import { useMemo } from 'react';
import { useOfferThreadsAddressedToMe, type MarketplaceOffer } from '@/hooks/useMarketplaceOffers';
import { useIncomingTradeRequests, usePendingTradeConfirmations } from '@/hooks/useTradeAttestations';

/**
 * Trade/offer activity for the logged-in user — the buying/selling steps that
 * deserve a nudge: a new offer on your listing, a counter-offer it's your turn
 * to answer, the outcome of YOUR offer (accepted / declined / withdrawn), a
 * request to confirm a completed trade, and a counterparty CONFIRMING the trade
 * (which is what turns it into mutual, reputation-building proof).
 *
 * All of it is derived from events already addressed to the user, so it needs no
 * extra infrastructure — the same events power the bell and the OS notifications.
 */
export type TradeNotificationType =
  | 'offer'
  | 'counter'
  | 'accepted'
  | 'declined'
  | 'withdrawn'
  | 'trade-request'
  | 'trade-confirm';

export interface TradeNotification {
  id: string;
  type: TradeNotificationType;
  createdAt: number;
  /** The other party (buyer for an offer, the requester for a request). */
  counterparty: string;
  amount?: number;
  currency?: string;
  /** In-kind offer (a swap/barter), when the sender offered an item. */
  offerItem?: string;
  listingPubkey: string;
  listingIdentifier: string;
  /** Present for offer/counter items, so the UI can act inline. */
  offer?: MarketplaceOffer;
}

export function useTradeNotifications(pubkey: string | undefined) {
  const { data: incoming = [], isLoading: offersLoading } = useOfferThreadsAddressedToMe(pubkey);
  const { data: requests = [], isLoading: requestsLoading } = useIncomingTradeRequests(pubkey);
  const { data: pendingConfirms = [], isLoading: confirmsLoading } = usePendingTradeConfirmations(pubkey);

  const notifications = useMemo<TradeNotification[]>(() => {
    const out: TradeNotification[] = [];

    // Every step addressed to me: a new offer, a counter it's my turn to answer,
    // or the outcome of my own offer (accepted / declined / withdrawn).
    for (const thread of incoming) {
      const latest = thread.latest;
      const type: TradeNotificationType =
        latest.status === 'open'
          ? latest.replyTo
            ? 'counter'
            : 'offer'
          : latest.status;
      out.push({
        id: latest.id,
        type,
        createdAt: latest.createdAt,
        counterparty: latest.author,
        amount: latest.amount,
        currency: latest.currency,
        offerItem: latest.offerItem,
        listingPubkey: latest.listingPubkey,
        listingIdentifier: latest.listingIdentifier,
        offer: latest,
      });
    }

    // "Please confirm our trade" requests (buyer → seller).
    for (const r of requests) {
      out.push({
        id: r.event.id,
        type: 'trade-request',
        createdAt: r.event.created_at,
        counterparty: r.requestor,
        listingPubkey: r.listing.pubkey,
        listingIdentifier: r.listing.identifier,
      });
    }

    // A counterparty has recorded/confirmed the deal and you haven't mirrored it
    // yet — confirming back is what makes it a mutual, reputation-building trade.
    for (const p of pendingConfirms) {
      out.push({
        id: `confirm:${p.eventId}`,
        type: 'trade-confirm',
        createdAt: p.createdAt,
        counterparty: p.seller,
        listingPubkey: p.listing.pubkey,
        listingIdentifier: p.listing.identifier,
      });
    }

    return out.sort((a, b) => b.createdAt - a.createdAt);
  }, [incoming, requests, pendingConfirms]);

  return { notifications, isLoading: offersLoading || requestsLoading || confirmsLoading };
}

/** "2,000 SATS + an 8.25 deck" — sats, an item, or both. */
function offerWhat(n: TradeNotification): string {
  const parts: string[] = [];
  if (n.amount) parts.push(`${n.amount.toLocaleString()} ${n.currency ?? 'SATS'}`);
  if (n.offerItem) parts.push(n.offerItem);
  return parts.join(' + ');
}

export function tradeNotificationText(n: TradeNotification): string {
  const what = offerWhat(n);
  switch (n.type) {
    case 'offer':
      return what ? `offered ${what}` : 'made an offer';
    case 'counter':
      return what ? `countered with ${what}` : 'sent a counter-offer';
    case 'accepted':
      return n.amount ? `accepted your offer — ${n.amount.toLocaleString()} ${n.currency ?? 'SATS'}` : 'accepted your offer';
    case 'declined':
      return 'declined your offer';
    case 'withdrawn':
      return 'withdrew their offer';
    case 'trade-request':
      return 'asked you to confirm a trade';
    case 'trade-confirm':
      return 'confirmed your trade — confirm back to build both reputations';
    default:
      return 'needs your attention';
  }
}