/* 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 run(ctx, argv) {
  let human = false
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '--help') {
      ctx.console.log(
        'usage: df [-h] [FILE]...\nSynthetic disk free for Bare OS (Hyperdrive model; not block devices).'
      )
      return
    }
    if (a === '-h' || a === '--human-readable') {
      human = true
      continue
    }
    if (a.startsWith('-')) {
      ctx.console.error('df: unsupported option ' + a)
      ctx.exitCode = 1
      return
    }
    paths.push(a)
  }
  function fmtK(n) {
    if (!human) return String(n)
    if (n < 1024) return n + 'K'
    if (n < 1024 * 1024) return (n / 1024).toFixed(1) + 'M'
    return (n / 1024 / 1024).toFixed(1) + 'G'
  }
  function parseMounts(text) {
    const out = []
    const lines = String(text || '')
      .split('\n')
      .map((s) => s.trim())
      .filter(Boolean)
    for (const line of lines) {
      const cols = line.split(/\s+/)
      if (cols.length < 4) continue
      out.push({
        filesystem: cols[0],
        mountpoint: cols[1],
        fstype: cols[2],
        options: cols[3]
      })
    }
    return out
  }
  function normalizePath(p) {
    const s = String(p || '').trim()
    if (!s) return '/'
    if (s === '/') return '/'
    return s.replace(/\/+$/, '') || '/'
  }
  function mountForPath(p, mounts) {
    const path = normalizePath(p)
    let best = null
    for (const m of mounts) {
      const mp = normalizePath(m.mountpoint)
      if (mp === '/') {
        if (!best) best = m
        continue
      }
      if (path === mp || path.startsWith(mp + '/')) {
        if (!best || mp.length > normalizePath(best.mountpoint).length) best = m
      }
    }
    return best
  }
  function statsFromSv(sv, fallbackTotalK, fallbackUsedK) {
    if (sv && typeof sv.f_blocks === 'number' && typeof sv.f_bfree === 'number') {
      const bsize = typeof sv.f_bsize === 'number' ? sv.f_bsize : 4096
      const totalK = Math.max(1024, Math.ceil((sv.f_blocks * bsize) / 1024))
      const freeB = sv.f_bavail ?? sv.f_bfree
      const freeK = Math.max(0, Math.ceil((freeB * bsize) / 1024))
      const usedK = Math.max(0, totalK - freeK)
      return { totalK, usedK, freeK }
    }
    const totalK = Math.max(1024, Number(fallbackTotalK) || 1024)
    const usedK = Math.max(0, Number(fallbackUsedK) || 0)
    return { totalK, usedK, freeK: Math.max(0, totalK - usedK) }
  }

  let totalK = 1024 * 1024
  let usedK = 4096
  /** @type {Record<string, unknown> | null} */
  let resources = null
  try {
    const buf = await ctx.vfs.readFile('/proc/bare_os_quotas')
    if (buf) {
      const j = JSON.parse(ctx.b4a.toString(buf))
      if (j && typeof j.pipelineMaxBytes === 'number')
        totalK = Math.max(1024, Math.ceil(j.pipelineMaxBytes / 1024) * 1024)
    }
  } catch {
    /* ignore */
  }
  try {
    const rbuf = await ctx.vfs.readFile('/proc/bare_os_resources')
    if (rbuf) {
      const j = JSON.parse(ctx.b4a.toString(rbuf))
      resources = j && typeof j === 'object' ? j : null
      const sv = j && j.statvfs
      const st = statsFromSv(sv, totalK, usedK)
      totalK = st.totalK
      usedK = st.usedK
    }
  } catch {
    /* ignore */
  }
  /** @type {{ filesystem: string, mountpoint: string, fstype: string, options: string }[]} */
  let mounts = []
  try {
    const mbuf = await ctx.vfs.readFile('/proc/mounts')
    if (mbuf) mounts = parseMounts(ctx.b4a.toString(mbuf))
  } catch {
    /* ignore */
  }
  if (!mounts.length) {
    mounts = [
      { filesystem: 'bare-hyperdrive', mountpoint: '/', fstype: 'hyperdrive', options: 'ro' }
    ]
  }
  /** @type {typeof mounts} */
  let selected = mounts
  if (paths.length) {
    const byMount = new Map()
    for (const p of paths) {
      const m = mountForPath(p, mounts)
      if (m) byMount.set(normalizePath(m.mountpoint), m)
    }
    selected = [...byMount.values()]
  }
  if (!selected.length) {
    ctx.console.error('df: no matching filesystems')
    ctx.exitCode = 1
    return
  }
  const sv =
    resources &&
    typeof resources === 'object' &&
    resources.statvfs &&
    typeof resources.statvfs === 'object'
      ? resources.statvfs
      : null
  const sysSv =
    sv && typeof sv.systemDrive === 'object' && sv.systemDrive
      ? sv.systemDrive
      : sv
  const base = statsFromSv(sysSv, totalK, usedK)

  ctx.console.log('Filesystem      1K-blocks     Used Available Use% Mounted on')
  for (const m of selected) {
    const st = base
    const pct = st.totalK > 0 ? Math.min(100, Math.round((st.usedK / st.totalK) * 100)) : 0
    ctx.console.log(
      String(m.filesystem || 'bare-hyperdrive').padEnd(15) +
        ' ' +
        fmtK(st.totalK).padStart(12) +
        ' ' +
        fmtK(st.usedK).padStart(8) +
        ' ' +
        fmtK(st.freeK).padStart(10) +
        ' ' +
        String(pct).padStart(3) +
        '% ' +
        String(m.mountpoint || '/')
    )
  }
}