/* 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 bareCatOut(ctx, s) {
  const w = globalThis.process?.stdout?.write
  if (typeof w === 'function') {
    w.call(globalThis.process.stdout, s)
  } else {
    ctx.console.log(s)
  }
}

/** @param {string} line @param {{ showTabs: boolean, showEnds: boolean, showNonprinting: boolean }} o */
function catTransformLine(line, o) {
  let out = ''
  for (let k = 0; k < line.length; k++) {
    const ch = line[k]
    const code = line.charCodeAt(k)
    if (o.showTabs && ch === '\t') {
      out += '^I'
      continue
    }
    if (o.showNonprinting && code < 32 && ch !== '\t') {
      out += '^' + String.fromCharCode(code + 64)
      continue
    }
    if (o.showNonprinting && code === 127) {
      out += '^?'
      continue
    }
    if (o.showNonprinting && code > 127) {
      out += 'M-' + String.fromCharCode(code - 128)
      continue
    }
    out += ch
  }
  if (o.showEnds) out += '$'
  return out
}

/**
 * @param {string} text
 * @param {{ numberLines: boolean, numberNonblank: boolean, showTabs: boolean, showEnds: boolean, showNonprinting: boolean }} opt
 */
function catFormat(text, opt) {
  const t = {
    showTabs: opt.showTabs,
    showEnds: opt.showEnds,
    showNonprinting: opt.showNonprinting
  }
  const useNum = opt.numberLines || opt.numberNonblank
  let n = 1
  let out = ''
  let i = 0
  while (i < text.length) {
    const j = text.indexOf('\n', i)
    const end = j === -1 ? text.length : j
    const rawLine = text.slice(i, end)
    const blank = rawLine.length === 0
    const lineOut = catTransformLine(rawLine, t)
    if (useNum) {
      const numThis =
        opt.numberNonblank && blank ? false : opt.numberLines || opt.numberNonblank
      if (numThis) {
        out += String(n).padStart(6, ' ') + '\t' + lineOut
        n++
      } else {
        out += lineOut
      }
    } else {
      out += lineOut
    }
    if (j === -1) break
    out += '\n'
    i = j + 1
  }
  return out
}

/** @returns {{ error?: string, opt: ReturnType<typeof defaultCatOpt>, files: string[] }} */
function parseCatArgv(argv) {
  const opt = {
    numberLines: false,
    numberNonblank: false,
    showTabs: false,
    showEnds: false,
    showNonprinting: false
  }
  const files = []
  let i = 1
  while (i < argv.length) {
    const a = argv[i]
    if (a === '--') {
      files.push(...argv.slice(i + 1))
      return { opt, files }
    }
    if (!a.startsWith('-')) {
      files.push(a)
      i++
      continue
    }
    const body = a.slice(1)
    if (body === '') {
      files.push('-')
      i++
      continue
    }
    for (let k = 0; k < body.length; k++) {
      const c = body[k]
      if (c === 'n') opt.numberLines = true
      else if (c === 'b') opt.numberNonblank = true
      else if (c === 'A') {
        opt.showTabs = true
        opt.showEnds = true
        opt.showNonprinting = true
      } else if (c === 'e') {
        opt.showEnds = true
        opt.showNonprinting = true
      } else if (c === 't') {
        opt.showTabs = true
        opt.showNonprinting = true
      } else if (c === 'E') opt.showEnds = true
      else if (c === 'T') opt.showTabs = true
      else if (c === 'v') opt.showNonprinting = true
      else return { error: 'cat: invalid option -- ' + c, opt, files: [] }
    }
    i++
  }
  if (opt.numberNonblank) opt.numberLines = false
  return { opt, files }
}

async function run(ctx, argv) {
  const parsed = parseCatArgv(argv)
  if (parsed.error) {
    ctx.console.error(parsed.error)
    ctx.exitCode = 1
    return
  }
  const { opt, files } = parsed
  const vfs = ctx.vfs
  const anyOpt =
    opt.numberLines ||
    opt.numberNonblank ||
    opt.showTabs ||
    opt.showEnds ||
    opt.showNonprinting

  async function emitOne(text) {
    const s = anyOpt ? catFormat(text, opt) : text
    bareCatOut(ctx, s)
  }

  if (!files.length) {
    const s = bareStdin(ctx)
    await emitOne(s)
    return
  }
  for (const f of files) {
    if (f === '-') {
      await emitOne(bareStdin(ctx))
      continue
    }
    const buf = await vfs.readFile(f)
    if (!buf) {
      ctx.console.error('cat: ' + f + ': No such file or directory')
      ctx.exitCode = 1
      continue
    }
    await emitOne(ctx.b4a.toString(buf))
  }
}