"use client";

import { useEffect, useId, useMemo, useState } from "react";
import type {
  FieldConfig,
  FieldHistoryEntry,
  FormConfig,
  ReportPayload,
  SelectOption,
  StageSectionConfig,
} from "@/types/form";
import { STAGE_OPTION_GROUP_ID } from "@/config/form";
import { StageIcon } from "./StageIcon";
import {
  FieldHistoryGroup,
  FieldHistoryRow,
  formatShortDate,
  computeDateRange,
  Chevron,
  numberFmt,
} from "./report/FieldHistory";
import { DateTimeline, generateAxisTicks } from "./report/DateTimeline";

interface ReportViewProps {
  config: FormConfig;
  cid: string;
  cs: string;
}

type LoadState =
  | { kind: "loading" }
  | { kind: "error"; message: string }
  | { kind: "ready"; data: ReportPayload };

type PathwayState = "past" | "current" | "future";

const STAGE_RANK: Record<string, number> = {
  Inquiry: 0,
  Organizing: 1,
  Feasibility: 2,
  "Business feasibility": 3,
  "Store Implementation": 4,
  "Stabilize newly opened co-op": 5,
};

export function ReportView({ config, cid, cs }: ReportViewProps) {
  const [load, setLoad] = useState<LoadState>({ kind: "loading" });

  useEffect(() => {
    let cancelled = false;
    async function go() {
      try {
        const url = new URL("/api/report", window.location.origin);
        url.searchParams.set("cid", cid);
        url.searchParams.set("cs", cs);
        const res = await fetch(url.toString(), { cache: "no-store" });
        if (!res.ok) {
          const text = await res.text();
          let message = `Could not load report (HTTP ${res.status}).`;
          try {
            const j = JSON.parse(text) as { error?: string };
            if (j.error) message = j.error;
          } catch { /* default */ }
          if (!cancelled) setLoad({ kind: "error", message });
          return;
        }
        const data: ReportPayload = await res.json();
        if (!cancelled) setLoad({ kind: "ready", data });
      } catch (e) {
        if (!cancelled) {
          setLoad({
            kind: "error",
            message: e instanceof Error ? e.message : "Unexpected error loading report.",
          });
        }
      }
    }
    void go();
    return () => {
      cancelled = true;
    };
  }, [cid, cs]);

  const sectionsToRender = useMemo(() => {
    if (load.kind !== "ready") return [];
    const { currentStage, fieldHistory } = load.data;
    const currentRank = STAGE_RANK[currentStage] ?? 0;
    return config.sections
      .map((section) => {
        const fieldsWithHistory = section.fields.filter(
          (f) => fieldHistory[f.name] && fieldHistory[f.name].length > 0,
        );
        const pathwayState: PathwayState =
          section.rank < currentRank ? "past" : section.rank === currentRank ? "current" : "future";
        return { section, fieldsWithHistory, pathwayState };
      })
      .filter((e) => e.fieldsWithHistory.length > 0);
  }, [load, config.sections]);

  if (load.kind === "loading") return <LoadingState />;
  if (load.kind === "error") return <ErrorState message={load.message} />;

  const { data } = load;
  const stageOpts = data.options?.[STAGE_OPTION_GROUP_ID] ?? [];
  const currentStageLabel =
    stageOpts.find((o) => o.value === data.currentStage)?.label ?? data.currentStage;
  const currentRank = STAGE_RANK[data.currentStage] ?? 0;

  const dateRange = computeDateRange(data.activities.map((a) => a.date));
  const totalActivities = data.activities.length;
  const totalFieldsTracked = Object.keys(data.fieldHistory).length;

  return (
    <div className="space-y-5">
      <ReportContextHeader
        orgName={data.orgName}
        currentStageLabel={currentStageLabel}
        currentRank={currentRank}
        totalActivities={totalActivities}
        totalFieldsTracked={totalFieldsTracked}
        dateRange={dateRange}
      />

      <DateTimeline sections={config.sections} fieldHistory={data.fieldHistory} />

      {sectionsToRender.length === 0 ? (
        <EmptyState />
      ) : (
        <ol className="relative space-y-5 md:pl-12">
          {sectionsToRender.map((entry, i) => {
            const { section, pathwayState, fieldsWithHistory } = entry;
            const nextState =
              i < sectionsToRender.length - 1 ? sectionsToRender[i + 1].pathwayState : undefined;
            return (
              <li key={section.id} className="relative list-none">
                <MobileStem show={i > 0} state={pathwayState} />
                <RailMarker rank={section.rank} state={pathwayState} nextState={nextState} />
                <ReportSection
                  section={section}
                  fields={fieldsWithHistory}
                  history={data.fieldHistory}
                  options={data.options ?? {}}
                  isCurrent={pathwayState === "current"}
                  defaultOpen={pathwayState === "current" || section.rank === 0}
                />
              </li>
            );
          })}
        </ol>
      )}
    </div>
  );
}

function ReportContextHeader({
  orgName,
  currentStageLabel,
  currentRank,
  totalActivities,
  totalFieldsTracked,
  dateRange,
}: {
  orgName: string;
  currentStageLabel: string;
  currentRank: number;
  totalActivities: number;
  totalFieldsTracked: number;
  dateRange: { from: string; to: string } | null;
}) {
  return (
    <header className="rounded-lg border border-rule bg-paper-2/40 px-6 py-5 sm:px-7 sm:py-6">
      <p className="text-[11px] uppercase tracking-[0.18em] text-ink-mute">Report for</p>
      <h1 className="mt-1 font-display text-3xl font-medium leading-tight tracking-tight text-ink sm:text-[34px]">
        {orgName}
      </h1>
      <div className="mt-4 flex items-center gap-3">
        <StageProgress currentRank={currentRank} />
        <span className="text-[10px] uppercase tracking-[0.16em] font-medium text-ink-mute">
          Current stage
        </span>
      </div>
      <p className="mt-1.5 font-display text-xl sm:text-2xl font-medium leading-tight tracking-tight text-leaf-800">
        {currentStageLabel || "—"}
      </p>
      <dl className="mt-5 grid grid-cols-3 gap-3 border-t border-rule-soft pt-4 text-sm sm:gap-6">
        <Stat label="Surveys" value={String(totalActivities)} />
        <Stat label="Fields tracked" value={String(totalFieldsTracked)} />
        <Stat
          label="Span"
          value={dateRange ? `${formatShortDate(dateRange.from)} - ${formatShortDate(dateRange.to)}` : "—"}
        />
      </dl>
    </header>
  );
}

function Stat({ label, value }: { label: string; value: string }) {
  return (
    <div>
      <dt className="text-[10px] uppercase tracking-[0.14em] font-medium text-ink-mute">
        {label}
      </dt>
      <dd className="mt-0.5 font-display text-base font-medium text-ink tabular-nums sm:text-lg">
        {value}
      </dd>
    </div>
  );
}

function StageProgress({ currentRank }: { currentRank: number }) {
  return (
    <div className="flex items-center gap-1.5" role="img" aria-label={`Stage ${currentRank} of 5`}>
      {[0, 1, 2, 3, 4, 5].map((r) => (
        <span
          key={r}
          className={
            "h-1.5 rounded-full transition-all " +
            (r < currentRank
              ? "w-2.5 bg-leaf-300"
              : r === currentRank
                ? "w-6 bg-leaf-700"
                : "w-2.5 bg-rule-soft")
          }
        />
      ))}
    </div>
  );
}

const MEMBERS_ACTUAL_NAME = "Members__current_";
const MEMBERS_GOAL_NAME = "Member_Goal_for_current_Stage";

/**
 * Dedicated comparison chart for the org's actual member-owner count vs the
 * goal it set for the current stage. Renders when at least one of the
 * two fields has historical data. Both series are drawn as step lines
 * (carry-forward semantics — a measurement holds until the next one
 * updates it, then extends to the right edge). Header carries a
 * current/goal summary with the gap; legend sits below the chart.
 */
function MembershipChart({
  membersField,
  goalField,
  membersHistory,
  goalHistory,
}: {
  membersField?: FieldConfig;
  goalField?: FieldConfig;
  membersHistory?: FieldHistoryEntry[];
  goalHistory?: FieldHistoryEntry[];
}) {
  const toPoints = (entries: FieldHistoryEntry[] | undefined) =>
    (entries ?? [])
      .slice()
      .reverse()
      .map((e) => ({
        t: new Date(e.date).getTime(),
        v: typeof e.value === "number" ? e.value : Number(e.value),
      }))
      .filter((p) => Number.isFinite(p.t) && Number.isFinite(p.v));

  const actualPoints = toPoints(membersHistory);
  const goalPoints = toPoints(goalHistory);
  if (actualPoints.length === 0 && goalPoints.length === 0) return null;

  // Combined axes
  const all = [...actualPoints, ...goalPoints];
  const times = all.map((p) => p.t);
  const values = all.map((p) => p.v);
  let minT = Math.min(...times);
  let maxT = Math.max(...times);
  if (minT === maxT) {
    // Single-point chart — pad the axis ±15 days so the dot isn't on
    // top of the y-axis line.
    const pad = 15 * 24 * 3600 * 1000;
    minT -= pad;
    maxT += pad;
  }
  // Always include 0 in y so growth from a small starting count reads true.
  const rawMin = Math.min(...values, 0);
  const rawMax = Math.max(...values);
  const yTicks = niceYTicks(rawMin, rawMax, 4);
  const yMin = yTicks[0];
  const yMax = yTicks[yTicks.length - 1];
  const yRange = yMax - yMin || 1;
  const tRange = maxT - minT || 1;

  // Chart geometry (viewBox units).
  const W = 580;
  const H = 200;
  const padL = 40;
  const padR = 28;
  const padT = 14;
  const padB = 30;
  const plotW = W - padL - padR;
  const plotH = H - padT - padB;

  const xOf = (t: number) => padL + ((t - minT) / tRange) * plotW;
  const yOf = (v: number) => padT + plotH - ((v - yMin) / yRange) * plotH;

  // Both Actual and Goal use a carry-forward step line: between measurements
  // the chart holds the prior value rather than interpolating diagonally,
  // and the final value extends flat to the right edge of the chart. This
  // way periods with no fresh measurement read as "unchanged since last
  // reported" instead of suggesting a smooth dip or rise that we don't
  // actually have evidence for.
  const actualCoords = actualPoints.map((p) => ({ x: xOf(p.t), y: yOf(p.v), v: p.v }));
  let actualPath = "";
  if (actualCoords.length === 1) {
    const c = actualCoords[0];
    actualPath = `M${c.x.toFixed(2)},${c.y.toFixed(2)} L${(W - padR).toFixed(2)},${c.y.toFixed(2)}`;
  } else if (actualCoords.length > 1) {
    const parts: string[] = [
      `M${actualCoords[0].x.toFixed(2)},${actualCoords[0].y.toFixed(2)}`,
    ];
    for (let i = 1; i < actualCoords.length; i++) {
      parts.push(`L${actualCoords[i].x.toFixed(2)},${actualCoords[i - 1].y.toFixed(2)}`);
      parts.push(`L${actualCoords[i].x.toFixed(2)},${actualCoords[i].y.toFixed(2)}`);
    }
    const last = actualCoords[actualCoords.length - 1];
    parts.push(`L${(W - padR).toFixed(2)},${last.y.toFixed(2)}`);
    actualPath = parts.join(" ");
  }
  const actualArea = actualPath
    ? `${actualPath} L${(W - padR).toFixed(2)},${yOf(yMin).toFixed(2)} L${actualCoords[0].x.toFixed(2)},${yOf(yMin).toFixed(2)} Z`
    : "";

  // Step the goal: hold each value until the next change, then extend
  // the final value to the right edge of the chart.
  const goalCoords = goalPoints.map((p) => ({ x: xOf(p.t), y: yOf(p.v), v: p.v }));
  let goalPath = "";
  if (goalCoords.length === 1) {
    const c = goalCoords[0];
    goalPath = `M${xOf(minT).toFixed(2)},${c.y.toFixed(2)} L${xOf(maxT).toFixed(2)},${c.y.toFixed(2)}`;
  } else if (goalCoords.length > 1) {
    const parts: string[] = [];
    parts.push(`M${goalCoords[0].x.toFixed(2)},${goalCoords[0].y.toFixed(2)}`);
    for (let i = 1; i < goalCoords.length; i++) {
      // step: horizontal to next x at previous y, then vertical to new y
      parts.push(`L${goalCoords[i].x.toFixed(2)},${goalCoords[i - 1].y.toFixed(2)}`);
      parts.push(`L${goalCoords[i].x.toFixed(2)},${goalCoords[i].y.toFixed(2)}`);
    }
    // Extend the most-recent goal to the right edge as a flat line.
    const lastG = goalCoords[goalCoords.length - 1];
    parts.push(`L${xOf(maxT).toFixed(2)},${lastG.y.toFixed(2)}`);
    goalPath = parts.join(" ");
  }

  // Summary stat: take most-recent of each series for the gap callout.
  const latestActual = actualPoints.length ? actualPoints[actualPoints.length - 1].v : null;
  const latestGoal = goalPoints.length ? goalPoints[goalPoints.length - 1].v : null;
  const gap =
    latestActual !== null && latestGoal !== null ? latestGoal - latestActual : null;
  const gapText =
    gap === null
      ? null
      : gap > 0
        ? `${numberFmt.format(gap)} to go`
        : gap < 0
          ? `${numberFmt.format(-gap)} above goal`
          : "at goal";
  const gapTone =
    gap === null
      ? ""
      : gap > 0
        ? "text-clay-700"
        : gap < 0
          ? "text-leaf-700"
          : "text-leaf-700";

  const xTicks = generateAxisTicks(minT, maxT);
  const todayT = Date.now();
  const todayInRange = todayT >= minT && todayT <= maxT;

  return (
    <section
      aria-labelledby="membership-chart-heading"
      className="rounded-lg border border-rule bg-paper-2/30 px-6 py-5 sm:px-7 sm:py-6"
    >
      <div className="flex flex-col gap-1 sm:flex-row sm:items-baseline sm:justify-between sm:gap-4">
        <div>
          <h2
            id="membership-chart-heading"
            className="font-display text-base font-medium leading-tight text-ink"
          >
            Membership — goal vs. actual
          </h2>
          <p className="mt-0.5 text-xs text-ink-mute">
            Member-owner count tracked over time against the goal set for the org&apos;s
            current stage.
          </p>
        </div>
        {latestActual !== null && (
          <p className="text-[11px] uppercase tracking-[0.1em] text-ink-mute tabular-nums">
            <span className="font-medium text-leaf-800">
              {numberFmt.format(latestActual)}
            </span>
            {latestGoal !== null && (
              <>
                {" of "}
                <span className="font-medium text-clay-700">
                  {numberFmt.format(latestGoal)}
                </span>
                {gapText && (
                  <span className={"ml-1.5 normal-case tracking-normal " + gapTone}>
                    · {gapText}
                  </span>
                )}
              </>
            )}
          </p>
        )}
      </div>

      <svg
        viewBox={`0 0 ${W} ${H}`}
        preserveAspectRatio="none"
        role="img"
        aria-label="Membership goal versus actual over time"
        className="mt-4 block h-48 w-full sm:h-52"
      >
        {/* Y-axis gridlines + value labels */}
        {yTicks.map((v, i) => {
          const y = yOf(v);
          return (
            <g key={i}>
              <line
                x1={padL}
                x2={W - padR}
                y1={y}
                y2={y}
                className="stroke-rule-soft"
                strokeWidth="0.5"
              />
              <text
                x={padL - 6}
                y={y}
                textAnchor="end"
                dominantBaseline="middle"
                className="fill-ink-mute text-[9px] tabular-nums"
              >
                {numberFmt.format(v)}
              </text>
            </g>
          );
        })}

        {/* Today guide */}
        {todayInRange && (
          <line
            x1={xOf(todayT)}
            x2={xOf(todayT)}
            y1={padT}
            y2={padT + plotH}
            className="stroke-clay-300"
            strokeWidth="0.75"
            strokeDasharray="2 3"
          />
        )}

        {/* Goal step line */}
        {goalPath && (
          <path
            d={goalPath}
            fill="none"
            className="stroke-clay-600"
            strokeWidth="1.4"
            strokeLinecap="round"
            strokeLinejoin="miter"
            strokeDasharray="5 3"
          />
        )}
        {goalCoords.map((c, i) => (
          <circle
            key={`g-${i}`}
            cx={c.x}
            cy={c.y}
            r="2.5"
            className="fill-clay-600"
          />
        ))}

        {/* Actual line with faint area fill */}
        {actualArea && (
          <path d={actualArea} className="fill-leaf-500" opacity="0.10" />
        )}
        {actualPath && (
          <path
            d={actualPath}
            fill="none"
            className="stroke-leaf-700"
            strokeWidth="1.75"
            strokeLinecap="round"
            strokeLinejoin="round"
          />
        )}
        {actualCoords.map((c, i) => (
          <circle
            key={`a-${i}`}
            cx={c.x}
            cy={c.y}
            r={i === actualCoords.length - 1 ? 3.5 : 2}
            className={i === actualCoords.length - 1 ? "fill-leaf-800" : "fill-leaf-700"}
          />
        ))}

        {/* Most-recent point value labels */}
        {actualCoords.length > 0 && (
          <text
            x={actualCoords[actualCoords.length - 1].x + 6}
            y={actualCoords[actualCoords.length - 1].y - 6}
            className="fill-leaf-800 text-[10px] font-medium tabular-nums"
          >
            {numberFmt.format(actualCoords[actualCoords.length - 1].v)}
          </text>
        )}
        {goalCoords.length > 0 && (
          <text
            x={xOf(maxT) - 4}
            y={goalCoords[goalCoords.length - 1].y - 6}
            textAnchor="end"
            className="fill-clay-700 text-[10px] font-medium tabular-nums"
          >
            {numberFmt.format(goalCoords[goalCoords.length - 1].v)}
          </text>
        )}

        {/* X-axis baseline + ticks */}
        <line
          x1={padL}
          x2={W - padR}
          y1={padT + plotH}
          y2={padT + plotH}
          className="stroke-rule"
          strokeWidth="0.75"
        />
        {xTicks.map((tk, i) => {
          const x = xOf(tk.t);
          return (
            <g key={i}>
              <line
                x1={x}
                x2={x}
                y1={padT + plotH}
                y2={padT + plotH + 3}
                className="stroke-rule"
                strokeWidth="0.75"
              />
              <text
                x={x}
                y={padT + plotH + 14}
                textAnchor="middle"
                className="fill-ink-mute text-[9px] uppercase tracking-[0.08em] tabular-nums"
              >
                {tk.label}
              </text>
            </g>
          );
        })}
      </svg>

      {/* Legend */}
      <ul className="mt-2 flex flex-wrap items-center gap-x-5 gap-y-1.5 text-[11px] text-ink-soft">
        <li className="inline-flex items-center gap-2">
          <span aria-hidden className="block h-px w-6 bg-leaf-700">
            <span className="relative -top-[3px] left-1/2 -translate-x-1/2 inline-block h-1.5 w-1.5 rounded-full bg-leaf-700" />
          </span>
          <span>
            Actual{membersField?.label && membersField.label !== "Member-Owners (current)" ? ` (${membersField.label})` : ""}
          </span>
        </li>
        <li className="inline-flex items-center gap-2">
          <span aria-hidden className="block h-px w-6 border-t border-dashed border-clay-600">
            <span className="relative -top-[3px] left-1/2 -translate-x-1/2 inline-block h-1.5 w-1.5 rounded-full bg-clay-600" />
          </span>
          <span>
            Goal{goalField?.label && goalField.label !== "Member-Owner Goal for current Stage" ? ` (${goalField.label})` : ""}
          </span>
        </li>
      </ul>
    </section>
  );
}

/**
 * Choose 3–5 round-number tick values that span [min, max]. Step is snapped
 * to 1 / 2 / 2.5 / 5 / 10 × 10^N so labels read as Y-axis values normally do.
 */
function niceYTicks(min: number, max: number, target = 4): number[] {
  if (!Number.isFinite(min) || !Number.isFinite(max)) return [0];
  if (min === max) return [min - 1, min, min + 1];
  const range = max - min;
  const rawStep = range / target;
  const magnitude = Math.pow(10, Math.floor(Math.log10(rawStep)));
  const normalized = rawStep / magnitude;
  let step: number;
  if (normalized < 1.5) step = 1 * magnitude;
  else if (normalized < 3) step = 2 * magnitude;
  else if (normalized < 4) step = 2.5 * magnitude;
  else if (normalized < 7) step = 5 * magnitude;
  else step = 10 * magnitude;
  const niceMin = Math.floor(min / step) * step;
  const niceMax = Math.ceil(max / step) * step;
  const ticks: number[] = [];
  for (let v = niceMin; v <= niceMax + step * 0.0001; v += step) {
    ticks.push(Math.round(v * 1e6) / 1e6); // de-jitter float arithmetic
  }
  return ticks;
}

function ReportSection({
  section,
  fields,
  history,
  options,
  isCurrent,
  defaultOpen,
}: {
  section: StageSectionConfig;
  fields: FieldConfig[];
  history: Record<string, FieldHistoryEntry[]>;
  options: Record<number, SelectOption[]>;
  isCurrent: boolean;
  defaultOpen: boolean;
}) {
  const [open, setOpen] = useState(defaultOpen);
  const headingId = useId();
  const panelId = useId();

  const cardClass = isCurrent
    ? "border-2 border-leaf-600 shadow-[0_1px_0_0_rgba(0,0,0,0.04),0_8px_24px_-12px_rgba(60,80,40,0.18)] bg-white/95"
    : "border border-rule bg-white/95 shadow-sm";

  return (
    <section
      aria-labelledby={headingId}
      className={"overflow-hidden rounded-lg transition " + cardClass}
    >
      <h2 id={headingId} className="m-0">
        <button
          type="button"
          onClick={() => setOpen((v) => !v)}
          aria-expanded={open}
          aria-controls={panelId}
          className={
            "group relative flex w-full items-center gap-4 px-5 py-4 text-left transition-colors sm:px-6 " +
            (isCurrent ? "bg-leaf-50/60" : "hover:bg-paper-2/60")
          }
        >
          <StageRankMark rank={section.rank} isCurrent={isCurrent} />
          <span className="flex-1 min-w-0">
            <span className="block font-display text-lg font-medium leading-tight tracking-tight text-ink sm:text-xl">
              {section.label}
            </span>
            <span className="mt-1 flex items-center gap-3 text-xs text-ink-mute">
              {isCurrent && (
                <span className="inline-flex items-center gap-1.5 rounded-full border border-clay-200 bg-clay-100/70 px-2 py-0.5 font-medium text-clay-700 uppercase tracking-[0.08em]">
                  <span className="h-1.5 w-1.5 rounded-full bg-clay-600" aria-hidden />
                  Current stage
                </span>
              )}
              <span className="tabular-nums">
                {fields.length} {fields.length === 1 ? "field" : "fields"} with entries
              </span>
            </span>
          </span>
          <Chevron open={open} />
        </button>
      </h2>

      <div
        id={panelId}
        role="region"
        aria-labelledby={headingId}
        hidden={!open}
        className="border-t border-rule-soft"
      >
        <div className="divide-y divide-rule-soft">
          {(() => {
            // Compute the slot for the inline Membership chart: render it
            // immediately after whichever of (Members current, Member Goal)
            // appears last among this section's fields-with-history. If
            // neither field is in this section, the index is -1 and the
            // chart is skipped — naturally scoping the chart to whichever
            // section those questions live in (Stage 0 today).
            const memberIdx = fields.findIndex((f) => f.name === MEMBERS_ACTUAL_NAME);
            const goalIdx = fields.findIndex((f) => f.name === MEMBERS_GOAL_NAME);
            const chartIdx = Math.max(memberIdx, goalIdx);
            const membersFieldInSection = memberIdx >= 0 ? fields[memberIdx] : undefined;
            const goalFieldInSection = goalIdx >= 0 ? fields[goalIdx] : undefined;

            // Build a map from field name → its group config (if any). A
            // field referenced in multiple groups belongs to the first one.
            const groupByField = new Map<string, { id: string; label?: string }>();
            for (const g of section.fieldGroups ?? []) {
              for (const fname of g.fields) {
                if (!groupByField.has(fname)) {
                  groupByField.set(fname, { id: g.id, label: g.label });
                }
              }
            }

            // Walk fields in declared order; whenever we hit one that
            // belongs to a group we haven't emitted yet, collect every
            // visible field from that group (those with history) and emit
            // them as one bordered cluster. Other group members get
            // skipped when we encounter them later in the loop.
            const fieldsWithHistorySet = new Set(fields.map((f) => f.name));
            const emittedGroups = new Set<string>();
            const out: React.ReactNode[] = [];

            fields.forEach((f, i) => {
              const grp = groupByField.get(f.name);
              if (grp && !emittedGroups.has(grp.id)) {
                emittedGroups.add(grp.id);
                const sectionGroup = (section.fieldGroups ?? []).find((g) => g.id === grp.id)!;
                const groupedFields = sectionGroup.fields
                  .map((name) => fields.find((ff) => ff.name === name))
                  .filter((ff): ff is FieldConfig => !!ff && fieldsWithHistorySet.has(ff.name));
                if (groupedFields.length === 0) return;
                out.push(
                  <FieldHistoryGroup
                    key={`group-${grp.id}`}
                    label={grp.label}
                    fields={groupedFields}
                    history={history}
                    options={options}
                  />,
                );
              } else if (!grp) {
                out.push(
                  <FieldHistoryRow
                    key={f.name}
                    field={f}
                    entries={history[f.name] ?? []}
                    options={options}
                  />,
                );
              }
              if (i === chartIdx && chartIdx >= 0) {
                out.push(
                  <div key={`chart-${f.name}`} className="bg-paper-2/20 px-5 py-5 sm:px-7 sm:py-6">
                    <MembershipChart
                      membersField={membersFieldInSection}
                      goalField={goalFieldInSection}
                      membersHistory={history[MEMBERS_ACTUAL_NAME]}
                      goalHistory={history[MEMBERS_GOAL_NAME]}
                    />
                  </div>,
                );
              }
            });

            return out;
          })()}
        </div>
      </div>
    </section>
  );
}

/**
 * Mirrors the form's FieldGroupCard: a leaf-tinted left rule + small
 * uppercase mini-label, with the grouped history rows stacked beneath
 * and separated by the same divide-y as the standalone rows. Eats only
 * ~14px of horizontal space (vs ~40px for a fully-boxed treatment).
 */
function StageRankMark({ rank, isCurrent }: { rank: number; isCurrent: boolean }) {
  return (
    <span aria-hidden className="relative inline-flex h-12 w-12 flex-shrink-0 items-center justify-center">
      <StageIcon
        rank={rank}
        className={
          "absolute inset-0 h-12 w-12 transition-opacity " +
          (isCurrent ? "text-leaf-700 opacity-100" : "text-leaf-600 opacity-50")
        }
      />
      <span
        className={
          "relative z-10 inline-flex h-5 w-5 items-center justify-center rounded-full text-[10px] font-semibold tabular-nums shadow-sm " +
          (isCurrent ? "bg-leaf-700 text-paper" : "bg-paper text-ink-soft border border-rule")
        }
        style={{ marginLeft: 28, marginTop: 28 }}
      >
        {rank}
      </span>
    </span>
  );
}

function RailMarker({
  rank,
  state,
  nextState,
}: {
  rank: number;
  state: PathwayState;
  nextState?: PathwayState;
}) {
  return (
    <div
      aria-hidden
      className="pointer-events-none hidden md:block absolute -left-9 top-0 bottom-0 w-7"
    >
      {nextState && (
        <span
          className={
            "absolute left-1/2 -translate-x-1/2 top-11 -bottom-11 " +
            (nextState === "future"
              ? "w-0 border-l border-dashed border-rule"
              : "w-px bg-leaf-500/70")
          }
        />
      )}
      <MarkerCircle rank={rank} state={state} />
    </div>
  );
}

function MarkerCircle({ rank, state }: { rank: number; state: PathwayState }) {
  if (state === "past") {
    return (
      <span className="absolute left-1/2 -translate-x-1/2 top-6 inline-flex h-5 w-5 items-center justify-center rounded-full bg-leaf-700 text-paper shadow-sm">
        <svg viewBox="0 0 12 12" fill="none" stroke="currentColor" strokeWidth="2.25" strokeLinecap="round" strokeLinejoin="round" className="h-2.5 w-2.5">
          <path d="M3 6.5l2 2 4-5" />
        </svg>
        <span className="sr-only">Stage {rank} (past)</span>
      </span>
    );
  }
  if (state === "current") {
    return (
      <span className="absolute left-1/2 -translate-x-1/2 top-6 inline-flex h-6 w-6 items-center justify-center rounded-full bg-leaf-700 text-paper text-[10px] font-semibold shadow-md ring-2 ring-leaf-100">
        {rank}
        <span className="sr-only">Stage {rank} (current)</span>
      </span>
    );
  }
  return (
    <span className="absolute left-1/2 -translate-x-1/2 top-6 inline-flex h-5 w-5 items-center justify-center rounded-full border border-dashed border-rule bg-paper text-ink-mute">
      <span className="text-[9px] font-medium tabular-nums">{rank}</span>
      <span className="sr-only">Stage {rank} (no entries)</span>
    </span>
  );
}

function MobileStem({ show, state }: { show: boolean; state: PathwayState }) {
  if (!show) return null;
  return (
    <div aria-hidden className="md:hidden -mt-4 mb-1.5 flex justify-center">
      <span
        className={
          "block h-4 " +
          (state === "future"
            ? "w-0 border-l border-dashed border-rule"
            : "w-px bg-leaf-500/70")
        }
      />
    </div>
  );
}

function LoadingState() {
  return (
    <div className="rounded-lg border border-rule bg-paper px-6 py-12 text-center">
      <div
        aria-hidden
        className="mx-auto mb-4 h-7 w-7 animate-spin rounded-full border-[1.5px] border-rule border-t-leaf-700"
      />
      <p className="font-display text-base text-ink-soft italic">Loading your activity report…</p>
    </div>
  );
}

function EmptyState() {
  return (
    <div className="rounded-lg border border-dashed border-rule bg-paper-2/30 px-6 py-10 text-center">
      <p className="font-display text-lg text-ink-soft">No entries on file yet.</p>
      <p className="mt-2 text-sm text-ink-mute">
        Your co-op&apos;s first survey will appear here once it&apos;s submitted.
      </p>
    </div>
  );
}

function ErrorState({ message }: { message: string }) {
  return (
    <div role="alert" className="rounded-lg border-2 border-clay-200 bg-clay-100/30 px-6 py-7">
      <h2 className="font-display text-xl font-medium text-clay-700">
        We couldn&apos;t open your report.
      </h2>
      <p className="mt-3 text-sm leading-relaxed text-ink-soft">{message}</p>
      <p className="mt-4 text-sm text-ink-soft">
        If this keeps happening, please contact your <a href="mailto:chris@fci.coop">Chris @ FCI</a>.
      </p>
    </div>
  );
}