bare-operating-system/packages/bare-os-seeder/kernel/bin/unexpand

/* 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 parseWidth(tabArg) {
  const n = parseInt(String(tabArg).split(',')[0].trim(), 10)
  return Number.isFinite(n) && n > 0 ? n : 8
}

function unexpandLine(line, w) {
  let out = ''
  let col = 0
  let i = 0
  while (i < line.length) {
    if (line[i] === ' ') {
      let j = i
      while (j < line.length && line[j] === ' ') j++
      const n = j - i
      const posMod = col % w
      if (posMod === 0 && n >= w) {
        const tabs = Math.floor(n / w)
        const rest = n % w
        for (let k = 0; k < tabs; k++) out += '\t'
        col += tabs * w
        i += tabs * w
        for (let k = 0; k < rest; k++) {
          out += ' '
          col++
          i++
        }
        continue
      }
      const toNext = posMod === 0 ? w : w - posMod
      if (n >= toNext && toNext > 0 && posMod !== 0) {
        out += '\t'
        col += toNext
        i += toNext
        continue
      }
      out += line.slice(i, j)
      col += n
      i = j
      continue
    }
    const ch = line[i]
    out += ch
    if (ch === '\t') col = (Math.floor(col / w) + 1) * w
    else if (ch === '\n' || ch === '\r') col = 0
    else col++
    i++
  }
  return out
}

async function run(ctx, argv) {
  let w = 8
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '-h' || a === '--help') {
      ctx.console.log(
        'usage: unexpand [-t N] [FILE]...\nConvert runs of spaces to tabs (width N, default 8).'
      )
      return
    }
    if (a === '-t' && argv[i + 1]) {
      w = parseWidth(argv[++i])
      continue
    }
    if (a.startsWith('-t') && a.length > 2) {
      w = parseWidth(a.slice(2))
      continue
    }
    if (a.startsWith('--tabs=')) {
      w = parseWidth(a.slice(7))
      continue
    }
    if (a.startsWith('-')) {
      ctx.console.error('unexpand: unsupported option ' + a)
      ctx.exitCode = 1
      return
    }
    paths.push(a)
  }
  const b4 = ctx.b4a
  function proc(text) {
    const lines = text.split('\n')
    for (let li = 0; li < lines.length; li++) {
      const isLast = li === lines.length - 1
      const line = lines[li]
      if (isLast && line === '' && lines.length > 1) continue
      ctx.console.log(unexpandLine(line, w))
    }
  }
  if (!paths.length) {
    proc(bareStdin(ctx))
    return
  }
  for (const p of paths) {
    if (p === '-') {
      proc(bareStdin(ctx))
      continue
    }
    const b = await ctx.vfs.readFile(p)
    if (!b) {
      ctx.console.error('unexpand: ' + p + ': No such file')
      ctx.exitCode = 1
      continue
    }
    proc(b4.toString(b))
  }
}