/* 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
}

/** Session env map (`vfs.env`, then `ctx.env`). Never throws. */
function bareOsEnv(ctx) {
  const v = ctx && ctx.vfs && ctx.vfs.env
  if (v && typeof v === 'object') return v
  const e = ctx && ctx.env
  if (e && typeof e === 'object') return e
  return {}
}

/**
 * Strict POSIX-ish decimal integer (no octal, no exponent, no empty).
 * @param {unknown} s
 * @returns {number}
 */
function bareOsParseDecInt(s) {
  const t = String(s == null ? '' : s).trim()
  if (!/^[+-]?(?:0|[1-9][0-9]*)$/.test(t)) return NaN
  const n = Number.parseInt(t, 10)
  return Number.isSafeInteger(n) ? n : NaN
}

/** @param {unknown} s */
function bareOsParseNonNegInt(s) {
  const n = bareOsParseDecInt(s)
  return n >= 0 ? n : NaN
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} name
 * @param {number} fallback
 * @param {number} [min]
 * @param {number} [max]
 */
function bareOsEnvInt(ctx, name, fallback, min, max) {
  const raw = bareOsEnv(ctx)[name]
  if (raw == null || raw === '') return fallback
  const n = Number.parseInt(String(raw), 10)
  if (!Number.isFinite(n)) return fallback
  let v = n
  if (min != null && v < min) v = min
  if (max != null && v > max) v = max
  return v
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} msg
 * @param {number} [code]
 */
function bareOsFail(ctx, msg, code) {
  if (msg) ctx.console.error(msg)
  ctx.exitCode = code == null ? 1 : code
}

/** @param {unknown} e */
function bareOsIsNotFoundErr(e) {
  const code = e && typeof e === 'object' ? e.code : ''
  if (code === 'ENOENT') return true
  const msg = String((e && e.message) || e || '')
  return /ENOENT|No such file|not found/i.test(msg)
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {unknown} buf
 * @returns {Uint8Array}
 */
function bareOsToU8(ctx, buf) {
  if (!buf) return new Uint8Array(0)
  if (buf instanceof Uint8Array) return buf
  if (ctx && ctx.b4a && typeof ctx.b4a.from === 'function') return ctx.b4a.from(buf)
  return new Uint8Array(buf)
}

/** @param {string} dir @param {string} name */
function bareOsJoinPath(dir, name) {
  const d = String(dir || '').replace(/\/+$/, '')
  const n = String(name || '').replace(/^\/+/, '')
  if (!d || d === '/') return '/' + n
  return d + '/' + n
}

/** @param {string} p */
function bareOsBaseName(p) {
  const t = String(p || '').replace(/\/+$/, '')
  if (!t || t === '/') return t === '/' ? '/' : ''
  const i = t.lastIndexOf('/')
  return i < 0 ? t : t.slice(i + 1) || t
}

/** @param {string} p */
function bareOsParentDir(p) {
  const t = String(p || '').replace(/\/+$/, '') || '/'
  if (t === '/') return '/'
  const i = t.lastIndexOf('/')
  return i <= 0 ? '/' : t.slice(0, i) || '/'
}

/** @param {string} p */
function bareOsNormPath(p) {
  return String(p || '').replace(/\/+$/, '') || '/'
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} p
 */
function bareOsResolvePath(ctx, p) {
  if (ctx && ctx.vfs && typeof ctx.vfs.resolveLogical === 'function') {
    try {
      return String(ctx.vfs.resolveLogical(p) || p)
    } catch {
      /* fall through */
    }
  }
  return String(p || '')
}

/**
 * True when dest is src or lives under src (self-copy / self-move).
 * @param {Record<string, unknown>} ctx
 * @param {string} src
 * @param {string} dest
 */
function bareOsDestInsideSrc(ctx, src, dest) {
  const s = bareOsNormPath(bareOsResolvePath(ctx, src))
  const d = bareOsNormPath(bareOsResolvePath(ctx, dest))
  if (s === d) return true
  if (s === '/') return d !== '/'
  return d === s || d.startsWith(s + '/')
}

const BARE_OS_B64_ALPH =
  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'

/** @param {Uint8Array} u8 */
function bareOsB64Encode(u8) {
  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 +=
      BARE_OS_B64_ALPH[(n >> 18) & 63] +
      BARE_OS_B64_ALPH[(n >> 12) & 63] +
      BARE_OS_B64_ALPH[(n >> 6) & 63] +
      BARE_OS_B64_ALPH[n & 63]
  }
  const rest = u8.length - i
  if (rest === 1) {
    const n = u8[i] << 16
    out += BARE_OS_B64_ALPH[(n >> 18) & 63] + BARE_OS_B64_ALPH[(n >> 12) & 63] + '=='
  } else if (rest === 2) {
    const n = (u8[i] << 16) | (u8[i + 1] << 8)
    out +=
      BARE_OS_B64_ALPH[(n >> 18) & 63] +
      BARE_OS_B64_ALPH[(n >> 12) & 63] +
      BARE_OS_B64_ALPH[(n >> 6) & 63] +
      '='
  }
  return out
}

/**
 * RFC 4648 Base64 decode (also accepts URL-safe alphabet). Rejects junk.
 * @param {string} s
 * @returns {Uint8Array}
 */
function bareOsB64Decode(s) {
  const t = String(s).replace(/\s+/g, '')
  if (!t) return new Uint8Array(0)
  if (t.length % 4 === 1) throw new Error('invalid base64 length')
  let pad = 0
  if (t.endsWith('==')) pad = 2
  else if (t.endsWith('=')) pad = 1
  const body = pad ? t.slice(0, t.length - pad) : t
  const bytes = []
  let buf = 0
  let bits = 0
  for (let i = 0; i < body.length; i++) {
    const c = body[i]
    let v = BARE_OS_B64_ALPH.indexOf(c)
    if (v < 0) {
      if (c === '-') v = 62
      else if (c === '_') v = 63
      else throw new Error('invalid base64 character')
    }
    buf = (buf << 6) | v
    bits += 6
    if (bits >= 8) {
      bits -= 8
      bytes.push((buf >> bits) & 255)
    }
  }
  if (pad) {
    const want = Math.floor((body.length * 6) / 8)
    if (bytes.length > want) bytes.length = want
  }
  return new Uint8Array(bytes)
}

/**
 * @param {string} s
 * @returns {Uint8Array}
 */
function bareOsHexDecode(s) {
  const t = String(s).replace(/\s+/g, '')
  if (t.length % 2 !== 0) throw new Error('odd hex length')
  const out = new Uint8Array(t.length / 2)
  for (let i = 0; i < out.length; i++) {
    const pair = t.slice(i * 2, i * 2 + 2)
    if (!/^[0-9a-fA-F]{2}$/.test(pair)) throw new Error('invalid hex')
    out[i] = Number.parseInt(pair, 16)
  }
  return out
}

/** @param {Uint8Array} u8 */
function bareOsHexEncode(u8) {
  let s = ''
  for (let i = 0; i < u8.length; i++) s += u8[i].toString(16).padStart(2, '0')
  return s
}

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 || '/')
    )
  }
}