94 lines
3.1 KiB
TypeScript
94 lines
3.1 KiB
TypeScript
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/**
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* Small server-side helpers shared by every provider adapter.
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*/
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/** An error that knows which HTTP status the API route should answer with. */
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export class ProviderError extends Error {
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constructor(
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message: string,
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public readonly status: number = 502,
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) {
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super(message);
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this.name = "ProviderError";
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}
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}
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/** Reads an API key from the environment, or fails with a clear message. */
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export function readKey(envKey: string): string {
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const key = process.env[envKey]?.trim();
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if (!key) {
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throw new ProviderError(`${envKey} is not configured`, 500);
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}
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return key;
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}
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interface FetchOptions {
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/** Seconds to cache the response. Weather barely changes in 10 minutes. */
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cacheSeconds?: number;
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headers?: Record<string, string>;
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}
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/**
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* Fetches JSON with caching (default 10 minutes) to protect free-tier quotas.
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* The URL often contains an API key, so it is never logged or echoed back.
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*/
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export async function fetchJson<T>(url: string, providerLabel: string, options: FetchOptions = {}): Promise<T> {
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const { cacheSeconds = 600, headers } = options;
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let response: Response;
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try {
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response = await fetch(url, { headers, next: { revalidate: cacheSeconds } });
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} catch {
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// DNS failure, offline, firewall… the request never got an answer.
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throw new ProviderError(`Couldn't reach ${providerLabel}. Check your connection and try again.`, 503);
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}
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if (response.status === 401 || response.status === 403) {
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throw new ProviderError(`${providerLabel} rejected the API key`, 401);
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}
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if (response.status === 429) {
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throw new ProviderError(`${providerLabel} rate limit reached. Try again shortly.`, 429);
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}
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if (!response.ok) {
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throw new ProviderError(`${providerLabel} responded with HTTP ${response.status}`, 502);
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}
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return (await response.json()) as T;
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}
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// ---------- Number and time helpers ----------
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/** Rounds to one decimal place so the JSON stays tidy. */
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export function round1(value: number): number {
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return Math.round(value * 10) / 10;
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}
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/** Same as round1, but passes null/undefined/NaN through as null. */
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export function maybe(value: number | null | undefined): number | null {
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return value === null || value === undefined || !Number.isFinite(value) ? null : round1(value);
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}
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/** Metres per second → km/h. */
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export function msToKph(ms: number): number {
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return round1(ms * 3.6);
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}
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export function maybeMsToKph(ms: number | null | undefined): number | null {
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return ms === null || ms === undefined ? null : msToKph(ms);
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}
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/** Unix seconds → ISO instant. */
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export function fromUnix(seconds: number): string {
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return new Date(seconds * 1000).toISOString();
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}
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/** Keeps the first `hours` of an hourly list, starting from the current hour. */
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export function nextHours<T extends { time: string }>(items: T[], hours: number): T[] {
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const startOfThisHour = Date.now() - 60 * 60 * 1000;
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return items.filter((item) => Date.parse(item.time) >= startOfThisHour).slice(0, hours);
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}
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/** The app shows at most 7 days of hourly data and 14 days of daily data. */
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export const MAX_HOURS = 168;
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export const MAX_DAYS = 14;
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