feat: add configurable wind units

lib/weather-utils.ts

@@ -11,8 +11,17 @@ import type {
 import { translate, type Language } from "@/lib/i18n";
 import { getProvinceFromTeryt, normalizeProvinceName } from "@/lib/provinces";
 import type { CurrentWeatherCondition } from "@/types/imgw-current";
+import type { WindSpeedUnit } from "@/types/units";
 
 const locales: Record<Language, string> = { pl: "pl-PL", en: "en-GB" };
+export const DEFAULT_WIND_SPEED_UNIT: WindSpeedUnit = "ms";
+export const WIND_SPEED_UNITS: WindSpeedUnit[] = ["ms", "kmh", "mph"];
+
+const windSpeedUnitLabels: Record<WindSpeedUnit, string> = {
+  ms: "m/s",
+  kmh: "km/h",
+  mph: "mph",
+};
 
 export function toNumber(value: unknown): number | null {
   if (typeof value === "number") return Number.isFinite(value) ? value : null;
@@ -108,10 +117,35 @@ export function formatHumidity(value: number | null, language: Language = "pl")
   return value === null ? translate(language, "common.noData") : `${Math.round(value)}%`;
 }
 
-export function formatWind(speed: number | null, direction?: number | null, language: Language = "pl") {
+export function isWindSpeedUnit(value: unknown): value is WindSpeedUnit {
+  return typeof value === "string" && WIND_SPEED_UNITS.includes(value as WindSpeedUnit);
+}
+
+export function getWindSpeedUnitLabel(unit: WindSpeedUnit) {
+  return windSpeedUnitLabels[unit];
+}
+
+export function convertWindSpeed(speed: number, unit: WindSpeedUnit) {
+  if (unit === "kmh") return speed * 3.6;
+  if (unit === "mph") return speed * 2.2369362921;
+  return speed;
+}
+
+export function formatWindSpeed(speed: number | null, language: Language = "pl", unit: WindSpeedUnit = DEFAULT_WIND_SPEED_UNIT) {
+  if (speed === null) return translate(language, "common.noData");
+  const convertedSpeed = convertWindSpeed(speed, unit);
+  const digits = unit === "ms" ? 1 : 0;
+  const formattedSpeed = new Intl.NumberFormat(locales[language], {
+    minimumFractionDigits: digits,
+    maximumFractionDigits: digits,
+  }).format(convertedSpeed);
+  return `${formattedSpeed} ${getWindSpeedUnitLabel(unit)}`;
+}
+
+export function formatWind(speed: number | null, direction?: number | null, language: Language = "pl", unit: WindSpeedUnit = DEFAULT_WIND_SPEED_UNIT) {
   if (speed === null) return translate(language, "common.noData");
   const directionLabel = direction === null || direction === undefined ? "" : ` ${getWindDirection(direction)}`;
-  return `${speed.toFixed(1)} m/s${directionLabel}`;
+  return `${formatWindSpeed(speed, language, unit)}${directionLabel}`;
 }
 
 export function formatRainfall(value: number | null, language: Language = "pl") {