/**
 * 曲线放大页（`/charts/{归档id}?s={曲线}`）—— 「所有曲线都能弹出新页面看大的」。
 *
 * 设计取舍：
 * - **Server Component**：数据从归档直出（URL 即快照地址，刷新/分享都还原同一张图）；
 *   曲线切换用 URL 参数（`?s=`），每个切换按钮就是一个 `<Link>`，不需要客户端状态。
 * - **一页一曲线、尽可能大**：放大页只干一件事 —— 把一条曲线画大。因此高度直接给足
 *   （`CHART_HEIGHT`），并给出该曲线的口径说明与买卖点标注。
 * - **数据只来自归档**：不重新跑回测、不从内存里取，避免「放大页与归档不一致」。
 * - 归档不存在 → 404；归档类型没有该曲线 → 如实说明并给回归档详情页的入口。
 */
import { notFound } from "next/navigation";
import Link from "next/link";

import { LwChart } from "@/components/charts/LwChart";
import { CHART, fmtNum } from "@/components/charts/theme";
import { Card, Pill, Banner } from "@/components/ui";
import type { LwFormatKey } from "@/components/charts/LwChart";
import {
  drawdownSeries,
  equitySeries,
  factorCurveNote,
  factorFormatKey,
  factorSeries,
  monthlySeries,
  portfolioMarkers,
  symbolMarkers,
  symbolSeries,
} from "@/lib/chartSeries";
import { experimentKindLabel } from "@/lib/labels";
import type { BacktestResult, ExperimentDetail } from "@/lib/types";

export const dynamic = "force-dynamic";

const BACKEND = (process.env.BACKEND_API_URL ?? "http://127.0.0.1:8000").replace(/\/$/, "");
/** 放大页的主要目的就是「看大图」，给足高度（窄屏靠 CSS 缩到视口内） */
const CHART_HEIGHT = 640;

async function serverGet<T>(path: string): Promise<T | null> {
  try {
    const r = await fetch(`${BACKEND}/api${path}`, { cache: "no-store" });
    if (!r.ok) return null;
    return (await r.json()) as T;
  } catch {
    return null;
  }
}

interface Option {
  key: string;
  label: string;
  hint: string;
}

/** 该归档里所有可放大的曲线（顺序即推荐阅读顺序） */
function optionsFor(result: BacktestResult): Option[] {
  const out: Option[] = [
    { key: "equity", label: "组合净值", hint: "含买卖点（成交日）" },
    { key: "drawdown", label: "回撤", hint: "距历史最高的回撤（%）" },
  ];
  for (const f of result.factor_curves ?? []) {
    out.push({ key: `factor:${f.name}`, label: `因子 · ${f.label}`, hint: "持仓加权平均原始值" });
  }
  for (const c of result.symbol_curves ?? []) {
    out.push({ key: `sym:${c.symbol}`, label: `个股 · ${c.symbol}`, hint: "持仓期累计收益（%）" });
  }
  if ((result.monthly_returns ?? []).length) {
    out.push({ key: "monthly", label: "月度收益", hint: "每月收益（%）" });
  }
  return out;
}

export default async function ChartPage({
  params,
  searchParams,
}: {
  params: Promise<{ id: string }>;
  searchParams: Promise<{ s?: string }>;
}) {
  const { id: rawId } = await params;
  const id = decodeURIComponent(rawId ?? "");
  const sp = await searchParams;
  const detail = await serverGet<ExperimentDetail>(`/experiments/${encodeURIComponent(id)}`);
  if (!detail) notFound();

  const result = detail.result as BacktestResult | null;
  const isBacktest = Boolean(result && Array.isArray(result.equity_curve));
  if (!isBacktest) {
    return (
      <Card icon="chartLine" title="该归档没有可放大的回测曲线">
        <Banner tone="info">
          归档 {id} 的类型是「{experimentKindLabel(detail.kind)}」，它的结果结构里没有净值 /
          因子曲线（这些曲线只在回测归档里）。这不是错误，只是曲线放大页不适用于该类型。
        </Banner>
        <div style={{ marginTop: 10 }}>
          <Link className="btn btn--sm" href={`/experiments/${encodeURIComponent(id)}`}>
            <span>打开归档详情</span>
          </Link>
        </div>
      </Card>
    );
  }

  const res = result as BacktestResult;
  const options = optionsFor(res);
  const want = sp?.s ?? options[0]?.key ?? "equity";
  const current = options.find((o) => o.key === want) ?? options[0];
  const factorKey = current?.key.startsWith("factor:") ? current.key.slice("factor:".length) : null;
  const symKey = current?.key.startsWith("sym:") ? current.key.slice("sym:".length) : null;

  let series = equitySeries(res);
  let markers = portfolioMarkers(
    res.fills,
    new Set(res.equity_curve.map((p) => p.date))
  );
  let formatKey: LwFormatKey = "num";
  let note = "组合净值（元）：每日收盘后按持仓市值结算；▲ 绿 = 当日有买入成交，▼ 红 = 当日有卖出成交。";
  let zeroLine = false;

  if (factorKey) {
    const curve = (res.factor_curves ?? []).find((f) => f.name === factorKey);
    if (curve) {
      const idx = (res.factor_curves ?? []).findIndex((f) => f.name === factorKey);
      series = [factorSeries(curve, idx)];
      formatKey = factorFormatKey(curve);
      note = factorCurveNote(curve);
      // 因子曲线上的买卖点：把组合的成交日标在因子曲线上，直接看「买卖发生在什么水平」
      markers = portfolioMarkers(res.fills, new Set(curve.points.map((p) => p.date)));
    }
  } else if (symKey) {
    const curve = (res.symbol_curves ?? []).find((c) => c.symbol === symKey);
    if (curve) {
      series = symbolSeries(curve);
      markers = symbolMarkers(curve);
      formatKey = "pct2";
      note =
        `${curve.symbol} 持仓期间的累计收益率（%，以建仓日收盘为 0% 基准，按日复利），` +
        "只在该股持仓的交易日落点；买卖点为实际成交。";
      zeroLine = true;
    }
  } else if (current?.key === "drawdown") {
    series = drawdownSeries(res);
    markers = [];
    formatKey = "pct2";
    note = "回撤（%）：净值相对历史最高点的跌幅，越负越深。";
    zeroLine = true;
  } else if (current?.key === "monthly") {
    series = monthlySeries(res);
    markers = [];
    formatKey = "pct2";
    note = "月度收益（%）：每个月末相对上月末的净值变化。";
    zeroLine = true;
  }

  const seriesLabel = series[0]?.label ?? current?.label ?? "曲线";

  return (
    <>
      <div className="between" style={{ margin: "4px 0 12px", gap: 12, flexWrap: "wrap" }}>
        <div className="row" style={{ gap: 8, flexWrap: "wrap" }}>
          <b style={{ fontSize: 16 }}>曲线放大</b>
          <Pill tone="accent">{experimentKindLabel(detail.kind)}</Pill>
          <span className="mono hint">{id}</span>
          {detail.created_at ? (
            <span className="hint">归档于 {String(detail.created_at).slice(0, 19).replace("T", " ")}</span>
          ) : null}
        </div>
        <div className="row" style={{ gap: 8 }}>
          <Link className="btn btn--sm" href={`/experiments/${encodeURIComponent(id)}`}>
            <span>打开归档详情</span>
          </Link>
        </div>
      </div>

      <div className="row" style={{ gap: 6, flexWrap: "wrap", marginBottom: 10 }}>
        {options.map((o) => (
          <Link
            key={o.key}
            className={o.key === current?.key ? "btn btn--sm btn--primary" : "btn btn--sm"}
            href={`/charts/${encodeURIComponent(id)}?s=${encodeURIComponent(o.key)}`}
            title={o.hint}
          >
            <span>{o.label}</span>
          </Link>
        ))}
      </div>

      <Card
        icon="chartLine"
        title={seriesLabel}
        tools={
          <Pill tone={series[0]?.type === "bar" ? "violet" : "pos"}>
            {series[0]?.data.length ?? 0} 个点
            {markers.length ? ` · ${markers.length} 个买卖标注` : ""}
          </Pill>
        }
      >
        <LwChart
          series={series}
          markers={markers}
          height={CHART_HEIGHT}
          formatKey={formatKey}
          zeroLine={zeroLine}
          ariaLabel={`${seriesLabel}（放大）`}
        />
        <div className="hint" style={{ marginTop: 8 }}>
          {note} 拖动 / 滚轮可缩放，双击图例可临时隐藏曲线；地址栏 URL 可直接分享或收藏
          （换设备打开还原同一张图，因为数据来自归档快照）。
        </div>
      </Card>

      {res.summary ? (
        <Card icon="gauge" title="这次回测的关键指标（与曲线同一份快照）">
          <div className="row" style={{ gap: 16, flexWrap: "wrap" }}>
            <span>
              区间 <span className="mono">{res.summary.start}</span> ~{" "}
              <span className="mono">{res.summary.end}</span>
            </span>
            <span>
              总收益{" "}
              <b className={res.summary.total_return_pct >= 0 ? "tone-pos" : "tone-neg"}>
                {res.summary.total_return_pct.toFixed(2)}%
              </b>
            </span>
            <span>年化 {res.summary.annual_return_pct.toFixed(2)}%</span>
            <span>Sharpe {res.summary.sharpe.toFixed(3)}</span>
            <span>最大回撤 {res.summary.max_drawdown_pct.toFixed(2)}%</span>
            <span>期末权益 {fmtNum(res.summary.final_equity)}</span>
            <span className="hint" style={{ color: CHART.faint }}>
              共 {res.summary.total_trades} 笔成交
            </span>
          </div>
        </Card>
      ) : null}
    </>
  );
}