// ZFS: pools, datasets, snapshots, and a schedule for taking and expiring them.
//
// Split out of the Disks tab on 2026-09-24. Disks is the hardware; this is the filesystem
// on top of it, which has enough of its own to say.
//
// On the schedule: `grid` has run zfSnap from root cron since before Ham Lab existed, and it
// works. So this reads and writes the same snapshot names — `2026-09-24_02.30.01--6w`, with
// the retention in the name — rather than inventing a second convention for the two tools to
// disagree over. An existing cron job is detected and shown, so the page tells the truth
// about the machine whether Ham Lab or something else is doing the work.
import { FormEvent, Fragment, useCallback, useEffect, useState } from 'react'
import { api, ARCView, CacheDev, Landing, PoolCaching, PoolWrites, ZFSExternal, ZFSInfo, ZFSOverview, ZFSPolicy, ZFSRun, ZFSSnapshot, ZFSWrites } from './api'
import { fmtBytes, fmtRate } from './fmt'
import { useRefreshMs } from './prefs'
import { fetchHistories } from './sensors'
import Sparkline from './Sparkline'
import { askText, askYes, Btn, Loading, Meter, Spinner, toast, useEscape } from './ui'

const ago = (t?: string | number) => {
  if (!t) return 'never'
  const s = Math.max(0, (Date.now() - new Date(t).getTime()) / 1000)
  return s < 60 ? 'just now' : s < 3600 ? `${Math.floor(s / 60)} min ago` : s < 86400 ? `${Math.floor(s / 3600)} h ago` : `${Math.floor(s / 86400)} d ago`
}
const soon = (t?: string) => {
  if (!t) return '—'
  const s = (new Date(t).getTime() - Date.now()) / 1000
  return s < 60 ? 'any moment' : s < 3600 ? `in ${Math.round(s / 60)} min` : s < 86400 ? `in ${Math.round(s / 3600)} h` : `in ${Math.round(s / 86400)} d`
}
const WEEKDAYS = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
const describe = (p: ZFSPolicy) => {
  const when = p.every === 'custom' ? `on ${p.cron}`
    : p.every === 'hourly' ? `every hour at :${(p.at.split(':')[1] ?? '00').padStart(2, '0')}`
    : p.every === 'daily' ? `every day at ${p.at}`
      : p.every === 'weekly' ? `every ${WEEKDAYS[p.weekday] ?? 'Sunday'} at ${p.at}`
        : `on day ${p.day} of the month at ${p.at}`
  return `${when} · keep ${p.keep_for}${p.recursive ? ' · recursive' : ''}`
}

// ---- pools and datasets (moved from the Disks tab) ----
function PoolCard({ p, onChanged }: { p: ZFSInfo['pools'][number]; onChanged: () => void }) {
  const scrubbing = /scrub in progress/i.test(p.scan ?? '')
  const paused = /scrub paused/i.test(p.scan ?? '')
  const [cfg, setCfg] = useState(false)
  const act = (a: 'start' | 'pause' | 'stop') => async () => {
    try { await api.zfsScrub(p.name, a); toast(`scrub ${a}: ok`); onChanged() } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
  }
  return (
    <section className="card">
      <div className="sub-head">
        <span className={'dot ' + (p.health === 'ONLINE' ? 'ok' : p.health === 'DEGRADED' ? 'warn' : 'bad')} />
        <span className="dname">{p.name}</span>
        <span className="badge">{p.health}</span>
        <span className="spacer" />
        <span className="num">{fmtBytes(p.alloc)} / {fmtBytes(p.size)} · {p.cap}%</span>
      </div>
      <Meter frac={p.cap / 100} cls={p.cap >= 90 ? 'bad' : p.cap >= 80 ? 'warn' : ''} />
      <div className="props" style={{ marginTop: 8 }}>
        <div><span className="k">Free</span><span>{fmtBytes(p.free)} · fragmentation {p.frag}% · dedup {p.dedup}</span></div>
        {p.scan && <div><span className="k">Scan</span><span style={{ whiteSpace: 'normal' }}>{p.scan}</span></div>}
        {p.errors && <div><span className="k">Errors</span><span className={p.errors.startsWith('No known') ? '' : 'warn-text'}>{p.errors}</span></div>}
      </div>
      <div className="svc-actions">
        {!scrubbing && <Btn className="btn" confirm={`Start a scrub of ${p.name}? It reads the whole pool and can take many hours.`} onClick={act('start')}>{paused ? 'Resume scrub' : 'Scrub'}</Btn>}
        {scrubbing && <Btn className="btn" onClick={act('pause')}>Pause scrub</Btn>}
        {(scrubbing || paused) && <Btn className="btn" confirm="Stop the scrub?" onClick={act('stop')}>Stop scrub</Btn>}
        <button className="btn" onClick={() => setCfg(!cfg)}>{cfg ? 'Hide vdevs' : 'Vdevs'}</button>
      </div>
      {cfg && <pre className="unit-file">{p.config}</pre>}
    </section>
  )
}

// A snapshot's name carries when it was taken and how long it lives — 2026-09-24_02.30.01--6w
// — so the explorer can say when each one goes without asking the server anything.
function snapMeta(full: string): { taken?: Date; expires?: Date } {
  const snap = full.split('@')[1] ?? ''
  const [body, ttl] = snap.split('--')
  const m = /(\d{4})-(\d{2})-(\d{2})_(\d{2})\.(\d{2})\.(\d{2})$/.exec(body)
  if (!m) return {}
  const taken = new Date(+m[1], +m[2] - 1, +m[3], +m[4], +m[5], +m[6])
  const a = /^(\d+)([mhdw])$/.exec(ttl ?? '')
  if (!a) return { taken }
  const ms = { m: 60e3, h: 3600e3, d: 86400e3, w: 7 * 86400e3 }[a[2]]!
  return { taken, expires: new Date(taken.getTime() + +a[1] * ms) }
}

// One dataset in the snapshot explorer: how many it has and what they cost, opening into
// the snapshots themselves, each of which can be taken now or deleted.
function DatasetRow({ d, onChanged }: { d: ZFSInfo['datasets'][number]; onChanged: () => void }) {
  const [snaps, setSnaps] = useState<ZFSSnapshot[] | null>(null)
  const [open, setOpen] = useState(false)
  const reload = useCallback(async () => {
    try { setSnaps(await api.zfsSnapshots(d.name)) } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err'); setSnaps([]) }
  }, [d.name])
  async function toggle() {
    setOpen(!open)
    if (!open && !snaps) await reload()
  }
  async function snapshot() {
    // zfSnap's name is the machine's local time, and snapMeta reads it back as local time — so the
    // default is built from local fields, not toISOString(), which is UTC and read seven hours wrong.
    const n = new Date(), two = (x: number) => String(x).padStart(2, '0')
    const def = `${n.getFullYear()}-${two(n.getMonth() + 1)}-${two(n.getDate())}_${two(n.getHours())}.${two(n.getMinutes())}.${two(n.getSeconds())}`
    const name = await askText(`Snapshot name for ${d.name}@`, def)
    if (!name) return
    try { await api.zfsSnapshot(d.name, name.trim()); toast(`${d.name}@${name.trim()} created`); await reload(); onChanged() }
    catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
  }
  async function destroy(s: ZFSSnapshot) {
    const short = s.name.split('@')[1]
    if (!await askYes(`Delete ${s.name}? It is removed from this dataset and from every dataset beneath it that has a snapshot of the same name. This cannot be undone.`, 'Delete')) return
    try { await api.deleteZfsSnapshot(s.name, true); toast(`${short} deleted`); await reload(); onChanged() }
    catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
  }
  const depth = d.name.split('/').length - 1
  return (
    <>
      <div className="ds-row" style={{ paddingLeft: 12 + depth * 16 }}>
        <span className="ds-name" onClick={toggle}><span className="chev">{open ? '▾' : '▸'}</span>{d.name.split('/').pop()}{d.type === 'volume' && <span className="badge">zvol</span>}</span>
        <span className="num">{d.snapshots}</span>
        <span className="num muted">{d.used_by_snapshots ? fmtBytes(d.used_by_snapshots) : '—'}</span>
        <span className="num muted">{fmtBytes(d.used)}</span>
        <span className="num muted">{fmtBytes(d.refer)}</span>
        <span className="ds-mount muted">{d.mount}</span>
      </div>
      {open && (
        <div className="ds-snaps">
          <div className="svc-actions"><Btn className="btn" onClick={snapshot}>Snapshot now</Btn><span className="muted small">{d.snapshots} snapshot{d.snapshots === 1 ? '' : 's'} · {fmtBytes(d.avail)} free on this dataset</span></div>
          {snaps === null ? <div className="muted"><Spinner /> listing…</div> : snaps.length === 0 ? <div className="muted">No snapshots.</div> : (
            <div className="snap-list">{snaps.slice().reverse().map((s) => {
              const { taken, expires } = snapMeta(s.name)
              const gone = expires && expires.getTime() < Date.now()
              return (
                <div key={s.name} className="snap">
                  <span className="mono snap-name" title={s.name}>{s.name.split('@')[1]}</span>
                  <span className="muted snap-when">{taken ? taken.toLocaleString() : new Date(s.created).toLocaleString()}</span>
                  <span className={'muted snap-exp' + (gone ? ' warn' : '')}>{expires ? (gone ? 'expired' : `expires ${expires.toLocaleDateString()}`) : 'kept'}</span>
                  <span className="num muted">{fmtBytes(s.used)}</span>
                  <Btn className="btn danger snap-del" onClick={() => destroy(s)}>Delete</Btn>
                </div>
              )
            })}</div>
          )}
        </div>
      )}
    </>
  )
}

// ---- schedules ----

function ExternalNotice({ x, mine, onAdopt }: { x: ExternalJob; mine: number; onAdopt: () => void }) {
  return (
    <div className={'notice' + (mine > 0 ? ' attn' : '')} style={{ marginBottom: 8 }}>
      <b>{x.tool}</b> is already taking snapshots on this machine, from cron as <b>{x.user}</b>:
      <div className="mono small" style={{ margin: '4px 0', wordBreak: 'break-all' }}>{x.schedule} &nbsp; {x.command}</div>
      <span className="muted">in {x.source}{x.last ? ` · last ran ${ago(x.last)}` : ''}</span>
      {mine > 0
        ? <div className="warn" style={{ marginTop: 6 }}>A Ham Lab schedule is running as well. Both use the same names and both only remove snapshots that have passed the expiry written into them, so they will not fight — but they will take twice as many. Keep one.</div>
        : <div className="svc-actions" style={{ marginTop: 6 }}>
            <Btn className="btn" onClick={onAdopt}>Adopt as a schedule</Btn>
            <span className="muted small">Copies it into a Ham Lab schedule you can edit here. Turn the old cron job off on the Jobs tab once you are happy with it.</span>
          </div>}
    </div>
  )
}
type ExternalJob = ZFSExternal

function ScheduleCard({ p, cron, next, last, onChanged, onEdit }: { p: ZFSPolicy; cron: string; next?: string; last: ZFSRun; onChanged: () => void; onEdit: () => void }) {
  const [busy, setBusy] = useState('')
  const run = async () => {
    if (!await askYes(`Take a snapshot of ${p.dataset} now? Snapshots past their retention are removed at the same time, as they would be on the schedule.`, 'Run now')) return
    setBusy('run')
    try { const r = await api.runZfsSchedule(p.id); toast(`${r.taken}${r.pruned.length ? ` · ${r.pruned.length} expired removed` : ''}`); onChanged() }
    catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') } finally { setBusy('') }
  }
  const remove = async () => {
    if (!await askYes(`Remove the schedule "${p.name}"? The snapshots it already took are left exactly as they are.`, 'Remove')) return
    try { await api.deleteZfsSchedule(p.id); toast('schedule removed'); onChanged() } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
  }
  const toggle = async () => {
    try { await api.saveZfsSchedule({ ...p, enabled: !p.enabled }); onChanged() } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
  }
  return (
    <section className="card">
      <div className="sub-head">
        <span className={'dot ' + (last.error ? 'bad' : p.enabled ? 'ok' : '')} />
        <span className="dname">{p.name || p.dataset}</span>
        {!p.enabled && <span className="badge">paused</span>}
        <span className="spacer" />
        <span className="muted small">{p.enabled ? soon(next) : 'not scheduled'}</span>
      </div>
      <div className="props" style={{ marginTop: 6 }}>
        <div><span className="k">Dataset</span><span className="mono">{p.dataset}</span></div>
        <div><span className="k">When</span><span>{describe(p)}</span></div>
        <div><span className="k">Cron</span><span className="mono small" title={`in ${'/etc/cron.d/hamlab-zfs'}`}>{cron}</span></div>
        <div><span className="k">Last run</span><span>{ago(last.at)}{last.pruned?.length ? ` · ${last.pruned.length} expired removed` : ''}</span></div>
        {last.taken && <div><span className="k">Last snapshot</span><span className="mono small">{last.taken.split('@')[1]}</span></div>}
        {p.keep_min > 0 && <div><span className="k">Floor</span><span>always keep the newest {p.keep_min}</span></div>}
      </div>
      {last.error && <div className="error" style={{ marginTop: 8 }}>{last.error}</div>}
      <div className="svc-actions">
        <Btn className="btn on" busy={busy === 'run'} onClick={run}>Run now</Btn>
        <button className="btn" onClick={onEdit}>Edit</button>
        <Btn className="btn" onClick={toggle}>{p.enabled ? 'Pause' : 'Resume'}</Btn>
        <Btn className="btn danger" onClick={remove}>Remove</Btn>
      </div>
    </section>
  )
}

const BLANK: Partial<ZFSPolicy> = { name: '', dataset: '', recursive: true, every: 'daily', at: '02:30', weekday: 0, day: 1, keep_for: '6w', keep_min: 1, enabled: true }

function ScheduleDialog({ p, datasets, onClose, onSaved }: { p: Partial<ZFSPolicy>; datasets: string[]; onClose: () => void; onSaved: () => void }) {
  const [f, setF] = useState<Partial<ZFSPolicy>>({ ...BLANK, ...p })
  const [err, setErr] = useState('')
  useEscape(onClose)
  const set = (k: keyof ZFSPolicy, v: unknown) => setF((x) => ({ ...x, [k]: v }))
  const save = async (e: FormEvent) => {
    e.preventDefault(); setErr('')
    try { await api.saveZfsSchedule({ ...f, name: (f.name || '').trim() || f.dataset }); onSaved() }
    catch (e) { setErr(e instanceof Error ? e.message : 'failed') }
  }
  return (
    <div className="modal-back" onClick={onClose}>
      <form className="modal" onClick={(e) => e.stopPropagation()} onSubmit={save}>
        <h3>{f.id ? 'Edit schedule' : 'New snapshot schedule'}</h3>
        <label className="muted">Dataset
          <select value={f.dataset} onChange={(e) => set('dataset', e.target.value)} required>
            <option value="">choose…</option>
            {datasets.map((d) => <option key={d} value={d}>{d}</option>)}
          </select>
        </label>
        <label className="muted">Name — what this schedule is for
          <input value={f.name} onChange={(e) => set('name', e.target.value)} placeholder={f.dataset || 'nightly'} maxLength={64} />
        </label>
        <label className="muted">How often
          <span className="chips">
            {(['hourly', 'daily', 'weekly', 'monthly', 'custom'] as const).map((k) => (
              <button type="button" key={k} className={'chip' + (f.every === k ? ' on' : '')} onClick={() => set('every', k)}>{k}</button>
            ))}
          </span>
        </label>
        {f.every === 'custom' ? (
          <label className="muted">Cron expression — minute hour day month weekday
            <input className="mono" value={f.cron ?? ''} onChange={(e) => set('cron', e.target.value)} placeholder="0 */6 * * *" spellCheck={false} required />
          </label>
        ) : (
          <label className="muted">At
            <input type="time" value={f.at} onChange={(e) => set('at', e.target.value)} />
          </label>
        )}
        {f.every === 'weekly' && (
          <label className="muted">On
            <select value={f.weekday} onChange={(e) => set('weekday', Number(e.target.value))}>
              {WEEKDAYS.map((d, i) => <option key={d} value={i}>{d}</option>)}
            </select>
          </label>
        )}
        {f.every === 'monthly' && (
          <label className="muted">Day of the month — 1 to 28, so every month has one
            <input type="number" min={1} max={28} value={f.day} onChange={(e) => set('day', Number(e.target.value))} />
          </label>
        )}
        <label className="muted">Snapshot name prefix — optional; the timestamp and retention follow it
          <input value={f.prefix ?? ''} onChange={(e) => set('prefix', e.target.value)} placeholder="none" spellCheck={false} />
        </label>
        <label className="muted">Keep for — written into each snapshot's name, as zfSnap does it: 6w, 30d, 12h
          <input value={f.keep_for} onChange={(e) => set('keep_for', e.target.value)} placeholder="6w" spellCheck={false} required />
        </label>
        <label className="muted">Always keep the newest — a floor, whatever their age
          <input type="number" min={0} max={99} value={f.keep_min} onChange={(e) => set('keep_min', Number(e.target.value))} />
        </label>
        <label className="muted" style={{ flexDirection: 'row', alignItems: 'center', gap: 8 }}>
          <input type="checkbox" checked={!!f.recursive} onChange={(e) => set('recursive', e.target.checked)} style={{ width: 'auto' }} />
          Recursive — one atomic snapshot of this dataset and everything under it
        </label>
        <label className="muted" style={{ flexDirection: 'row', alignItems: 'center', gap: 8 }}>
          <input type="checkbox" checked={!!f.enabled} onChange={(e) => set('enabled', e.target.checked)} style={{ width: 'auto' }} />
          Enabled
        </label>
        {err && <div className="error">{err}</div>}
        <div className="svc-actions">
          <button type="submit" className="btn on" disabled={!f.dataset || !f.keep_for}>Save</button>
          <span className="spacer" />
          <button type="button" className="btn" onClick={onClose}>Cancel</button>
        </div>
      </form>
    </div>
  )
}

// adopt reads an existing cron job into the fields of a new schedule, so replacing it is a
// matter of checking the numbers rather than retyping them. zfSnap's own flags are read
// where they can be: -a <age> is the retention, -r is recursive.
function adopt(x: ExternalJob, fallbackDataset: string): Partial<ZFSPolicy> {
  const cmd = x.command
  const keep = /-a\s+(\d+[mhdwMy])/.exec(cmd)?.[1] ?? /--\s*(\d+[mhdw])\b/.exec(cmd)?.[1] ?? '6w'
  const f = x.schedule.trim().split(/\s+/)
  const min = Number(f[0]), hour = Number(f[1])
  const simple = f.length === 5 && Number.isInteger(min) && Number.isInteger(hour) && f[2] === '*' && f[3] === '*' && f[4] === '*'
  const ds = /\b(tank[\w/-]*)\b/.exec(cmd)?.[1] ?? fallbackDataset
  return {
    ...BLANK, name: `${x.tool} (adopted)`, dataset: ds,
    recursive: /\s-[a-zA-Z]*r\b/.test(cmd), // -r, or -r folded into another flag group
    every: simple ? 'daily' : 'custom',
    at: simple ? `${String(hour).padStart(2, '0')}:${String(min).padStart(2, '0')}` : '02:30',
    cron: simple ? '' : x.schedule.trim(),
    keep_for: keep, keep_min: 1, enabled: true,
  }
}

// ---- the cache: the ARC in RAM, and what each pool has in front of its disks ----
//
// Two kinds of number. The live ones (size, the hit rate over the last sampling interval)
// come from the sampler, which also keeps their history for the sparklines; the since-boot
// counters, the tunables and the pool layout come with the same request from the storage
// package. A tier a pool does not have is named and said to be absent, with what that means,
// because "nothing shown" and "none fitted" are different answers.

const hitPct = (h: number, m: number) => (h + m > 0 ? (h / (h + m)) * 100 : NaN)
const fmtPct = (v: number) => (Number.isNaN(v) ? '—' : `${v.toFixed(1)}%`)
const fmtN = (n: number) => n.toLocaleString()
const cssVar = (n: string) => getComputedStyle(document.documentElement).getPropertyValue(n).trim() || '#3987e5'

function Tier({ name, what, devs, none, note }: { name: string; what: string; devs: CacheDev[]; none: string; note?: string }) {
  return (
    <div className="arc-tier">
      <span className="k" title={what}>{name}</span>
      <span className="arc-tier-v">
        {devs.length === 0 ? <span className="none">{none}</span> : devs.map((x) => (
          <span key={x.name} className="mono" title={x.name}>
            {x.name}{x.size ? ` · ${fmtBytes(x.alloc ?? 0)} of ${fmtBytes(x.size)} used` : ''}{x.health && x.health !== 'ONLINE' ? ` · ${x.health}` : ''}
          </span>
        ))}
        {devs.length > 0 && note && <span className="muted small">{note}</span>}
      </span>
    </div>
  )
}

function PoolTiers({ p, v }: { p: PoolCaching; v: ARCView }) {
  const L = v.detail.lifetime, z = v.detail.zil, a = v.live
  return (
    <section className="card">
      <div className="sub-head">
        <span className="dname">{p.pool}</span>
        <span className="badge">caching tiers</span>
        <span className="spacer" />
        <span className="muted small mono" title="primarycache: what the ARC may hold for this pool · secondarycache: what an L2ARC may hold">primarycache={p.primarycache || '?'} · secondarycache={p.secondarycache || '?'}</span>
      </div>
      <div className="arc-tiers">
        <Tier name="L2ARC" what="cache devices: a second-level read cache on flash, fed with what the ARC evicts" devs={p.cache}
          none={`none — a read that misses RAM goes to the pool's disks. ${fmtBytes(L.EvictL2Eligible)} evicted from RAM since boot would have been eligible for one.`}
          note={a ? `${fmtBytes(a.l2_size)} cached (${fmtBytes(a.l2_asize)} on device) · ${fmtPct(hitPct(L.L2Hits, L.L2Misses))} hit since boot · ${fmtBytes(L.L2ReadBytes)} read, ${fmtBytes(L.L2WriteBytes)} written` : undefined} />
        <Tier name="SLOG" what="log devices: where synchronous writes are committed before they reach the pool" devs={p.log}
          none={`none — the intent log is on the pool's own vdevs: ${fmtN(z.commits)} commits, ${fmtBytes(z.NormalWrite)} written to it since boot`}
          note={`${fmtN(z.commits)} commits · ${fmtBytes(z.SlogWrite)} written to the log device since boot${z.NormalWrite ? `, ${fmtBytes(z.NormalWrite)} to the pool` : ''}`} />
        <Tier name="Special" what="special allocation class: metadata and small blocks kept on their own (faster) vdev" devs={p.special}
          none="none — metadata lives with the data on the same vdevs" />
        <Tier name="Dedup" what="deduplication: a table of every block's checksum, in the ARC and on disk" devs={p.dedup}
          none={!p.dedup_prop || p.dedup_prop === 'off' ? `off · ratio ${p.dedup_ratio || '1.00x'}` : `${p.dedup_prop} · ratio ${p.dedup_ratio} · the table lives in the ARC and on the data vdevs`} />
        {p.spare.length > 0 && <Tier name="Spares" what="hot spares: take over when a vdev member fails" devs={p.spare} none="" />}
      </div>
      <div className="muted small mono" style={{ marginTop: 8 }}>sync={p.sync || '?'} · logbias={p.logbias || '?'} · compression={p.compression || '?'} · recordsize={p.recordsize || '?'}</div>
    </section>
  )
}

// ---- the write path: the dirty buffer in RAM, what each pool writes, and a landing tier ----
//
// A write reaches a pool in up to three steps. If a landing tier fronts the pool (a mergerfs
// pool whose first branch is fast storage and whose last is the pool), new files land there
// first and a mover drains them. Either way the data then waits in RAM as dirty buffers, and
// each txg sync writes it to the disks. Each step's live number is here, with its history.

const dur = (s: number) => (!Number.isFinite(s) || s <= 0 ? '—' : s < 90 ? `${Math.round(s)} s` : s < 5400 ? `${Math.round(s / 60)} min` : `${(s / 3600).toFixed(1)} h`)
type WHist = Record<string, number[]>
const wIds = (w: ZFSWrites) => ['zfs.write.dirty', ...w.pools.flatMap((p) => {
  const b = `zfs.${p.pool}.`
  return [b + 'write_bps', b + 'logical_bps', ...(p.landing ? [b + 'landing.pending_bytes', b + 'landing.in_bps', b + 'landing.drain_bps'] : [])]
})]

function MoverLine({ l }: { l: Landing }) {
  const m = l.mover
  if (!m) return <div className="notice" style={{ marginTop: 6 }}>No mover is reporting for this landing tier (nothing in <span className="mono">/run/landing-mover/</span>). Files that land here stay here until something moves them.</div>
  const frac = m.current_size > 0 ? m.partial / m.current_size : 0
  return (
    <>
      <div className="props" style={{ marginTop: 6 }}>
        <div><span className="k">Mover</span><span>
          <span className={'badge ' + (m.state === 'moving' ? 'on' : m.state === 'idle' ? '' : 'warn')}>{m.state}</span>
          {' '}{m.state === 'moving' && m.batch_files > 1 ? `batch of ${m.batch_files} files, ${fmtBytes(m.batch_bytes)}` : m.state === 'holding' ? 'a mount it needs is missing — waiting' : m.state === 'stopped' ? `no word since ${ago(m.updated_ms)}` : `queue ${m.queue}`}
          {m.state === 'moving' && m.queue > 0 ? ` · ${m.queue} more queued` : ''}
        </span></div>
        {m.state === 'moving' && m.current && <div><span className="k">Now</span><span className="mono small" title={m.current}>{m.current}{m.current_size ? ` · ${fmtBytes(m.partial)} of ${fmtBytes(m.current_size)}` : ''}</span></div>}
        <div><span className="k">Since start</span><span>{fmtN(m.moved_files)} files · {fmtBytes(m.moved_bytes)} moved · running {ago(m.started_ms).replace(' ago', '')}</span></div>
        {m.last_move && <div><span className="k">Last moved</span><span className="mono small" title={m.last_move}>{m.last_move} · {ago(m.last_move_ms)}</span></div>}
        <div><span className="k">Rules</span><span className="muted">a file moves once it has been closed and left alone for {m.settle} s · limit {m.bwlimit && m.bwlimit !== '0' ? `${m.bwlimit}B/s` : 'none'} · oldest first</span></div>
        {m.last_error && <div><span className="k">Last error</span><span className="warn-text" style={{ whiteSpace: 'normal' }}>{m.last_error} · {ago(m.last_error_ms)}</span></div>}
      </div>
      {m.state === 'moving' && m.current_size > 0 && <Meter frac={frac} cls="" />}
    </>
  )
}

function LandingBlockInner({ l, pending, inn, drain }: { l: Landing; pending: number[]; inn: number[]; drain: number[] }) {
  const eta = l.drain_bps > 0 ? l.pending_bytes / l.drain_bps : NaN
  const fill = l.size > 0 ? l.used / l.size : 0
  return (
    <div className="landing-tier">
      <div className="arc-tier"><span className="k" title="a mergerfs pool puts new files on this branch first; a mover drains them onto the pool">Landing</span>
        <span className="arc-tier-v"><span className="mono" title={`${l.branch} → ${l.pool_branch} via ${l.mount}`}>{l.branch}{l.device ? ` · ${l.device}` : ''}{l.fstype ? ` · ${l.fstype}` : ''} · in front of {l.pool_branch} as {l.mount}</span></span>
      </div>
      <div className="sub-head" style={{ marginTop: 6 }}>
        <span className="muted small">{fmtBytes(l.used)} of {fmtBytes(l.size)} used</span><span className="spacer" />
        <span className="num">{l.pending_files ? `${fmtN(l.pending_files)}${l.pending_partial ? '+' : ''} waiting · ${fmtBytes(l.pending_bytes)}` : 'nothing waiting'}</span>
      </div>
      <Meter frac={fill} />
      <div className="props" style={{ marginTop: 6 }}>
        <div><span className="k">Waiting</span><span>{l.pending_files ? `${fmtN(l.pending_files)}${l.pending_partial ? '+' : ''} files, ${fmtBytes(l.pending_bytes)} · oldest landed ${ago(l.oldest_ms)}` : 'nothing — everything that landed is on the pool'}<span className="muted small"> · counted {ago(l.counted_ms)}</span></span></div>
        <div><span className="k">Arriving</span><span>{fmtRate(l.in_bps)}{l.device ? <span className="muted small"> · writes to {l.device}</span> : ''}</span></div>
        <div><span className="k">To the pool</span><span>{fmtRate(l.drain_bps)}{l.pending_bytes > 0 ? ` · ${Number.isFinite(eta) ? `clear in about ${dur(eta)}` : 'not draining right now'}` : ''}</span></div>
      </div>
      <MoverLine l={l} />
      <div className="arc-sparks">
        <div>
          <div className="muted small">Waiting on the landing tier · {fmtBytes(l.pending_bytes)}</div>
          <Sparkline series={[{ name: 'waiting', values: pending, color: cssVar('--s1') }]} format={fmtBytes} height={40} />
        </div>
        <div>
          <div className="muted small">Arriving {fmtRate(l.in_bps)} · to the pool {fmtRate(l.drain_bps)}</div>
          <Sparkline series={[
            { name: 'arriving', values: inn, color: cssVar('--s1') },
            { name: 'to the pool', values: drain, color: cssVar('--ok') },
          ]} format={fmtRate} height={40} />
        </div>
      </div>
    </div>
  )
}

function WritePath({ w, p, h }: { w: ZFSWrites; p: PoolWrites; h: WHist }) {
  const b = `zfs.${p.pool}.`
  const throttling = w.delayed_per_sec > 0 || w.over_max_per_sec > 0
  const delayAt = (w.limit * w.delay_min_pct) / 100
  const ratio = p.write_bps > 0 && p.logical_bps > 0 ? p.logical_bps / p.write_bps : 0
  return (
    <section className="card">
      <div className="sub-head">
        <span className={'dot ' + (w.over_max_per_sec > 0 ? 'bad' : throttling ? 'warn' : 'ok')} />
        <span className="dname">{p.pool}</span>
        <span className="badge">write path</span>
        <span className="spacer" />
        <span className="num">{fmtRate(p.write_bps)} to disk</span>
      </div>
      {p.landing
        ? <LandingBlockWithHist l={p.landing} h={h} b={b} />
        : <div className="arc-tiers"><div className="arc-tier"><span className="k" title="a fast tier new files land on before the pool">Landing</span><span className="arc-tier-v"><span className="none">none — writes go straight into the pool's RAM buffer</span></span></div></div>}
      <div className="arc-sparks">
        <div>
          <div className="muted small">RAM write buffer · {fmtBytes(w.dirty)} of {fmtBytes(w.limit)}</div>
          <Sparkline series={[{ name: 'waiting in RAM', values: h['zfs.write.dirty'] ?? [], color: cssVar('--s1') }]} max={w.limit || undefined} format={fmtBytes} height={44} />
        </div>
        <div>
          <div className="muted small">Writes · {fmtRate(p.write_bps)} to disk · {fmtRate(p.logical_bps)} from programs</div>
          <Sparkline series={[
            { name: 'to disk', values: h[b + 'write_bps'] ?? [], color: cssVar('--s1') },
            { name: 'from programs', values: h[b + 'logical_bps'] ?? [], color: cssVar('--ok') },
          ]} format={fmtRate} height={44} />
        </div>
      </div>
      <div className="props" style={{ marginTop: 8 }}>
        <div><span className="k">In RAM</span><span title="dirty data: written by programs, not yet on the disks. For all pools together — ZFS keeps no live per-pool figure">{fmtBytes(w.dirty)} waiting · holds up to {fmtBytes(w.limit)} {w.limit < w.dirty_max ? `(half the ARC target; zfs_dirty_data_max is ${fmtBytes(w.dirty_max)})` : '(zfs_dirty_data_max)'}</span></div>
        <div><span className="k">Throttle</span><span title="past zfs_delay_min_dirty_percent of the buffer, ZFS makes each write wait a little so the disks can catch up; at the limit, writes stop until a sync frees room">
          {w.over_max_per_sec > 0 ? <span className="warn-text">{fmtN(w.over_max_per_sec)}/s writes stopped at the limit</span> : w.delayed_per_sec > 0 ? <span className="warn-text">slowing {fmtN(w.delayed_per_sec)} writes/s — the disks are the limit now</span> : 'not slowing anything'}
          <span className="muted"> · starts at {w.delay_min_pct}% ({fmtBytes(delayAt)})</span></span></div>
        <div><span className="k">To disk</span><span>{fmtRate(p.write_bps)} written by syncs{ratio > 0 ? ` · ${fmtRate(p.logical_bps)} from programs (${ratio >= 1 ? `${ratio.toFixed(2)}x compressed` : 'parity and metadata included'})` : ''}<span className="muted"> · a sync at least every {w.txg_timeout_sec} s, sooner as the buffer fills</span></span></div>
      </div>
    </section>
  )
}

function LandingBlockWithHist({ l, h, b }: { l: Landing; h: WHist; b: string }) {
  return <LandingBlockInner l={l} pending={h[b + 'landing.pending_bytes'] ?? []} inn={h[b + 'landing.in_bps'] ?? []} drain={h[b + 'landing.drain_bps'] ?? []} />
}

function ARCSection() {
  const [v, setV] = useState<ARCView | null>(null)
  const [hist, setHist] = useState<{ size: number[]; hit: number[] }>({ size: [], hit: [] })
  const [whist, setWhist] = useState<WHist>({})
  const [err, setErr] = useState('')
  const rate = useRefreshMs()
  useEffect(() => {
    let stop = false
    const poll = async () => {
      let r: ARCView | null = null
      try { r = await api.zfsARC(); if (!stop) { setV(r); setErr('') } } catch (e) { if (!stop) setErr(e instanceof Error ? e.message : 'failed') }
      try {
        const extra = r?.writes ? wIds(r.writes) : []
        const hs = await fetchHistories(['zfs.arc.size', 'zfs.arc.hit_pct', ...extra].join(','))
        if (!stop) {
          setHist({ size: hs.find((h) => h.id === 'zfs.arc.size')?.v ?? [], hit: hs.find((h) => h.id === 'zfs.arc.hit_pct')?.v ?? [] })
          setWhist(Object.fromEntries(hs.filter((h) => extra.includes(h.id)).map((h) => [h.id, h.v])))
        }
      } catch { /* the sparklines stay empty; the numbers still show */ }
    }
    poll()
    const t = setInterval(poll, rate)
    return () => { stop = true; clearInterval(t) }
  }, [rate])

  if (err && !v) return <div className="error">{err}</div>
  if (!v) return <div className="muted"><Spinner /> reading the cache…</div>
  const d = v.detail, a = v.live
  if (!d.available || !a) return <div className="notice">The ZFS module reports no ARC statistics on this machine.</div>

  const L = d.lifetime
  const ratio = a.compressed > 0 ? a.uncompressed / a.compressed : 0
  const maxSet = d.tunables.zfs_arc_max && d.tunables.zfs_arc_max !== '0'
  const atFloor = a.target <= a.min * 1.02
  const rows: [string, number, number][] = [
    ['Demand data', L.DemandDataHits, L.DemandDataMisses], ['Demand metadata', L.DemandMetaHits, L.DemandMetaMisses],
    ['Prefetch data', L.PrefetchDataHits, L.PrefetchDataMisses], ['Prefetch metadata', L.PrefetchMetaHits, L.PrefetchMetaMisses],
  ]
  return (
    <>
      <section className="card">
        <div className="sub-head">
          <span className={'dot ' + (a.no_grow ? 'warn' : 'ok')} />
          <span className="dname">ARC</span>
          <span className="badge">in RAM</span>
          <span className="spacer" />
          <span className="num">{fmtBytes(a.size)} / {fmtBytes(a.max)} · {Math.round((a.size / a.max) * 100)}%</span>
        </div>
        <Meter frac={a.size / a.max} cls="" />
        {a.no_grow && (
          <div className="notice attn" style={{ marginTop: 8 }}>
            <b>Held by memory pressure.</b> ZFS is not letting the cache grow (<span className="mono">arc_no_grow</span>): the system is short of free memory
            {atFloor ? <>, and the target sits at its floor of <b>{fmtBytes(a.min)}</b> against a ceiling of {fmtBytes(a.max)}</> : ''}.
            {' '}Whatever no longer fits is read from the disks.
          </div>
        )}
        <div className="arc-sparks">
          <div>
            <div className="muted small">Size · ceiling {fmtBytes(a.max)}</div>
            <Sparkline series={[{ name: 'size', values: hist.size, color: cssVar('--s1') }]} max={a.max} format={fmtBytes} height={48} />
          </div>
          <div>
            <div className="muted small">Hit rate · {a.hit_pct_known ? `${a.hit_pct.toFixed(1)}% now` : 'no reads yet'} · {fmtN(Math.round(a.reads_per_sec))} reads/s</div>
            <Sparkline series={[{ name: 'hit rate', values: hist.hit, color: cssVar('--ok') }]} max={100} format={(x) => `${x.toFixed(1)}%`} height={48} />
          </div>
        </div>
        <div className="props" style={{ marginTop: 8 }}>
          <div><span className="k">Target</span><span title="c: what the ARC may hold right now, between its floor (c_min) and ceiling (c_max)">{fmtBytes(a.target)} · floor {fmtBytes(a.min)} · ceiling {fmtBytes(a.max)} {maxSet ? '(zfs_arc_max)' : '(default: half of RAM)'}</span></div>
          <div><span className="k">Hit rate</span><span>{a.hit_pct_known ? `${a.hit_pct.toFixed(1)}% now` : 'idle'} · {a.lifetime_hit_pct.toFixed(1)}% since boot · {fmtN(a.hits)} hits, {fmtN(a.misses)} misses</span></div>
          <div><span className="k">Holds</span><span title="MRU: seen once · MFU: seen again · dirty: written, not yet on disk">MRU {fmtBytes(a.mru)} · MFU {fmtBytes(a.mfu)} · dirty {fmtBytes(a.anon)}</span></div>
          <div><span className="k">Of which</span><span>data {fmtBytes(a.data)} · metadata {fmtBytes(a.metadata)} · headers {fmtBytes(a.headers)}</span></div>
          <div><span className="k">Compressed</span><span>{ratio > 0 ? `${fmtBytes(a.uncompressed)} held in ${fmtBytes(a.compressed)} · ${ratio.toFixed(2)}x` : 'not compressed'}</span></div>
          <div><span className="k">Ghosts</span><span title="what was evicted recently and is still remembered, so a re-read can grow the right list">MRU {fmtBytes(a.mru_ghost)} · MFU {fmtBytes(a.mfu_ghost)}</span></div>
          <div><span className="k">Prefetch</span><span title="zfetch: the read-ahead that guesses the next blocks of a sequential read">{d.tunables.zfs_prefetch_disable === '1' ? 'disabled (zfs_prefetch_disable)' : `${fmtPct(hitPct(d.zfetch.Hits, d.zfetch.Misses))} of ${fmtN(d.zfetch.Hits + d.zfetch.Misses)} predictions since boot`}</span></div>
          <div><span className="k">dbuf cache</span><span title="the small cache of decompressed buffers in front of the ARC">{fmtBytes(d.dbuf.Size)} of {fmtBytes(d.dbuf.Target)} · {fmtPct(hitPct(d.dbuf.Hits, d.dbuf.Misses))} hits</span></div>
          <div><span className="k">Pressure</span><span title="since boot: throttles are allocations ZFS made wait for memory; prunes are metadata evictions asked of the filesystems">{fmtN(a.throttles)} throttles · {fmtN(a.prunes)} prunes · {fmtN(a.evict_skip)} evict skips</span></div>
        </div>
        <div className="arc-break">
          <span className="head">Since boot</span><span className="head num">hit rate</span><span className="head num">hits</span><span className="head num">misses</span>
          {rows.map(([k, h, m]) => <Fragment key={k}><span>{k}</span><span className="num">{fmtPct(hitPct(h, m))}</span><span className="num">{fmtN(h)}</span><span className="num">{fmtN(m)}</span></Fragment>)}
          <span><b>All reads</b></span><span className="num"><b>{fmtPct(hitPct(L.Hits, L.Misses))}</b></span><span className="num">{fmtN(L.Hits)}</span><span className="num">{fmtN(L.Misses)}</span>
        </div>
      </section>
      {d.pools.length > 0 && <div className="cards full" style={{ marginTop: 8 }}>{d.pools.map((p) => <PoolTiers key={p.pool} p={p} v={v} />)}</div>}
      {v.writes && v.writes.pools.length > 0 && (
        <>
          <div className="dash-bar" style={{ marginTop: 12 }}><h2 className="section">Writes</h2><span className="spacer" />
            <span className="muted small">what is waiting to reach each pool, and how fast it is getting there</span>
          </div>
          <div className="cards full">{v.writes.pools.map((p) => <WritePath key={p.pool} w={v.writes!} p={p} h={whist} />)}</div>
        </>
      )}
    </>
  )
}

// ---- page ----

export default function ZFS() {
  const [ov, setOv] = useState<ZFSOverview | null>(null)
  const [err, setErr] = useState('')
  const [editing, setEditing] = useState<Partial<ZFSPolicy> | null>(null)
  const rate = useRefreshMs()

  const load = useCallback(async () => {
    try { setOv(await api.zfsOverview()); setErr('') } catch (e) { setErr(e instanceof Error ? e.message : 'failed') }
  }, [])
  useEffect(() => { load() }, [load])
  useEffect(() => { const t = setInterval(load, Math.max(5000, rate * 10)); return () => clearInterval(t) }, [load, rate])

  if (err && !ov) return <div className="dash"><div className="error">{err}</div></div>
  if (!ov) return <div className="dash"><Loading label="Reading ZFS…" /></div>
  const zfs: ZFSInfo = ov.zfs
  const datasets = zfs.datasets.filter((d) => d.type !== 'volume').map((d) => d.name)
  const mine = ov.policies.filter((x) => x.policy.enabled).length

  if (!zfs.available) return <div className="dash"><div className="notice">{zfs.message || 'No ZFS on this host.'}</div></div>

  return (
    <div className="dash">
      <div className="dash-bar"><h2 className="section">Pools</h2></div>
      {zfs.pools.length === 0 && <div className="notice">ZFS is present but no pools are imported.</div>}
      <div className="cards full">{zfs.pools.map((p) => <PoolCard key={p.name} p={p} onChanged={load} />)}</div>

      <div className="dash-bar" style={{ marginTop: 12 }}><h2 className="section">Cache</h2><span className="spacer" />
        <span className="muted small">the ARC in RAM, and what each pool has in front of its disks</span>
      </div>
      <ARCSection />

      <div className="dash-bar" style={{ marginTop: 12 }}><h2 className="section">Snapshot schedules</h2><span className="spacer" />
        <Btn className="btn on" onClick={() => setEditing({ ...BLANK, dataset: zfs.pools[0]?.name ?? '' })}>+ New schedule</Btn>
      </div>
      {ov.external && <ExternalNotice x={ov.external} mine={mine} onAdopt={() => setEditing(adopt(ov.external!, zfs.pools[0]?.name ?? ''))} />}
      {ov.policies.length === 0 && !ov.external && <div className="notice">Nothing is taking snapshots on a schedule. Snapshots are written the way zfSnap writes them, with the retention in the name, so anything already here is understood.</div>}
      <div className="cards">{ov.policies.map(({ policy, cron, next, last }) => (
        <ScheduleCard key={policy.id} p={policy} cron={cron} next={next} last={last ?? {}} onChanged={load} onEdit={() => setEditing(policy)} />
      ))}</div>

      <div className="dash-bar" style={{ marginTop: 12 }}><h2 className="section">Snapshots</h2><span className="spacer" />
        <span className="muted small">{zfs.datasets.reduce((a, d) => a + d.snapshots, 0)} across {zfs.datasets.length} datasets · open one to browse, take or delete</span>
      </div>
      <section className="card ds-table">
        <div className="ds-row head">
          <span>Dataset</span><span className="num">Snapshots</span><span className="num">They use</span>
          <span className="num">Dataset uses</span><span className="num">Referenced</span><span>Mount</span>
        </div>
        {zfs.datasets.map((d) => <DatasetRow key={d.name} d={d} onChanged={load} />)}
      </section>

      {editing && <ScheduleDialog p={editing} datasets={datasets.length ? datasets : zfs.pools.map((p) => p.name)} onClose={() => setEditing(null)} onSaved={() => { setEditing(null); load() }} />}
    </div>
  )
}