/** 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
}

/** Plain-text manual formatter (prepended before src/man.js; no import in /bin/man). */

function bareManParseWidth(env) {
  const raw = env && env.MANWIDTH != null ? String(env.MANWIDTH).trim() : ''
  const n = raw ? Number.parseInt(raw, 10) : 72
  if (!Number.isFinite(n)) return 72
  return Math.max(40, Math.min(n, 200))
}

function bareManUseAnsi(ctx) {
  const env = ctx.env || {}
  if (env.NO_COLOR != null && String(env.NO_COLOR) !== '') return false
  const out = ctx.stdout
  return Boolean(out && out.isTTY)
}

function bareManBold(s, on) {
  if (!on) return s
  return '\x1b[1m' + s + '\x1b[0m'
}

function bareManWrap(text, width) {
  const words = String(text).replace(/\s+/g, ' ').trim().split(' ')
  const lines = []
  let cur = ''
  for (const w of words) {
    const next = cur ? cur + ' ' + w : w
    if (next.length <= width) cur = next
    else {
      if (cur) lines.push(cur)
      cur = w.length > width ? w.slice(0, width) : w
      while (cur.length > width) {
        lines.push(cur.slice(0, width))
        cur = cur.slice(width)
      }
    }
  }
  if (cur) lines.push(cur)
  return lines
}

/** Indent fixed-width command lines; hard-wrap only when longer than width. */
function bareManRenderExampleCode(code, width) {
  const indent = '       '
  const max = Math.max(20, width - indent.length)
  const out = []
  for (const line of String(code).split('\n')) {
    if (line.length <= max) {
      out.push(indent + line)
      continue
    }
    let rest = line
    while (rest.length > max) {
      out.push(indent + rest.slice(0, max))
      rest = rest.slice(max)
    }
    if (rest) out.push(indent + rest)
  }
  return out.join('\n')
}

/** Keep newlines; hard-wrap long lines only (for handbook / preformatted text). */
function bareManRenderPreserve(text, width) {
  const indent = '       '
  const max = Math.max(20, width - indent.length)
  const out = []
  for (const line of String(text).split('\n')) {
    if (line === '') {
      out.push('')
      continue
    }
    let rest = line
    while (rest.length > max) {
      out.push(indent + rest.slice(0, max))
      rest = rest.slice(max)
    }
    out.push(indent + rest)
  }
  return out.join('\n') + '\n'
}

function bareManFlushBlock(lines, width, prefixFirst, prefixRest) {
  const out = []
  let first = true
  for (const line of lines) {
    const wrapped = bareManWrap(line, width - (first ? prefixFirst.length : prefixRest.length))
    for (let i = 0; i < wrapped.length; i++) {
      const p = i === 0 && first ? prefixFirst : prefixRest
      out.push(p + wrapped[i])
      first = false
    }
  }
  return out.join('\n') + '\n'
}

function bareManRenderPage(page, ctx, width) {
  const ansi = bareManUseAnsi(ctx)
  const H = (s) => bareManBold(s, ansi) + '\n'
  let s = ''
  s += H('NAME')
  s += page.name + '(' + page.section + ') - ' + page.title + '\n\n'
  s += H('SYNOPSIS')
  for (const line of page.synopsis) {
    s += '       ' + line + '\n'
  }
  s += '\n'
  s += H('DESCRIPTION')
  if (page.descriptionMode === 'preserve') {
    s += bareManRenderPreserve(page.description, width)
  } else {
    s += bareManFlushBlock([page.description], width, '', '       ')
  }
  if (page.options && page.options.length) {
    s += '\n' + H('OPTIONS')
    for (const o of page.options) {
      const head = o.flag + '\t'
      const rest = o.meaning
      s += bareManFlushBlock([rest], width, '       ' + head, '              ')
    }
  }
  if (page.examples && page.examples.length) {
    s += '\n' + H('EXAMPLES')
    s +=
      bareManFlushBlock(
        [
          'tl;dr-style snippets (like cheat.sh). Copy, adapt paths; pipelines are shell-simulated on Bare OS.'
        ],
        width,
        '',
        '       '
      ) + '\n'
    for (const ex of page.examples) {
      if (ex.caption) {
        s +=
          bareManFlushBlock(
            ['# ' + ex.caption],
            width,
            '',
            '       '
          ) + '\n'
      }
      s += bareManRenderExampleCode(ex.code, width) + '\n\n'
    }
  }
  if (page.environment && page.environment.length) {
    s += '\n' + H('ENVIRONMENT')
    for (const e of page.environment) s += '       ' + e + '\n'
  }
  if (page.files && page.files.length) {
    s += '\n' + H('FILES')
    for (const f of page.files) s += '       ' + f + '\n'
  }
  if (page.exitStatus && page.exitStatus.length) {
    s += '\n' + H('EXIT STATUS')
    for (const e of page.exitStatus) s += '       ' + e + '\n'
  }
  if (page.diagnostics && page.diagnostics.length) {
    s += '\n' + H('DIAGNOSTICS')
    for (const d of page.diagnostics) s += '       ' + d + '\n'
  }
  if (page.builtins && page.builtins.length) {
    s += '\n' + H('SHELL BUILTINS')
    for (const b of page.builtins) {
      s += '\n' + bareManBold(b.name, ansi) + '\n'
      if (b.synopsis && b.synopsis.length) {
        for (const line of b.synopsis) s += '       ' + line + '\n'
      }
      s += bareManFlushBlock([b.description], width, '       ', '       ')
      if (b.options && b.options.length) {
        for (const o of b.options) {
          const head = o.flag + '\t'
          s += bareManFlushBlock([o.meaning], width, '       ' + head, '              ')
        }
      }
      if (b.examples && b.examples.length) {
        s += '\n' + bareManBold('  Examples', ansi) + '\n'
        for (const ex of b.examples) {
          if (ex.caption) {
            s +=
              bareManFlushBlock(
                ['# ' + ex.caption],
                width,
                '       ',
                '       '
              ) + '\n'
          }
          s += bareManRenderExampleCode(ex.code, width) + '\n\n'
        }
      }
    }
  }
  if (page.bareOsNotes) {
    s += '\n' + H('BARE OS NOTES')
    s += bareManFlushBlock([page.bareOsNotes], width, '', '       ')
  }
  if (page.seeAlso && page.seeAlso.length) {
    s += '\n' + H('SEE ALSO')
    const parts = page.seeAlso.map((r) => r.name + '(' + r.section + ')')
    s += '       ' + parts.join(', ') + '\n'
  }
  if (page.stub) {
    s += '\n' + H('STATUS')
    s += '       This command is a stub or intentionally limited on Bare OS.\n'
  }
  return s
}

async function run(ctx, argv) {
  const env = ctx.env || {}
  const width = bareManParseWidth(env)
  const args = argv.slice(1)

  function usage() {
    ctx.console.error(
      'usage: man [-k keyword] [-f name] [-l] [[section] name]\n' +
        '       Section 1: /bin; section 7: handbook + developer guide (man handbook, man devguide).\n' +
        '       Data: /share/man/man.json on the system drive.'
    )
    ctx.exitCode = 2
  }

  if (args.length === 0) {
    usage()
    return
  }

  let mode = 'page'
  let kWord = ''
  let fName = ''
  const rest = []
  for (let i = 0; i < args.length; i++) {
    const a = args[i]
    if (a === '--') {
      rest.push(...args.slice(i + 1))
      break
    }
    if (a === '-k' || a === '--apropos') {
      mode = 'apropos'
      kWord = args[++i] || ''
      if (!kWord) {
        usage()
        return
      }
      continue
    }
    if (a === '-f' || a === '--whatis') {
      mode = 'whatis'
      fName = args[++i] || ''
      if (!fName) {
        usage()
        return
      }
      continue
    }
    if (a === '-l' || a === '--list') {
      mode = 'list'
      continue
    }
    if (a.startsWith('-')) {
      ctx.console.error('man: unknown option: ' + a)
      ctx.exitCode = 2
      return
    }
    rest.push(a)
  }

  const drive = ctx.drive
  if (!drive || typeof drive.get !== 'function') {
    ctx.console.error('man: no system drive in context')
    ctx.exitCode = 1
    return
  }

  let buf
  try {
    buf = await drive.get('/share/man/man.json', { follow: true })
  } catch {
    buf = null
  }
  if (!buf) {
    ctx.console.error('man: manual database not found (/share/man/man.json)')
    ctx.exitCode = 1
    return
  }

  let db
  try {
    db = JSON.parse(ctx.b4a.toString(buf))
  } catch (e) {
    ctx.console.error('man: invalid manual database: ' + (e.message || e))
    ctx.exitCode = 1
    return
  }

  if (!db.pages || !db.index) {
    ctx.console.error('man: malformed manual database')
    ctx.exitCode = 1
    return
  }

  if (mode === 'list') {
    const CAT_ORDER = ['coreutils', 'extra', 'handbook', 'devguide']
    const CAT_HEADING = {
      coreutils: 'Section 1 — /bin utilities',
      extra: 'Section 1 — Git and shell',
      handbook: 'Section 7 — Handbook',
      devguide: 'Section 7 — Developer guide'
    }
    function listCategoryOf(p) {
      const c = p.listCategory
      if (c === 'coreutils' || c === 'extra' || c === 'handbook' || c === 'devguide')
        return c
      if (p.section === 7) {
        const n = p.name
        if (n.startsWith('devguide-') || n === 'bare-os-developer-guide') return 'devguide'
        return 'handbook'
      }
      if (p.name === 'git' || p.name === 'bare-os-shell') return 'extra'
      return 'coreutils'
    }
    const rows = db.pages.map((p) => ({
      n: p.name,
      s: p.section,
      cat: listCategoryOf(p)
    }))
    rows.sort((a, b) => {
      const ia = CAT_ORDER.indexOf(a.cat)
      const ib = CAT_ORDER.indexOf(b.cat)
      const ca = ia === -1 ? 99 : ia
      const cb = ib === -1 ? 99 : ib
      if (ca !== cb) return ca - cb
      if (a.n !== b.n) return a.n < b.n ? -1 : 1
      return a.s - b.s
    })
    let prevCat = ''
    for (const r of rows) {
      if (r.cat !== prevCat) {
        if (prevCat !== '') ctx.console.log('')
        ctx.console.log(CAT_HEADING[r.cat] || r.cat)
        prevCat = r.cat
      }
      ctx.console.log('  ' + r.n + '(' + r.s + ')')
    }
    return
  }

  if (mode === 'apropos') {
    const needle = kWord.toLowerCase()
    const seen = new Set()
    const hits = []
    if (db.apropos && Array.isArray(db.apropos)) {
      for (const row of db.apropos) {
        if (typeof row.kw !== 'string') continue
        if (!row.kw.includes(needle)) continue
        const idx = row.pageRef
        if (typeof idx !== 'number' || !db.pages[idx]) continue
        if (seen.has(idx)) continue
        seen.add(idx)
        const p = db.pages[idx]
        hits.push(p.name + '(' + p.section + ') - ' + p.title)
      }
    }
    hits.sort()
    for (const line of hits) ctx.console.log(line)
    return
  }

  if (mode === 'whatis') {
    const key = fName.toLowerCase()
    const idx = db.index[key]
    if (idx === undefined || !db.pages[idx]) {
      ctx.console.error('man: nothing appropriate for ' + fName)
      ctx.exitCode = 1
      return
    }
    const p = db.pages[idx]
    ctx.console.log(p.name + '(' + p.section + ') - ' + p.title)
    return
  }

  if (rest.length === 0) {
    usage()
    return
  }

  /** @type {number | null} */
  let sectionExplicit = null
  let name = rest[0]
  if (rest.length >= 2 && /^[0-9]+$/.test(rest[0])) {
    sectionExplicit = Number.parseInt(rest[0], 10)
    name = rest[1]
  }

  if (sectionExplicit !== null && (sectionExplicit < 1 || sectionExplicit > 8)) {
    ctx.console.error('man: section must be between 1 and 8')
    ctx.exitCode = 2
    return
  }

  const idx = db.index[String(name).toLowerCase()]
  if (idx === undefined || !db.pages[idx]) {
    ctx.console.error('man: no manual entry for ' + name)
    ctx.exitCode = 1
    return
  }

  const page = db.pages[idx]
  if (sectionExplicit !== null && page.section !== sectionExplicit) {
    ctx.console.error(
      'man: no entry for ' + name + ' in section ' + sectionExplicit + ' (see man -l)'
    )
    ctx.exitCode = 1
    return
  }
  ctx.console.log(bareManRenderPage(page, ctx, width).replace(/\n$/, ''))
}