Fix upcoming forecast hour filtering

lib/forecast-utils.ts

@@ -50,9 +50,40 @@ function getWarsawForecastHour(date = new Date()) {
   return `${getPart("year")}-${getPart("month")}-${getPart("day")}T${getPart("hour")}:00`;
 }
 
+function parseForecastHour(time: string) {
+  const match = time.match(/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2})/);
+  if (!match) return null;
+  const [, year, month, day, hour, minute] = match;
+  const timestamp = Date.UTC(Number(year), Number(month) - 1, Number(day), Number(hour), Number(minute));
+  return Number.isFinite(timestamp) ? timestamp : null;
+}
+
+function getForecastHourOfDay(time: string) {
+  const match = time.match(/T(\d{2}):/);
+  return match ? Number(match[1]) : null;
+}
+
 export function getUpcomingHourlyForecast(hours: HourlyForecast[], limit = 24) {
   const currentHour = getWarsawForecastHour();
-  return hours.filter((hour) => hour.time >= currentHour).slice(0, limit);
+  const currentTimestamp = parseForecastHour(currentHour);
+  const upcomingHours = currentTimestamp === null
+    ? hours.filter((hour) => hour.time >= currentHour)
+    : hours.filter((hour) => {
+      const hourTimestamp = parseForecastHour(hour.time);
+      return hourTimestamp === null ? hour.time >= currentHour : hourTimestamp >= currentTimestamp;
+    });
+
+  if (upcomingHours.length) return upcomingHours.slice(0, limit);
+
+  const currentHourOfDay = getForecastHourOfDay(currentHour);
+  const fallbackHours = currentHourOfDay === null
+    ? hours
+    : hours.filter((hour) => {
+      const forecastHourOfDay = getForecastHourOfDay(hour.time);
+      return forecastHourOfDay === null || forecastHourOfDay >= currentHourOfDay;
+    });
+
+  return (fallbackHours.length ? fallbackHours : hours).slice(0, limit);
 }
 
 export function getHourlyForecastForDay(hours: HourlyForecast[], date: string) {