feat: add Open-Meteo weather forecast

app/api/forecast/route.ts

@@ -0,0 +1,39 @@
+import { NextResponse } from "next/server";
+
+const FORECAST_URL = "https://api.open-meteo.com/v1/forecast";
+
+function parseCoordinate(value: string | null, min: number, max: number) {
+  if (!value?.trim()) return null;
+  const coordinate = Number(value);
+  return Number.isFinite(coordinate) && coordinate >= min && coordinate <= max ? coordinate : null;
+}
+
+export async function GET(request: Request) {
+  const { searchParams } = new URL(request.url);
+  const latitude = parseCoordinate(searchParams.get("latitude"), -90, 90);
+  const longitude = parseCoordinate(searchParams.get("longitude"), -180, 180);
+  if (latitude === null || longitude === null) {
+    return NextResponse.json({ error: "Invalid coordinates." }, { status: 400 });
+  }
+
+  const params = new URLSearchParams({
+    latitude: String(latitude),
+    longitude: String(longitude),
+    hourly: "temperature_2m,apparent_temperature,precipitation_probability,precipitation,weather_code,wind_speed_10m",
+    daily: "weather_code,temperature_2m_max,temperature_2m_min,precipitation_probability_max,precipitation_sum,sunrise,sunset",
+    timezone: "Europe/Warsaw",
+    forecast_hours: "24",
+    forecast_days: "7",
+    wind_speed_unit: "ms",
+  });
+
+  try {
+    const response = await fetch(`${FORECAST_URL}?${params}`, { next: { revalidate: 900 } });
+    if (!response.ok) return NextResponse.json({ error: "Forecast service is unavailable." }, { status: 502 });
+    return NextResponse.json(await response.json(), {
+      headers: { "Cache-Control": "public, s-maxage=900, stale-while-revalidate=1800" },
+    });
+  } catch {
+    return NextResponse.json({ error: "Forecast service is unavailable." }, { status: 502 });
+  }
+}