import { useEffect, useState } from "react";
import { Award } from "lucide-react";
import { Link, useSearchParams } from "react-router-dom";
import { getVisitorEventLeaderboard } from "../lib/api";
import { getAttendeeToken } from "../lib/attendeeAuth";
import { HeaderMobile } from "../components/HeaderMobile";
import { MobileShell } from "../components/MobileShell";
import { readStoredVisitorContext } from "../types/visitorContext";
import type { VisitorLeaderboardRow } from "../lib/api";

function Medal({ tier }: { tier: "gold" | "silver" | "bronze" }) {
  const cls =
    tier === "gold"
      ? "text-amber-500"
      : tier === "silver"
        ? "text-slate-400"
        : "text-amber-800";
  return <Award className={`size-6 ${cls}`} strokeWidth={1.5} />;
}

function medalForRank(rank: number): "gold" | "silver" | "bronze" | null {
  if (rank === 1) return "gold";
  if (rank === 2) return "silver";
  if (rank === 3) return "bronze";
  return null;
}

export function LeaderboardPage() {
  const [searchParams] = useSearchParams();
  const urlEventId = searchParams.get("event_id")?.trim() || "";
  const ctx = readStoredVisitorContext();
  const eventId = urlEventId || ctx?.eventId || "";

  const [rows, setRows] = useState<VisitorLeaderboardRow[]>([]);
  const [yourRank, setYourRank] = useState<number | null>(null);
  const [yourTotal, setYourTotal] = useState<number | null>(null);
  const [loading, setLoading] = useState(false);
  const [err, setErr] = useState<string | null>(null);

  useEffect(() => {
    if (!eventId) {
      setRows([]);
      setYourRank(null);
      setYourTotal(null);
      return;
    }
    let cancelled = false;
    setLoading(true);
    setErr(null);
    getVisitorEventLeaderboard(eventId, { limit: 50 })
      .then((r) => {
        if (cancelled) return;
        setRows(r.leaderboard);
        if (getAttendeeToken()) {
          const y = r.your;
          setYourRank(y?.rank ?? null);
          setYourTotal(typeof y?.total === "number" ? y.total : null);
        } else {
          setYourRank(null);
          setYourTotal(null);
        }
      })
      .catch((e) => {
        if (!cancelled) setErr(e instanceof Error ? e.message : "Could not load leaderboard.");
      })
      .finally(() => {
        if (!cancelled) setLoading(false);
      });
    return () => {
      cancelled = true;
    };
  }, [eventId]);

  const top5 = rows.slice(0, 5);
  const signedIn = Boolean(getAttendeeToken());

  return (
    <MobileShell className="relative">
      <HeaderMobile logoUrl={ctx?.event?.logoUrl} eventId={eventId || null} />
      <div className="eb-gradient-auth flex flex-1 flex-col items-center px-6 pb-10 pt-6">
        <Award className="size-[68px] text-amber-300" strokeWidth={1.25} />
        <h1 className="mt-1 font-inter text-xl font-semibold text-white">Leaderboard</h1>

        <div className="mt-6 w-full max-w-[354px] rounded-xl bg-whit card-bg shadow-[0_8px_12px_6px_rgba(0,0,0,0.15),0_4px_4px_rgba(0,0,0,0.3)]">
          <div className="p-4">
            <div className="eb-rank-highlight flex flex-col gap-2 rounded-3xl border-4 border-white px-4 py-4 text-white shadow-[0_9px_16px_rgba(0,0,0,0.14)]">
              <p className="text-center font-inter text-base font-semibold uppercase tracking-wide">Your rank</p>
              <div className="flex items-center justify-center gap-4">
                <span className="font-inter text-5xl font-bold drop-shadow-[0_4px_4px_rgba(0,0,0,0.25)]">
                  {!signedIn ? "—" : loading ? "…" : yourRank != null ? yourRank : "—"}
                </span>
                <span className="rounded-xl bg-[#cff7d3] px-4 py-2 text-sm font-medium text-[#009951] shadow-sm">
                  {!signedIn
                    ? "Sign in"
                    : loading
                      ? "…"
                      : yourTotal != null
                        ? `${yourTotal} points`
                        : "0 points"}
                </span>
              </div>
            </div>
            <h2 className="mt-6 font-inter text-base font-semibold text-[#24282f]">Top participants</h2>
            {err ? (
              <p className="mt-3 text-xs text-red-600">{err}</p>
            ) : loading && rows.length === 0 ? (
              <p className="mt-3 text-xs text-[rgba(36,40,47,0.67)]">Loading…</p>
            ) : top5.length === 0 ? (
              <p className="mt-3 text-xs text-[rgba(36,40,47,0.67)]">
                No scores yet. Complete activities and earn points when organizers enable rewards.
              </p>
            ) : (
              <ul className="mt-3 flex flex-col gap-3">
                {top5.map((row) => {
                  const medal = medalForRank(row.rank);
                  return (
                    <li
                      key={row.participantId}
                      className="flex items-center gap-3 border-b border-[#ededed] pb-3 last:border-0"
                    >
                      <span className="shrink-0 rounded bg-[#ebffee] px-3 py-2 text-xs font-medium text-[#009951] shadow-sm">
                        #{row.rank} · {row.total} pts
                      </span>
                      <span className="min-w-0 flex-1 text-sm font-semibold text-[#24282f]">{row.displayName}</span>
                      {medal ? <Medal tier={medal} /> : null}
                    </li>
                  );
                })}
              </ul>
            )}
          </div>
        </div>

        <Link
          to={eventId ? `/rewards?event_id=${encodeURIComponent(eventId)}` : "/rewards"}
          className="mt-6 font-inter font-semibold text-[var(--theme-text-color)] underline"
        >
          Rewards
        </Link>
      </div>
    </MobileShell>
  );
}