/* 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 sumSysv(u8) {
  let crc = 0
  for (let i = 0; i < u8.length; i++) crc += u8[i]
  crc = (crc & 0xffff) + ((crc >> 16) & 0xffff)
  crc = (crc & 0xffff) + ((crc >> 16) & 0xffff)
  return crc & 0xffff
}

function sumBsd(u8) {
  let cksum = 0
  for (let i = 0; i < u8.length; i++) {
    cksum = (cksum >> 1) + ((cksum & 1) << 15)
    cksum = (cksum + u8[i]) & 0xffff
  }
  return cksum
}

async function run(ctx, argv) {
  let bsd = false
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '-h' || a === '--help') {
      ctx.console.log(
        'usage: sum [-r] [FILE]...\n' +
          '  -r  BSD algorithm (default is SysV / CRC16-style sum)'
      )
      ctx.exitCode = 0
      return
    }
    if (a === '-r') bsd = true
    else if (a.startsWith('-') && a !== '-') {
      ctx.console.error('sum: unsupported option ' + a)
      ctx.exitCode = 1
      return
    } else paths.push(a)
  }
  const b4 = ctx.b4a
  function one(name, buf) {
    const u8 = buf instanceof Uint8Array ? buf : new Uint8Array(buf)
    const blocks = Math.ceil(u8.length / 512) || 1
    const v = bsd ? sumBsd(u8) : sumSysv(u8)
    ctx.console.log(v + '\t' + blocks + '\t' + name)
  }
  if (!paths.length || (paths.length === 1 && paths[0] === '-')) {
    one('-', b4.from(bareStdin(ctx)))
    return
  }
  for (const p of paths) {
    if (p === '-') {
      one('-', b4.from(bareStdin(ctx)))
      continue
    }
    const b = await ctx.vfs.readFile(p)
    if (!b) {
      ctx.console.error('sum: ' + p + ': No such file')
      ctx.exitCode = 1
      continue
    }
    one(p, b)
  }
}