75 lines
2.8 KiB
TypeScript
75 lines
2.8 KiB
TypeScript
import { toSeverity } from "../describe";
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import { fetchJson } from "../http";
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import type { WeatherAlert } from "../types";
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/**
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* Active US weather alerts from the National Weather Service (free, no key).
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* Docs: https://www.weather.gov/documentation/services-web-api
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*
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* NWS asks every app to identify itself with a User-Agent containing contact
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* info, so set NWS_CONTACT in .env.local (an email or website).
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* Outside the US this returns nothing, which is fine.
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*/
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interface NwsResponse {
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features: {
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properties: {
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event: string;
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headline: string | null;
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severity: string;
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senderName: string;
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onset: string | null;
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effective: string;
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ends: string | null;
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expires: string;
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description: string;
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instruction: string | null;
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};
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}[];
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}
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/** Rough boxes around US states and territories — skips pointless calls elsewhere. */
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function mightBeInUS(lat: number, lon: number): boolean {
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const mainland = lat > 24 && lat < 50 && lon > -125 && lon < -66;
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const alaska = lat > 51 && lat < 72 && (lon < -129 || lon > 172);
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const hawaii = lat > 18 && lat < 23 && lon > -161 && lon < -154;
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const caribbean = lat > 17 && lat < 19 && lon > -68 && lon < -64; // Puerto Rico, USVI
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const pacific = lat > 13 && lat < 21 && lon > 144 && lon < 146; // Guam, Northern Marianas
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return mainland || alaska || hawaii || caribbean || pacific;
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}
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let warnedMissingContact = false;
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function buildNwsUserAgent(): string {
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const explicit = process.env.NWS_CONTACT?.trim();
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if (explicit) return `WayfarerWeather/1.0 (${explicit})`;
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const deployedHost = process.env.VERCEL_PROJECT_PRODUCTION_URL?.trim() || process.env.VERCEL_URL?.trim();
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if (deployedHost) return `WayfarerWeather/1.0 (https://${deployedHost})`;
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if (process.env.NODE_ENV === "production" && !warnedMissingContact) {
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warnedMissingContact = true;
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console.warn("[Wayfarer] Set NWS_CONTACT (email or site URL) so api.weather.gov requests include contact details.");
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}
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return "WayfarerWeather/1.0 (local-dev)";
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}
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export async function getNwsAlerts(lat: number, lon: number): Promise<WeatherAlert[]> {
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if (!mightBeInUS(lat, lon)) return [];
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const point = `${lat.toFixed(4)},${lon.toFixed(4)}`;
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const data = await fetchJson<NwsResponse>(`https://api.weather.gov/alerts/active?point=${point}`, "National Weather Service", {
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cacheSeconds: 300, // alerts matter; refresh more often
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headers: { "User-Agent": buildNwsUserAgent(), Accept: "application/geo+json" },
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});
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return data.features.map(({ properties: p }) => ({
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title: p.headline ?? p.event,
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severity: toSeverity(p.severity),
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source: p.senderName,
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starts: p.onset ?? p.effective,
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ends: p.ends ?? p.expires,
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description: p.description,
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instruction: p.instruction,
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}));
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}
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