/**
 * Bare-compatible process helpers.
 *
 * bare-subprocess (mapped from `child_process` in Bare) provides spawn /
 * spawnSync only — not Node's execFile. Collectors should use this module.
 */
import { spawn, spawnSync } from 'child_process'

/**
 * @param {unknown} buf
 * @param {BufferEncoding|'buffer'|undefined} encoding
 */
function decode(buf, encoding = 'utf8') {
  if (buf == null) return encoding === 'buffer' ? Buffer.alloc(0) : ''
  if (encoding === 'buffer') {
    return Buffer.isBuffer(buf) ? buf : Buffer.from(buf)
  }
  if (typeof buf === 'string') return buf
  return Buffer.from(buf).toString(encoding || 'utf8')
}

/**
 * Run a command and return stdout/stderr (Promise), Bare-safe.
 *
 * @param {string} file
 * @param {string[]} [args]
 * @param {{
 *   cwd?: string,
 *   env?: NodeJS.ProcessEnv,
 *   timeout?: number,
 *   encoding?: BufferEncoding|'buffer',
 *   maxBuffer?: number,
 * }} [opts]
 * @returns {Promise<{ stdout: string|Buffer, stderr: string|Buffer }>}
 */
export function execFile(file, args = [], opts = {}) {
  const encoding = opts.encoding ?? 'utf8'
  const timeout = Number(opts.timeout) || 0
  const maxBuffer = Number(opts.maxBuffer) || 4 * 1024 * 1024

  return new Promise((resolve, reject) => {
    let child
    try {
      child = spawn(file, args, {
        cwd: opts.cwd,
        env: opts.env,
        stdio: ['ignore', 'pipe', 'pipe'],
      })
    } catch (err) {
      reject(err)
      return
    }

    /** @type {Buffer[]} */
    const outChunks = []
    /** @type {Buffer[]} */
    const errChunks = []
    let outLen = 0
    let errLen = 0
    let settled = false
    /** @type {ReturnType<typeof setTimeout>|null} */
    let timer = null

    const settle = (err, result) => {
      if (settled) return
      settled = true
      if (timer) clearTimeout(timer)
      if (err) reject(err)
      else resolve(result)
    }

    if (timeout > 0) {
      timer = setTimeout(() => {
        try {
          child.kill()
        } catch {
          // ignore
        }
        const err = new Error(`Command timed out: ${file}`)
        err.killed = true
        settle(err)
      }, timeout)
    }

    const onChunk = (chunks, which) => (chunk) => {
      const buf = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk)
      if (which === 'out') {
        outLen += buf.length
        if (outLen > maxBuffer) {
          try {
            child.kill()
          } catch {
            // ignore
          }
          settle(new Error(`stdout maxBuffer exceeded: ${file}`))
          return
        }
      } else {
        errLen += buf.length
        if (errLen > maxBuffer) {
          try {
            child.kill()
          } catch {
            // ignore
          }
          settle(new Error(`stderr maxBuffer exceeded: ${file}`))
          return
        }
      }
      chunks.push(buf)
    }

    if (child.stdout) child.stdout.on('data', onChunk(outChunks, 'out'))
    if (child.stderr) child.stderr.on('data', onChunk(errChunks, 'err'))
    child.on('error', (err) => settle(err))
    child.on('close', (code, signal) => {
      const stdout = decode(Buffer.concat(outChunks), encoding)
      const stderr = decode(Buffer.concat(errChunks), encoding)
      if (code && code !== 0) {
        const err = new Error(`Command failed: ${file} ${args.join(' ')}`)
        err.status = code
        err.code = code
        err.signal = signal
        err.stdout = stdout
        err.stderr = stderr
        settle(err)
        return
      }
      settle(null, { stdout, stderr })
    })
  })
}

/**
 * Synchronous helper for short tools (zfs/unbound-style).
 *
 * @param {string} file
 * @param {string[]} [args]
 * @param {{ cwd?: string, env?: NodeJS.ProcessEnv, encoding?: BufferEncoding|'buffer', maxBuffer?: number }} [opts]
 */
export function execFileSync(file, args = [], opts = {}) {
  const encoding = opts.encoding ?? 'utf8'
  const res = spawnSync(file, args, {
    cwd: opts.cwd,
    env: opts.env,
    maxBuffer: opts.maxBuffer || 4 * 1024 * 1024,
  })
  if (res.error) throw res.error
  const stdout = decode(res.stdout, encoding)
  const stderr = decode(res.stderr, encoding)
  if (res.status && res.status !== 0) {
    const err = new Error(`Command failed: ${file} ${args.join(' ')}`)
    err.status = res.status
    err.code = res.status
    err.signal = res.signal
    err.stdout = stdout
    err.stderr = stderr
    throw err
  }
  return { stdout, stderr, status: res.status ?? 0 }
}