/* BARE_OS_BIN_API 1.0.0 — bump when staged /bin script semantics change (see developer guide). */
/** Shared helpers for drive-resident /bin scripts (prepended before each command). */
function bareStdin(ctx) {
  return typeof ctx.shellStdin === 'string' ? ctx.shellStdin : ''
}

/** @param {number} mode @param {'file' | 'directory' | 'symlink'} type */
function bareFormatModeString(mode, type) {
  const typeChar = type === 'directory' ? 'd' : type === 'symlink' ? 'l' : '-'
  const perm = mode & 0o777
  const r = (bit) => (perm & bit ? 'r' : '-')
  const w = (bit) => (perm & bit ? 'w' : '-')
  const x = (bit) => (perm & bit ? 'x' : '-')
  return (
    typeChar +
    r(0o400) +
    w(0o200) +
    x(0o100) +
    r(0o040) +
    w(0o020) +
    x(0o010) +
    r(0o004) +
    w(0o002) +
    x(0o001)
  )
}

/** @param {number} mtimeMs @param {number} [nowMs] */
function bareFormatLsMtime(mtimeMs, nowMs) {
  const now = nowMs != null ? nowMs : Date.now()
  const d = new Date(mtimeMs)
  const months = [
    'Jan',
    'Feb',
    'Mar',
    'Apr',
    'May',
    'Jun',
    'Jul',
    'Aug',
    'Sep',
    'Oct',
    'Nov',
    'Dec'
  ]
  const mon = months[d.getMonth()]
  const day = String(d.getDate()).padStart(2, ' ')
  const sixMo = 180 * 24 * 3600 * 1000
  if (Math.abs(now - mtimeMs) > sixMo) {
    const yr = String(d.getFullYear()).padStart(4, ' ')
    return mon + ' ' + day + '  ' + yr
  }
  const hh = String(d.getHours()).padStart(2, '0')
  const mm = String(d.getMinutes()).padStart(2, '0')
  return mon + ' ' + day + ' ' + hh + ':' + mm
}

/** @param {number} size */
function barePosixBlocks(size) {
  return Math.ceil(Number(size) / 512) || 0
}

/**
 * Raw stdout for NUL/binary when **`process.stdout.write`** is missing.
 * If **`ctx.bareOsBinWrite(Uint8Array|string)`** is set (tests / host), use it.
 * @param {Record<string, unknown>} ctx
 * @param {string | Uint8Array} chunk
 * @returns {boolean}
 */
function bareOsEmitRaw(ctx, chunk) {
  if (typeof ctx.bareOsBinWrite === 'function') {
    const b4 = ctx.b4a
    const u8 =
      typeof chunk === 'string'
        ? b4 && typeof b4.from === 'function'
          ? b4.from(chunk)
          : new TextEncoder().encode(chunk)
        : chunk
    ctx.bareOsBinWrite(u8 instanceof Uint8Array ? u8 : new Uint8Array(u8))
    return true
  }
  const w = globalThis.process?.stdout?.write
  if (typeof w === 'function') {
    w.call(globalThis.process.stdout, chunk)
    return true
  }
  return false
}

function splitSuffix(prefix, i) {
  const a = 'abcdefghijklmnopqrstuvwxyz'
  const hi = Math.floor(i / 26) % 26
  const lo = i % 26
  return prefix + a[hi] + a[lo]
}

async function run(ctx, argv) {
  let lineCount = 1000
  let byteCount = null
  let prefix = 'x'
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '-h' || a === '--help') {
      ctx.console.log(
        'usage: split [-l N] [-b N] [INPUT [PREFIX]]\nSplit INPUT into pieces (default -l 1000).'
      )
      return
    }
    if (a === '-l' && argv[i + 1]) {
      lineCount = parseInt(argv[++i], 10)
      byteCount = null
      if (!Number.isFinite(lineCount) || lineCount < 1) lineCount = 1000
      continue
    }
    if (a.startsWith('-l') && a.length > 2) {
      lineCount = parseInt(a.slice(2), 10)
      byteCount = null
      continue
    }
    if (a === '-b' && argv[i + 1]) {
      byteCount = parseInt(argv[++i], 10)
      lineCount = null
      if (!Number.isFinite(byteCount) || byteCount < 1) byteCount = 512
      continue
    }
    if (a.startsWith('-')) {
      ctx.console.error('split: unsupported option ' + a)
      ctx.exitCode = 1
      return
    }
    paths.push(a)
  }
  const maxFiles =
    parseInt(ctx.vfs.env.BARE_OS_SPLIT_MAX_FILES || '10000', 10) || 10000
  let inputPath = '-'
  if (paths.length === 1) inputPath = paths[0]
  else if (paths.length >= 2) {
    inputPath = paths[0]
    prefix = paths[1]
  }
  const b4 = ctx.b4a
  let text
  if (inputPath === '-') text = bareStdin(ctx)
  else {
    const b = await ctx.vfs.readFile(inputPath)
    if (!b) {
      ctx.console.error('split: cannot read ' + inputPath)
      ctx.exitCode = 1
      return
    }
    text = b4.toString(b)
  }
  if (byteCount != null) {
    const u8 = b4.from(text)
    let off = 0
    let idx = 0
    while (off < u8.length) {
      if (idx >= maxFiles) {
        ctx.console.error('split: too many output files')
        ctx.exitCode = 1
        return
      }
      const chunk = u8.subarray(off, off + byteCount)
      off += byteCount
      await ctx.vfs.writeFile(splitSuffix(prefix, idx), chunk)
      idx++
    }
    return
  }
  const endsNl = text.endsWith('\n')
  const lines = text.split('\n')
  if (endsNl && lines.length && lines[lines.length - 1] === '') lines.pop()
  let idx = 0
  let batch = []
  function flush(forceNl) {
    if (!batch.length) return
    if (idx >= maxFiles) {
      ctx.console.error('split: too many output files')
      ctx.exitCode = 1
      return
    }
    const body =
      batch.join('\n') + (forceNl || batch.length === lineCount ? '\n' : '')
    const p = splitSuffix(prefix, idx)
    idx++
    batch = []
    return ctx.vfs.writeFile(p, b4.from(body))
  }
  for (let li = 0; li < lines.length; li++) {
    batch.push(lines[li])
    if (batch.length >= lineCount) {
      await flush(true)
      if (ctx.exitCode) return
    }
  }
  if (batch.length) {
    const tailNl = endsNl
    const body = batch.join('\n') + (tailNl ? '\n' : '')
    if (idx >= maxFiles) {
      ctx.console.error('split: too many output files')
      ctx.exitCode = 1
      return
    }
    await ctx.vfs.writeFile(splitSuffix(prefix, idx), b4.from(body))
  }
}