"use client";

import {
  BarChart,
  Bar,
  XAxis,
  YAxis,
  Tooltip,
  ReferenceLine,
  ResponsiveContainer,
  Cell,
} from "recharts";

export interface TornadoEntry {
  param_name: string;
  low_value: number;
  high_value: number;
  base_kpi: number;
  low_kpi: number;
  high_kpi: number;
  swing: number;
}

interface Props {
  entries: TornadoEntry[];
  kpiLabel?: string;
  baseValue?: number;
}

interface ChartRow {
  name: string;
  low: number;
  high: number;
  base: number;
  lowLabel: string;
  highLabel: string;
}

export function TornadoChart({ entries, kpiLabel = "Equity IRR", baseValue }: Props) {
  if (entries.length === 0) return null;

  const base = baseValue ?? entries[0]?.base_kpi ?? 0;
  const isPercent = kpiLabel.toLowerCase().includes("irr") || kpiLabel.toLowerCase().includes("cuf");

  const fmtKpi = (v: number) =>
    isPercent ? `${(v * 100).toFixed(1)}%` : v.toFixed(2);

  const data: ChartRow[] = entries.map((e) => ({
    name: e.param_name,
    low: Math.min(e.low_kpi, e.high_kpi) - base,
    high: Math.max(e.low_kpi, e.high_kpi) - base,
    base,
    lowLabel: fmtKpi(Math.min(e.low_kpi, e.high_kpi)),
    highLabel: fmtKpi(Math.max(e.low_kpi, e.high_kpi)),
  }));

  const absMax = Math.max(...data.map((d) => Math.max(Math.abs(d.low), Math.abs(d.high))));
  const domain = [-absMax * 1.1, absMax * 1.1];

  return (
    <div>
      <h3 className="font-semibold mb-3 text-sm">
        Sensitivity: {kpiLabel} (base = {fmtKpi(base)})
      </h3>
      <ResponsiveContainer width="100%" height={Math.max(200, entries.length * 45)}>
        <BarChart
          data={data}
          layout="vertical"
          margin={{ top: 0, right: 40, left: 120, bottom: 0 }}
        >
          <XAxis
            type="number"
            domain={domain}
            tickFormatter={(v) => isPercent ? `${(v * 100).toFixed(1)}%` : v.toFixed(2)}
            tick={{ fontSize: 10 }}
          />
          <YAxis type="category" dataKey="name" tick={{ fontSize: 11 }} width={120} />
          <Tooltip
            formatter={(value) => {
              const v = typeof value === "number" ? value : 0;
              return [
                `${fmtKpi(base + v)} (Δ ${isPercent ? `${(v * 100).toFixed(1)}%` : v.toFixed(2)})`,
                "",
              ];
            }}
          />
          <ReferenceLine x={0} stroke="#888" strokeWidth={1.5} />
          <Bar dataKey="low" name="Low" stackId="a" fill="transparent" />
          <Bar dataKey="high" name="High" stackId="a" radius={[0, 3, 3, 0]}>
            {data.map((entry, index) => (
              <Cell key={index} fill={entry.high >= 0 ? "#10b981" : "#f43f5e"} />
            ))}
          </Bar>
        </BarChart>
      </ResponsiveContainer>
    </div>
  );
}