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

/**
 * Line-oriented stdin for Bare/Pear (no node:readline) and Node fallback.
 * Pear-terminal uses bare-readline + bare-stdio; we mirror that after Node readline.
 */

import { createInterface as bareReadlineCreateInterface } from 'bare-readline'

/**
 * Strip C0 controls; apply BS (0x08) and DEL (0x7F) for raw SSH line fallback.
 * @param {string} s
 */
export function sanitizeInteractiveShellLine(s) {
  let out = ''
  for (let i = 0; i < s.length; i++) {
    const c = s.charCodeAt(i)
    if (c === 8 || c === 127) {
      out = out.slice(0, -1)
      continue
    }
    if (c < 32 && c !== 9) continue
    out += s[i]
  }
  return out
}

/**
 * Interactive line editor (cursor, echo, history) — same engine as the Pear console.
 * Caller should call **`close()`** when the session ends to detach input listeners.
 *
 * bare-readline treats **`prompt: ''` as falsy** and falls back to `'> '`, which flashes
 * after each `new Readline` (e.g. SSH recycle). Use a non-empty placeholder or pass
 * **`initialPrompt`** so the constructor’s first `prompt()` matches the real PS1.
 *
 * @param {import('stream').Readable} stdin
 * @param {import('stream').Writable} stdout
 * @param {{ initialPrompt?: string }} [opts]
 * @returns {Promise<{ readLine: (prompt: string) => Promise<string | null>, close: () => void }>}
 */
export async function createBareReadlineSession(stdin, stdout, opts = {}) {
  if (typeof bareReadlineCreateInterface !== 'function') {
    throw new Error('bare-readline: createInterface missing')
  }
  const initial =
    typeof opts.initialPrompt === 'string' && opts.initialPrompt.length > 0
      ? opts.initialPrompt
      : ' '
  const rl = bareReadlineCreateInterface({
    input: stdin,
    output: stdout,
    prompt: initial
  })
  return {
    readLine(prompt) {
      return new Promise((resolve) => {
        rl.setPrompt(prompt)
        rl.prompt()
        rl.once('line', (line) => {
          resolve(line)
        })
      })
    },
    close() {
      try {
        rl.close()
      } catch {
        /* ignore */
      }
    }
  }
}

/**
 * @param {import('stream').Readable} stdin
 * @param {import('stream').Writable} stdout
 * @returns {(prompt: string) => Promise<string>}
 */
export async function createBareReadlineQuestion(stdin, stdout) {
  const { readLine } = await createBareReadlineSession(stdin, stdout)
  return readLine
}

/**
 * @param {import('stream').Readable} stdin
 * @param {import('stream').Writable} stdout
 * @returns {(prompt: string) => Promise<string | null>}
 */
export function createStreamLineReader(stdin, stdout) {
  let buf = ''
  /** @type {string[]} */
  const queue = []
  /** @type {((line: string | null) => void)[]} */
  const waiters = []

  function deliver(line) {
    if (waiters.length) waiters.shift()(line)
    else queue.push(line)
  }

  function onData(chunk) {
    const s =
      typeof chunk === 'string' ? chunk : Buffer.from(chunk).toString('utf8')
    buf += s
    while (buf.length) {
      const n = buf.indexOf('\n')
      const r = buf.indexOf('\r')
      if (n === -1 && r === -1) break
      let cut
      let ateCr = false
      if (n === -1) {
        cut = r
        ateCr = true
      } else if (r === -1) {
        cut = n
      } else if (r < n) {
        cut = r
        ateCr = true
      } else {
        cut = n
      }
      const raw = buf.slice(0, cut)
      buf = buf.slice(cut + 1)
      if (ateCr && buf.length && buf[0] === '\n') buf = buf.slice(1)
      deliver(String(raw).replace(/\r/g, ''))
    }
  }

  function flushRemainder() {
    if (buf.length) {
      deliver(buf.replace(/\r$/, ''))
      buf = ''
    }
  }

  function onEnd() {
    flushRemainder()
    while (waiters.length) waiters.shift()(null)
  }

  if (typeof stdin.setEncoding === 'function') stdin.setEncoding('utf8')
  stdin.on('data', onData)
  stdin.on('end', onEnd)
  stdin.on('error', onEnd)
  if (typeof stdin.resume === 'function') stdin.resume()

  return function readLine(prompt) {
    if (typeof stdout.write === 'function') {
      // DECTCEM: show cursor (boot splash / curses often hide it; dumb fallback has no redraw)
      stdout.write('\x1b[?25h\x1b[0m' + prompt)
    }
    if (queue.length) return Promise.resolve(queue.shift() ?? null)
    return new Promise((resolve) => waiters.push(resolve))
  }
}

/**
 * @returns {boolean}
 */
export function looksLikeInteractiveStdin(stdin) {
  return Boolean(
    stdin &&
    typeof stdin.on === 'function' &&
    typeof stdin.resume === 'function'
  )
}