SkateSpots/src/hooks/useNutzap.ts

import { useNostr } from '@nostrify/react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { useCurrentUser } from './useCurrentUser';
import { useNostrPublish } from './useNostrPublish';

import { useToast } from './useToast';
import type { NostrEvent } from '@nostrify/nostrify';

// NIP-61 Kinds
export const NUTZAP_INFO_KIND = 10019; // User's nutzap receiving preferences
export const NUTZAP_KIND = 9321; // Nutzap event
export const NUTZAP_HISTORY_KIND = 7376; // Nutzap redemption history

export interface NutzapInfo {
  pubkey: string;
  relays: string[];
  mints: Array<{ url: string; units: string[] }>;
  p2pkPubkey?: string;
}

export interface Nutzap {
  id: string;
  pubkey: string; // sender
  recipientPubkey: string;
  eventId?: string;
  mintUrl: string;
  amount: number;
  unit: string;
  comment?: string;
  proofs: string[];
  createdAt: number;
}

// Parse a kind:10019 nutzap info event
function parseNutzapInfo(event: NostrEvent): NutzapInfo | null {
  const relays: string[] = [];
  const mints: Array<{ url: string; units: string[] }> = [];
  let p2pkPubkey: string | undefined;

  for (const tag of event.tags) {
    if (tag[0] === 'relay' && tag[1]) {
      relays.push(tag[1]);
    } else if (tag[0] === 'mint' && tag[1]) {
      const units = tag.slice(2);
      mints.push({ url: tag[1], units: units.length > 0 ? units : ['sat'] });
    } else if (tag[0] === 'pubkey' && tag[1]) {
      p2pkPubkey = tag[1];
    }
  }

  if (relays.length === 0 && mints.length === 0) {
    return null;
  }

  return {
    pubkey: event.pubkey,
    relays,
    mints,
    p2pkPubkey,
  };
}

// Parse a kind:9321 nutzap event
function parseNutzap(event: NostrEvent): Nutzap | null {
  const proofs: string[] = [];
  let mintUrl = '';
  let unit = 'sat';
  let recipientPubkey = '';
  let eventId: string | undefined;
  let amount = 0;

  for (const tag of event.tags) {
    if (tag[0] === 'proof' && tag[1]) {
      proofs.push(tag[1]);
      // Try to extract amount from proof
      try {
        const proof = JSON.parse(tag[1]);
        if (proof.amount) {
          amount += proof.amount;
        }
      } catch {
        // Ignore parse errors
      }
    } else if (tag[0] === 'u' && tag[1]) {
      mintUrl = tag[1];
    } else if (tag[0] === 'unit' && tag[1]) {
      unit = tag[1];
    } else if (tag[0] === 'p' && tag[1]) {
      recipientPubkey = tag[1];
    } else if (tag[0] === 'e' && tag[1]) {
      eventId = tag[1];
    }
  }

  if (!mintUrl || proofs.length === 0 || !recipientPubkey) {
    return null;
  }

  return {
    id: event.id,
    pubkey: event.pubkey,
    recipientPubkey,
    eventId,
    mintUrl,
    amount,
    unit,
    comment: event.content || undefined,
    proofs,
    createdAt: event.created_at,
  };
}

/**
 * Get a user's nutzap info (kind:10019)
 */
export function useNutzapInfo(pubkey: string | undefined) {
  const { nostr } = useNostr();

  return useQuery({
    queryKey: ['nutzap-info', pubkey],
    queryFn: async (c) => {
      if (!pubkey) return null;

      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(5000)]);
      const events = await nostr.query([
        {
          kinds: [NUTZAP_INFO_KIND],
          authors: [pubkey],
          limit: 1,
        },
      ], { signal });

      if (events.length === 0) return null;

      return parseNutzapInfo(events[0]);
    },
    enabled: !!pubkey,
    staleTime: 1000 * 60 * 5, // 5 minutes
  });
}

/**
 * Get nutzaps received by a user or for a specific event
 */
export function useNutzaps(params: { pubkey?: string; eventId?: string }) {
  const { nostr } = useNostr();

  return useQuery({
    queryKey: ['nutzaps', params.pubkey, params.eventId],
    queryFn: async (c) => {
      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(8000)]);
      
      const filters: Parameters<typeof nostr.query>[0] = [];
      
      if (params.eventId) {
        filters.push({
          kinds: [NUTZAP_KIND],
          '#e': [params.eventId],
          limit: 100,
        });
      } else if (params.pubkey) {
        filters.push({
          kinds: [NUTZAP_KIND],
          '#p': [params.pubkey],
          limit: 100,
        });
      }

      if (filters.length === 0) return [];

      const events = await nostr.query(filters, { signal });

      const nutzaps: Nutzap[] = [];
      for (const event of events) {
        const nutzap = parseNutzap(event);
        if (nutzap) {
          nutzaps.push(nutzap);
        }
      }

      return nutzaps.sort((a, b) => b.createdAt - a.createdAt);
    },
    enabled: !!(params.pubkey || params.eventId),
    staleTime: 1000 * 30, // 30 seconds
  });
}

/**
 * Check if the current user can receive nutzaps
 */
export function useCanReceiveNutzaps() {
  const { user } = useCurrentUser();
  const { data: nutzapInfo } = useNutzapInfo(user?.pubkey);

  return {
    canReceive: !!(nutzapInfo && nutzapInfo.mints.length > 0 && nutzapInfo.p2pkPubkey),
    nutzapInfo,
  };
}

/**
 * Setup nutzap receiving (publish kind:10019)
 */
export function useSetupNutzapReceiving() {
  const { user } = useCurrentUser();
  const { mutateAsync: publishEvent } = useNostrPublish();
  const { toast } = useToast();
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: async ({
      mints,
      relays,
      p2pkPubkey,
    }: {
      mints: Array<{ url: string; units?: string[] }>;
      relays: string[];
      p2pkPubkey: string;
    }) => {
      if (!user) throw new Error('Must be logged in');

      const tags: string[][] = [];

      // Add relays
      for (const relay of relays) {
        tags.push(['relay', relay]);
      }

      // Add mints with units
      for (const mint of mints) {
        const mintTag = ['mint', mint.url, ...(mint.units || ['sat'])];
        tags.push(mintTag);
      }

      // Add P2PK pubkey (MUST be different from main Nostr pubkey)
      tags.push(['pubkey', p2pkPubkey]);

      await publishEvent({
        kind: NUTZAP_INFO_KIND,
        content: '',
        tags,
      });

      return { mints, relays, p2pkPubkey };
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['nutzap-info'] });
      toast({
        title: 'Nutzap receiving enabled',
        description: 'You can now receive ecash zaps!',
      });
    },
    onError: (error) => {
      toast({
        title: 'Setup failed',
        description: error instanceof Error ? error.message : 'Failed to setup nutzap receiving',
        variant: 'destructive',
      });
    },
  });
}

/**
 * Whether in-app nutzap SENDING is available.
 *
 * Nutzap sending (NIP-61) requires minting Cashu proofs that are P2PK-locked to
 * the recipient's `p2pkPubkey` plus DLEQ proofs. Getting P2PK locking wrong would
 * lock funds to the wrong key — i.e. lost sats — so sending is intentionally
 * DISABLED until it can be implemented and audited against the wallet's P2PK
 * capabilities. Nutzap RECEIVING setup (kind 10019) and reading received nutzaps
 * work today.
 *
 * UI should gate any "send nutzap" affordance behind this flag and fall back to
 * regular Lightning zaps (which support paying from the Cashu balance anyway).
 */
export const NUTZAP_SENDING_ENABLED = false;

/**
 * Send a nutzap to someone.
 *
 * NOT YET IMPLEMENTED — see {@link NUTZAP_SENDING_ENABLED}. This mutation always
 * rejects with a clear message so nothing silently appears to succeed. Do not
 * wire a visible "send" button to this until sending is implemented; use the
 * regular Lightning zap flow (ZapDialog), which can pay from the Cashu balance.
 *
 * Full implementation would require:
 * 1. Check for tokens on one of the recipient's mints (swap in if needed)
 * 2. Mint/swap proofs P2PK-locked to recipient.p2pkPubkey
 * 3. Include DLEQ proofs
 * 4. Publish kind:9321 with `proof`, `u` (mint), `p` (recipient), optional `e`
 */
export function useSendNutzap() {
  const { user } = useCurrentUser();
  const { toast } = useToast();
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: async (_params: {
      recipientPubkey: string;
      recipientNutzapInfo: NutzapInfo;
      eventId?: string;
      eventKind?: number;
      amount: number;
      comment?: string;
    }) => {
      if (!user) throw new Error('Must be logged in');
      // Guarded off to avoid locking funds to the wrong key. See NUTZAP_SENDING_ENABLED.
      throw new Error(
        'Nutzap sending is not available yet — use a regular Lightning zap (you can pay it straight from your Cashu balance).'
      );
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['nutzaps'] });
    },
    onError: (error) => {
      toast({
        title: 'Nutzap sending unavailable',
        description: error instanceof Error ? error.message : 'Use a Lightning zap instead',
        variant: 'destructive',
      });
    },
  });
}

/**
 * Get total nutzaps received for an event
 */
export function useNutzapTotal(eventId: string | undefined) {
  const { data: nutzaps } = useNutzaps({ eventId });

  if (!nutzaps) {
    return { count: 0, totalAmount: 0 };
  }

  return {
    count: nutzaps.length,
    totalAmount: nutzaps.reduce((sum, nz) => sum + nz.amount, 0),
  };
}