import { useState } from 'react';
import { Link } from 'react-router-dom';
import { nip19 } from 'nostr-tools';
import { Card, CardContent } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Badge } from '@/components/ui/badge';
import { Input } from '@/components/ui/input';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useAuthor } from '@/hooks/useAuthor';
import { useToast } from '@/hooks/useToast';
import {
  useOfferActions,
  useListingOffers,
  type MarketplaceOffer,
  type OfferThread,
} from '@/hooks/useMarketplaceOffers';
import { useSendDirectMessage } from '@/hooks/useDirectMessages';
import { saveReceipt } from '@/lib/receipts';
import { genUserName } from '@/lib/genUserName';
import type { MarketplaceItem } from '@/lib/types';
import { PayWithSats } from '@/components/PayWithSats';
import { Handshake, CheckCircle, X, Loader2, ArrowLeftRight, Undo2, Zap } from 'lucide-react';
import { useTranslation } from '@/contexts/language';

type TFunc = (key: string, params?: Record<string, string | number>) => string;

function PeerName({ pubkey }: { pubkey: string }) {
  const author = useAuthor(pubkey);
  const name = author.data?.metadata?.name ?? genUserName(pubkey);
  return (
    <Link to={`/${nip19.npubEncode(pubkey)}`} className="font-bold text-white hover:text-[#ccff00]">
      {name}
    </Link>
  );
}

function statusBadge(status: MarketplaceOffer['status'], t: TFunc) {
  switch (status) {
    case 'accepted':
      return <Badge className="bg-[#ccff00]/15 text-[#ccff00] border border-[#ccff00]/30">{t('marketUi.offers.accepted')}</Badge>;
    case 'declined':
      return <Badge className="bg-red-500/15 text-red-400 border border-red-500/30">{t('marketUi.offers.declined')}</Badge>;
    case 'withdrawn':
      return <Badge variant="secondary" className="bg-gray-700 text-gray-400">{t('marketUi.offers.withdrawn')}</Badge>;
    default:
      return <Badge className="bg-orange-500/15 text-orange-400 border border-orange-500/30">{t('marketUi.offers.open')}</Badge>;
  }
}

function amountLabel(m: MarketplaceOffer, t: TFunc): string {
  const parts: string[] = [];
  if (m.amount) parts.push(`${m.amount.toLocaleString()} ${m.currency ?? 'SATS'}`);
  if (m.offerItem) parts.push(m.offerItem);
  return parts.length ? parts.join(' + ') : t('marketUi.offers.noAmount');
}

/**
 * Offers for a listing, as a **negotiation thread**. Either side can accept,
 * decline, withdraw, or **counter** with a new amount — and it's always clear
 * whose turn it is.
 */
export function ListingOffersPanel({ item, isOwner }: { item: MarketplaceItem; isOwner: boolean }) {
  const { t } = useTranslation();
  const { user, metadata } = useCurrentUser();
  const { data } = useListingOffers({ pubkey: item.pubkey, identifier: item.identifier });
  const { respondToOffer, counterOffer } = useOfferActions();
  const { mutateAsync: sendDM } = useSendDirectMessage();
  const { toast } = useToast();
  const [busy, setBusy] = useState<string | null>(null);
  const [counterFor, setCounterFor] = useState<string | null>(null);
  const [counterAmount, setCounterAmount] = useState('');
  const [counterItem, setCounterItem] = useState('');
  const [payFor, setPayFor] = useState<OfferThread | null>(null);
  const [paidThreads, setPaidThreads] = useState<Set<string>>(() => new Set());

  if (!user || !data) return null;

  const mine = data.threads.filter((t) => t.buyer === user.pubkey || t.seller === user.pubkey);
  if (mine.length === 0) return null;

  const nudge = async (to: string, content: string) => {
    try {
      await sendDM({ recipients: to, content });
    } catch {
      /* DM is a best-effort extra nudge; the event itself already carries it */
    }
  };

  const respond = async (thread: OfferThread, status: 'accepted' | 'declined') => {
    setBusy(thread.latest.id);
    try {
      // On accept, attach my Lightning address (if I have one) so the buyer can
      // pay in-app. If I have none, their side falls back to my profile `lud16`.
      const myLud16 = metadata?.lud16?.trim();
      await respondToOffer(
        thread.latest,
        status,
        undefined,
        status === 'accepted' && myLud16 ? { pointer: myLud16, kind: 'lnaddress' } : undefined,
      );
      await nudge(
        thread.latest.author,
        status === 'accepted'
          ? t('marketUi.offers.dmAccepted')
          : t('marketUi.offers.dmDeclined'),
      );
      toast({ title: status === 'accepted' ? t('marketUi.offers.offerAccepted') : t('marketUi.offers.offerDeclined') });
    } catch (e) {
      toast({
        title: t('marketUi.offers.respondFailed'),
        description: e instanceof Error ? e.message : t('marketUi.offers.somethingWrong'),
        variant: 'destructive',
      });
    } finally {
      setBusy(null);
    }
  };

  const withdraw = async (thread: OfferThread) => {
    setBusy(thread.latest.id);
    try {
      await respondToOffer(thread.latest, 'withdrawn');
      toast({ title: t('marketUi.offers.offerWithdrawn') });
    } catch (e) {
      toast({
        title: t('marketUi.offers.withdrawFailed'),
        description: e instanceof Error ? e.message : t('marketUi.offers.somethingWrong'),
        variant: 'destructive',
      });
    } finally {
      setBusy(null);
    }
  };

  const sendCounter = async (thread: OfferThread) => {
    const amount = Number(counterAmount);
    const hasAmount = counterAmount.trim() !== '' && Number.isFinite(amount) && amount > 0;
    if (!hasAmount && !counterItem.trim()) {
      toast({ title: t('marketUi.offers.enterAmountOrItem'), variant: 'destructive' });
      return;
    }
    setBusy(thread.latest.id);
    try {
      await counterOffer({
        listing: { pubkey: item.pubkey, identifier: item.identifier },
        previous: thread.latest,
        amount: hasAmount ? amount : undefined,
        offerItem: counterItem,
      });
      const what = [hasAmount ? `${amount.toLocaleString()} sats` : null, counterItem.trim() || null]
        .filter(Boolean)
        .join(' + ');
      await nudge(thread.latest.author, `↩️ ${t('marketUi.offers.counterDm')}: ${what}`);
      toast({ title: t('marketUi.offers.counterSent'), description: t('marketUi.offers.counterSentBody') });
      setCounterFor(null);
      setCounterAmount('');
      setCounterItem('');
    } catch (e) {
      toast({
        title: t('marketUi.offers.counterFailed'),
        description: e instanceof Error ? e.message : t('marketUi.offers.somethingWrong'),
        variant: 'destructive',
      });
    } finally {
      setBusy(null);
    }
  };

  return (
    <Card className="bg-black/90 border-2 border-orange-500/25">
      <CardContent className="space-y-3 p-4">
        <h3 className="flex items-center gap-2 text-sm font-bold uppercase tracking-wide text-orange-400">
          <Handshake className="h-4 w-4" /> {isOwner ? t('marketUi.offers.titleOwner', { count: mine.length }) : t('marketUi.offers.titleBuyer')}
        </h3>

        {mine.map((thread) => {
          const latest = thread.latest;
          const other = latest.author === user.pubkey
            ? latest.buyer === user.pubkey
              ? latest.seller
              : latest.buyer
            : latest.author;
          const myTurn = thread.awaiting === user.pubkey;
          const history = thread.messages.slice(0, -1);

          return (
            <div
              key={`${thread.listingCoord}:${thread.buyer}`}
              className="space-y-2 rounded-xl border border-white/10 bg-white/[0.03] p-3"
            >
              <div className="flex flex-wrap items-center gap-2">
                <span className="text-sm text-gray-200">
                  <PeerName pubkey={other} />
                </span>
                {statusBadge(latest.status, t)}
                <span className="ml-auto text-sm font-bold text-[#ccff00]">{amountLabel(latest, t)}</span>
              </div>

              {/* Earlier rounds — the volley, so the haggling is visible. */}
              {history.length > 0 && (
                <div className="space-y-0.5 border-l border-white/10 pl-2">
                  {history.map((m) => (
                    <p key={m.id} className="text-[11px] text-gray-500">
                      {m.author === user.pubkey ? t('marketUi.offers.you') : t('marketUi.offers.them')}: {amountLabel(m, t)}
                      {m.status !== 'open' ? ` · ${m.status}` : ''}
                    </p>
                  ))}
                </div>
              )}

              {latest.message && <p className="text-xs text-gray-400">{latest.message}</p>}

              {/* Buyer on an accepted deal: settle it straight from the wallet. */}
              {latest.status === 'accepted' && user.pubkey === thread.buyer && (
                paidThreads.has(`${thread.listingCoord}:${thread.buyer}`) ? (
                  <p className="flex items-center gap-1.5 text-xs font-bold text-green-400">
                    <CheckCircle className="h-3.5 w-3.5" /> {t('marketUi.offers.paidAskConfirm')}
                  </p>
                ) : (
                  <Button
                    size="sm"
                    onClick={() => setPayFor(thread)}
                    className="w-full gap-1.5 bg-[#ccff00] font-bold text-black hover:bg-[#ccff00]/90"
                  >
                    <Zap className="h-3.5 w-3.5" /> {t('marketUi.offers.payWithSats')}
                  </Button>
                )
              )}

              {/* My turn: accept, decline, or counter. */}
              {myTurn && (
                <>
                  <div className="flex gap-2 pt-1">
                    <Button
                      size="sm"
                      onClick={() => respond(thread, 'accepted')}
                      disabled={busy === latest.id}
                      className="flex-1 gap-1.5 bg-[#ccff00] font-bold text-black hover:bg-[#ccff00]/90"
                    >
                      {busy === latest.id ? <Loader2 className="h-3.5 w-3.5 animate-spin" /> : <CheckCircle className="h-3.5 w-3.5" />}
                      {t('marketUi.offers.accept')}
                    </Button>
                    <Button
                      size="sm"
                      variant="outline"
                      onClick={() => respond(thread, 'declined')}
                      disabled={busy === latest.id}
                      className="flex-1 gap-1.5 border-red-500/30 text-red-400 hover:bg-red-500/10"
                    >
                      <X className="h-3.5 w-3.5" /> {t('marketUi.offers.decline')}
                    </Button>
                    <Button
                      size="sm"
                      variant="outline"
                      onClick={() => {
                        setCounterFor(counterFor === latest.id ? null : latest.id);
                        setCounterAmount(latest.amount ? String(Math.round(latest.amount)) : '');
                        setCounterItem(latest.offerItem ?? '');
                      }}
                      className="flex-1 gap-1.5 border-orange-500/40 text-orange-400 hover:bg-orange-500/10"
                    >
                      <ArrowLeftRight className="h-3.5 w-3.5" /> {t('marketUi.offers.counter')}
                    </Button>
                  </div>
                  {counterFor === latest.id && (
                    <div className="space-y-2">
                      <div className="flex items-center gap-2">
                        <Input
                          autoFocus
                          type="number"
                          inputMode="numeric"
                          value={counterAmount}
                          onChange={(e) => setCounterAmount(e.target.value)}
                          placeholder={t('marketUi.offers.counterPlaceholder')}
                          className="h-9 border-white/15 bg-white/5 text-sm text-white"
                        />
                        <Button
                          size="sm"
                          onClick={() => sendCounter(thread)}
                          disabled={busy === latest.id}
                          className="shrink-0 gap-1.5 bg-orange-500 font-bold text-black hover:bg-orange-500/90"
                        >
                          {busy === latest.id ? <Loader2 className="h-3.5 w-3.5 animate-spin" /> : null}
                          {t('marketUi.offers.send')}
                        </Button>
                      </div>
                      <Input
                        value={counterItem}
                        onChange={(e) => setCounterItem(e.target.value)}
                        placeholder={t('marketUi.offers.counterItemPlaceholder')}
                        className="h-9 border-white/15 bg-white/5 text-sm text-white"
                      />
                    </div>
                  )}
                </>
              )}

              {/* Their turn: waiting, with the option to pull my own offer. */}
              {!myTurn && latest.status === 'open' && (
                <div className="flex items-center gap-2">
                  <p className="flex-1 text-xs text-gray-500">
                    {t('marketUi.offers.waitingOn')} <PeerName pubkey={other} /> {t('marketUi.offers.waitingOnSuffix')}
                  </p>
                  {latest.author === user.pubkey && (
                    <Button
                      size="sm"
                      variant="outline"
                      onClick={() => withdraw(thread)}
                      disabled={busy === latest.id}
                      className="shrink-0 gap-1.5 border-white/15"
                    >
                      <Undo2 className="h-3.5 w-3.5" /> {t('marketUi.offers.withdraw')}
                    </Button>
                  )}
                </div>
              )}
            </div>
          );
        })}

        {payFor && (
          <PayWithSats
            open={!!payFor}
            onOpenChange={(o) => { if (!o) setPayFor(null); }}
            sellerPubkey={payFor.latest.seller}
            amountSats={payFor.latest.amount}
            pointer={payFor.latest.payment}
            pointerKind={payFor.latest.paymentKind}
            onPaid={(receipt) => {
              // Carry the verifiable receipt to the confirm step (same coord key).
              if (receipt) saveReceipt(payFor.listingCoord, receipt);
              setPaidThreads((prev) => new Set(prev).add(`${payFor.listingCoord}:${payFor.buyer}`));
            }}
          />
        )}
      </CardContent>
    </Card>
  );
}