package backup

import (
	"context"
	"errors"
	"fmt"
	"gitea.dooplex.hu/admin/felhom-controller/internal/i18n"
	"gitea.dooplex.hu/admin/felhom-controller/internal/util"
	"os"
	"path/filepath"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
)

// ── The backup side of the guarded update (update arc slice 4, controller v0.237.0) ─────────────
//
// 09-update-architecture.md §3 decision 1 (operator ruling 2026-09-02): the safety copy for an update
// is a VERIFIED RECENT BACKUP as a PRECONDITION — not a new copy mechanism invented for the update
// path. So everything in this file composes machinery that already exists and is proven live:
// the Tier-2 unit restore's own predicate (R-102/R-103), the nightly legs (DB dump, volume dump,
// unit capture, Tier-2 mirror), the pre-restore safety dump (R-361) and the R-379 hold.
//
// The stacks package cannot import this one, so the update job reaches all of it through the
// stacks.UpdateGuards interface, implemented by an adapter in cmd/controller/main.go.

// Tier2RestorePoint is the answer to "could this app be restored from its Tier-2 copy, and from
// when?" — the predicate the destructive „Teljes visszaállítás" action is gated on.
//
// EXTRACTED, NOT DUPLICATED (slice 4). Until v0.237.0 this computation lived inline in the backups
// page handler (buildAppBackupRows). The update path needs exactly the same question answered, and
// a second copy of a predicate is how this project's two copies of `namespaceRoot` came to differ
// (R-203). So there is one function, and the page and the update both call it.
type Tier2RestorePoint struct {
	// Restorable — the copy holds an OPENABLE recovery unit (Tier2Coverage.CanRestoreUnit).
	Restorable bool
	// CopyDate — the date the unit restore NAMES: the package's own manifest date, falling back to the
	// copy date (Tier2Coverage.UnitRestoreDate, R-403). RFC3339 as recorded, "" when unknown.
	CopyDate string
	// CopyDateProven — a copy actually SUCCEEDED (LastSuccess is set), never merely an attempt (R-101).
	CopyDateProven bool
	// PackagePreserved — the newest run PRESERVED an older package instead of refreshing it (R-403).
	PackagePreserved bool
	// CopyLastSuccess — the RFC3339 time of the last Tier-2 copy that succeeded.
	CopyLastSuccess string
	// DataDate (v0.275.0, R-696) — the mirrored unit's DATA time (unitNewestArtifact on the mirror): when
	// the data the copy holds was written, which a mirror run copies but never makes newer. "" = unknown.
	DataDate string
}

// restorePointFromCoverage is the pure half of the predicate.
func restorePointFromCoverage(cov Tier2Coverage) Tier2RestorePoint {
	pkgDate, preserved := cov.UnitRestoreDate()
	return Tier2RestorePoint{
		Restorable:       cov.CanRestoreUnit(),
		CopyDate:         pkgDate,
		CopyDateProven:   cov.CopyLastSuccess != "",
		PackagePreserved: preserved,
		CopyLastSuccess:  cov.CopyLastSuccess,
		DataDate:         cov.UnitDataDate,
	}
}

// Tier2UnitRestorePoint resolves the app's recorded Tier-2 copy and returns the restore point. The
// error is the same refusal Tier2RestoreCoverage raises (no copy, drive gone, pre-v2 layout).
func (m *Manager) Tier2UnitRestorePoint(stackName string) (Tier2RestorePoint, error) {
	cov, err := m.Tier2RestoreCoverage(stackName)
	if err != nil {
		return Tier2RestorePoint{}, err
	}
	return restorePointFromCoverage(cov), nil
}

// ProvenCopyTime returns WHEN the data this copy would restore was last proven copied, and false when
// there is no proven, restorable copy at all.
//
// WHY NOT CopyDate, measured rather than assumed. CopyDate is the unit MANIFEST's created_at, and a
// capture rewrites the manifest only when the app's DEFINITION changes (compose, app.yaml, controller
// version) — a nightly DB dump keeps the same file name, so it does not move it. Measured on demo-hp
// 2026-09-13: bookstack's Tier-2 mirror held `bookstack-mariadb.sql` written 2026-09-13T00:30Z while
// its manifest still read 2026-09-12T02:15:29Z. Judging "recent" by that date would call a fresh copy
// stale — and, worse, a "back up first" run would not move it either on a quiet app, so the update
// would be refused forever.
//
// So the age is the last SUCCESSFUL copy (LastSuccess), which the Tier-2 run records only when it
// actually mirrored the unit — EXCEPT when the run preserved an older package (R-403), in which case
// the package date is the honest one, because that is what the copy really holds.
func (p Tier2RestorePoint) ProvenCopyTime() (time.Time, bool) {
	if !p.Restorable || !p.CopyDateProven {
		return time.Time{}, false
	}
	src := p.CopyLastSuccess
	if p.PackagePreserved {
		src = p.CopyDate
	}
	t, err := time.Parse(time.RFC3339, src)
	if err != nil {
		return time.Time{}, false
	}
	// v0.275.0 (R-696): a mirror run copies the unit's data; it never makes the data newer. When the
	// mirror's data time is known and older than the copy, the data time is the copy's age — a mirror
	// taken right after an update, of a unit whose dump is from before it, is as old as that dump.
	if d, derr := time.Parse(time.RFC3339, p.DataDate); derr == nil && d.Before(t) {
		return d, true
	}
	return t, true
}

// ── R-475: any backup tier lets an app update (operator ruling 2026-09-13, controller v0.239.0) ────
//
// Until v0.239.0 the update's precondition was Tier2UnitRestorePoint alone, so an app with no second
// drive could never be updated — even with a fresh recovery unit on its own drive and an off-site
// snapshot from last night. The ruling: every backup counts. Tier2UnitRestorePoint itself is NOT
// changed; the backups page still calls it for the „Teljes visszaállítás" action, which really does
// restore from the second drive only.

// Backup tiers, as the update precondition and the hold sentence name them.
const (
	UpdateTierLocal       = 1 // the app's own recovery unit on its drive — „helyi" on the restore page
	UpdateTierSecondDrive = 2 // the Tier-2 mirror on another drive
	UpdateTierOffsite     = 3 // the off-site restic repository
)

// updateTierOrder is the preference order the ruling set: the second drive, then the app's own unit,
// then off-site. The first tier holding a copy the caller ACCEPTS is chosen.
var updateTierOrder = []int{UpdateTierSecondDrive, UpdateTierLocal, UpdateTierOffsite}

// updateTierOrderBindData (R-479, operator ruling 2026-09-13, v0.241.0) is the order for an app whose
// DATA lives in bind-mounted files outside its recovery unit: second drive, OFF-SITE, own unit. The own
// unit then holds the definition and the database dumps but not the files, so a route back that names
// it would restore settings and not data — measured on demo-hp with gokapi (v0.239.0: „a beállítások
// visszaálltak … adatot nem"). Off-site carries the mandatory file legs; it comes before the unit.
var updateTierOrderBindData = []int{UpdateTierSecondDrive, UpdateTierOffsite, UpdateTierLocal}

// DataOutsideUnit reports whether the app keeps data in bind-mounted files that the recovery unit does
// not hold — i.e. the app has classified binds. Nil provider or no binds → false (the unit holds the
// data: named volumes and database dumps). Pinned by TestR479_.
func (m *Manager) DataOutsideUnit(stackName string) bool {
	if m == nil || m.stackProvider == nil {
		return false
	}
	binds, has := m.stackProvider.GetStackClassifiedBinds(stackName)
	return has && len(binds) > 0
}

// UpdateTierOrderFor is the tier order the update walks for this app (R-475 / R-479).
func (m *Manager) UpdateTierOrderFor(stackName string) []int {
	if m.DataOutsideUnit(stackName) {
		return updateTierOrderBindData
	}
	return updateTierOrder
}

// UpdateCopyHolds is the customer phrase for what a copy on `tier` holds for this app — the second half
// of the R-479 ruling: the hold sentence names WHAT the chosen copy holds, not only where it is.
//
// v0.264.0 (R-606): the phrase is a bundle key — it is a PROMISE ABOUT WHETHER THE HOUSEHOLD'S FILES
// COME BACK and must reach an English household in English. The value returned (and stored in the
// hold) is still the Hungarian, byte for byte; copyHoldsIn maps it back to its key at render time, so
// a hold written by any earlier version localises too.
func (m *Manager) UpdateCopyHolds(stackName string, tier int) string {
	return util.Text(i18n.Default, updateCopyHoldsKey(m.DataOutsideUnit(stackName), tier))
}

// UpdateCopyHoldsKey is the same verdict as UpdateCopyHolds, as its bundle KEY (R-647, v0.265.0). The
// app_update_held event carries the key, not the Hungarian phrase: the hub prints the raw details as
// the mail's `Note:` line, and an English household read „a beállításokat, …" there.
func (m *Manager) UpdateCopyHoldsKey(stackName string, tier int) string {
	return updateCopyHoldsKey(m.DataOutsideUnit(stackName), tier)
}

func updateCopyHoldsKey(outside bool, tier int) string {
	switch tier {
	case UpdateTierLocal:
		if outside {
			return "hold.copy_holds.db_only"
		}
		return "hold.copy_holds.volumes"
	case UpdateTierSecondDrive, UpdateTierOffsite:
		if outside {
			return "hold.copy_holds.files"
		}
		return "hold.copy_holds.volumes"
	}
	return ""
}

// copyHoldKeys are the phrases a hold may have stored; the stored value is the Hungarian.
var copyHoldKeys = []string{"hold.copy_holds.db_only", "hold.copy_holds.volumes", "hold.copy_holds.files"}

// copyHoldsIn renders a STORED copy-holds phrase in lang. An unknown phrase is returned as stored —
// never an empty clause (a hold must not lose the sentence that says what the copy holds).
func copyHoldsIn(lang, stored string) string {
	for _, k := range copyHoldKeys {
		if util.Text(i18n.Default, k) == stored {
			return util.Text(lang, k)
		}
	}
	return stored
}

// UpdateTierLabel is a tier's name in the customer's hold sentence (Hungarian). "" for an unknown tier.
func UpdateTierLabel(tier int) string { return UpdateTierLabelIn(i18n.Default, tier) }

// UpdateTierLabelIn is UpdateTierLabel in lang (v0.264.0, R-606).
func UpdateTierLabelIn(lang string, tier int) string {
	switch tier {
	case UpdateTierSecondDrive, UpdateTierLocal, UpdateTierOffsite:
		return util.Text(lang, fmt.Sprintf("hold.update.tier.%d", tier))
	}
	return ""
}

// updateOffsiteCheckTimeout bounds the off-site lookup. An update must not stall on an unreachable
// Storage Box: past this the off-site copy counts as ABSENT (with a WARN), and the update carries on
// with backing up first. A var only so a test can shorten it.
var updateOffsiteCheckTimeout = 15 * time.Second

// UpdateTierPoint is one proven, restorable copy of an app on one tier.
type UpdateTierPoint struct {
	Tier int
	// At is when the data in that copy was last proven written: Tier 2 ProvenCopyTime (capped by the
	// mirror's data time), Tier 1 the unit's DATA time (ListRestorePoints → unitNewestArtifact), Tier 3
	// the newest snapshot, capped by the data time the box recorded when it pushed it (v0.275.0, R-696).
	At time.Time
}

// UpdateRestorePoints walks the tiers in preference order (2, 1, 3) and returns the FIRST copy that
// accept admits (nil accepts any), whether one was found, and every copy it looked at on the way.
//
// It stops at the first accepted copy, so a box with a fresh second-drive copy never touches the
// network. The AGE rule is the caller's (stacks applies backup_max_age through accept) — that is what
// makes "the age rule applies to whichever tier is chosen" one rule, not three (R-475 Scenario M).
func (m *Manager) UpdateRestorePoints(ctx context.Context, stackName string, accept func(UpdateTierPoint) bool) (UpdateTierPoint, bool, []UpdateTierPoint) {
	var seen []UpdateTierPoint
	for _, tier := range m.UpdateTierOrderFor(stackName) {
		p, ok := m.updateTierPoint(ctx, stackName, tier)
		if !ok {
			continue
		}
		seen = append(seen, p)
		if accept == nil || accept(p) {
			return p, true, seen
		}
	}
	return UpdateTierPoint{}, false, seen
}

func (m *Manager) updateTierPoint(ctx context.Context, stackName string, tier int) (UpdateTierPoint, bool) {
	switch tier {
	case UpdateTierSecondDrive:
		get := m.updateTier2PointFn
		if get == nil {
			get = m.Tier2UnitRestorePoint
		}
		rp, err := get(stackName)
		if err != nil {
			if m.isDebug() {
				m.logger.Printf("[DEBUG] [backup] update precondition for %s: no Tier-2 copy (%v)", stackName, err)
			}
			return UpdateTierPoint{}, false
		}
		at, ok := rp.ProvenCopyTime()
		return UpdateTierPoint{Tier: tier, At: at}, ok
	case UpdateTierLocal:
		list := m.updateTier1PointsFn
		if list == nil {
			list = m.ListRestorePoints
		}
		pts, _ := list(stackName)
		for _, rp := range pts {
			if at, err := time.Parse(time.RFC3339, rp.Time); err == nil {
				return UpdateTierPoint{Tier: tier, At: at}, true
			}
		}
		return UpdateTierPoint{}, false
	case UpdateTierOffsite:
		times := m.updateOffsiteTimesFn
		if times == nil {
			if m.settings == nil || !m.OffboxConfigured() {
				return UpdateTierPoint{}, false
			}
			times = m.OffsiteSnapshotTimes
		}
		cctx, cancel := context.WithTimeout(ctx, updateOffsiteCheckTimeout)
		defer cancel()
		got, err := times(cctx)
		if err != nil {
			if !errors.Is(err, errNoOffsiteTarget) {
				m.logger.Printf("[WARN] [backup] update precondition for %s: the off-site copy could not be checked within %s (%v) — counted as ABSENT", stackName, updateOffsiteCheckTimeout, err)
			}
			return UpdateTierPoint{}, false
		}
		if at, ok := got[stackName]; ok && !at.IsZero() {
			return UpdateTierPoint{Tier: tier, At: m.offsiteDataTime(stackName, at)}, true
		}
	}
	return UpdateTierPoint{}, false
}

// CanBackUpApp reports whether "back up first" can run for this app at all right now — the second
// half of R-475 Scenario L: an app with no copy anywhere is refused only when this is false too.
// Cheap and read-only; RunAppBackupNow re-checks everything when it actually runs.
func (m *Manager) CanBackUpApp(stackName string) (bool, string) {
	if m == nil {
		return false, "backup is not enabled on this box"
	}
	if m.stackProvider == nil {
		return false, "stack provider not configured"
	}
	if m.migrationActive() {
		return false, "a data migration is running"
	}
	drivePath := m.GetAppDrivePath(stackName)
	if drivePath == "" || !filepath.IsAbs(drivePath) {
		return false, "the app's drive cannot be resolved"
	}
	if m.settings != nil && (m.settings.IsDisconnected(drivePath) || m.settings.IsDecommissioned(drivePath)) {
		return false, fmt.Sprintf("the app's drive %s is not available", drivePath)
	}
	return true, ""
}

// UpdateBusy reports whether something else is ALREADY touching this app's data, which refuses an
// update before anything moves (slice 4 Scenario D). The reason is operator-English; the customer
// sentence is chosen by the caller.
//
// IsRunning is box-wide, deliberately: the backup/restore single-flight is box-wide, and an update's
// "back up first" leg needs that same flag — an update started beside a running backup would either
// wait on it invisibly or fail half-way.
func (m *Manager) UpdateBusy(stackName string) (bool, string) {
	if m == nil {
		return false, ""
	}
	if m.IsRunning() {
		return true, "a backup or restore is running (single-flight held)"
	}
	if st := m.RestoreStatus(); st.Running {
		return true, fmt.Sprintf("restore op %q is running for %q", st.Op, st.Stack)
	}
	for _, held := range m.appStop.HeldStacks() {
		if held == stackName {
			return true, "an app-data operation (volume dump / export / reconstitute) is holding it"
		}
	}
	return false, ""
}

// ErrUpdateBackupNoUnit is returned when a "back up first" run completed but the app still has no
// openable Tier-2 unit — typically Tier 2 is switched off for the app or has no second target.
var ErrUpdateBackupNoUnit = util.MsgError("err.backup.a_frissites_elotti_mentes_lefutott_de")

// RunAppBackupNow runs THIS app's backup legs now, in the nightly order, and then its Tier-2 copy:
// database dump(s) → volume dump (if the app has named volumes) → recovery-unit capture → Tier-2
// mirror. It is the "back up first" of slice 4 Scenario B.
//
// Composed, not reinvented: every leg is the one runDBDumpsInternal and RunAllTier2 already run,
// including the R-181 reserve (admitApp) before the first write and the R-166 app-stop marker inside
// DumpAppVolumesSafe. What differs is only the scope — one app instead of all of them — because an
// update must not bounce every other app on the box to back up one.
func (m *Manager) RunAppBackupNow(ctx context.Context, stackName string) error {
	if m.stackProvider == nil {
		return fmt.Errorf("stack provider not configured")
	}
	if m.migrationActive() {
		return util.MsgError("err.backup.adatathelyezes_folyamatban_a_mentes_most_nem")
	}
	if err := m.acquireRunning(); err != nil {
		return err
	}
	m.logger.Printf("[INFO] [backup] update pre-backup for %s: starting (DB dump → volume dump → unit capture → Tier 2)", stackName)
	start := time.Now()
	var nsRoot string
	legErr := func() error {
		defer m.releaseRunning()
		defer m.beginAdmissionRun()()

		drivePath := m.GetAppDrivePath(stackName)
		if drivePath == "" || !filepath.IsAbs(drivePath) {
			return util.MsgError("err.backup.az_alkalmazas_meghajtoja_nem_hatarozhato_meg")
		}
		if m.settings != nil && (m.settings.IsDisconnected(drivePath) || m.settings.IsDecommissioned(drivePath)) {
			return util.MsgError("err.backup.az_alkalmazas_meghajtoja_nem_elerheto", drivePath)
		}
		if !m.admitApp(stackName) {
			return util.MsgError("err.backup.nincs_eleg_szabad_hely_a_menteshez", drivePath)
		}
		nsRoot = m.namespaceRoot(drivePath)

		discover := m.discoverDBs
		if discover == nil {
			discover = func(ctx context.Context) ([]DiscoveredDB, error) {
				return DiscoverDatabases(ctx, m.logger, m.isDebug(), m.knownStackNames())
			}
		}
		dbs, err := discover(ctx)
		if err != nil {
			return util.MsgError("err.backup.adatbazis_felderites_sikertelen", err)
		}
		dumped := 0
		for _, db := range dbs {
			if db.StackName != stackName {
				continue
			}
			res := m.dumpOneOrDefault(ctx, db, AppDBDumpPath(nsRoot, stackName))
			if res.Error != nil {
				return util.MsgError("err.backup.adatbazis_mentes_sikertelen", db.ContainerName, res.Error)
			}
			dumped++
			m.stampDataFile(stackName, RecoveryUnitPath(nsRoot, stackName), "db-dumps/"+filepath.Base(res.FilePath))
			m.logger.Printf("[INFO] [backup] update pre-backup for %s: database dump OK (%s, %s)", stackName, db.ContainerName, humanizeBytes(res.Size))
		}

		if len(m.stackProvider.GetDockerVolumes(stackName)) > 0 {
			dump := m.dumpVolumesSafe
			if dump == nil {
				dump = m.DumpAppVolumesSafe
			}
			if err := dump(stackName); err != nil {
				return util.MsgError("err.backup.kotetmentes_sikertelen", err)
			}
			m.logger.Printf("[INFO] [backup] update pre-backup for %s: volume dump OK", stackName)
		}

		if err := m.CaptureRecoveryUnit(stackName); err != nil {
			return util.MsgError("err.backup.a_mentesi_egyseg_rogzitese_sikertelen", err)
		}
		m.logger.Printf("[INFO] [backup] update pre-backup for %s: recovery unit captured (%d database dump(s))", stackName, dumped)
		return nil
	}()
	if legErr != nil {
		m.logger.Printf("[ERROR] [backup] update pre-backup for %s FAILED after %s: %v", stackName, time.Since(start).Round(time.Millisecond), legErr)
		return legErr
	}

	m.updatePreBackupTail(stackName, nsRoot, time.Now())
	m.logger.Printf("[INFO] [backup] update pre-backup for %s: complete in %s", stackName, time.Since(start).Round(time.Millisecond))
	return nil
}

// updatePreBackupTail is what "back up first" does after the capture succeeded (R-475).
//
//  1. It marks the app's OWN unit as proven current NOW. CaptureRecoveryUnit leaves the manifest alone
//     when nothing changed (the checksum skip), and Tier 1's age is the newest artifact's mtime — so on
//     an app with no database and no named volume a fresh "back up first" would leave Tier 1 as old as
//     its last definition change, and the update would be refused forever. That is the trap
//     ProvenCopyTime documents for Tier 2, one tier down. The capture has just compared the unit with
//     the live definition, so "current as of now" is exactly what it established.
//  2. It runs the Tier-2 copy, and a Tier-2 failure is a WARN, not a failure: the update may lean on
//     any tier, and the Tier-1 unit it can lean on was just written. Pinned by
//     TestR475_PreBackupTail_Tier2FailureIsAWarnAndTheOwnUnitIsFresh.
func (m *Manager) updatePreBackupTail(stackName, nsRoot string, now time.Time) {
	if nsRoot != "" {
		if err := os.Chtimes(RecoveryUnitManifestPath(nsRoot, stackName), now, now); err != nil {
			m.logger.Printf("[WARN] [backup] update pre-backup for %s: could not mark the recovery unit as proven current (%v) — its own-unit copy may read older than it is", stackName, err)
		}
	}
	runOne := m.perAppTier2
	if runOne == nil {
		runOne = m.RunTier2
	}
	if err := runOne(stackName); err != nil {
		m.logger.Printf("[WARN] [backup] update pre-backup for %s: Tier 2 copy FAILED: %v — not fatal: the app's own recovery unit was just captured, and an update may lean on any tier (R-475)", stackName, err)
	}
}

// WriteUpdateSafetyDump takes the last-minute database copy an update makes just before it moves the
// pin: "the state the customer was in a minute ago". It is writeSafetyDump (R-361) unchanged — the
// same `pre-restore-` undo naming, the same pruning to three, the same never-the-canonical-name rule
// — so it is also picked up by the same exclusions (it never enters a manifest's db_dumps).
//
// Returns the paths written; an app with no database returns (nil, nil), which is a no-op and never a
// failure (measured in writeSafetyDump: `len(mine) == 0` returns an empty set).
func (m *Manager) WriteUpdateSafetyDump(ctx context.Context, stackName string) ([]string, error) {
	nsRoot := m.AppNamespaceRoot(stackName)
	if nsRoot == "" {
		return nil, util.MsgError("err.backup.az_alkalmazas_mentesi_helye_nem_hatarozhato")
	}
	set, err := m.writeSafetyDump(ctx, stackName, nsRoot)
	if err != nil {
		return nil, err
	}
	var paths []string
	for _, f := range set.Files {
		paths = append(paths, f.Path)
	}
	if len(paths) == 0 {
		m.logger.Printf("[INFO] [backup] update safety dump for %s: the app has no database — nothing to copy (no-op)", stackName)
	} else {
		m.logger.Printf("[INFO] [backup] update safety dump for %s: %d file(s) %v", stackName, len(paths), paths)
	}
	return paths, nil
}

// UpdateHoldFmt is the customer sentence for an app held after a failed update. Arguments: the app,
// the time of the failure, the TIER of the copy it can be restored from (UpdateTierLabel), and that
// copy's PROVEN date. One named string so a test asserts it verbatim instead of retyping Hungarian
// (R-364). Since v0.239.0 (R-475) it names the tier: the copy may be on any of three, and each is
// restored from a different place on the Mentések page.
const UpdateHoldFmt = "A(z) %s frissítése %s-kor nem sikerült, és az alkalmazás nem indult el az új verzióval. " +
	"Az alkalmazás biztonsági okból leállítva marad, hogy az adatai ne sérüljenek. " +
	"Visszaállítható a Mentések oldalon ebből a biztonsági mentésből: %s, %s — ez a másolat %s."

// UpdateHoldTierFmt is the v0.239.0–v0.240.0 sentence, kept for a hold that recorded a tier but not
// what the copy holds (CopyHolds empty).
const UpdateHoldTierFmt = "A(z) %s frissítése %s-kor nem sikerült, és az alkalmazás nem indult el az új verzióval. " +
	"Az alkalmazás biztonsági okból leállítva marad, hogy az adatai ne sérüljenek. " +
	"Visszaállítható a Mentések oldalon ebből a biztonsági mentésből: %s, %s."

// UpdateHoldLegacyFmt is the v0.237.0–v0.238.1 sentence, kept for a hold written before the tier was
// recorded (CopyTier 0) — every such hold named a Tier-2 copy, but it did not SAY so, and rewriting
// it now would state a fact the record does not hold.
const UpdateHoldLegacyFmt = "A(z) %s frissítése %s-kor nem sikerült, és az alkalmazás nem indult el az új verzióval. " +
	"Az alkalmazás biztonsági okból leállítva marad, hogy az adatai ne sérüljenek. " +
	"Visszaállítható a(z) %s-i biztonsági mentésből a Mentések oldalon."

// holdTimeZone is where the customer-facing hold sentence renders its times. The same zone the web
// layer renders the Mentések page's copy dates in (web.getTimezone), so the date in the hold text and
// the date on the page it points at are the same string.
func holdTimeZone() *time.Location {
	if loc, err := time.LoadLocation("Europe/Budapest"); err == nil {
		return loc
	}
	return time.UTC
}

func fmtHoldTime(rfc3339 string) string {
	t, err := time.Parse(time.RFC3339, rfc3339)
	if err != nil {
		return rfc3339
	}
	return t.In(holdTimeZone()).Format("2006-01-02 15:04")
}

// HoldAfterFailedUpdate records that an app is held stopped because its new version did not come up
// healthy. Same storage and same gate as the R-379 hold — every start path that already refuses a
// restore hold refuses this one without being touched.
//
// It returns the error rather than only logging it, unlike holdAppAfterFailedRollback: the update job
// has just stopped the app on the strength of this record, and an unrecorded hold is a stopped app
// that the next restart button will quietly start again. The caller logs it at ERROR and keeps the
// failure on the page.
func (m *Manager) HoldAfterFailedUpdate(stackName string, at time.Time, copyDate time.Time, copyTier int) error {
	return m.HoldAfterFailedUpdateHolding(stackName, at, copyDate, copyTier, "", "")
}

// HoldAfterFailedUpdateHolding is HoldAfterFailedUpdate with the R-479 phrase for what the copy holds;
// "" records none (the tier-only sentence). The adapter in main.go computes the phrase with
// UpdateCopyHolds at hold time.
//
// undoState (v0.263.0) is what a FAILED undo left the data as (stacks.UndoState*), "" when no undo was
// attempted. RestoreHoldFor puts it in front of the sentence, so the household reads that the box
// already tried to put the app back, and in what state that left the data.
func (m *Manager) HoldAfterFailedUpdateHolding(stackName string, at time.Time, copyDate time.Time, copyTier int, copyHolds, undoState string) error {
	if m == nil || m.settings == nil {
		return fmt.Errorf("no settings wired — the update hold for %s cannot be persisted", stackName)
	}
	h := settings.RestoreHold{
		Stack:     stackName,
		At:        at.UTC().Format(time.RFC3339),
		Reason:    settings.HoldReasonUpdateFailed,
		UndoState: undoState,
	}
	if !copyDate.IsZero() {
		h.CopyDate = copyDate.UTC().Format(time.RFC3339)
		h.CopyTier = copyTier
		h.CopyHolds = copyHolds
	}
	if err := m.settings.SetRestoreHold(h); err != nil {
		return fmt.Errorf("persisting the update hold for %s: %w", stackName, err)
	}
	m.logger.Printf("[WARN] [backup] %s is HELD STOPPED after a failed update (restore point: tier %d %q, %s; holds: %q; undo: %q)", stackName, h.CopyTier, UpdateTierLabel(h.CopyTier), h.CopyDate, h.CopyHolds, h.UndoState)
	return nil
}

// isHeld reports whether the nightly legs must leave an app alone: it carries ANY hold, OR a guarded
// update is moving it right now.
//
// THE SECOND HALF WAS FOUND LIVE, v0.238.0 Scenario F on demo-hp 2026-09-13. During the update's
// 5-minute health wait the app is not yet held, and the periodic capture ran at 10:17:09 and wrote
// the NEW definition (alpine:3.20, which never started) into the app's PRIMARY unit, 53 s before the
// hold landed at 10:18:02. The Tier-2 mirror the hold names was intact only because the Tier-2 run is
// daily — a nightly Tier-2 falling inside a verify window would have mirrored the broken definition
// over the very copy the customer is told to restore from. An app mid-update has a restore point that
// must not move, exactly like a held one.
func (m *Manager) isHeld(stackName string) bool {
	held, _ := m.RestoreHoldFor(stackName)
	if held {
		return true
	}
	return m.updatingCheck != nil && m.updatingCheck(stackName)
}

// SetUpdatingCheck wires the "is a guarded update moving this app" question (stacks.Manager.IsUpdating).
// INIT-ONLY, in main.go — pinned by TestSlice4_UpdatingCheckIsWiredAtStartup. The backup package cannot
// import stacks, which is why it is a seam.
func (m *Manager) SetUpdatingCheck(fn func(stackName string) bool) {
	m.updatingCheck = fn
}

// clearUpdateHoldAfterRestore lifts an UPDATE hold once a person has restored the app successfully.
//
// "A person clears it by restoring" — slice 4 Part 3. The restore just put the app back on the
// definition and data of its recovery unit and started it, which is the exact route back the hold
// text names; leaving the hold in place would refuse the next restart of an app that is now fine.
//
// A RESTORE hold (R-379) is deliberately NOT cleared here: that hold means a previous restore already
// left the database in an unknown state, and it stays operator-cleared (`-clear-restore-hold`).
func (m *Manager) clearUpdateHoldAfterRestore(stackName string) {
	if m.settings == nil {
		return
	}
	h, ok := m.settings.GetRestoreHold(stackName)
	if !ok || h.Reason != settings.HoldReasonUpdateFailed {
		return
	}
	if _, err := m.settings.ClearRestoreHold(stackName); err != nil {
		m.logger.Printf("[ERROR] [backup] %s was restored, but its update hold could not be cleared: %v", stackName, err)
		return
	}
	m.logger.Printf("[INFO] [backup] %s: restore completed — the update hold (set %s) is CLEARED", stackName, h.At)
	// R-671 (v0.272.0): the undo copies the hold kept describe the state this restore just replaced. They
	// were kept so the hold's data stayed recoverable; once the app is restored whole they are dead weight
	// (measured 2026-09-24 on 9202: three nextcloud copies, ~0.9 GiB, outlived the hold and nothing named
	// them). Removed here, and only here — never for a restore hold (R-379), never while an update moves the
	// app. Pinned by TestR671_RestoreThatClearsAnUpdateHoldRemovesItsUndoCopies.
	if m.undoCopyRemover != nil && (m.updatingCheck == nil || !m.updatingCheck(stackName)) {
		n := m.undoCopyRemover(stackName)
		m.logger.Printf("[INFO] [backup] %s: removed %d undo cop(y/ies) the lifted update hold had kept (R-671)", stackName, n)
	}
}

// SetUndoCopyRemover wires the undo-copy cleanup (R-671): stacks.Manager.RemoveUndoCopies. INIT-ONLY, main.go —
// pinned by TestUndoCopyRemoverIsWiredAtStartup (an AST walk). The backup package cannot import stacks.
func (m *Manager) SetUndoCopyRemover(fn func(stackName string) int) {
	m.undoCopyRemover = fn
}

// UpdateHeldStacks is the set of apps held stopped after a failed update (R-660, v0.268.0) — the
// FOURTH way the product stops an app on purpose, and until v0.268.0 the one `classifyRunStates` did
// not know: each hold's `app_update_held` was followed ~11 s later by an `app_start_failed` for the
// same app (chaos rounds 8 and 11, 2026-09-23 night). A RESTORE hold (R-379) is not in the set: it
// has no event of its own, so the app-down alarm stays its only voice. Nil-safe.
func (m *Manager) UpdateHeldStacks() map[string]bool {
	if m == nil || m.settings == nil {
		return nil
	}
	var out map[string]bool
	for _, h := range m.settings.ListRestoreHolds() {
		// v0.269.0 (decision 28): an app the box stopped for a crash loop / OOM storm is stopped BY THE
		// PRODUCT and has its own event (app_stopped_unhealthy) — the same class as an update hold.
		if h.Reason != settings.HoldReasonUpdateFailed && h.Reason != settings.HoldReasonUnhealthyStop {
			continue
		}
		if out == nil {
			out = map[string]bool{}
		}
		out[h.Stack] = true
	}
	return out
}

// ── R-659 (v0.268.0): the hold names only a copy that can bring the app back WHOLE ────────────────
//
// MEASURED 2026-09-24 00:00 on 9202 (chaos round 11): nextcloud's update and its undo both failed; the
// hold named „saját meghajtó" (the precondition copy — decision 8 lets an update lean on any tier);
// the household pressed exactly that restore and was REFUSED, because the unit holds no copy of the
// app's files on the drive (R-538). The box had no other copy, so nothing on any page brought the app
// back. Operator ruling 2026-09-24 (`09` §3 decision 25, option A): the hold names only a copy that
// brings the app back whole; with none, it says so, says support is informed, and support is told.
//
// THE TRUTH TABLE, read from the restores' OWN refusals (measured from source, v0.267.0), not from
// what each tier stores:
//
//	app                         own unit (1)         second drive (2)                     off-site (3)
//	no declared drive files     whole (unit restore) whole („Teljes visszaállítás")        whole (full restore)
//	declared drive files        NOT — refused (R-538) NOT — its unit restore is refused     whole („Teljes
//	(DeclaredDriveFileLegs)                          by the same guard; its file restore   visszaállítás (fájlok
//	                                                 only ADDS missing files, no database  + adatbázis)")
//
// So the question is asked of the SAME predicate the refusal uses (DeclaredDriveFileLegs), and a test
// pins that the two cannot drift (TestR659_TruthTableAgreesWithTheRestoresRefusal). Tier 2 holds a
// file app's files AND its unit, but no single action brings the app back whole from it — R-661.

// WholeOnTier reports whether a copy on `tier` can bring this app back WHOLE through the restore the
// Mentések page offers for that tier.
func (m *Manager) WholeOnTier(stackName string, tier int) bool {
	switch tier {
	case UpdateTierOffsite:
		return true
	case UpdateTierLocal:
		return !m.HasDriveFileLegs(stackName)
	case UpdateTierSecondDrive:
		if !m.HasDriveFileLegs(stackName) {
			return true
		}
		// v0.269.0 (decision 26): a file app is whole on the second drive when the mirror holds BOTH an
		// openable unit and its file legs — RestoreTier2Whole brings back both.
		cov, err := m.Tier2RestoreCoverage(stackName)
		return err == nil && cov.CanRestoreUnit() && cov.CanRestore()
	}
	return false
}

// HoldCopies walks EVERY tier (not only until the first acceptable one, as the update does) and
// returns the newest copy that brings the app back whole, whether there is one, and every copy seen.
func (m *Manager) HoldCopies(ctx context.Context, stackName string) (UpdateTierPoint, bool, []UpdateTierPoint) {
	var seen []UpdateTierPoint
	var best UpdateTierPoint
	found := false
	for _, tier := range []int{UpdateTierSecondDrive, UpdateTierLocal, UpdateTierOffsite} {
		p, ok := m.updateTierPoint(ctx, stackName, tier)
		if !ok {
			continue
		}
		seen = append(seen, p)
		if m.WholeOnTier(stackName, tier) && (!found || p.At.After(best.At)) {
			best, found = p, true
		}
	}
	return best, found, seen
}

// HoldAfterFailedUpdateWhole records the update hold naming the newest WHOLE copy, or — with none —
// a hold that names nothing and says support is informed (NoWholeCopy). The copies seen are recorded
// either way. Returns whether no whole copy exists.
func (m *Manager) HoldAfterFailedUpdateWhole(ctx context.Context, stackName string, at time.Time, undoState string) (bool, error) {
	best, found, seen := m.HoldCopies(ctx, stackName)
	var seenS []string
	for _, p := range seen {
		seenS = append(seenS, fmt.Sprintf("tier %d at %s", p.Tier, p.At.UTC().Format(time.RFC3339)))
	}
	if !found {
		if m == nil || m.settings == nil {
			return true, fmt.Errorf("no settings wired — the update hold for %s cannot be persisted", stackName)
		}
		h := settings.RestoreHold{Stack: stackName, At: at.UTC().Format(time.RFC3339), Reason: settings.HoldReasonUpdateFailed,
			UndoState: undoState, NoWholeCopy: true, CopiesSeen: seenS}
		if err := m.settings.SetRestoreHold(h); err != nil {
			return true, fmt.Errorf("persisting the update hold for %s: %w", stackName, err)
		}
		m.logger.Printf("[ERROR] [backup] %s is HELD STOPPED after a failed update and NO copy on this box brings it back whole (seen: %v; drive files declared: %v; undo: %q) — support must act (R-659)",
			stackName, seenS, m.HasDriveFileLegs(stackName), undoState)
		return true, nil
	}
	if err := m.HoldAfterFailedUpdateHolding(stackName, at, best.At, best.Tier, m.UpdateCopyHolds(stackName, best.Tier), undoState); err != nil {
		return false, err
	}
	if h, ok := m.settings.GetRestoreHold(stackName); ok {
		h.CopiesSeen = seenS
		_ = m.settings.SetRestoreHold(h)
	}
	return false, nil
}

// FreshWholeCopy answers decision 13's `files_may_change` mark for the automatic update leg (v0.271.0):
// is there a copy on this box, younger than maxAge, that brings the app back WHOLE — the SAME truth
// table the hold uses (WholeOnTier, decisions 25 and 26), so the leg and the hold cannot disagree about
// what "whole" means. The string says why, for the leg's log.
func (m *Manager) FreshWholeCopy(ctx context.Context, stackName string, maxAge time.Duration, now time.Time) (bool, string) {
	best, found, seen := m.HoldCopies(ctx, stackName)
	if !found {
		return false, fmt.Sprintf("no copy on this box brings it back whole (%d copies seen; drive files declared: %v)", len(seen), m.HasDriveFileLegs(stackName))
	}
	if age := now.Sub(best.At); age > maxAge {
		return false, fmt.Sprintf("the newest whole copy (tier %d, %s) is %s old, limit %s", best.Tier, best.At.UTC().Format(time.RFC3339), age.Round(time.Minute), maxAge)
	}
	return true, fmt.Sprintf("tier %d copy from %s", best.Tier, best.At.UTC().Format(time.RFC3339))
}

// HoldNoWholeCopy reports whether the app's hold names no copy (R-659) — the page then offers no
// restore button for it.
func (m *Manager) HoldNoWholeCopy(stackName string) bool {
	if m == nil || m.settings == nil {
		return false
	}
	h, ok := m.settings.GetRestoreHold(stackName)
	return ok && h.Reason == settings.HoldReasonUpdateFailed && h.NoWholeCopy
}

// UpdateHold returns the stored update hold, for the operator event (R-659).
func (m *Manager) UpdateHold(stackName string) (settings.RestoreHold, bool) {
	if m == nil || m.settings == nil {
		return settings.RestoreHold{}, false
	}
	h, ok := m.settings.GetRestoreHold(stackName)
	if !ok || h.Reason != settings.HoldReasonUpdateFailed {
		return settings.RestoreHold{}, false
	}
	return h, true
}

// ── Decision 28 (v0.269.0): the box stops an app in a crash loop or an out-of-memory storm ─────────

// UnhealthyRepeatWindow is how soon a second stop counts as a repeat: the sentence then says support is
// informed.
const UnhealthyRepeatWindow = 24 * time.Hour

// HoldUnhealthy records that the box stopped `stack` (kind "crash_loop" or "oom_storm") and returns the
// trip number: 1, or 2 when the previous stop was less than 24 h ago. Same store as every hold, so no
// start path — the boot sweep, the drive gate, the nightly legs — revives it silently.
func (m *Manager) HoldUnhealthy(stack, kind string, at time.Time) (int, error) {
	if m == nil || m.settings == nil {
		return 0, fmt.Errorf("no settings wired — the unhealthy stop of %s cannot be recorded", stack)
	}
	trip := 1
	if last, ok := m.settings.LastUnhealthyStop(stack); ok && at.Sub(last) < UnhealthyRepeatWindow {
		trip = 2
	}
	h := settings.RestoreHold{Stack: stack, At: at.UTC().Format(time.RFC3339), Reason: settings.HoldReasonUnhealthyStop,
		UnhealthyKind: kind, Trip: trip}
	if err := m.settings.SetRestoreHold(h); err != nil {
		return trip, fmt.Errorf("persisting the unhealthy stop of %s: %w", stack, err)
	}
	if err := m.settings.RecordUnhealthyStop(stack, at); err != nil {
		m.logger.Printf("[WARN] [backup] %s: recording the stop time failed: %v", stack, err)
	}
	m.logger.Printf("[WARN] [backup] %s is STOPPED by the box: %s (trip %d within %s) — Start gives it one more try (decision 28)", stack, kind, trip, UnhealthyRepeatWindow)
	return trip, nil
}

// LiftUnhealthyStop is the Start button's half: an unhealthy-stop hold is lifted, any other kind stays.
func (m *Manager) LiftUnhealthyStop(stack string) bool {
	if m == nil || m.settings == nil {
		return false
	}
	ok, err := m.settings.ClearUnhealthyStopHold(stack)
	if err != nil {
		m.logger.Printf("[ERROR] [backup] lifting the unhealthy stop of %s failed: %v", stack, err)
		return false
	}
	return ok
}

// HoldKind names the kind of hold in force ("" when none): update_failed, unhealthy_stop, or "restore".
func (m *Manager) HoldKind(stack string) string {
	if m == nil || m.settings == nil {
		return ""
	}
	h, ok := m.settings.GetRestoreHold(stack)
	if !ok {
		return ""
	}
	if h.Reason == "" {
		return "restore"
	}
	return h.Reason
}