import { db } from '@/lib/db'

/**
 * Zusammenfassung der Ladewerte für den Adminbereich.
 *
 * Ausgewertet wird der **Median und das 75. Perzentil**, nicht der Mittelwert:
 * ein einzelner Ausreisser auf einem alten Laptop soll die Zahl nicht
 * bestimmen. Zielwerte aus docs/09-performance-und-ux.md.
 */

const TAGE = 7

export type VitalSummary = {
  metric: string
  count: number
  median: number
  p75: number
}

export async function summarizeVitals(): Promise<{
  metriken: VitalSummary[]
  routen: { route: string; metric: string; p75: number; count: number }[]
}> {
  const seit = new Date(Date.now() - TAGE * 86_400_000)

  const metriken = await db.$queryRaw<
    { metric: string; count: bigint; median: number; p75: number }[]
  >`
    SELECT "metric",
           count(*) AS count,
           percentile_cont(0.5)  WITHIN GROUP (ORDER BY "value") AS median,
           percentile_cont(0.75) WITHIN GROUP (ORDER BY "value") AS p75
      FROM "WebVital"
     WHERE "at" >= ${seit}
     GROUP BY "metric"
     ORDER BY "metric"
  `

  const routen = await db.$queryRaw<
    { route: string; metric: string; p75: number; count: bigint }[]
  >`
    SELECT "route", "metric",
           percentile_cont(0.75) WITHIN GROUP (ORDER BY "value") AS p75,
           count(*) AS count
      FROM "WebVital"
     WHERE "at" >= ${seit} AND "metric" = 'LCP'
     GROUP BY "route", "metric"
     HAVING count(*) >= 3
     ORDER BY p75 DESC
     LIMIT 8
  `

  return {
    metriken: metriken.map((zeile) => ({
      metric: zeile.metric,
      count: Number(zeile.count),
      median: zeile.median,
      p75: zeile.p75,
    })),
    routen: routen.map((zeile) => ({
      route: zeile.route,
      metric: zeile.metric,
      p75: zeile.p75,
      count: Number(zeile.count),
    })),
  }
}

/** Millisekunden lesbar machen; CLS ist dimensionslos. */
export function formatVital(metric: string, wert: number): string {
  if (metric === 'CLS') return wert.toFixed(3)
  if (wert >= 1000) return `${(wert / 1000).toFixed(2)} s`
  return `${Math.round(wert)} ms`
}