"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 {
  PageHeader,
  Card,
  Pill,
  Field,
  Btn,
  Banner,
  Progress,
  Empty,
  BacktestMetrics,
  MonthlyReturnsTable,
  UnimplementedNote,
} from "@/components/ui";
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(() => {
    let alive = true;
    apiGet<FactorMeta[]>("/factors")
      .then((list) => {
        if (!alive) return;
        setFactors(list);
        if (list.length > 0 && !list.some((f) => f.name === factor)) {
          setFactor(list[0].name);
        }
      })
      .catch((e: Error) => alive && setError(e.message));
    const { start: s, end: e } = recentRange();
    setStart(s);
    setEnd(e);
    return () => {
      alive = false;
    };
  }, []);

  async function run() {
    if (!factor) return;
    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);
      setJobId("");
    }
  }

  return (
    <>
      <PageHeader
        title="选股回测"
        sub="以单个因子的横截面排序构建 Top N 组合并完整回测：净值 / 回撤 / 月度收益 / 持仓明细。"
        actions={
          result ? (
            <Pill tone="pos" icon="check">
              最近一次回测已完成
            </Pill>
          ) : null
        }
      />

      <Card title="研究参数（Research Specification）" icon="gauge">
        <div className="form-grid">
          <Field label="因子">
            <select
              className="input"
              value={factor}
              onChange={(e) => setFactor(e.target.value)}
            >
              {factors.map((f) => (
                <option key={f.name} value={f.name}>
                  {f.name}
                </option>
              ))}
            </select>
          </Field>
          <Field label="Top N">
            <input
              type="number"
              className="input"
              min={1}
              max={50}
              value={topN}
              onChange={(e) => setTopN(Number(e.target.value))}
            />
          </Field>
          <Field label="调仓频率">
            <select
              className="input"
              value={rebalance}
              onChange={(e) => setRebalance(e.target.value as "monthly" | "weekly")}
            >
              <option value="monthly">月度</option>
              <option value="weekly">周度</option>
            </select>
          </Field>
          <Field label="开始日期">
            <input type="date" className="input" value={start} onChange={(e) => setStart(e.target.value)} />
          </Field>
          <Field label="结束日期">
            <input type="date" className="input" value={end} onChange={(e) => setEnd(e.target.value)} />
          </Field>
          <Field label="标的范围">
            <label className="row" style={{ gap: 6, color: "var(--text-2)", fontSize: 13, cursor: "pointer" }}>
              <input type="checkbox" checked={excludeSt} onChange={(e) => setExcludeSt(e.target.checked)} />
              剔除 ST
            </label>
          </Field>
          <Btn variant="primary" icon="play" loading={running} disabled={running} onClick={run}>
            {running ? "后台运行中…" : "运行回测"}
          </Btn>
        </div>

        {running ? (
          <div style={{ marginTop: 14 }}>
            <Progress
              value={35}
              label={
                <>
                  任务 <span className="mono">{jobId || "排队中…"}</span> 后台执行中，请稍候…
                </>
              }
            />
          </div>
        ) : null}
        {error ? <div style={{ marginTop: 12 }}><Banner tone="error">{error}</Banner></div> : null}
      </Card>

      {!result && !running && !error ? (
        <Card>
          <Empty
            icon="gauge"
            title="尚未运行回测"
            hint="设置上方参数后运行；完成展示净值曲线、回撤、月度收益与最新持仓。"
          />
        </Card>
      ) : null}

      {result ? <ResultView result={result} /> : null}
    </>
  );
}

function ResultView({ result }: { result: BacktestResult }) {
  const s = result.summary;
  const last = result.positions.at(-1);
  const holdings = result.positions.filter((p) => p.date === last?.date);

  return (
    <>
      <div className="between" style={{ margin: "6px 0 14px" }}>
        <div className="row">
          <Pill tone="pos" icon="check">完成</Pill>
          <Pill tone="violet" icon="target">Top N 等权</Pill>
          <Pill>{s.start} ~ {s.end}</Pill>
        </div>
        <div className="row" style={{ fontSize: 22, fontWeight: 700 }}>
          总收益 <SignedText value={s.total_return_pct} />
        </div>
      </div>

      <BacktestMetrics s={s} />

      <div className="chart-grid">
        <Card icon="chartLine" title="净值曲线" tools={<Pill tone="pos">期末 {s.final_equity.toLocaleString()}</Pill>}>
          <LineChart data={result.equity_curve} color="#3ddc97" fill height={300} xFmt={(d) => d.slice(5)} yFmt={(v) => v.toFixed(2)} />
        </Card>
        <Card icon="chartLine" title="回撤（%）" tools={<Pill tone="neg">最大 {s.max_drawdown_pct.toFixed(2)}%</Pill>}>
          <LineChart data={result.drawdown} color="#ff7a7a" height={300} xFmt={(d) => d.slice(5)} yFmt={(v) => v.toFixed(2) + "%"} />
        </Card>
      </div>

      <Card icon="calendar" title="月度收益（%）">
        <MonthlyReturnsTable rows={result.monthly_returns} />
      </Card>

      <Card icon="target" title={`最新持仓 · ${last?.date ?? "—"}`}>
        {holdings.length === 0 ? (
          <Empty title="无持仓记录" hint="回测区间内没有产生持仓。" />
        ) : (
          <div className="chips">
            {holdings.map((p) => (
              <span className="chip" key={p.symbol}>
                <b className="mono">{p.symbol}</b>
                {(p.weight * 100).toFixed(0)}%
              </span>
            ))}
          </div>
        )}
      </Card>

      <UnimplementedNote items={result.unimplemented} />
    </>
  );
}

function SignedText({ value }: { value: number }) {
  const cls = value >= 0 ? "tone-pos" : "tone-neg";
  return (
    <span className={cls}>
      {value > 0 ? "+" : ""}
      {value.toFixed(2)}%
    </span>
  );
}