import type { TickerOverview, ValuationResponse } from "@/types/api";
import { fmtCurrency, fmtPct } from "@/lib/format";

type ValState = "idle" | "loading" | "ready" | "error";

type Props = {
  overview: TickerOverview;
  valuation: ValuationResponse | null;
  valState: ValState;
};

function barPositions(price: number, iv: number): {
  leftPct: number;
  widthPct: number;
  pricePct: number;
  ivPct: number;
  isPremium: boolean;
} {
  const padding = 0.1;
  const min = Math.min(price, iv) * (1 - padding);
  const max = Math.max(price, iv) * (1 + padding);
  const range = max - min;
  if (range === 0) return { leftPct: 50, widthPct: 0, pricePct: 50, ivPct: 50, isPremium: false };

  const pricePct = ((price - min) / range) * 100;
  const ivPct = ((iv - min) / range) * 100;
  const leftPct = Math.min(pricePct, ivPct);
  const widthPct = Math.abs(pricePct - ivPct);

  return { leftPct, widthPct, pricePct, ivPct, isPremium: price > iv };
}

export function PriceVsValueCard({ overview, valuation, valState }: Props) {
  if (valState === "idle" || valState === "loading" || valState === "error") return null;

  const dcf = valuation?.dcf;
  if (!dcf?.available || dcf.intrinsic_value_per_share == null) return null;

  const price = overview.quote.price ?? overview.range_52w.price;
  if (price == null) return null;

  const iv = dcf.intrinsic_value_per_share;
  const { leftPct, widthPct, pricePct, ivPct, isPremium } = barPositions(price, iv);
  const pct = ((price - iv) / iv) * 100;
  const pctLabel = isPremium
    ? `Trading at ${pct.toFixed(1)}% premium to DCF`
    : `Trading at ${Math.abs(pct).toFixed(1)}% discount to DCF`;

  const [leftLabel, rightLabel] = isPremium
    ? [`IV ${fmtCurrency(iv)}`, `Price ${fmtCurrency(price)}`]
    : [`Price ${fmtCurrency(price)}`, `IV ${fmtCurrency(iv)}`];

  return (
    <section className="psm-card">
      <div className="psm-card-head">
        <div>
          <div className="psm-eyebrow">Price vs Value</div>
          <h2 className="psm-card-title">Intrinsic Value</h2>
        </div>
      </div>
      <div className="psm-pvv-figures">
        <span className="psm-pvv-current">{fmtCurrency(price)}</span>
        <span className={`psm-pvv-iv ${isPremium ? "negative" : "positive"}`}>
          {isPremium ? "↑" : "↓"} IV {fmtCurrency(iv)}
        </span>
      </div>
      <div className="psm-pvv-rail">
        <div
          className="psm-pvv-fill"
          style={{
            left: `${leftPct}%`,
            width: `${widthPct}%`,
            background: isPremium ? "var(--negative)" : "var(--positive)",
            opacity: 0.5,
          }}
        />
        <div className="psm-pvv-tick price" style={{ left: `${pricePct}%` }} />
        <div className="psm-pvv-tick iv" style={{ left: `${ivPct}%` }} />
      </div>
      <div className="psm-pvv-rail-labels">
        <span>{leftLabel}</span>
        <span>{rightLabel}</span>
      </div>
      <p className="psm-pvv-meta">
        {pctLabel} · WACC {fmtPct(dcf.wacc)} · {dcf.projection_years}yr
        {dcf.growth_rate_used != null ? ` · growth ${fmtPct(dcf.growth_rate_used)}` : ""}
      </p>
    </section>
  );
}