import type { UiMetricValue } from "./types";

const byteUnits = ["B", "KB", "MB", "GB", "TB"];

export function formatMetricValue(metric: UiMetricValue): string {
  if (metric.kind === "text") return String(metric.value);

  const value = typeof metric.value === "number" ? metric.value : Number(metric.value);
  const precision = metric.precision ?? inferPrecision(value);
  const unit = metric.unit ?? defaultUnit(metric.kind);

  if (metric.kind === "bytes") return formatBytes(value, precision);
  if (metric.kind === "percent") return `${value.toFixed(precision)}%`;
  if (metric.kind === "temperature") return `${value.toFixed(precision)}°C`;
  return `${value.toFixed(precision)}${unit ? ` ${unit}` : ""}`;
}

export function clampPercent(value = 0): number {
  if (!Number.isFinite(value)) return 0;
  return Math.max(0, Math.min(100, value));
}

function defaultUnit(kind: UiMetricValue["kind"]): string {
  if (kind === "percent") return "%";
  if (kind === "temperature") return "C";
  if (kind === "latency") return "ms";
  return "";
}

function inferPrecision(value: number): number {
  return Number.isInteger(value) ? 0 : 1;
}

function formatBytes(value: number, precision: number): string {
  let size = value;
  let index = 0;
  while (size >= 1024 && index < byteUnits.length - 1) {
    size /= 1024;
    index += 1;
  }

  return `${size.toFixed(precision)} ${byteUnits[index]}`;
}