/* 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
}

/**
 * Minimal iconv(1): UTF-8 pass-through only (Bare userland text is UTF-8).
 */

function normEnc(s) {
  const t = String(s || '')
    .trim()
    .toLowerCase()
    .replace(/[-_]/g, '')
  if (t === 'utf8' || t === 'utf8bom') return 'utf-8'
  if (t === 'latin1' || t === 'iso88591' || t === 'cp819') return 'iso-8859-1'
  if (t === 'utf16le' || t === 'utf16') return 'utf-16le'
  if (t === 'utf16be') return 'utf-16be'
  return t
}

/**
 * @param {Uint8Array} u8
 * @param {string} enc TextDecoder label
 * @returns {string}
 */
function decodeToString(u8, enc) {
  const dec = new TextDecoder(enc, { fatal: true })
  return dec.decode(u8)
}

/**
 * @param {string} s
 * @param {string} enc TextEncoder only does utf-8; special-case UTF-16
 * @param {typeof import('b4a')} b4a
 */
function encodeFromString(s, enc, b4a) {
  if (enc === 'utf-8' || enc === 'utf8') {
    return b4a.from(s, 'utf8')
  }
  if (enc === 'utf-16le') {
    const out = new Uint8Array(s.length * 2)
    for (let i = 0; i < s.length; i++) {
      const c = s.charCodeAt(i)
      out[i * 2] = c & 0xff
      out[i * 2 + 1] = (c >> 8) & 0xff
    }
    return out
  }
  if (enc === 'utf-16be') {
    const out = new Uint8Array(s.length * 2)
    for (let i = 0; i < s.length; i++) {
      const c = s.charCodeAt(i)
      out[i * 2] = (c >> 8) & 0xff
      out[i * 2 + 1] = c & 0xff
    }
    return out
  }
  if (enc === 'iso-8859-1') {
    const out = new Uint8Array(s.length)
    for (let i = 0; i < s.length; i++) {
      const c = s.charCodeAt(i)
      out[i] = c > 255 ? 0x3f : c & 0xff
    }
    return out
  }
  throw new Error('iconv: unsupported output encoding')
}

async function run(ctx, argv) {
  let fromEnc = 'utf-8'
  let toEnc = 'utf-8'
  let file = null
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '--') continue
    if (a === '-f' || a === '--from-code') {
      i++
      if (i >= argv.length) {
        ctx.console.error('iconv: option requires an argument')
        ctx.exitCode = 1
        return
      }
      fromEnc = normEnc(argv[i])
      continue
    }
    if (a === '-t' || a === '--to-code') {
      i++
      if (i >= argv.length) {
        ctx.console.error('iconv: option requires an argument')
        ctx.exitCode = 1
        return
      }
      toEnc = normEnc(argv[i])
      continue
    }
    if (a.startsWith('-')) {
      ctx.console.error('iconv: unsupported option: ' + a)
      ctx.exitCode = 1
      return
    }
    file = a
    break
  }

  const supported = new Set([
    'utf-8',
    'iso-8859-1',
    'utf-16le',
    'utf-16be'
  ])
  if (!supported.has(fromEnc) || !supported.has(toEnc)) {
    ctx.console.error(
      'iconv: unsupported encoding pair (supported: utf-8, iso-8859-1, utf-16le, utf-16be)'
    )
    ctx.exitCode = 1
    return
  }

  let u8
  if (file) {
    const raw = await ctx.vfs.readFile(file)
    if (raw == null) {
      ctx.console.error('iconv: ' + file + ': cannot read')
      ctx.exitCode = 1
      return
    }
    u8 = raw instanceof Uint8Array ? raw : ctx.b4a.from(raw)
  } else {
    u8 = ctx.b4a.from(bareStdin(ctx), 'utf8')
  }

  let mid = ''
  try {
    mid = decodeToString(u8, fromEnc)
  } catch (e) {
    ctx.console.error('iconv: invalid input for ' + fromEnc + ': ' + (e?.message || e))
    ctx.exitCode = 1
    return
  }

  let outU8
  try {
    outU8 = encodeFromString(mid, toEnc, ctx.b4a)
  } catch (e) {
    ctx.console.error('iconv: ' + (e?.message || e))
    ctx.exitCode = 1
    return
  }

  const w = globalThis.process?.stdout?.write
  if (typeof w === 'function') w.call(globalThis.process.stdout, outU8)
  else if (toEnc === 'utf-8' || toEnc === 'utf8') {
    ctx.console.log(ctx.b4a.toString(outU8, 'utf8'))
  } else {
    ctx.console.error('iconv: binary output requires a TTY with binary stdout')
    ctx.exitCode = 1
  }
}