"use client";

import { useEffect, useState } from "react";
import { apiGet } from "@/lib/api";
import { submitJob, waitJob } from "@/lib/jobs";
import type { BacktestResult, FactorMeta, ResearchSpec } from "@/lib/types";
import { recentRange } from "@/lib/dates";
import { LineChart } from "@/components/LineChart";

export default function BacktestPage() {
  const [factors, setFactors] = useState<FactorMeta[]>([]);
  const [factor, setFactor] = useState("momentum_60");
  const [topN, setTopN] = useState(5);
  const [rebalance, setRebalance] = useState<"monthly" | "weekly">("monthly");
  const [start, setStart] = useState("");
  const [end, setEnd] = useState("");
  const [excludeSt, setExcludeSt] = useState(true);
  const [result, setResult] = useState<BacktestResult | null>(null);
  const [running, setRunning] = useState(false);
  const [jobId, setJobId] = useState("");
  const [error, setError] = useState("");

  useEffect(() => {
    apiGet<FactorMeta[]>("/factors")
      .then(setFactors)
      .catch((e: Error) => setError(e.message));
    const { start: s, end: e } = recentRange();
    setStart(s);
    setEnd(e);
  }, []);

  async function run() {
    setRunning(true);
    setError("");
    setJobId("");
    setResult(null);
    try {
      const spec: ResearchSpec = {
        type: "backtest",
        universe: { exclude_st: excludeSt, min_listing_days: 0 },
        factors: [{ name: factor, weight: 1 }],
        selection: { top_n: topN },
        rebalance,
        period: [start, end],
      };
      // 异步 Job：后台执行（全市场可能数十秒），轮询到终态
      const { job_id } = await submitJob(spec);
      setJobId(job_id);
      const out = await waitJob<BacktestResult>(job_id);
      if (out.status === "success" && out.result) {
        setResult(out.result);
      } else {
        setError(`任务${out.status}${out.error ? `：${out.error}` : ""}`);
      }
    } catch (e) {
      setError((e as Error).message);
    } finally {
      setRunning(false);
    }
  }

  const s = result?.summary;
  return (
    <>
      <h1>选股回测</h1>
      <div className="card">
        <h2>研究参数（Research Specification）</h2>
        <div className="form-grid">
          <label className="muted">
            因子
            <select value={factor} onChange={(e) => setFactor(e.target.value)}>
              {factors.map((f) => (
                <option key={f.name} value={f.name}>
                  {f.name}
                </option>
              ))}
            </select>
          </label>
          <label className="muted">
            Top N
            <input
              type="number"
              min={1}
              max={50}
              value={topN}
              onChange={(e) => setTopN(Number(e.target.value))}
            />
          </label>
          <label className="muted">
            调仓
            <select
              value={rebalance}
              onChange={(e) => setRebalance(e.target.value as "monthly" | "weekly")}
            >
              <option value="monthly">月度</option>
              <option value="weekly">周度</option>
            </select>
          </label>
          <label className="muted">
            开始
            <input type="date" value={start} onChange={(e) => setStart(e.target.value)} />
          </label>
          <label className="muted">
            结束
            <input type="date" value={end} onChange={(e) => setEnd(e.target.value)} />
          </label>
          <label className="muted">
            <input
              type="checkbox"
              checked={excludeSt}
              onChange={(e) => setExcludeSt(e.target.checked)}
            />{" "}
            剔除 ST
          </label>
          <button className="primary" onClick={run} disabled={running}>
            {running ? "后台运行中…" : "运行回测"}
          </button>
        </div>
        {running && jobId && <div className="muted">任务 {jobId} 后台执行中，请稍候…</div>}
        {error && <div className="error">{error}</div>}
      </div>

      {result && s && (
        <>
          <div className="card">
            <h2>
              结果 · {s.total_return_pct.toFixed(2)}%{" "}
              <span className={s.total_return_pct >= 0 ? "good" : "bad"}>
                {s.total_return_pct >= 0 ? "▲" : "▼"}
              </span>
            </h2>
            <div className="stat-grid">
              <div className="stat">
                <div className="label">期末净值</div>
                <div className="value">{s.final_equity.toLocaleString()}</div>
              </div>
              <div className="stat">
                <div className="label">年化收益</div>
                <div className="value">{s.annual_return_pct.toFixed(2)}%</div>
              </div>
              <div className="stat">
                <div className="label">Sharpe</div>
                <div className="value">{s.sharpe.toFixed(2)}</div>
              </div>
              <div className="stat">
                <div className="label">最大回撤</div>
                <div className="value bad">{s.max_drawdown_pct.toFixed(2)}%</div>
              </div>
              <div className="stat">
                <div className="label">胜率（按交易）</div>
                <div className="value">{s.win_rate_pct.toFixed(1)}%</div>
              </div>
              <div className="stat">
                <div className="label">交易笔数 / 换手</div>
                <div className="value">
                  {s.total_trades} / {s.avg_turnover_pct.toFixed(0)}%
                </div>
              </div>
            </div>
            <div style={{ marginTop: 12 }}>
              <LineChart title="净值曲线" data={result.equity_curve} color="#34d399" />
            </div>
            <LineChart
              title="回撤（%）"
              data={result.drawdown}
              color="#f87171"
            />
          </div>

          <div className="card">
            <h2>月度收益（%）</h2>
            <table>
              <thead>
                <tr>
                  <th>月份</th>
                  <th>收益</th>
                </tr>
              </thead>
              <tbody>
                {result.monthly_returns.map((m) => (
                  <tr key={`${m.year}-${m.month}`}>
                    <td>
                      {m.year}-{String(m.month).padStart(2, "0")}
                    </td>
                    <td className={m.return_pct >= 0 ? "good" : "bad"}>
                      {m.return_pct.toFixed(2)}%
                    </td>
                  </tr>
                ))}
              </tbody>
            </table>
          </div>

          <div className="card">
            <h2>最新持仓</h2>
            {(() => {
              const last = new Map<string, number>();
              for (const p of result.positions) last.set(p.date, 0);
              const lastDate = [...last.keys()].at(-1);
              const pos = result.positions.filter((p) => p.date === lastDate);
              return (
                <div className="row">
                  {pos.map((p) => (
                    <span key={p.symbol} className="stat">
                      {p.symbol} · {(p.weight * 100).toFixed(0)}%
                    </span>
                  ))}
                </div>
              );
            })()}
          </div>

          <div className="card">
            <h2>未建模约束（如实标注）</h2>
            <ul className="muted">
              {result.unimplemented.map((u, i) => (
                <li key={i}>{u}</li>
              ))}
            </ul>
          </div>
        </>
      )}
    </>
  );
}