import { WebVitalsMetrics, WebVitalsRatings } from './lighthouse-types.js';
import { WebVitalsRating, WEB_VITALS_THRESHOLDS } from './lighthouse-constants.js';
export function getWebVitalsRating(
metric: keyof typeof WEB_VITALS_THRESHOLDS,
value: number
): WebVitalsRating {
const thresholds = WEB_VITALS_THRESHOLDS[metric];
if (value <= thresholds.GOOD) {
return WebVitalsRating.GOOD;
}
if (value <= thresholds.NEEDS_IMPROVEMENT) {
return WebVitalsRating.NEEDS_IMPROVEMENT;
}
return WebVitalsRating.POOR;
}
export function calculateWebVitalsRatings(
metrics: WebVitalsMetrics
): Partial<Record<keyof WebVitalsMetrics, WebVitalsRating>> {
const ratings: Partial<Record<keyof WebVitalsMetrics, WebVitalsRating>> = {};
if (metrics.fcp !== null) {
ratings.fcp = getWebVitalsRating('FCP', metrics.fcp);
}
if (metrics.lcp !== null) {
ratings.lcp = getWebVitalsRating('LCP', metrics.lcp);
}
if (metrics.fid !== null) {
ratings.fid = getWebVitalsRating('FID', metrics.fid);
}
if (metrics.cls !== null && metrics.cls > 0) {
ratings.cls = getWebVitalsRating('CLS', metrics.cls);
}
if (metrics.ttfb !== null) {
ratings.ttfb = getWebVitalsRating('TTFB', metrics.ttfb);
}
return ratings;
}
export function createPerformanceObserver(
entryTypes: string[],
callback: (entries: PerformanceEntry[]) => void,
buffered = true
): PerformanceObserver | null {
try {
const observer = new PerformanceObserver((list) => {
callback(Array.from(list.getEntries()));
});
const options: PerformanceObserverInit = { entryTypes };
if (buffered) {
(options as any).buffered = true;
}
observer.observe(options);
return observer;
} catch (error) {
if (buffered) {
try {
const observer = new PerformanceObserver((list) => {
callback(Array.from(list.getEntries()));
});
observer.observe({ entryTypes });
return observer;
} catch {
return null;
}
}
return null;
}
}
