Add Web Push warning notification backend

lib/push-service.ts

@@ -0,0 +1,71 @@
+import webPush, { type PushSubscription } from "web-push";
+import type { Language } from "@/lib/i18n";
+import { formatProvinceName } from "@/lib/provinces";
+import type { WeatherWarning } from "@/types/imgw";
+import type { WarningPushSubscription } from "@/types/notifications";
+
+const VAPID_PUBLIC_KEY = process.env.WEB_PUSH_VAPID_PUBLIC_KEY;
+const VAPID_PRIVATE_KEY = process.env.WEB_PUSH_VAPID_PRIVATE_KEY;
+const VAPID_SUBJECT = process.env.WEB_PUSH_VAPID_SUBJECT ?? "mailto:alerts@wtr.local";
+
+let configured = false;
+
+export function getVapidPublicKey() {
+  return VAPID_PUBLIC_KEY ?? null;
+}
+
+export function isWebPushConfigured() {
+  return Boolean(VAPID_PUBLIC_KEY && VAPID_PRIVATE_KEY);
+}
+
+function ensureWebPushConfigured() {
+  if (!VAPID_PUBLIC_KEY || !VAPID_PRIVATE_KEY) throw new Error("Web Push VAPID keys are not configured.");
+  if (!configured) {
+    webPush.setVapidDetails(VAPID_SUBJECT, VAPID_PUBLIC_KEY, VAPID_PRIVATE_KEY);
+    configured = true;
+  }
+}
+
+function getWarningLevelLabel(warning: WeatherWarning, language: Language) {
+  if (warning.level === null) return language === "pl" ? "stopień nieokreślony" : "level not specified";
+  return language === "pl" ? `stopień ${warning.level}` : `level ${warning.level}`;
+}
+
+function formatWarningValidity(warning: WeatherWarning, language: Language) {
+  if (!warning.validFrom && !warning.validTo) return null;
+  const locale = language === "pl" ? "pl-PL" : "en-GB";
+  const formatter = new Intl.DateTimeFormat(locale, {
+    day: "2-digit",
+    month: "2-digit",
+    hour: "2-digit",
+    minute: "2-digit",
+  });
+  const from = warning.validFrom ? formatter.format(new Date(warning.validFrom)) : null;
+  const to = warning.validTo ? formatter.format(new Date(warning.validTo)) : null;
+  if (from && to) return language === "pl" ? `od ${from} do ${to}` : `from ${from} to ${to}`;
+  if (from) return language === "pl" ? `od ${from}` : `from ${from}`;
+  return language === "pl" ? `do ${to}` : `until ${to}`;
+}
+
+function buildWarningPayload(preference: WarningPushSubscription, warning: WeatherWarning) {
+  const province = formatProvinceName(preference.province, preference.language);
+  const title = warning.title || (preference.language === "pl" ? "Ostrzeżenie meteorologiczne" : "Weather warning");
+  const validity = formatWarningValidity(warning, preference.language);
+  const level = getWarningLevelLabel(warning, preference.language);
+  const bodyParts = preference.language === "pl"
+    ? [`${province}: ${level}`, validity, warning.probability !== null ? `prawdopodobieństwo ${warning.probability}%` : null]
+    : [`${province}: ${level}`, validity, warning.probability !== null ? `${warning.probability}% probability` : null];
+
+  return {
+    title: `IMGW: ${title}`,
+    body: bodyParts.filter(Boolean).join(" · "),
+    url: "/warnings",
+    warningId: warning.id,
+  };
+}
+
+export async function sendWarningNotification(preference: WarningPushSubscription, warning: WeatherWarning) {
+  ensureWebPushConfigured();
+  const payload = JSON.stringify(buildWarningPayload(preference, warning));
+  await webPush.sendNotification(preference.subscription as PushSubscription, payload);
+}