/* 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
}

/**
 * base64 — encode or decode Base64 (RFC 4648).
 * Uses btoa/atob or Buffer when available; otherwise a small inline encoder.
 */
function bareB64EncodeBytes(u8) {
  const B = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
  let out = ''
  let i = 0
  for (; i + 2 < u8.length; i += 3) {
    const n = (u8[i] << 16) | (u8[i + 1] << 8) | u8[i + 2]
    out += B[(n >> 18) & 63] + B[(n >> 12) & 63] + B[(n >> 6) & 63] + B[n & 63]
  }
  const rest = u8.length - i
  if (rest === 1) {
    const n = u8[i] << 16
    out += B[(n >> 18) & 63] + B[(n >> 12) & 63] + '=='
  } else if (rest === 2) {
    const n = (u8[i] << 16) | (u8[i + 1] << 8)
    out += B[(n >> 18) & 63] + B[(n >> 12) & 63] + B[(n >> 6) & 63] + '='
  }
  return out
}

function bareB64DecodeToU8(s) {
  const t = String(s).replace(/\s+/g, '')
  if (typeof globalThis.Buffer !== 'undefined') {
    return new Uint8Array(globalThis.Buffer.from(t, 'base64'))
  }
  if (typeof globalThis.atob === 'function') {
    const bin = globalThis.atob(t)
    const out = new Uint8Array(bin.length)
    for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i) & 255
    return out
  }
  throw new Error('base64 decode requires Buffer or atob')
}

async function run(ctx, argv) {
  let decode = false
  let wrap = 76
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '-h' || a === '--help') {
      ctx.console.log(
        'usage: base64 [-d] [-w COLS] [FILE]\n' +
          '       base64 --decode [-w COLS] [FILE]\n' +
          'Default: encode stdin or FILE; -d/--decode decodes to raw bytes on stdout.'
      )
      ctx.exitCode = 0
      return
    }
    if (a === '-d' || a === '--decode') {
      decode = true
      continue
    }
    if ((a === '-w' || a === '--wrap') && argv[i + 1]) {
      wrap = Number.parseInt(argv[++i], 10)
      if (!Number.isFinite(wrap) || wrap < 0) wrap = 0
      continue
    }
    if (a.startsWith('-')) {
      ctx.console.error('base64: unsupported option ' + a)
      ctx.exitCode = 1
      return
    }
    paths.push(a)
  }
  const b4 = ctx.b4a
  let buf
  if (!paths.length || paths[0] === '-') {
    buf = b4.from(bareStdin(ctx))
  } else {
    const b = await ctx.vfs.readFile(paths[0])
    if (!b) {
      ctx.console.error('base64: cannot read ' + paths[0])
      ctx.exitCode = 1
      return
    }
    buf = b instanceof Uint8Array ? b : new Uint8Array(b)
  }
  if (decode) {
    const text = new TextDecoder().decode(buf)
    let raw
    try {
      raw = bareB64DecodeToU8(text)
    } catch (e) {
      ctx.console.error('base64: ' + (e.message || e))
      ctx.exitCode = 1
      return
    }
    if (!bareOsEmitRaw(ctx, raw)) {
      ctx.console.error(
        'base64: decode output requires process.stdout.write or ctx.bareOsBinWrite'
      )
      ctx.exitCode = 1
    }
    return
  }
  let enc
  if (typeof globalThis.btoa === 'function') {
    let s = ''
    const step = 0x8000
    for (let i = 0; i < buf.length; i += step) {
      const chunk = buf.subarray(i, i + step)
      s += String.fromCharCode.apply(null, chunk)
    }
    enc = globalThis.btoa(s)
  } else {
    enc = bareB64EncodeBytes(buf)
  }
  if (wrap > 0) {
    const lines = []
    for (let i = 0; i < enc.length; i += wrap) {
      lines.push(enc.slice(i, i + wrap))
    }
    ctx.console.log(lines.join('\n'))
  } else {
    ctx.console.log(enc)
  }
}