import type { PolyModel } from "@/lib/ai/core/types";

/** "$0.25", "$10", "—" — USD per 1M tokens. Server- and client-safe. */
export function formatPrice(v: number | null | undefined): string {
  if (v === undefined || v === null || Number.isNaN(v)) return "—";
  if (v === 0) return "$0";
  if (v < 0.01) return `$${v.toFixed(4).replace(/0+$/, "")}`;
  if (v < 1) return `$${v.toFixed(2)}`;
  return `$${Number.isInteger(v) ? v : v.toFixed(2).replace(/\.?0+$/, "")}`;
}

/** "$2 / $10" input / output per 1M. */
export function formatPricePair(m: PolyModel): string {
  const p = m.pricing;
  if (!p || (p.inputPerMillion === undefined && p.outputPerMillion === undefined)) return "—";
  return `${formatPrice(p.inputPerMillion)} / ${formatPrice(p.outputPerMillion)}`;
}

export function formatContext(n: number | null | undefined): string {
  if (!n) return "—";
  if (n >= 1_000_000) return `${(n / 1_000_000).toFixed(2).replace(/\.?0+$/, "")}M`;
  if (n >= 1_000) return `${(n / 1_000).toFixed(1).replace(/\.?0+$/, "")}K`;
  return String(n);
}

/** ISO date → "Sep 8, 2026" (UTC, deterministic for SSR). */
export function formatIsoDate(v: unknown): string {
  if (typeof v !== "string" || !v) return "—";
  const d = new Date(v);
  if (Number.isNaN(d.getTime())) return v;
  return d.toLocaleDateString("en-US", { month: "short", day: "numeric", year: "numeric", timeZone: "UTC" });
}