import type { Metadata } from 'next'
import { Suspense } from 'react'
import { requirePermission } from '@/lib/auth/current'
import { collectHealth, type ComponentState } from '@/lib/health/check'
import { de } from '@/lib/i18n/de'
import { formatVital, summarizeVitals } from '@/lib/dashboard/vitals'
import { SkeletonLine } from '@/components/Skeleton'

export const metadata: Metadata = { title: de.health.heading }
export const dynamic = 'force-dynamic'

const STATE_LABEL: Record<ComponentState, string> = {
  up: de.health.ok,
  degraded: de.health.degraded,
  down: de.health.down,
}

async function SystemState() {
  const report = await collectHealth()
  return (
    <table className="w-full max-w-(--container-measure) border-collapse text-sm">
      <caption className="pb-2 text-left font-condensed text-xs text-text-dim">
        {de.health.checkedAt(new Date(report.checkedAt).toLocaleString('de-DE'))}
      </caption>
      <thead>
        <tr className="border-b border-line text-left text-xs text-text-dim">
          <th scope="col" className="py-1.5 pr-4 font-normal">
            {de.health.service}
          </th>
          <th scope="col" className="py-1.5 font-normal">
            {de.health.state}
          </th>
        </tr>
      </thead>
      <tbody>
        {Object.entries(report.components).map(([key, value]) => (
          <tr key={key} className="border-b border-line/60">
            <td className="py-2 pr-4">{de.health.components[key] ?? key}</td>
            <td className="py-2">
              {/* Zustand als Text, nicht nur als Farbe. */}
              <span className="font-condensed">{STATE_LABEL[value.status]}</span>
              {value.detail ? (
                <span className="ml-2 font-mono text-2xs text-text-dim">{value.detail}</span>
              ) : null}
            </td>
          </tr>
        ))}
      </tbody>
    </table>
  )
}

export default async function SystemPage() {
  await requirePermission('admin')

  return (
    <section>
      <h2 className="font-condensed">{de.health.heading}</h2>
      <Suspense
        fallback={
          <div className="mt-6">
            <SkeletonLine width="14rem" />
            <SkeletonLine />
            <SkeletonLine />
            <SkeletonLine />
          </div>
        }
      >
        <div className="mt-6">
          <SystemState />
        </div>
      </Suspense>
    
      <section className="mt-10">
        <h2 className="font-condensed">{de.vitals.heading}</h2>
        <p className="mt-2 max-w-(--container-measure) text-sm text-text-dim">
          {de.vitals.intro}
        </p>
        <div className="mt-4">
          <VitalsTable />
        </div>
      </section>

      <section className="mt-10">
        <h2 className="font-condensed">{de.export.heading}</h2>
        <p className="mt-2 max-w-(--container-measure) text-sm text-text-dim">
          {de.export.databaseHint}
        </p>
        <p className="mt-3 flex flex-wrap gap-4 font-condensed text-xs">
          <a href="/api/admin/export?kind=database">{de.export.database}</a>
          <a href="/api/admin/export?kind=bundle">{de.export.bundle}</a>
        </p>
      </section>
    </section>
  )
}

/**
 * Die Ladewerte der letzten sieben Tage. Median und 75. Perzentil, kein
 * Mittelwert - ein Ausreisser auf einem alten Laptop soll die Zahl nicht
 * bestimmen.
 */
async function VitalsTable() {
  const { metriken, routen } = await summarizeVitals()

  if (metriken.length === 0) {
    return <p className="text-text-dim">{de.vitals.empty}</p>
  }

  return (
    <div className="space-y-8">
      {/* Auf schmalen Schirmen scrollt die Tabelle in sich, statt die Seite
          breiter zu machen. Siehe docs/09-performance-und-ux.md. */}
      <div className="overflow-x-auto">
      <table className="w-full min-w-[28rem] border-collapse text-xs">
        <thead>
          <tr className="border-b border-line text-left font-condensed text-text-dim">
            <th className="py-1">{de.vitals.metric}</th>
            <th className="py-1">{de.vitals.median}</th>
            <th className="py-1">{de.vitals.p75}</th>
            <th className="py-1">{de.vitals.count}</th>
            <th className="py-1">{de.vitals.target}</th>
          </tr>
        </thead>
        <tbody>
          {metriken.map((zeile) => (
            <tr key={zeile.metric} className="border-b border-line">
              <td className="py-1 font-mono">{zeile.metric}</td>
              <td className="py-1">{formatVital(zeile.metric, zeile.median)}</td>
              <td className="py-1">{formatVital(zeile.metric, zeile.p75)}</td>
              <td className="py-1 text-text-dim">{zeile.count}</td>
              <td className="py-1 text-text-dim">{de.vitals.targets[zeile.metric] ?? ''}</td>
            </tr>
          ))}
        </tbody>
      </table>
      </div>

      {routen.length > 0 ? (
        <div>
          <h3 className="font-condensed text-xs text-text-dim">{de.vitals.worstRoutes}</h3>
          <div className="overflow-x-auto">
          <table className="mt-2 w-full min-w-[24rem] border-collapse text-xs">
            <tbody>
              {routen.map((zeile) => (
                <tr key={zeile.route} className="border-b border-line">
                  <td className="py-1 font-mono">{zeile.route}</td>
                  <td className="py-1">{formatVital(zeile.metric, zeile.p75)}</td>
                  <td className="py-1 text-text-dim">{zeile.count}</td>
                </tr>
              ))}
            </tbody>
          </table>
          </div>
        </div>
      ) : null}
    </div>
  )
}