/* 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
}

async function readLines(ctx, path) {
  const b4 = ctx.b4a
  if (path === '-') return bareStdin(ctx).split('\n')
  const b = await ctx.vfs.readFile(path)
  if (!b) return null
  return b4.toString(b).split('\n')
}

/**
 * Deterministic PRNG for tests/repro: xorshift32 seeded by env.
 * @param {string} seed
 */
function seededRandom(seed) {
  let x = 2166136261 >>> 0
  for (let i = 0; i < seed.length; i++) {
    x ^= seed.charCodeAt(i)
    x = Math.imul(x, 16777619) >>> 0
  }
  if (x === 0) x = 0x9e3779b9
  return () => {
    x ^= x << 13
    x ^= x >>> 17
    x ^= x << 5
    x >>>= 0
    return x / 4294967296
  }
}

async function run(ctx, argv) {
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '-h' || a === '--help') {
      ctx.console.log(
        'usage: shuf [FILE]...\nShuffle lines; memory-capped via BARE_OS_SHUF_MAX_LINES.'
      )
      return
    }
    if (a.startsWith('-')) {
      ctx.console.error('shuf: unsupported option ' + a)
      ctx.exitCode = 1
      return
    }
    paths.push(a)
  }
  const cap =
    parseInt(ctx.vfs.env.BARE_OS_SHUF_MAX_LINES || '50000', 10) || 50000
  if (!paths.length) paths.push('-')
  const b4 = ctx.b4a
  const seed = String(ctx.vfs?.env?.BARE_OS_SHUF_SEED || '').trim()
  const rand = seed ? seededRandom(seed) : Math.random
  const lines = []
  for (const p of paths) {
    const L = await readLines(ctx, p)
    if (L == null) {
      ctx.console.error('shuf: ' + p + ': No such file')
      ctx.exitCode = 1
      return
    }
    const trim = L.length && L[L.length - 1] === '' ? L.slice(0, -1) : L
    for (const ln of trim) {
      if (lines.length >= cap) {
        ctx.console.error('shuf: input exceeds line cap')
        ctx.exitCode = 1
        return
      }
      lines.push(ln)
    }
  }
  for (let i = lines.length - 1; i > 0; i--) {
    const j = Math.floor(rand() * (i + 1))
    const t = lines[i]
    lines[i] = lines[j]
    lines[j] = t
  }
  for (const ln of lines) ctx.console.log(ln)
}