/**
 * 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.
 */

/**
 * @param {import('stream').Readable} stdin
 * @param {import('stream').Writable} stdout
 * @returns {(prompt: string) => Promise<string>}
 */
export async function createBareReadlineQuestion(stdin, stdout) {
  const mod = await import('bare-readline')
  const createInterface = mod.createInterface ?? mod.default?.createInterface
  if (typeof createInterface !== 'function') {
    throw new Error('bare-readline: createInterface missing')
  }
  const rl = createInterface({
    input: stdin,
    output: stdout,
    prompt: ''
  })
  return (prompt) =>
    new Promise((resolve) => {
      rl.setPrompt(prompt)
      rl.prompt()
      rl.once('line', (line) => {
        resolve(line)
      })
    })
}

/**
 * @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
    let i
    while ((i = buf.indexOf('\n')) !== -1) {
      const raw = buf.slice(0, i)
      buf = buf.slice(i + 1)
      deliver(raw.replace(/\r$/, ''))
    }
  }

  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') stdout.write(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'
  )
}