feat: add consent-based GPS location

app/api/locations/reverse/route.ts

@@ -0,0 +1,65 @@
+import { NextResponse } from "next/server";
+
+const REVERSE_GEOCODING_URL = "https://nominatim.openstreetmap.org/reverse";
+const USER_AGENT = "wtr./1.0 (https://git.zvcloud.net/zv/wtr)";
+
+interface RawReverseLocation {
+  name?: string;
+  display_name?: string;
+  address?: {
+    city?: string;
+    town?: string;
+    village?: string;
+    municipality?: string;
+    state?: string;
+  };
+}
+
+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 ? Number(coordinate.toFixed(3)) : 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);
+  const language = searchParams.get("language") === "en" ? "en" : "pl";
+  if (latitude === null || longitude === null) {
+    return NextResponse.json({ error: "Invalid coordinates." }, { status: 400 });
+  }
+
+  const params = new URLSearchParams({
+    format: "jsonv2",
+    lat: String(latitude),
+    lon: String(longitude),
+    zoom: "10",
+    addressdetails: "1",
+    "accept-language": language,
+  });
+
+  try {
+    const response = await fetch(`${REVERSE_GEOCODING_URL}?${params}`, {
+      next: { revalidate: 86400 },
+      headers: { Accept: "application/json", "User-Agent": USER_AGENT },
+    });
+    if (!response.ok) return NextResponse.json({ error: "Reverse geocoding is unavailable." }, { status: 502 });
+    const data = await response.json() as RawReverseLocation;
+    const name = data.address?.city
+      ?? data.address?.town
+      ?? data.address?.village
+      ?? data.address?.municipality
+      ?? data.name
+      ?? data.display_name?.split(",")[0]?.trim();
+    if (!name) return NextResponse.json({ error: "Place name is unavailable." }, { status: 404 });
+    return NextResponse.json({
+      name,
+      province: data.address?.state ?? null,
+    }, {
+      headers: { "Cache-Control": "public, s-maxage=86400, stale-while-revalidate=604800" },
+    });
+  } catch {
+    return NextResponse.json({ error: "Reverse geocoding is unavailable." }, { status: 502 });
+  }
+}