70 lines
1.9 KiB
JavaScript
70 lines
1.9 KiB
JavaScript
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const DEFAULT_NOMINATIM_BASE = 'https://nominatim.openstreetmap.org';
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const MIN_REQUEST_INTERVAL_MS = 1000;
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const ALLOWED_HOSTS = new Set(['nominatim.openstreetmap.org']);
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let lastRequestAt = 0;
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function assertAllowedHost(url) {
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const host = new URL(url).hostname.toLowerCase();
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if (!ALLOWED_HOSTS.has(host)) {
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throw new Error(`[nominatim] Host not allowlisted: ${host}`);
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}
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}
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function getUserAgent() {
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return process.env.NOMINATIM_USER_AGENT ?? 'DeckHearth/1.0';
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}
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async function throttle() {
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const now = Date.now();
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const elapsed = now - lastRequestAt;
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if (elapsed < MIN_REQUEST_INTERVAL_MS) {
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await new Promise((resolve) => setTimeout(resolve, MIN_REQUEST_INTERVAL_MS - elapsed));
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}
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lastRequestAt = Date.now();
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}
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/**
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* @param {string} zip Five-digit US zip code.
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* @param {{ fetchImpl?: typeof fetch }} [options]
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* @returns {Promise<{ lat: number, lng: number, displayName: string } | null>}
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*/
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export async function geocodeUsZip(zip, { fetchImpl = fetch } = {}) {
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const base = process.env.NOMINATIM_BASE_URL ?? DEFAULT_NOMINATIM_BASE;
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const url = new URL('/search', base);
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url.searchParams.set('postalcode', zip);
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url.searchParams.set('country', 'US');
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url.searchParams.set('format', 'json');
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url.searchParams.set('limit', '1');
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assertAllowedHost(url.toString());
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await throttle();
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const response = await fetchImpl(url.toString(), {
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headers: { 'User-Agent': getUserAgent() },
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});
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if (!response.ok) {
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throw new Error(`[nominatim] HTTP ${response.status}`);
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}
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const results = await response.json();
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if (!Array.isArray(results) || results.length === 0) {
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return null;
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}
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const hit = results[0];
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const lat = Number(hit.lat);
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const lng = Number(hit.lon);
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if (!Number.isFinite(lat) || !Number.isFinite(lng)) {
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return null;
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}
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return {
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lat,
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lng,
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displayName: hit.display_name ?? `${zip}, US`,
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};
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}
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