import { useMemo, useState } from 'react';
import { Link } from 'react-router-dom';
import { nip19 } from 'nostr-tools';
import { ShieldCheck, Users } from 'lucide-react';
import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';
import { useAuthor } from '@/hooks/useAuthor';
import { useBatchTrustScores } from '@/hooks/useBatchTrustScores';
import { genUserName } from '@/lib/genUserName';
import { cn } from '@/lib/utils';

const TRUSTED_THRESHOLD = 60;

function AttendeeRow({ pubkey, trusted }: { pubkey: string; trusted: boolean }) {
  const author = useAuthor(pubkey);
  const name = author.data?.metadata?.name ?? genUserName(pubkey);
  const pic = author.data?.metadata?.picture;

  const npub = (() => {
    try {
      return nip19.npubEncode(pubkey);
    } catch {
      return null;
    }
  })();

  const inner = (
    <div className="flex items-center gap-3 rounded-lg px-2 py-1.5 transition-colors hover:bg-white/5">
      <Avatar className="h-8 w-8">
        <AvatarImage src={pic} alt={name} />
        <AvatarFallback className="text-[10px] font-bold">
          {name.slice(0, 2).toUpperCase()}
        </AvatarFallback>
      </Avatar>
      <span className="min-w-0 flex-1 truncate text-sm font-medium text-gray-200">{name}</span>
      {trusted && (
        <span
          className="flex items-center gap-1 rounded-full bg-[#ccff00]/15 px-2 py-0.5 text-[10px] font-black uppercase tracking-wide text-[#ccff00]"
          title="Someone you follow or a trusted mapper"
        >
          <ShieldCheck className="h-3 w-3" />
          Trusted
        </span>
      )}
    </div>
  );

  if (!npub) return inner;
  return <Link to={`/${npub}`}>{inner}</Link>;
}

/**
 * Full attendee list for a host: tabbed Going / Interested, each row showing a
 * face + name, plus a "trust signal" summarizing how many of the Going crowd
 * are people the viewer follows or trusted mappers (skate events live or die on
 * whether real locals show up).
 */
export function AttendeeList({
  going,
  tentative,
  className,
}: {
  going: string[];
  tentative: string[];
  className?: string;
}) {
  const [tab, setTab] = useState<'going' | 'tentative'>('going');

  const allPubkeys = useMemo(() => [...new Set([...going, ...tentative])], [going, tentative]);
  const { data: trustScores } = useBatchTrustScores(allPubkeys);

  const trustedGoing = useMemo(
    () => going.filter((pk) => (trustScores?.get(pk) ?? 0) >= TRUSTED_THRESHOLD).length,
    [going, trustScores],
  );

  if (going.length === 0 && tentative.length === 0) {
    return (
      <p className={cn('text-sm text-muted-foreground', className)}>
        No RSVPs yet — be the first to say you're going.
      </p>
    );
  }

  const list = tab === 'going' ? going : tentative;

  return (
    <div className={cn('space-y-3', className)}>
      {/* Trust signal */}
      {going.length > 0 && (
        <div className="flex items-center gap-2 rounded-lg border border-[#ccff00]/20 bg-[#ccff00]/5 px-3 py-2">
          <Users className="h-4 w-4 flex-shrink-0 text-[#ccff00]" />
          <p className="text-xs text-gray-300">
            <span className="font-black text-white">{going.length}</span> going
            {trustedGoing > 0 && (
              <>
                {' · '}
                <span className="font-black text-[#ccff00]">{trustedGoing}</span> you trust
              </>
            )}
          </p>
        </div>
      )}

      {/* Tabs */}
      <div className="flex gap-1.5">
        <button
          type="button"
          onClick={() => setTab('going')}
          className={cn(
            'flex-1 rounded-lg py-1.5 text-xs font-black uppercase tracking-wide transition-all',
            tab === 'going'
              ? 'bg-green-500 text-black'
              : 'bg-white/5 text-gray-400 hover:text-white',
          )}
        >
          Going ({going.length})
        </button>
        <button
          type="button"
          onClick={() => setTab('tentative')}
          className={cn(
            'flex-1 rounded-lg py-1.5 text-xs font-black uppercase tracking-wide transition-all',
            tab === 'tentative'
              ? 'bg-[#ccff00] text-black'
              : 'bg-white/5 text-gray-400 hover:text-white',
          )}
        >
          Interested ({tentative.length})
        </button>
      </div>

      {/* List */}
      {list.length > 0 ? (
        <div className="max-h-72 space-y-0.5 overflow-y-auto pr-1">
          {list.map((pk) => (
            <AttendeeRow
              key={pk}
              pubkey={pk}
              trusted={(trustScores?.get(pk) ?? 0) >= TRUSTED_THRESHOLD}
            />
          ))}
        </div>
      ) : (
        <p className="py-4 text-center text-sm text-muted-foreground">
          {tab === 'going' ? 'Nobody has confirmed yet.' : 'Nobody marked interested yet.'}
        </p>
      )}
    </div>
  );
}