/**
 * Hyperdrive-resident kernel (staged as /boot/init.js).
 * Loaded by the booter with an injected ctx object (trusted replication source).
 *
 * Boot order: /etc/os-release → /etc/motd → /etc/bare-os/rc → /etc/bare-os/rc.d/*
 * (sorted; digit-prefixed snippet names) → session banner → interactive loop.
 * Use ctx.registerKernelShutdownHook(fn) for teardown before initd disposers.
 */

/**
 * @param {Record<string, unknown>} ctx
 */
function wantBootTrace(ctx) {
  const v = ctx.env && ctx.env.BARE_OS_BOOT_TRACE
  return v === '1' || v === 'true'
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} label
 * @param {() => void | Promise<void>} fn
 */
async function bootTimed(ctx, label, fn) {
  const t0 = Date.now()
  await fn()
  if (wantBootTrace(ctx)) {
    ctx.console.error(`[boot] ${label}: ${Date.now() - t0}ms`)
  }
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} text
 */
async function runRcLines(ctx, text) {
  const { execLine, console } = ctx
  for (const line of text.split(/\r?\n/)) {
    const t = line.trim()
    if (!t || t.startsWith('#')) continue
    try {
      await execLine(t)
    } catch (e) {
      console.error((e && e.message) || String(e))
    }
  }
}

/**
 * @param {Record<string, unknown>} ctx
 */
async function printOsRelease(ctx) {
  const { drive, b4a, console } = ctx
  try {
    const rel = await drive.get('/etc/os-release')
    if (rel) console.log(b4a.toString(rel))
  } catch (e) {
    console.error((e && e.message) || String(e))
  }
}

/**
 * @param {Record<string, unknown>} ctx
 */
async function printMotd(ctx) {
  const { drive, b4a, console } = ctx
  try {
    const motd = await drive.get('/etc/motd')
    if (motd) console.log(b4a.toString(motd).trimEnd())
  } catch (e) {
    console.error((e && e.message) || String(e))
  }
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} drivePath absolute path on system drive
 * @param {string} label for errors
 */
async function runRcFileAt(ctx, drivePath, label) {
  const { drive, b4a, console } = ctx
  try {
    const buf = await drive.get(drivePath)
    if (!buf) return
    await runRcLines(ctx, b4a.toString(buf))
  } catch (e) {
    console.error(`${label}: ` + ((e && e.message) || String(e)))
  }
}

/**
 * Only run rc.d files whose name starts with a digit (e.g. `10-local`).
 * Skips README*, *.md, dotfiles, and *~ so documentation is never exec'd as shell.
 * @param {string} name basename from readdir
 */
function isBareOsRcSnippetFile(name) {
  if (!name || name.startsWith('.') || name.endsWith('~')) return false
  if (/^README(\.|$)/i.test(name)) return false
  if (/\.md$/i.test(name)) return false
  return /^[0-9]/.test(name)
}

/**
 * Optional snippets under /etc/bare-os/rc.d/ — executed in lexicographic order.
 * @param {Record<string, unknown>} ctx
 */
async function runBareOsRcDir(ctx) {
  const { drive, b4a, console } = ctx
  try {
    /** @type {string[]} */
    const names = []
    try {
      for await (const n of drive.readdir('/etc/bare-os/rc.d')) names.push(n)
    } catch {
      return
    }
    names.sort()
    for (const name of names) {
      if (!isBareOsRcSnippetFile(name)) continue
      const p = `/etc/bare-os/rc.d/${name}`
      try {
        const buf = await drive.get(p)
        if (!buf) continue
        await runRcLines(ctx, b4a.toString(buf))
      } catch (e) {
        console.error(`rc.d/${name}: ` + ((e && e.message) || String(e)))
      }
    }
  } catch (e) {
    console.error((e && e.message) || String(e))
  }
}

/**
 * @param {Record<string, unknown>} ctx
 */
async function printSessionBanner(ctx) {
  const { drive, b4a, console } = ctx
  for (const p of ['/etc/bare-os/banner', '/etc/issue']) {
    try {
      const buf = await drive.get(p)
      if (buf) {
        console.log(b4a.toString(buf).trimEnd())
        return
      }
    } catch {
      /* ignore */
    }
  }
  const defaultBanner =
    'Bare operating system — guest session (login [--new] <passphrase> to unlock) | shell: cd, export, if/fi, && || ;, |, exit | services: systemctl list-units, journalctl -u UNIT | try: help, ls /bin, crontab -l'
  if (ctx.bareOsSkipRepl) {
    console.log(
      'Bare operating system — non-interactive session (BARE_OS_SKIP_REPL).'
    )
    return
  }
  console.log(defaultBanner)
}

async function start(ctx) {
  const { readLine, execLine, console } = ctx
  await bootTimed(ctx, 'os-release', () => printOsRelease(ctx))
  await bootTimed(ctx, 'motd', () => printMotd(ctx))
  await bootTimed(ctx, 'rc', () => runRcFileAt(ctx, '/etc/bare-os/rc', 'rc'))
  await bootTimed(ctx, 'rc.d', () => runBareOsRcDir(ctx))
  await printSessionBanner(ctx)
  while (true) {
    const line = await readLine('')
    if (line == null) break
    const t = line.trim()
    if (t === '') continue
    let status = 'ok'
    try {
      status = await execLine(t)
    } catch (e) {
      console.error((e && e.message) || String(e))
    }
    if (status === 'exit') break
  }
}