkey,
            createdAt: event.created_at,
            event,
            content: event.content,
            targetEventId,
            rsvpStatus: status,
          });
        } else if (event.kind === EVENT_UPDATE_KIND) {
          // A host posted an update to an event I RSVP'd to (I'm p-tagged).
          // SECURITY: only trust it if the author is the event's host (from the
          // `a` coordinate) or a SkateSpots admin — otherwise a stranger could
          // spam fake "event cancelled" notifications by p-tagging RSVPers.
          const updateCoord = event.tags.find(([t]) => t === 'a')?.[1];
          const updateHost = updateCoord?.split(':')[1];
          if (event.pubkey !== updateHost && !isAdminPubkey(event.pubkey)) continue;
          out.push({
            id: event.id,
            type: 'event-update',
            pubkey: event.pubkey,
            createdAt: event.created_at,
            event,
            content: event.content,
            targetEventId,
          });
        }
      }

      // Newest first.
      out.sort((a, b) => b.createdAt - a.createdAt);
      return out;
    },
  });

  return {
    notifications: query.data ?? [],
    isLoading: query.isLoading,
  };
}

/** Human-readable verb for each activity type. */
export function activityVerb(n: ActivityNotification): string {
  switch (n.type) {
    case 'reaction':
      return n.content && n.content !== '+' ? `reacted ${n.content}` : 'liked your post';
    case 'repost':
      return 'reposted you';
    case 'zap':
      return n.amountSats ? `zapped you ${n.amountSats.toLocaleString()} sats` : 'zapped you';
    case 'mention':
      return 'mentioned you';
    case 'reply':
      return 'replied to you';
    case 'rsvp':
      return n.rsvpStatus === 'accepted'
        ? "is going to your event"
        : n.rsvpStatus === 'tentative'
          ? 'is interested in your event'
          : "can't make your event";
    case 'event-update':
      return 'posted an event update';
    default:
      return 'interacted with you';
  }
}