bare-operating-system/packages/bare-os-booter/lib/cli/repl-session.js

import {
  createFishReadLine,
  disableFishRawMode,
  releaseFishStdin
} from './fish-readline.js'
import {
  bindReplDebugStream,
  isReplDebug,
  replDbg,
  unbindReplDebugStream
} from './debug-repl.js'
import {
  bareInitdShutdownActiveUnitsReverse,
  runKernelShutdownHooks,
  stopBareInitd
} from '../initd/bare-initd.js'
import { wrapReadLineWithReplHistoryPersist } from './cli-readline.js'

/**
 * Kernel `console` must write to the same stream as the line editor so cursor stays in sync.
 * @param {import('stream').Writable} stream
 * @returns {import('console').Console | Record<string, (...args: unknown[]) => void>}
 */
function createFishSyncedConsole(stream) {
  const Cons = globalThis.Console
  if (typeof Cons === 'function') {
    return new Cons(stream, stream)
  }
  const writeLn = (...args) => {
    stream.write(
      args.map((a) => (typeof a === 'string' ? a : String(a))).join(' ') + '\n'
    )
  }
  return {
    log: writeLn,
    info: writeLn,
    debug: writeLn,
    error: writeLn,
    warn: writeLn
  }
}

/**
 * One TTY session for the kernel: `readLine`, `console`, and `writeScreen` share `stdout`.
 * When the TTY supports raw mode, fish-style editing is the primary implementation (not a
 * second layer on top of bare-readline output).
 *
 * @param {{
 *   stdin: import('stream').Readable | null,
 *   stdout: import('stream').Writable | null,
 *   rawReadLine: (p: string) => Promise<string | null>,
 *   interactiveAvailable: boolean,
 *   skipInteractive: boolean,
 *   ctx: Record<string, unknown>
 * }} args
 */
export async function createKernelReplSession({
  stdin,
  stdout,
  rawReadLine,
  interactiveAvailable,
  skipInteractive,
  ctx
}) {
  const baseConsole = globalThis.console

  if (isReplDebug() && stdout) bindReplDebugStream(stdout)

  function writeScreen(chunk) {
    const s = typeof chunk === 'string' ? chunk : String(chunk)
    if (isReplDebug()) {
      replDbg(
        'repl-writeScreen',
        'write',
        `len=${s.length}`,
        `dest=${stdout && typeof stdout.write === 'function' ? 'sessionStdout' : 'process.stdout'}`,
        JSON.stringify(s.length > 64 ? s.slice(0, 64) + '…' : s)
      )
    }
    if (stdout && typeof stdout.write === 'function') {
      stdout.write(s)
    } else if (
      globalThis.process?.stdout &&
      typeof globalThis.process.stdout.write === 'function'
    ) {
      globalThis.process.stdout.write(s)
    }
  }

  const fishOff = globalThis.process?.env?.BARE_OS_FISH === '0'
  let fishRead = null

  if (isReplDebug()) {
    replDbg(
      'repl',
      'createKernelReplSession',
      JSON.stringify({
        skipInteractive,
        interactiveAvailable,
        fishOff,
        hasStdin: Boolean(stdin),
        hasStdout: Boolean(stdout)
      })
    )
  }

  if (!skipInteractive && interactiveAvailable && !fishOff && stdin && stdout) {
    fishRead = await createFishReadLine(ctx, {
      stdin,
      stdout,
      writeScreen
    })
    if (isReplDebug()) {
      replDbg(
        'repl',
        'createFishReadLine result',
        fishRead ? 'attached' : 'null (fallback rawReadLine)'
      )
    }
    if (fishRead && stdout && typeof stdout.write === 'function') {
      stdout.write(
        '\x1b[0m[bare-os-booter] Fish-style TTY line editor active\n'
      )
    }
  }

  let outConsole = baseConsole
  if (fishRead && stdout) {
    outConsole = createFishSyncedConsole(stdout)
  }

  if (isReplDebug()) {
    replDbg(
      'repl',
      'console binding',
      fishRead
        ? 'createFishSyncedConsole(session stdout)'
        : 'process global console'
    )
  }

  const coreReadLine = async (prompt) => {
    if (isReplDebug()) {
      replDbg(
        'repl-readLine',
        'invoke',
        `impl=${fishRead ? 'fish' : 'raw'}`,
        JSON.stringify(
          typeof prompt === 'string' ? prompt.slice(0, 100) : prompt
        )
      )
    }
    const line = await (fishRead || rawReadLine)(prompt)
    if (isReplDebug()) {
      replDbg(
        'repl-readLine',
        'resolved',
        line === null ? 'null' : `string len=${line.length}`,
        line != null ? JSON.stringify(line.slice(0, 120)) : ''
      )
    }
    if (line == null && !skipInteractive && !interactiveAvailable) {
      baseConsole.log(
        '(No interactive stdin — leaving booter and replication running. Close the app to quit.)'
      )
      await new Promise(() => {})
    }
    return line
  }

  const histPersistOn =
    globalThis.process?.env?.BARE_OS_REPL_HISTORY === '1' ||
    globalThis.process?.env?.BARE_OS_REPL_HISTORY === 'true'
  const readLine =
    !fishRead &&
    histPersistOn &&
    ctx &&
    ctx.personalDrive &&
    typeof ctx.personalDrive.put === 'function'
      ? wrapReadLineWithReplHistoryPersist(coreReadLine, ctx)
      : coreReadLine

  async function cleanup() {
    if (isReplDebug())
      replDbg('repl', 'cleanup', fishRead ? 'fish teardown' : 'noop')
    await bareInitdShutdownActiveUnitsReverse(ctx)
    await runKernelShutdownHooks()
    stopBareInitd()
    if (fishRead && stdin) {
      disableFishRawMode(stdin)
      releaseFishStdin(stdin)
    }
    unbindReplDebugStream()
  }

  return {
    writeScreen,
    readLine,
    console: outConsole,
    cleanup,
    fishActive: Boolean(fishRead),
    /** Set when fish owns the TTY; used to suspend/resume around host subprocesses. */
    fishStdin: fishRead ? stdin : null
  }
}