/**
 * Core Web Vitals reporting via PostHog.
 *
 * Tracks LCP, INP, CLS, FCP, and TTFB as PostHog events so we can
 * build dashboards and correlate performance with product usage.
 *
 * Each metric fires once per page load. PostHog captures 100% of
 * sessions (vs Sentry's 20% sample), giving better coverage.
 */
import { onLCP, onINP, onCLS, onFCP, onTTFB } from 'web-vitals'
import type { Metric } from 'web-vitals'
import posthog from 'posthog-js'

function sendToPostHog(metric: Metric) {
  // Only send if PostHog is loaded
  if (!(posthog as unknown as { __loaded?: boolean }).__loaded) return

  posthog.capture('web_vitals', {
    metric_name: metric.name,
    metric_value: metric.value,
    metric_rating: metric.rating,
    metric_delta: metric.delta,
    metric_id: metric.id,
    page_path: window.location.pathname,
  })
}

/** Register all Web Vitals observers. Call once after PostHog init. */
export function initWebVitals() {
  onLCP(sendToPostHog)
  onINP(sendToPostHog)
  onCLS(sendToPostHog)
  onFCP(sendToPostHog)
  onTTFB(sendToPostHog)
}