/**
 * VerifyCardPage — /verify/:naddr
 *
 * VERIFIER-FIRST: a door person scans a QR (or taps an NFC tag) and needs one
 * answer in half a second — ✅ / ❌ — then the facts. The technical detail is
 * tucked below. No account, no app needed to verify.
 *
 * It is deliberately honest about what it does and does NOT prove.
 */
import { useParams, useSearchParams, Link } from 'react-router-dom';
import { useQuery } from '@tanstack/react-query';
import { nip19, verifyEvent } from 'nostr-tools';
import { useSeoMeta } from '@unhead/react';
import { BadgeCheck, ShieldAlert, ShieldX, Loader2, ExternalLink } from 'lucide-react';

import { useNostr } from '@/hooks/useNostr';
import { useAuthor } from '@/hooks/useAuthor';
import { useTranslation } from '@/contexts/language';
import { genUserName } from '@/lib/genUserName';
import { RIDER_CARD_KIND, PARK_ACCESS_CARD_KIND, passExpiry } from '@/lib/riderCard';
import { SKATE_SPOT_KIND, SKATE_SHOP_KIND, SKATE_CREW_KIND, CALENDAR_EVENT_KIND, CALENDAR_RSVP_KIND } from '@/lib/types';
import type { NostrEvent } from '@nostrify/nostrify';

interface ParsedNaddr {
  kind: number;
  pubkey: string;
  identifier: string;
  relays: string[];
}

function parseNaddr(value: string): ParsedNaddr | null {
  try {
    const d = nip19.decode(value);
    if (d.type !== 'naddr') return null;
    const { kind, pubkey, identifier, relays } = d.data;
    return { kind, pubkey, identifier, relays: relays ?? [] };
  } catch {
    return null;
  }
}

function shortNpub(hex: string): string {
  if (!hex) return '—';
  try { const n = nip19.npubEncode(hex); return `${n.slice(0, 12)}…${n.slice(-6)}`; } catch { return hex.slice(0, 12); }
}

type Tone = 'good' | 'warn' | 'bad';

export default function VerifyCardPage() {
  const { t } = useTranslation();
  const { naddr = '' } = useParams<{ naddr: string }>();
  const [searchParams] = useSearchParams();
  const holderParam = searchParams.get('h') ?? '';
  const holderHex = (() => {
    if (!holderParam) return '';
    if (/^[0-9a-f]{64}$/i.test(holderParam)) return holderParam.toLowerCase();
    try { const d = nip19.decode(holderParam); return d.type === 'npub' ? d.data : ''; } catch { return ''; }
  })();
  const { nostr } = useNostr();
  const parsed = parseNaddr(naddr);

  useSeoMeta({ title: 'Verify — SkateSpots', description: 'Verify a SkateSpots card or access pass.' });

  const result = useQuery({
    queryKey: ['verify-card', naddr],
    enabled: !!parsed,
    staleTime: 60_000,
    queryFn: async (c) => {
      if (!parsed) return { status: 'notfound' as const };
      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(8000)]);
      const events = await nostr.query(
        [{ kinds: [parsed.kind], authors: [parsed.pubkey], '#d': [parsed.identifier], limit: 1 }],
        { signal },
      );
      const event = events[0] as NostrEvent | undefined;
      if (!event) return { status: 'notfound' as const };
      if (!verifyEvent(event)) return { status: 'invalid' as const };

      // Access pass — confirm the issuer OWNS the target it names (a venue spot
      // 30818, or an event 31923 for a check-in pass).
      let venue: { status: 'none' | 'verified' | 'mismatch'; title?: string; coord?: string; kind?: number } = { status: 'none' };
      if (event.kind === PARK_ACCESS_CARD_KIND) {
        const aTag = event.tags.find(([n]) => n === 'a')?.[1];
        if (aTag) {
          venue = { status: 'mismatch', coord: aTag };
          const [k, pk, dTag] = aTag.split(':');
          const kindNum = Number(k);
          if ((kindNum === SKATE_SPOT_KIND || kindNum === SKATE_SHOP_KIND || kindNum === CALENDAR_EVENT_KIND) && pk && dTag) {
            try {
              const targets = await nostr.query(
                [{ kinds: [kindNum], authors: [pk], '#d': [dTag], limit: 1 }],
                { signal },
              );
              const target = targets[0] as NostrEvent | undefined;
              if (target) {
                venue = {
                  status: target.pubkey === event.pubkey ? 'verified' : 'mismatch',
                  title: target.tags.find(([n]) => n === 'title')?.[1] || target.tags.find(([n]) => n === 'name')?.[1],
                  coord: aTag,
                  kind: kindNum,
                };
              }
            } catch { /* leave mismatch */ }
          }
        }
      }

      return { status: 'valid' as const, event, venue };
    },
  });

  // Event ticket: the holder carries ?h=<npub> in the QR, so a door can confirm
  // they actually RSVP'd to the organiser's event.
  const ticket = useQuery<{ status: string }>({
    queryKey: ['ticket-rsvp', naddr, holderHex],
    enabled: !!parsed && parsed.kind === CALENDAR_EVENT_KIND && !!holderHex,
    queryFn: async (c) => {
      if (!parsed || !holderHex) return { status: 'none' };
      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(8000)]);
      const coord = `${parsed.kind}:${parsed.pubkey}:${parsed.identifier}`;
      const events = await nostr.query(
        [{ kinds: [CALENDAR_RSVP_KIND], authors: [holderHex], '#a': [coord], limit: 5 }],
        { signal },
      );
      const ev = [...events].sort((a, b) => b.created_at - a.created_at)[0];
      if (!ev) return { status: 'none' };
      return { status: ev.tags.find(([n]) => n === 'status')?.[1] ?? 'accepted' };
    },
  });

  const author = useAuthor(parsed?.pubkey ?? '');
  const issuerName = author.data?.metadata?.name ?? (parsed ? genUserName(parsed.pubkey) : '');

  const data = result.data;
  const valid = data && data.status === 'valid' ? data : undefined;
  const event = valid?.event;
  const venue = valid?.venue;
  const validThru = event?.tags.find(([n]) => n === 'valid-thru')?.[1];
  const expiry = passExpiry(validThru);
  const accessLevel = event?.tags.find(([n]) => n === 'access-level')?.[1];
  const holderPubkey = event?.tags.find(([n]) => n === 'p')?.[1];
  const revoked = !!event && event.tags.some(([n, v]) => n === 'status' && v === 'revoked');

  const isPark = event?.kind === PARK_ACCESS_CARD_KIND;
  const isTicket = event?.kind === CALENDAR_EVENT_KIND;
  const isCrew = event?.kind === SKATE_CREW_KIND;
  const isRider = event?.kind === RIDER_CARD_KIND;

  // ── The single verdict a door person needs at a glance ──────────────────────
  let tone: Tone = 'warn';
  let label = t('cardUi.verify.notFound');
  let sub = t('cardUi.verify.notFoundDesc');

  if (!parsed) {
    tone = 'bad'; label = t('cardUi.verify.invalidLink'); sub = t('cardUi.verify.invalidLinkDesc');
  } else if (data?.status === 'invalid') {
    tone = 'bad'; label = t('cardUi.verify.invalid'); sub = t('cardUi.verify.invalidDesc');
  } else if (data?.status === 'notfound') {
    tone = 'warn'; label = t('cardUi.verify.notFound'); sub = t('cardUi.verify.notFoundDesc');
  } else if (event) {
    if (isPark && revoked) { tone = 'bad'; label = t('cardUi.v.revoked'); sub = t('cardUi.v.revokedDesc'); }
    else if (isPark && expiry === 'expired') { tone = 'bad'; label = t('cardUi.v.expired'); sub = t('cardUi.v.expiredDesc'); }
    else if (isPark && venue?.status === 'mismatch') { tone = 'warn'; label = t('cardUi.v.unverifiedIssuer'); sub = t('cardUi.v.unverifiedIssuerDesc'); }
    else if (isPark && venue?.status === 'none') { tone = 'warn'; label = t('cardUi.v.notBound'); sub = t('cardUi.v.notBoundDesc'); }
    else if (isTicket) {
      // Fail CLOSED: only green when a holder is bound AND their RSVP is positive.
      // Missing `?h=`, a loading/errored RSVP, or "none" must not read as admitted.
      const rs = ticket.data?.status;
      const confirmed = !!holderHex && (rs === 'accepted' || rs === 'going' || rs === 'tentative' || rs === 'interested');
      if (confirmed) { tone = 'good'; label = t('cardUi.v.admitted'); sub = t('cardUi.v.admittedDesc'); }
      else if (!holderHex) { tone = 'warn'; label = t('cardUi.v.noHolder'); sub = t('cardUi.v.noHolderDesc'); }
      else { tone = 'warn'; label = t('cardUi.v.noRsvp'); sub = t('cardUi.v.noRsvpDesc'); }
    }
    else if (isPark) { tone = 'good'; label = t('cardUi.v.valid'); sub = t('cardUi.v.validDesc'); }
    else { tone = 'good'; label = t('cardUi.verify.authentic'); sub = t('cardUi.verify.authenticDesc'); }
  }

  const toneRing = tone === 'good' ? 'border-green-500/40 from-green-500/15 text-green-400'
    : tone === 'warn' ? 'border-amber-500/40 from-amber-500/15 text-amber-400'
      : 'border-red-500/40 from-red-500/15 text-red-400';
  const Icon = tone === 'good' ? BadgeCheck : tone === 'warn' ? ShieldAlert : ShieldX;

  // Facts a verifier actually reads.
  const facts: Array<{ label: string; value: string }> = [];
  if (isPark) {
    if (holderPubkey) facts.push({ label: t('cardUi.verify.holder'), value: shortNpub(holderPubkey) });
    if (venue?.title || issuerName) facts.push({ label: venue?.kind === CALENDAR_EVENT_KIND ? t('cardUi.verify.organiser') : t('cardUi.verify.venue'), value: venue?.title || issuerName });
    if (validThru) facts.push({ label: t('cardUi.verify.validThru'), value: validThru });
    if (accessLevel) facts.push({ label: t('cardUi.verify.accessLevel'), value: accessLevel });
  } else if (isTicket) {
    if (holderHex) facts.push({ label: t('cardUi.verify.ticketHolder'), value: shortNpub(holderHex) });
    const title = event?.tags.find(([n]) => n === 'title')?.[1];
    if (title) facts.push({ label: t('cardUi.verify.kindEvent'), value: title });
  } else if (isCrew) {
    const name = event?.tags.find(([n]) => n === 'name')?.[1];
    if (name) facts.push({ label: t('cardUi.verify.kindCrew'), value: name });
  } else if (isRider) {
    facts.push({ label: t('cardUi.verify.issuedBy'), value: issuerName });
  }

  const kindLabel = isPark ? t('cardUi.verify.kindPark') : isCrew ? t('cardUi.verify.kindCrew') : isTicket ? t('cardUi.verify.kindEvent') : t('cardUi.verify.kindRider');

  return (
    <div className="mx-auto max-w-lg px-4 py-6">
      {/* Verdict hero — the whole point of the page */}
      {parsed && result.isLoading ? (
        <div className="flex flex-col items-center justify-center gap-3 py-24 text-gray-400">
          <Loader2 className="h-8 w-8 animate-spin" />
          <span className="text-xs font-black uppercase tracking-widest">{t('cardUi.verify.checking')}</span>
        </div>
      ) : (
        <>
          <div className={`rounded-3xl border bg-gradient-to-b to-transparent p-8 text-center ${toneRing}`}>
            <Icon className="mx-auto h-16 w-16" />
            <div className="mt-3 text-4xl font-black uppercase tracking-tight">{label}</div>
            <p className="mx-auto mt-2 max-w-xs text-sm text-gray-300">{sub}</p>
          </div>

          {event && (
            <>
              {/* Facts */}
              {facts.filter((f) => f.value).length > 0 && (
                <div className="mt-4 grid grid-cols-2 gap-3">
                  {facts.filter((f) => f.value).map((f) => (
                    <div key={f.label} className="rounded-xl border border-white/10 bg-black/40 px-3 py-3">
                      <div className="text-[10px] uppercase tracking-widest text-gray-500">{f.label}</div>
                      <div className="mt-1 break-words text-sm font-bold text-white">{f.value}</div>
                    </div>
                  ))}
                </div>
              )}

              {/* Technical detail (collapsed) */}
              <details className="mt-4 rounded-xl border border-white/10 bg-black/40">
                <summary className="cursor-pointer px-4 py-3 text-[11px] font-black uppercase tracking-widest text-gray-500">
                  {t('cardUi.verify.details')}
                </summary>
                <div className="divide-y divide-white/5 border-t border-white/5">
                  <Row label={t('cardUi.verify.kind')} value={kindLabel} />
                  <Row label={t('cardUi.verify.issuedBy')} value={issuerName} />
                  {isPark && venue && (
                    <Row
                      label={venue.kind === CALENDAR_EVENT_KIND ? t('cardUi.verify.organiser') : t('cardUi.verify.venue')}
                      value={venue.status === 'verified' ? t('cardUi.verify.venueVerified', { name: venue.title ?? '' }) : venue.status === 'mismatch' ? t('cardUi.verify.venueMismatch') : t('cardUi.verify.venueNone')}
                    />
                  )}
                  {isTicket && ticket.data && (
                    <Row
                      label={t('cardUi.verify.rsvp')}
                      value={(ticket.data.status === 'accepted' || ticket.data.status === 'going') ? t('cardUi.verify.rsvpGoing') : (ticket.data.status === 'tentative' || ticket.data.status === 'interested') ? t('cardUi.verify.rsvpInterested') : t('cardUi.verify.rsvpNone')}
                    />
                  )}
                </div>
              </details>

              <div className="mt-5 flex flex-col gap-2">
                {parsed && (
                  isCrew ? (
                    <Link to={`/crew/${parsed.pubkey}/${parsed.identifier}`} className="inline-flex items-center justify-center gap-1.5 text-center text-sm text-[#ccff00] hover:underline">
                      {t('cardUi.crew.viewCrew')} <ExternalLink className="h-3.5 w-3.5" />
                    </Link>
                  ) : isTicket ? (
                    <Link to={`/event/${parsed.pubkey}/${parsed.identifier}`} className="inline-flex items-center justify-center gap-1.5 text-center text-sm text-[#ccff00] hover:underline">
                      {t('cardUi.event.viewEvent')} <ExternalLink className="h-3.5 w-3.5" />
                    </Link>
                  ) : (
                    <Link to={`/card/${nip19.npubEncode(parsed.pubkey)}`} className="inline-flex items-center justify-center gap-1.5 text-center text-sm text-[#ccff00] hover:underline">
                      {t('cardUi.verify.viewCard')} <ExternalLink className="h-3.5 w-3.5" />
                    </Link>
                  )
                )}
                <p className="mt-1 text-center text-[11px] text-gray-600">{t('cardUi.verify.disclaimer')}</p>
              </div>
            </>
          )}
        </>
      )}
    </div>
  );
}

function Row({ label, value }: { label: string; value: string }) {
  return (
    <div className="flex items-center justify-between gap-4 px-4 py-3">
      <span className="text-[11px] uppercase tracking-widest text-gray-500">{label}</span>
      <span className="text-right text-sm font-bold text-white">{value}</span>
    </div>
  );
}