import test from 'brittle'
import { readFile } from 'node:fs/promises'
import { createContext, runInContext } from 'node:vm'
import { dirname, join } from 'node:path'
import { fileURLToPath } from 'node:url'

const __dirname = dirname(fileURLToPath(import.meta.url))
const helpersPath = join(__dirname, '../lib/baretop-ui-helpers.js')
const composePath = join(__dirname, '../lib/baretop-compose.js')
const largeProcPath = join(__dirname, 'fixtures/baretop-large-process-table.json')
const largeNetPath = join(__dirname, 'fixtures/baretop-large-net-summary.json')

function pctl(samples, p) {
  const sorted = samples.slice().sort((a, b) => a - b)
  if (!sorted.length) return 0
  const idx = Math.max(
    0,
    Math.min(sorted.length - 1, Math.floor((p / 100) * (sorted.length - 1)))
  )
  return sorted[idx]
}

test('baretop perf baseline emits KPI envelope', async (t) => {
  const helpers = await readFile(helpersPath, 'utf8')
  const compose = await readFile(composePath, 'utf8')
  const proc = JSON.parse(await readFile(largeProcPath, 'utf8'))
  const net = JSON.parse(await readFile(largeNetPath, 'utf8'))
  const ctx = createContext({})
  runInContext(helpers + '\n' + compose, ctx)

  const composeSamples = []
  const emitSamples = []
  const emitBytes = []
  const dropRatio = []
  const fetchSamples = []

  for (let i = 0; i < 40; i++) {
    const t0 = Date.now()
    const rows = ctx.bareTopSortProcessRows(
      ctx.bareTopProcessRowsFromTable(proc),
      'cpu',
      false,
      { sortWallMs: 1000 }
    )
    const netLines = ctx.bareTopNetTabLines(net, 120, { maxLines: 220 })
    const frame = ['baretop-perf-baseline', 'rows=' + rows.length].concat(netLines)
    const composeMs = Date.now() - t0
    composeSamples.push(composeMs)
    fetchSamples.push(5 + (i % 4))
    const e0 = Date.now()
    const emit = ctx.bareTopEmitFrame(
      {},
      { write() {} },
      frame.join('\r\n'),
      {
        prevLines: null,
        rows: 40,
        cols: 120,
        incrementalFrameDiff: false,
        useLineHash: false,
        fullscreenPanel: false,
        cup: (r, c) => `\\x1b[${r};${c}H`
      }
    )
    emitSamples.push(Date.now() - e0)
    emitBytes.push(emit.wrotePatch ? emit.patchLen : frame.join('\r\n').length)
    dropRatio.push(0)
  }

  const kpi = {
    fetchMs: { p50: pctl(fetchSamples, 50), p95: pctl(fetchSamples, 95) },
    composeMs: { p50: pctl(composeSamples, 50), p95: pctl(composeSamples, 95) },
    emitMs: { p50: pctl(emitSamples, 50), p95: pctl(emitSamples, 95) },
    emitBytes: { p50: pctl(emitBytes, 50), p95: pctl(emitBytes, 95) },
    droppedRefreshPct: {
      p50: pctl(dropRatio, 50),
      p95: pctl(dropRatio, 95)
    }
  }

  t.ok(kpi.fetchMs.p50 >= 0)
  t.ok(kpi.composeMs.p95 >= kpi.composeMs.p50)
  t.ok(kpi.emitBytes.p95 >= kpi.emitBytes.p50)
  t.ok(kpi.droppedRefreshPct.p50 >= 0)
  t.ok(kpi.composeMs.p95 <= 30, 'compose p95 budget <= 30ms')
  t.ok(kpi.emitMs.p95 <= 15, 'emit p95 budget <= 15ms')
  t.ok(kpi.fetchMs.p95 <= 12, 'fetch p95 budget <= 12ms')
})