bare-operating-system/kernel/bin/expand

/* 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
}

/**
 * @param {string} tabArg
 * @returns {number[]}
 */
function parseTabStops(tabArg) {
  const raw = String(tabArg || '').trim()
  if (!raw) return [8]
  const parts = raw.split(',')
  /** @type {number[]} */
  const out = []
  for (const p of parts) {
    const n = parseInt(p.trim(), 10)
    if (Number.isFinite(n) && n > 0) out.push(n)
  }
  if (!out.length) return [8]
  out.sort((a, b) => a - b)
  /** @type {number[]} */
  const uniq = []
  for (const x of out) {
    if (uniq.length === 0 || uniq[uniq.length - 1] !== x) uniq.push(x)
  }
  return uniq
}

function nextTabStop(col, stops) {
  if (stops.length === 1) {
    const w = stops[0]
    return (Math.floor(col / w) + 1) * w
  }
  for (const s of stops) {
    if (s > col) return s
  }
  const last = stops[stops.length - 1]
  const prev = stops[stops.length - 2]
  const step = Math.max(1, last - prev)
  let x = last
  while (x <= col) x += step
  return x
}

function expandLine(line, stops) {
  let col = 0
  let out = ''
  for (let i = 0; i < line.length; i++) {
    const ch = line[i]
    if (ch === '\t') {
      const target = nextTabStop(col, stops)
      while (col < target) {
        out += ' '
        col++
      }
    } else {
      out += ch
      if (ch === '\n' || ch === '\r') col = 0
      else col++
    }
  }
  return out
}

async function run(ctx, argv) {
  let tabArg = '8'
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '-h' || a === '--help') {
      ctx.console.log(
        'usage: expand [-t LIST] [FILE]...\n' +
          'Convert tabs to spaces. -t takes one width (e.g. 8) or a comma-separated ' +
          'increasing tab stop list (e.g. 1,4,8); with multiple stops, later intervals repeat.'
      )
      return
    }
    if (a === '-t' && argv[i + 1]) {
      tabArg = argv[++i]
      continue
    }
    if (a.startsWith('-t') && a.length > 2) {
      tabArg = a.slice(2)
      continue
    }
    if (a.startsWith('--tabs=')) {
      tabArg = a.slice(7)
      continue
    }
    if (a.startsWith('-')) {
      ctx.console.error('expand: unsupported option ' + a)
      ctx.exitCode = 1
      return
    }
    paths.push(a)
  }
  const stops = parseTabStops(tabArg)
  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(expandLine(line, stops))
    }
  }
  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('expand: ' + p + ': No such file')
      ctx.exitCode = 1
      continue
    }
    proc(b4.toString(b))
  }
}