#!/usr/bin/env node
/**
 * Performance budget gate from latest Lighthouse site report.
 * Usage:
 *   node scripts/a11y/audit-perf-gate.mjs [--min=85] [--max-lcp=2500] [--require]
 * Env: MIM_PERF_GATE_MIN, MIM_PERF_GATE_MAX_LCP_MS, MIM_PERF_GATE_REQUIRE=1
 */
import { readFileSync, existsSync } from 'node:fs'
import { dirname, join } from 'node:path'
import { fileURLToPath } from 'node:url'

const __dirname = dirname(fileURLToPath(import.meta.url))
const repoRoot = join(__dirname, '../..')
const reportPath = join(repoRoot, 'reports/status/mim4u-site-lighthouse-latest.json')

const minArg = process.argv.find((a) => a.startsWith('--min='))
const lcpArg = process.argv.find((a) => a.startsWith('--max-lcp='))
const minScore = Number(minArg?.split('=')[1] || process.env.MIM_PERF_GATE_MIN || 85)
const maxLcpMs = Number(lcpArg?.split('=')[1] || process.env.MIM_PERF_GATE_MAX_LCP_MS || 2500)
const requireReport = process.argv.includes('--require') || process.env.MIM_PERF_GATE_REQUIRE === '1'

if (!existsSync(reportPath)) {
  const msg = `Perf gate: no report at ${reportPath} — run npm run a11y:site-lighthouse`
  if (requireReport) {
    console.error(msg)
    process.exit(1)
  }
  console.warn(`${msg} (skipped)`)
  process.exit(0)
}

const report = JSON.parse(readFileSync(reportPath, 'utf8'))
const perf = report.scores?.performance
const lcpMs = report.lcpMs

console.log(
  `Perf gate: performance=${perf ?? 'n/a'} (min ${minScore})${lcpMs != null ? `, LCP=${lcpMs}ms (max ${maxLcpMs})` : ''}`,
)

let failed = false

if (typeof perf !== 'number') {
  console.error('Perf gate: performance score missing from report')
  if (requireReport) failed = true
} else if (perf < minScore) {
  console.error(`Perf gate FAILED: performance ${perf} < ${minScore}`)
  failed = true
}

if (typeof lcpMs === 'number' && lcpMs > maxLcpMs) {
  console.error(`Perf gate FAILED: LCP ${lcpMs}ms > ${maxLcpMs}ms`)
  failed = true
}

if (failed) {
  console.error('Run CWV sprint / npm run a11y:site-lighthouse after deploy.')
  process.exit(1)
}

console.log('Perf gate passed.')
process.exit(0)