"use client";

// 시장 overview: 등락 상위 / 등락 하위 / 거래대금 상위 / 거래량 상위 4 컬럼.
// /api/markets/movers 응답을 그대로 표 형태로 렌더.
// 거래대금 = close × volume, 단위 억원. 토스 톤의 핵심 랭킹.

import Link from "next/link";
import { useEffect, useState } from "react";
import { api, type Mover, type MoversResponse } from "../lib/api";

export function MarketsOverview() {
  const [data, setData] = useState<MoversResponse | null>(null);
  const [err, setErr] = useState<string | null>(null);

  useEffect(() => {
    let alive = true;
    api
      .movers("ALL", 10)
      .then((r) => {
        if (alive) setData(r);
      })
      .catch((e) => {
        if (alive) setErr(e instanceof Error ? e.message : String(e));
      });
    return () => {
      alive = false;
    };
  }, []);

  if (err)
    return (
      <div className="rounded-lg border border-zinc-800 bg-zinc-900/30 p-4 text-xs text-zinc-500">
        시장 overview 로딩 실패: {err}
      </div>
    );
  if (!data)
    return (
      <div className="rounded-lg border border-zinc-800 bg-zinc-900/30 p-4 text-xs text-zinc-500">
        시장 overview 로딩 중…
      </div>
    );

  // 아직 ohlcv_daily 가 비어 있으면 모든 리스트가 빈 배열로 옴 — 안내만.
  const empty =
    !data.gainers.length &&
    !data.losers.length &&
    !data.by_volume.length &&
    !data.by_trading_value.length;
  if (empty)
    return (
      <div className="rounded-lg border border-zinc-800 bg-zinc-900/30 p-4 text-xs text-zinc-500">
        시장 데이터 준비 중. ohlcv_daily 가 채워지면 자동으로 표시됩니다.
      </div>
    );

  return (
    <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-4">
      <MoverList title="등락 상위" items={data.gainers} />
      <MoverList title="등락 하위" items={data.losers} />
      <MoverList
        title="거래대금 상위"
        items={data.by_trading_value}
        metric="trading_value"
      />
      <MoverList title="거래량 상위" items={data.by_volume} metric="volume" />
    </div>
  );
}

type Metric = "price" | "volume" | "trading_value";

function MoverList({
  title,
  items,
  metric = "price",
}: {
  title: string;
  items: Mover[];
  metric?: Metric;
}) {
  return (
    <div className="rounded-lg border border-zinc-800 bg-zinc-900/30 p-3">
      <div className="mb-2 text-xs font-medium text-zinc-300">{title}</div>
      {items.length === 0 ? (
        <div className="text-[11px] text-zinc-500">데이터 없음</div>
      ) : (
        <ul className="divide-y divide-zinc-800">
          {items.map((m, i) => (
            <MoverRow key={m.code} rank={i + 1} m={m} metric={metric} />
          ))}
        </ul>
      )}
    </div>
  );
}

function MoverRow({
  rank,
  m,
  metric,
}: {
  rank: number;
  m: Mover;
  metric: Metric;
}) {
  const pct = m.pct_change;
  const tone =
    pct == null || pct === 0
      ? "text-zinc-400"
      : pct > 0
      ? "text-rose-400"
      : "text-sky-400";

  let primary: string;
  if (metric === "volume") {
    primary = fmtVol(m.volume);
  } else if (metric === "trading_value") {
    primary = fmtKrw(m.trading_value ?? null);
  } else {
    primary =
      m.close != null
        ? m.close.toLocaleString(undefined, { maximumFractionDigits: 0 })
        : "—";
  }

  return (
    <li>
      <Link
        href={`/${m.code}`}
        className="flex items-center justify-between gap-2 py-1.5 text-xs hover:bg-zinc-800/40"
      >
        <div className="flex min-w-0 items-center gap-2">
          <span className="w-4 shrink-0 text-zinc-500">{rank}</span>
          <span className="min-w-0 truncate text-zinc-100">{m.name}</span>
        </div>
        <div className="shrink-0 text-right tabular-nums">
          <div className="text-zinc-100">{primary}</div>
          <div className={`text-[10px] ${tone}`}>
            {pct != null ? `${pct >= 0 ? "+" : ""}${pct.toFixed(2)}%` : ""}
          </div>
        </div>
      </Link>
    </li>
  );
}

function fmtVol(n: number | null): string {
  if (n == null) return "—";
  if (n >= 1e8) return `${(n / 1e8).toFixed(1)}억`;
  if (n >= 1e4) return `${(n / 1e4).toFixed(1)}만`;
  return n.toLocaleString();
}

// 거래대금 원 → 억/조 표기. 토스에서 가장 흔한 단위.
function fmtKrw(n: number | null): string {
  if (n == null) return "—";
  if (n >= 1e12) return `${(n / 1e12).toFixed(2)}조`;
  if (n >= 1e8) return `${Math.round(n / 1e8).toLocaleString()}억`;
  if (n >= 1e4) return `${(n / 1e4).toFixed(0)}만`;
  return n.toLocaleString();
}