"use client";

import { useQuery } from "@tanstack/react-query";
import { getKpis, type KpiSummary } from "@/lib/api";

interface Props {
  scenarioIds: string[];
  scenarioNames: Record<string, string>;
}

const KPI_LABELS: { key: keyof KpiSummary; label: string; format: "pct" | "num" | "inr" }[] = [
  { key: "solved_tariff_inr_per_kwh", label: "Tariff (₹/kWh)", format: "inr" },
  { key: "equity_irr", label: "Equity IRR", format: "pct" },
  { key: "project_irr", label: "Project IRR", format: "pct" },
  { key: "min_dscr", label: "Min DSCR", format: "num" },
  { key: "avg_dscr", label: "Avg DSCR", format: "num" },
  { key: "total_capex_cr", label: "Total Capex (Cr)", format: "num" },
  { key: "lcoe_inr_per_kwh", label: "LCOE (₹/kWh)", format: "inr" },
  { key: "payback_years", label: "Payback (yrs)", format: "num" },
  { key: "solar_y1_cuf", label: "Solar Y1 CUF", format: "pct" },
  { key: "wind_y1_plf", label: "Wind Y1 PLF", format: "pct" },
  { key: "rtc_cuf_achieved", label: "RTC CUF", format: "pct" },
  { key: "total_shortfall_mwh", label: "Shortfall (MWh)", format: "num" },
  { key: "total_mcp_revenue_cr", label: "MCP Revenue (Cr)", format: "num" },
];

function fmtCell(v: number | null | undefined, format: "pct" | "num" | "inr"): string {
  if (v == null) return "—";
  if (format === "pct") return `${(v * 100).toFixed(1)}%`;
  if (format === "inr") return `₹${v.toFixed(2)}`;
  return v.toFixed(2);
}

function KpiRow({
  rowKey,
  label,
  format,
  kpiMap,
  ids,
}: {
  rowKey: keyof KpiSummary;
  label: string;
  format: "pct" | "num" | "inr";
  kpiMap: Record<string, KpiSummary>;
  ids: string[];
}) {
  const values = ids.map((id) => kpiMap[id]?.[rowKey] as number | null | undefined);
  const nums = values.filter((v): v is number => v != null);
  const best = nums.length > 0 ? Math.max(...nums) : null;

  return (
    <tr className="border-t">
      <td className="px-3 py-1.5 text-sm font-medium text-muted-foreground">{label}</td>
      {ids.map((id, i) => {
        const v = values[i];
        const isBest = v != null && v === best && nums.length > 1;
        return (
          <td
            key={id}
            className={`px-3 py-1.5 text-sm tabular-nums text-right ${isBest ? "font-semibold text-green-700" : ""}`}
          >
            {fmtCell(v, format)}
          </td>
        );
      })}
    </tr>
  );
}

export function ScenarioCompare({ scenarioIds, scenarioNames }: Props) {
  const queries = scenarioIds.map((id) =>
    // eslint-disable-next-line react-hooks/rules-of-hooks
    useQuery({
      queryKey: ["kpis", id],
      queryFn: () => getKpis(id),
    })
  );

  const kpiMap: Record<string, KpiSummary> = {};
  for (let i = 0; i < scenarioIds.length; i++) {
    const data = queries[i].data;
    if (data) kpiMap[scenarioIds[i]] = data;
  }

  const isLoading = queries.some((q) => q.isLoading);

  if (isLoading) {
    return <div className="text-muted-foreground text-sm py-4">Loading comparison…</div>;
  }

  return (
    <div className="overflow-x-auto border rounded">
      <table className="w-full text-xs">
        <thead className="bg-muted/50">
          <tr>
            <th className="px-3 py-2 text-left font-medium">KPI</th>
            {scenarioIds.map((id) => (
              <th key={id} className="px-3 py-2 text-right font-medium">
                {scenarioNames[id] ?? id.slice(0, 8)}
              </th>
            ))}
          </tr>
        </thead>
        <tbody>
          {KPI_LABELS.map(({ key, label, format }) => (
            <KpiRow
              key={key}
              rowKey={key}
              label={label}
              format={format}
              kpiMap={kpiMap}
              ids={scenarioIds}
            />
          ))}
        </tbody>
      </table>
    </div>
  );
}