Add Web Push warning notification backend

app/api/notifications/subscriptions/route.ts

@@ -0,0 +1,59 @@
+import { NextResponse } from "next/server";
+import { upsertPushSubscription, removePushSubscription } from "@/lib/push-store";
+import { isWebPushConfigured } from "@/lib/push-service";
+import { normalizeProvinceName } from "@/lib/provinces";
+import type { Language } from "@/lib/i18n";
+import type { BrowserPushSubscription } from "@/types/notifications";
+
+export const runtime = "nodejs";
+
+function isBrowserPushSubscription(value: unknown): value is BrowserPushSubscription {
+  if (!value || typeof value !== "object") return false;
+  const subscription = value as Partial<BrowserPushSubscription>;
+  return typeof subscription.endpoint === "string"
+    && subscription.endpoint.startsWith("https://")
+    && typeof subscription.keys?.p256dh === "string"
+    && typeof subscription.keys.auth === "string";
+}
+
+export async function POST(request: Request) {
+  if (!isWebPushConfigured()) {
+    return NextResponse.json({ error: "Web Push is not configured." }, { status: 503 });
+  }
+
+  const body = await request.json().catch(() => null) as {
+    subscription?: unknown;
+    province?: unknown;
+    language?: unknown;
+    enabled?: unknown;
+  } | null;
+  const subscription = body?.subscription;
+  const province = normalizeProvinceName(typeof body?.province === "string" ? body.province : null);
+  const language: Language = body?.language === "en" ? "en" : "pl";
+
+  if (!isBrowserPushSubscription(subscription) || !province) {
+    return NextResponse.json({ error: "Invalid push subscription." }, { status: 400 });
+  }
+
+  const now = new Date().toISOString();
+  upsertPushSubscription({
+    endpoint: subscription.endpoint,
+    subscription,
+    province,
+    language,
+    enabled: body?.enabled !== false,
+    createdAt: now,
+    updatedAt: now,
+  });
+
+  return NextResponse.json({ ok: true });
+}
+
+export async function DELETE(request: Request) {
+  const body = await request.json().catch(() => null) as { endpoint?: unknown } | null;
+  if (typeof body?.endpoint !== "string" || !body.endpoint) {
+    return NextResponse.json({ error: "Invalid push subscription endpoint." }, { status: 400 });
+  }
+  removePushSubscription(body.endpoint);
+  return NextResponse.json({ ok: true });
+}