SkateSpots/src/hooks/useSpotChat.ts

import { useNostr } from '@nostrify/react';
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import { useCallback } from 'react';
import type { NostrEvent } from '@nostrify/nostrify';

import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useSkateRelays } from '@/hooks/useSkateRelays';
import { SPOT_CHAT_KIND } from '@/lib/types';

/**
 * Spot Chat — ephemeral, geohash-anchored local chat channels.
 *
 * Inspired by BitChat's location-channel concept, reframed for skaters and
 * kept fully SkateSpots-native (our own kind + tag conventions, not interop).
 *
 * Each message is an ephemeral event (kind 24899) tagged with a geohash `g`.
 * Anyone viewing the same geohash channel sees the same live conversation.
 * Because the events are ephemeral, relays are not expected to store them
 * long-term — matching the "here and now" vibe of a spot's side-groupchat.
 */

/** A single parsed chat message. */
export interface SpotChatMessage {
  id: string;
  pubkey: string;
  content: string;
  createdAt: number;
  geohash: string;
  /** IRC-style action message (`/me does a kickflip`). */
  isAction: boolean;
}

/** Geohash precision presets, mirroring BitChat's Block / Neighborhood / City. */
export type ChatPrecision = 'block' | 'neighborhood' | 'city';

export const CHAT_PRECISION_LENGTH: Record<ChatPrecision, number> = {
  block: 8, // ~40m
  neighborhood: 6, // ~1.2km
  city: 5, // ~5km
};

export const CHAT_PRECISION_LABEL: Record<ChatPrecision, string> = {
  block: 'Block',
  neighborhood: 'Neighborhood',
  city: 'City',
};

/**
 * Normalize a geohash to a given precision (channel key).
 * Lower precision = larger area = more people in the channel.
 */
export function channelGeohash(geohash: string, precision: ChatPrecision): string {
  return geohash.slice(0, CHAT_PRECISION_LENGTH[precision]).toLowerCase();
}

/** Parse a raw event into a chat message, or null if invalid. */
function parseSpotChatMessage(event: NostrEvent, channel: string): SpotChatMessage | null {
  if (event.kind !== SPOT_CHAT_KIND) return null;

  const g = event.tags.find(([name]) => name === 'g')?.[1]?.toLowerCase();
  if (!g) return null;

  // The message must belong to this channel (its geohash starts with the
  // channel key, so a block-level message shows up in the neighborhood channel).
  if (!g.startsWith(channel)) return null;

  const content = event.content.trim();
  if (!content || content.length > 500) return null;

  const isAction = content.startsWith('/me ');

  return {
    id: event.id,
    pubkey: event.pubkey,
    content: isAction ? content.slice(4).trim() : content,
    createdAt: event.created_at,
    geohash: g,
    isAction,
  };
}

/**
 * Subscribe to (poll) messages for a geohash channel.
 * Polls every few seconds so the channel feels live without a persistent socket.
 */
export function useSpotChat(geohash: string | undefined, precision: ChatPrecision = 'block') {
  const { querySkateContent, getQueryKeySuffix } = useSkateRelays();

  const channel = geohash ? channelGeohash(geohash, precision) : '';

  return useQuery({
    queryKey: ['spot-chat', channel, getQueryKeySuffix()],
    queryFn: async (c) => {
      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(8000)]);

      // Only keep messages from roughly the last 24h — this is "here and now" chat.
      const since = Math.floor(Date.now() / 1000) - 24 * 60 * 60;

      const events = await querySkateContent(
        [
          {
            kinds: [SPOT_CHAT_KIND],
            '#g': [channel],
            since,
            limit: 200,
          },
        ],
        { signal },
      );

      const messages: SpotChatMessage[] = [];
      const seen = new Set<string>();
      for (const event of events) {
        if (seen.has(event.id)) continue;
        seen.add(event.id);
        const msg = parseSpotChatMessage(event, channel);
        if (msg) messages.push(msg);
      }

      // Oldest first for chat display.
      return messages.sort((a, b) => a.createdAt - b.createdAt);
    },
    enabled: !!channel,
    staleTime: 5000,
    refetchInterval: 8000, // Poll for new messages
  });
}

/**
 * Send a message to a geohash channel.
 * Publishes to the community relay + the user's write relays so both
 * SkateSpots users and the sender's own network see it.
 */
export function useSendSpotChat() {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();
  const { getWriteRelays } = useSkateRelays();
  const queryClient = useQueryClient();

  const send = useCallback(
    async (geohash: string, precision: ChatPrecision, content: string) => {
      if (!user) throw new Error('You must be logged in to chat');

      const channel = channelGeohash(geohash, precision);
      const trimmed = content.trim().slice(0, 500);
      if (!trimmed) return;

      const event = await user.signer.signEvent({
        kind: SPOT_CHAT_KIND,
        content: trimmed,
        created_at: Math.floor(Date.now() / 1000),
        tags: [
          ['g', channel],
          ['n', 'skate'], // SkateSpots-native namespace marker
          ['alt', `Spot Chat message in geohash ${channel}`],
        ],
      });

      const relays = getWriteRelays();
      await Promise.allSettled(
        relays.map((url) => nostr.relay(url).event(event, { signal: AbortSignal.timeout(8000) })),
      );

      return event;
    },
    [user, nostr, getWriteRelays],
  );

  return useMutation({
    mutationFn: async ({
      geohash,
      precision,
      content,
    }: {
      geohash: string;
      precision: ChatPrecision;
      content: string;
    }) => {
      return send(geohash, precision, content);
    },
    onSuccess: (_data, variables) => {
      const channel = channelGeohash(variables.geohash, variables.precision);
      queryClient.invalidateQueries({ queryKey: ['spot-chat', channel] });
    },
  });
}