package engine

import (
	"context"
	"encoding/json"
	"fmt"
	"net/netip"
	"reflect"
	"slices"
	"strings"
	"time"

	"github.com/miekg/dns"

	"jarl/internal/auth"
	"jarl/internal/dnsname"
	"jarl/internal/model"
	"jarl/internal/rr"
	"jarl/internal/validate"
)

// IDAllocator reserves object IDs.
type IDAllocator func(ctx context.Context, n int) ([]int64, error)

type expander struct {
	ctx      context.Context
	st       *model.State // working state: base plus the changeset's ops so far
	alloc    IDAllocator
	p        *auth.Principal
	now      time.Time
	warnings []string
	// exposures classifies the views as public or private (nil in tests:
	// every view private).
	exposures func(*model.State) []validate.Exposure
	// ptrForced are the address sets whose PTR records the request being
	// expanded asked to update (ptrForce).
	ptrForced map[rrKey]bool
	// sharing are the local sets the request deletes so that the shared
	// version reaches them (dropOverrides).
	sharing map[rrKey]bool
}

func (x *expander) ids(n int) ([]int64, error) {
	ids, err := x.alloc(x.ctx, n)
	if err != nil {
		return nil, fmt.Errorf("allocating IDs: %w", err)
	}
	return ids, nil
}

func mustJSON(v any) json.RawMessage {
	b, err := json.Marshal(v)
	if err != nil {
		panic(err)
	}
	return b
}

func newOp(kind string, id int64, base int, data any, summary string) model.Op {
	op := model.Op{Kind: kind, ID: id, BaseVersion: base, Summary: summary}
	if data != nil {
		op.Data = mustJSON(data)
	}
	return op
}

// resolveZone finds the zone a record request refers to.
func (x *expander) resolveZone(zoneID int64, zone, view string) (*model.Zone, error) {
	if zoneID != 0 {
		z := x.st.Zones[zoneID]
		if z == nil {
			return nil, errf(KindNotFound, "zone %d does not exist", zoneID)
		}
		return z, nil
	}
	if zone == "" {
		return nil, errf(KindBadRequest, "the zone is missing (zone_id or zone)")
	}
	return FindZoneRef(x.st, zone, view, func(z *model.Zone) bool { return x.p.CanSeeZone(z.Name, x.st.ViewName(z)) })
}

// FindZoneRef finds a zone by name and optional view name. Without a
// view, a name in several views needs one, counting only the zones sees
// allows (nil: all): a token for one view finds that view's zone.
func FindZoneRef(st *model.State, zone, view string, sees func(*model.Zone) bool) (*model.Zone, error) {
	name, err := ParseZoneName(zone)
	if err != nil {
		return nil, errf(KindBadRequest, "%v", err)
	}
	if view != "" {
		v := st.ViewByName(view)
		if v == nil {
			return nil, errf(KindNotFound, "view %q does not exist", view)
		}
		z := st.FindZone(name, v.ID)
		if z == nil {
			return nil, errf(KindNotFound, "zone %s does not exist in view %s", dnsname.Display(name), v.Name)
		}
		return z, nil
	}
	zs := st.ZonesNamed(name)
	if sees != nil && len(zs) > 1 {
		var vis []*model.Zone
		for _, z := range zs {
			if sees(z) {
				vis = append(vis, z)
			}
		}
		zs = vis // none: not found, without naming the views
	}
	st.SortByView(zs)
	switch len(zs) {
	case 0:
		return nil, errf(KindNotFound, "zone %s does not exist", dnsname.Display(name))
	case 1:
		return zs[0], nil
	}
	var views []string
	for _, z := range zs {
		views = append(views, st.ViewName(z))
	}
	return nil, errf(KindBadRequest, "zone %s exists in several views (%s); say which view", dnsname.Display(name), strings.Join(views, ", "))
}

func zoneDesc(st *model.State, z *model.Zone) string {
	s := dnsname.Display(z.Name)
	if v := st.ViewName(z); v != "" {
		s += " [" + v + "]"
	}
	return s
}

func ttlText(o model.Opt[uint32]) string {
	if o.Set && !o.Null {
		return fmt.Sprintf(" %d", o.Value)
	}
	return ""
}

// InitialSerial returns the first serial for a new zone.
func InitialSerial(policy string, now time.Time) uint32 {
	switch policy {
	case model.SerialIncrement:
		return 1
	case model.SerialUnixtime:
		return uint32(now.Unix())
	}
	return dateSerial(now)
}

func dateSerial(now time.Time) uint32 {
	y, m, d := now.UTC().Date()
	return uint32(y*1000000 + int(m)*10000 + d*100)
}

func (x *expander) expand(req Request) ([]model.Op, error) {
	x.ptrForced, x.sharing = nil, nil
	ops, err := x.expandOne(req)
	if err != nil {
		return nil, err
	}
	switch req.Op {
	case OpRecordCreate, OpRecordUpdate, OpRecordDelete, OpRRSetReplace, OpRecordDisable, OpRecordEnable:
		// Changes to linked zones reach the other zones of the link, then
		// PTR records follow the addresses in each view.
		if ops, err = x.linkSync(ops); err != nil {
			return nil, err
		}
		return x.ptrSync(ops)
	case OpZoneFillPTR:
		return x.linkSync(ops)
	}
	return ops, nil
}

func (x *expander) expandOne(req Request) ([]model.Op, error) {
	switch req.Op {
	case OpZoneLink:
		return x.zoneLink(req)
	case OpZoneUnlink:
		return x.zoneUnlink(req)
	case OpZoneCreate:
		return x.zoneCreate(req)
	case OpZoneFillPTR:
		return x.zoneFillPTR(req)
	case OpReverseDismiss, OpReverseUndismiss:
		return x.reverseDismiss(req, req.Op == OpReverseDismiss)
	case OpZoneUpdate, OpZoneDelete:
		z := x.st.Zones[req.ID]
		if z == nil {
			return nil, errf(KindNotFound, "zone %d does not exist", req.ID)
		}
		verb := "update"
		if req.Op == OpZoneDelete {
			verb = "delete"
			if n := len(x.st.ZoneRecords(z.ID)); n > 0 {
				verb += fmt.Sprintf(" (with its %d records)", n)
			}
		} else if d := zoneToggle(req, z); d != nil {
			if *d {
				x.warnings = append(x.warnings, disabledZoneEffect(x.st, z))
				return []model.Op{x.versioned(req, z.Version, "disable zone "+zoneDesc(x.st, z))}, nil
			}
			return []model.Op{x.versioned(req, z.Version, "enable zone "+zoneDesc(x.st, z))}, nil
		}
		ops := []model.Op{x.versioned(req, z.Version, "zone "+verb+" "+zoneDesc(x.st, z))}
		if req.Op == OpZoneDelete {
			if rest := x.st.LinkedWith(z); len(rest) == 1 {
				ops = append(ops, x.unlinkOps(rest[0], "unlink zone "+zoneDesc(x.st, rest[0])+": the zone it was linked with is deleted")...)
			}
		} else {
			var in ZoneInput
			if err := decode(req.Data, &in); err != nil {
				return nil, err
			}
			if in.LinkGroup != nil && *in.LinkGroup != z.LinkGroup {
				return nil, errf(KindBadRequest, "link zones with zone.link and zone.unlink (jarl zone link / unlink)")
			}
			if in.LinkWith != "" {
				return nil, errf(KindBadRequest, "link_with is for new zones; link existing ones with zone.link (jarl zone link)")
			}
			// An update that leaves the zone as it is stages nothing (a
			// settings form saved without changes).
			if zoneUnchanged(x.st, z, &in) {
				return nil, nil
			}
		}
		return ops, nil
	case OpRecordCreate:
		return x.recordCreate(req)
	case OpRecordUpdate:
		return x.recordUpdate(req)
	case OpRecordDelete:
		return x.recordDelete(req)
	case OpRRSetReplace:
		return x.rrsetReplace(req)
	case OpRecordDisable, OpRecordEnable:
		return x.recordSetDisabled(req, req.Op == OpRecordDisable)
	case OpViewCreate:
		return x.viewCreate(req)
	case OpViewUpdate, OpViewDelete:
		v := x.st.Views[req.ID]
		if v == nil {
			return nil, errf(KindNotFound, "view %d does not exist", req.ID)
		}
		return []model.Op{x.versioned(req, v.Version, strings.TrimPrefix(req.Op, "view.")+" view "+v.Name)}, nil
	case OpViewReorder:
		var in ReorderInput
		if err := decode(req.Data, &in); err != nil {
			return nil, err
		}
		var names []string
		for _, id := range in.IDs {
			if v := x.st.Views[id]; v != nil {
				names = append(names, v.Name)
			}
		}
		return []model.Op{newOp(OpViewReorder, 0, 0, in, "reorder views: "+strings.Join(names, ", "))}, nil
	case OpACLCreate:
		return x.simpleCreate(req, OpACLCreate, func(data json.RawMessage) (string, error) {
			var in ACLInput
			if err := decode(data, &in); err != nil {
				return "", err
			}
			if in.Name == nil {
				return "", errf(KindBadRequest, "an ACL needs a name")
			}
			return "create ACL " + *in.Name, nil
		})
	case OpACLUpdate, OpACLDelete:
		a := x.st.ACLs[req.ID]
		if a == nil {
			return nil, errf(KindNotFound, "ACL %d does not exist", req.ID)
		}
		return []model.Op{x.versioned(req, a.Version, strings.TrimPrefix(req.Op, "acl.")+" ACL "+a.Name)}, nil
	case OpTSIGCreate:
		return x.tsigCreate(req)
	case OpTSIGUpdate, OpTSIGDelete:
		k := x.st.Keys[req.ID]
		if k == nil {
			return nil, errf(KindNotFound, "TSIG key %d does not exist", req.ID)
		}
		return []model.Op{x.versioned(req, k.Version, strings.TrimPrefix(req.Op, "tsig.")+" TSIG key "+k.Name)}, nil
	case OpOptionCreate:
		return x.optionCreate(req)
	case OpOptionUpdate, OpOptionDelete:
		o := x.st.Options[req.ID]
		if o == nil {
			return nil, errf(KindNotFound, "option %d does not exist", req.ID)
		}
		summary := strings.TrimPrefix(req.Op, "option.") + " " + optionLabel(x.st, o)
		if req.Op == OpOptionUpdate {
			var in OptionInput
			if err := decode(req.Data, &in); err != nil {
				return nil, err
			}
			if in.Value != nil {
				summary += ": " + o.Value + " → " + *in.Value
			}
		}
		return []model.Op{x.versioned(req, o.Version, summary)}, nil
	case OpSettingsUpdate:
		return []model.Op{newOpRaw(OpSettingsUpdate, 0, 0, req.Data, "update settings")}, nil
	case OpExposureAck, OpExposureUnack:
		return x.exposureAck(req, req.Op == OpExposureAck)
	case OpBlocklistCreate:
		return x.blocklistCreate(req)
	case OpBlocklistUpdate, OpBlocklistDelete:
		b := x.st.Blocklists[req.ID]
		if b == nil {
			return nil, errf(KindNotFound, "blocklist %d does not exist", req.ID)
		}
		verb := "change"
		if req.Op == OpBlocklistDelete {
			verb = "delete"
		}
		return []model.Op{x.versioned(req, b.Version, verb+" blocklist "+b.Name)}, nil
	case OpBlockingPause:
		var in BlockingPauseInput
		if err := decode(req.Data, &in); err != nil {
			return nil, err
		}
		summary := "resume blocking"
		if in.Until != nil {
			summary = "pause blocking until " + in.Until.Local().Format("2006-01-02 15:04")
		} else if in.Indefinitely {
			summary = "pause blocking until resumed"
		}
		return []model.Op{newOpRaw(OpBlockingPause, 0, 0, req.Data, summary)}, nil
	case OpBlockRuleCreate:
		return x.blockRuleCreate(req)
	case OpBlockRuleUpdate, OpBlockRuleDelete:
		r := x.st.BlockRules[req.ID]
		if r == nil {
			return nil, errf(KindNotFound, "rule %d does not exist", req.ID)
		}
		verb := "change rule: "
		if req.Op == OpBlockRuleDelete {
			verb = "delete rule: "
		}
		return []model.Op{x.versioned(req, r.Version, verb+ruleLabel(r))}, nil
	case OpBlockStepCreate:
		return x.blockStepCreate(req)
	case OpBlockStepUpdate, OpBlockStepDelete:
		s := x.st.BlockSteps[req.ID]
		if s == nil {
			return nil, errf(KindNotFound, "blocking step %d does not exist", req.ID)
		}
		verb := "change blocking step "
		if req.Op == OpBlockStepDelete {
			verb = "delete blocking step "
		}
		return []model.Op{x.versioned(req, s.Version, verb+s.Name)}, nil
	case OpClientGroupCreate:
		return x.clientGroupCreate(req)
	case OpClientGroupUpdate, OpClientGroupDelete:
		g := x.st.ClientGroups[req.ID]
		if g == nil {
			return nil, errf(KindNotFound, "client group %d does not exist", req.ID)
		}
		verb := "change client group "
		if req.Op == OpClientGroupDelete {
			verb = "delete client group "
		}
		return []model.Op{x.versioned(req, g.Version, verb+g.Name)}, nil
	}
	return nil, errf(KindBadRequest, "unknown operation %q", req.Op)
}

func newOpRaw(kind string, id int64, base int, data json.RawMessage, summary string) model.Op {
	return model.Op{Kind: kind, ID: id, BaseVersion: base, Data: data, Summary: summary}
}

// versioned builds an update/delete operation, recording the object's
// version for conflict detection.
func (x *expander) versioned(req Request, current int, summary string) model.Op {
	base := req.BaseVersion
	if base == 0 {
		base = current
	}
	return newOpRaw(req.Op, req.ID, base, req.Data, summary)
}

func (x *expander) simpleCreate(req Request, kind string, describe func(json.RawMessage) (string, error)) ([]model.Op, error) {
	summary, err := describe(req.Data)
	if err != nil {
		return nil, err
	}
	ids, err := x.ids(1)
	if err != nil {
		return nil, err
	}
	return []model.Op{newOpRaw(kind, ids[0], 0, req.Data, summary)}, nil
}

func (x *expander) zoneCreate(req Request) ([]model.Op, error) {
	var in ZoneInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	if in.Name == nil || strings.TrimSpace(*in.Name) == "" {
		return nil, errf(KindBadRequest, "a zone needs a name")
	}
	name, err := ParseZoneName(*in.Name)
	if err != nil {
		return nil, errf(KindBadRequest, "%v", err)
	}
	in.Name = &name
	if in.Type == nil {
		in.Type = model.Ptr(model.ZonePrimary)
	}
	zt, err := normalizeZoneType(*in.Type)
	if err != nil {
		return nil, errf(KindBadRequest, "%v", err)
	}
	in.Type = &zt
	viewGiven := in.View != nil || in.ViewID != nil
	if in.View != nil {
		if *in.View != "" {
			v := x.st.ViewByName(*in.View)
			if v == nil {
				return nil, errf(KindNotFound, "view %q does not exist", *in.View)
			}
			in.ViewID = &v.ID
		}
		in.View = nil
	}
	if !viewGiven && in.LinkWith == "" && in.CloneFrom == 0 && dnsname.IsReverse(name) {
		// A reverse zone belongs in the private view whose records use
		// its addresses (docs/reverse.md).
		v, err := reverseViewFor(x.st, x.publicViews(), name)
		if err != nil {
			return nil, err
		}
		if v != nil {
			in.ViewID = &v.ID
		}
	}
	var moveOps []model.Op
	var moved []*model.Record
	if zt == model.ZonePrimary {
		// The records a parent zone in the view has under the new zone
		// move into it: named answers those names from the new zone, so
		// left behind they would never be served again.
		vid := int64(0)
		if in.ViewID != nil {
			vid = *in.ViewID
		}
		if parent := x.parentZone(name, vid); parent != nil {
			moved = x.recordsUnder(parent, name)
			switch {
			case len(moved) == 0:
			case parent.LinkGroup != 0:
				x.warnings = append(x.warnings, fmt.Sprintf("zone %s is linked, so its %d records under %s stay there (hidden by the new zone): move them by hand", zoneDesc(x.st, parent), len(moved), dnsname.Display(name)))
				moved = nil
			default:
				for _, r := range moved {
					ri := RecordInput{Name: model.Ptr(r.Name), Type: model.Ptr(r.Type), Data: model.Ptr(r.Data)}
					if r.TTL != nil {
						ri.TTL = model.Some(*r.TTL)
					}
					if r.Comment != "" {
						ri.Comment = model.Ptr(r.Comment)
					}
					if r.Disabled {
						ri.Disabled = model.Ptr(true)
					}
					in.Records = append(in.Records, ri)
					moveOps = append(moveOps, newOp(OpRecordDelete, r.ID, r.Version, nil, fmt.Sprintf("move %s %s %s from zone %s into the new zone", r.Name, r.Type, r.Data, zoneDesc(x.st, parent))))
				}
			}
		}
	}
	fill, fillOther := in.Fill, in.FillOtherViews
	in.Fill, in.FillOtherViews = false, false
	if fill {
		if zt != model.ZonePrimary {
			return nil, errf(KindBadRequest, "fill only applies to primary zones")
		}
		if _, ok := dnsname.PrefixFromReverse(name); !ok {
			return nil, errf(KindBadRequest, "fill only applies to reverse zones of whole octets or nibbles (like 10.0.10.0/24)")
		}
		vid := int64(0)
		if in.ViewID != nil {
			vid = *in.ViewID
		}
		fills := PTRFills(x.st, vid, name, moved, fillOther)
		if len(fills) == 0 {
			x.warnings = append(x.warnings, fmt.Sprintf("no A or AAAA record of %s has an address in %s, so there was nothing to fill it with", viewOrServer(x.st, vid), dnsname.Display(name)))
		}
		if !fillOther {
			if h := otherViewsHint(x.st, vid, name, moved, len(fills), "to add PTR records for them in this view too: jarl zone fill-ptr ZONE --other-views"); h != "" {
				x.warnings = append(x.warnings, h)
			}
		}
		x.warnings = append(x.warnings, fillWarnings(fills)...)
		for _, f := range fills {
			in.Records = append(in.Records, RecordInput{Name: model.Ptr(f.Name), Type: model.Ptr("PTR"), Data: model.Ptr(f.Target)})
		}
	}
	nameservers := in.Nameservers
	records := in.Records
	cloneFrom := in.CloneFrom
	zoneOpts := in.Options
	linkWith := in.LinkWith
	in.Nameservers, in.Records, in.CloneFrom, in.Options, in.LinkWith, in.LinkGroup = nil, nil, 0, nil, "", nil
	if linkWith != "" {
		if cloneFrom != 0 {
			return nil, errf(KindBadRequest, "give clone_from or link_with, not both")
		}
		v := x.st.ViewByName(linkWith)
		if v == nil {
			return nil, errf(KindNotFound, "view %q does not exist", linkWith)
		}
		o := x.st.FindZone(name, v.ID)
		if o == nil {
			return nil, errf(KindNotFound, "view %s has no zone %s to link with", v.Name, dnsname.Display(name))
		}
		if o.Type != model.ZonePrimary || zt != model.ZonePrimary {
			return nil, errf(KindBadRequest, "only primary zones can be linked")
		}
		cloneFrom = o.ID
	}

	set := x.st.Settings
	var src *model.Zone
	if cloneFrom != 0 {
		src = x.st.Zones[cloneFrom]
		if src == nil {
			return nil, errf(KindNotFound, "zone %d (clone_from) does not exist", cloneFrom)
		}
		if src.Name != name {
			return nil, errf(KindBadRequest, "clone_from must be a zone with the same name in another view (it is %s)", dnsname.Display(src.Name))
		}
		if !x.p.Can(zoneAction(x.st, src, false)) || !x.p.Can(recordAction(x.st, src, "", "", false)) {
			return nil, errf(KindForbidden, "permission denied: you can't read zone %s", zoneDesc(x.st, src))
		}
	}
	if zt == model.ZonePrimary {
		if len(nameservers) == 0 && src == nil {
			nameservers = set.Nameservers
		}
		if len(nameservers) == 0 && src == nil {
			return nil, errf(KindBadRequest, "a primary zone needs at least one name server: give nameservers, or set default name servers in the settings")
		}
		if in.SOA == nil {
			in.SOA = &SOAInput{}
		}
		s := in.SOA
		if src != nil {
			// Copy the source zone's SOA and TTL unless overridden.
			if s.MName == nil {
				s.MName = model.Ptr(src.SOA.MName)
			}
			if s.RName == nil {
				s.RName = model.Ptr(src.SOA.RName)
			}
			if s.Refresh == nil {
				s.Refresh = model.Ptr(src.SOA.Refresh)
			}
			if s.Retry == nil {
				s.Retry = model.Ptr(src.SOA.Retry)
			}
			if s.Expire == nil {
				s.Expire = model.Ptr(src.SOA.Expire)
			}
			if s.Minimum == nil {
				s.Minimum = model.Ptr(src.SOA.Minimum)
			}
			if in.DefaultTTL == nil {
				in.DefaultTTL = model.Ptr(src.DefaultTTL)
			}
		}
		if s.MName == nil {
			first, err := dnsname.Owner(nameservers[0], name)
			if err != nil {
				return nil, errf(KindBadRequest, "%v", err)
			}
			s.MName = &first
		}
		if s.RName == nil {
			if set.RName != "" {
				s.RName = model.Ptr(set.RName)
			} else {
				s.RName = model.Ptr("hostmaster." + name)
			}
		}
		if s.Refresh == nil {
			s.Refresh = model.Ptr(set.Refresh)
		}
		if s.Retry == nil {
			s.Retry = model.Ptr(set.Retry)
		}
		if s.Expire == nil {
			s.Expire = model.Ptr(set.Expire)
		}
		if s.Minimum == nil {
			s.Minimum = model.Ptr(set.NegativeTTL)
		}
		if in.DefaultTTL == nil {
			in.DefaultTTL = model.Ptr(set.DefaultTTL)
		}
		if s.Serial == nil {
			policy := set.SerialPolicy
			if in.SerialPolicy != nil && *in.SerialPolicy != "" {
				policy = *in.SerialPolicy
			}
			serial := InitialSerial(policy, x.now)
			if src != nil && serialGreater(src.SOA.Serial, serial) {
				serial = src.SOA.Serial
			}
			s.Serial = &serial
		}
	} else if len(nameservers) > 0 || len(records) > 0 || src != nil {
		return nil, errf(KindBadRequest, "nameservers, records and clone_from only apply to primary zones")
	}

	type recSpec struct {
		in      RecordInput
		summary string
	}
	var recs []recSpec
	seen := map[string]bool{}
	addRec := func(ri RecordInput) error {
		tmp := &model.Zone{Name: name, Type: zt}
		owner, p, err := parseRecord(tmp, deref(ri.Name), deref(ri.Type), deref(ri.Data))
		if err != nil {
			return err
		}
		k := owner + "|" + p.Type + "|" + strings.ToLower(p.Data)
		if seen[k] {
			return nil
		}
		seen[k] = true
		ri.Name, ri.Type, ri.Data = &owner, &p.Type, &p.Data
		recs = append(recs, recSpec{ri, fmt.Sprintf("add %s%s IN %s %s", owner, ttlText(ri.TTL), p.Type, p.Data)})
		return nil
	}
	for _, ns := range nameservers {
		target, err := dnsname.Owner(ns, name)
		if err != nil {
			return nil, errf(KindBadRequest, "name server %q: %v", ns, err)
		}
		if err := addRec(RecordInput{Name: model.Ptr("@"), Type: model.Ptr("NS"), Data: model.Ptr(target)}); err != nil {
			return nil, err
		}
	}
	var linkOps []model.Op
	if src != nil && linkWith != "" {
		// The new zone joins src's link, or starts one with src: then
		// all of src's records become shared.
		group := src.LinkGroup
		if group == 0 {
			group = src.ID
			linkOps = x.shareAllOps(src, group)
		}
		in.LinkGroup = &group
	}
	if src != nil {
		for _, r := range x.st.ZoneRecords(src.ID) {
			if linkWith != "" && src.LinkGroup != 0 && r.SharedID == 0 {
				continue // local to src's view
			}
			ri := RecordInput{Name: model.Ptr(r.Name), Type: model.Ptr(r.Type), Data: model.Ptr(r.Data), Comment: model.Ptr(r.Comment)}
			if linkWith != "" {
				id := r.SharedID
				if id == 0 {
					id = r.ID
				}
				ri.SharedID = &id
			}
			if r.Disabled {
				ri.Disabled = model.Ptr(true)
			}
			if r.TTL != nil {
				ri.TTL = model.Some(*r.TTL)
			} else {
				ri.TTL = model.Opt[uint32]{Set: true, Null: true}
			}
			if err := addRec(ri); err != nil {
				return nil, err
			}
		}
	}
	for _, ri := range records {
		ri.ZoneID, ri.Zone, ri.View = 0, "", ""
		if err := addRec(ri); err != nil {
			return nil, err
		}
	}
	ids, err := x.ids(1 + len(recs) + len(zoneOpts))
	if err != nil {
		return nil, err
	}
	summary := fmt.Sprintf("create %s zone %s", zt, dnsname.Display(name))
	if in.ViewID != nil && *in.ViewID != 0 {
		if v := x.st.Views[*in.ViewID]; v != nil {
			summary += " in view " + v.Name
		}
	}
	if src != nil && linkWith != "" {
		summary += " (linked with " + zoneDesc(x.st, src) + ")"
	} else if src != nil {
		summary += " (copy of " + zoneDesc(x.st, src) + ")"
	}
	ops := append(linkOps, newOp(OpZoneCreate, ids[0], 0, in, summary))
	for i, zo := range zoneOpts {
		oi := OptionInput{Scope: model.Ptr(model.ScopeZone), ScopeID: model.Ptr(ids[0]), Name: model.Ptr(zo.Name), Value: model.Ptr(zo.Value)}
		if zo.Comment != "" {
			oi.Comment = model.Ptr(zo.Comment)
		}
		ops = append(ops, newOp(OpOptionCreate, ids[1+len(recs)+i], 0, oi, fmt.Sprintf("set zone %s option %s %s", dnsname.Display(name), zo.Name, zo.Value)))
	}
	for i, r := range recs {
		r.in.ZoneID = ids[0]
		ops = append(ops, newOp(OpRecordCreate, ids[1+i], 0, r.in, r.summary))
	}
	return append(ops, moveOps...), nil
}

// parentZone returns the most specific primary zone in a view that
// contains name (not name itself).
func (x *expander) parentZone(name string, viewID int64) *model.Zone {
	var best *model.Zone
	for _, z := range x.st.ZonesInView(viewID) {
		if z.Type == model.ZonePrimary && dnsname.IsStrictSubdomain(name, z.Name) && (best == nil || len(z.Name) > len(best.Name)) {
			best = z
		}
	}
	return best
}

// recordsUnder returns a zone's records at or below name, except a
// delegation's NS and DS records and its glue, which belong to the parent.
func (x *expander) recordsUnder(z *model.Zone, name string) []*model.Record {
	all := x.st.ZoneRecords(z.ID)
	var ns []string
	for _, r := range all {
		if r.Name == name && r.Type == "NS" {
			ns = append(ns, strings.ToLower(r.Data))
		}
	}
	var out []*model.Record
	for _, r := range all {
		if !dnsname.IsSubdomain(r.Name, name) {
			continue
		}
		if r.Name == name && (r.Type == "NS" || r.Type == "DS") {
			continue
		}
		if (r.Type == "A" || r.Type == "AAAA") && slices.Contains(ns, strings.ToLower(r.Name)) {
			continue // glue
		}
		out = append(out, r)
	}
	return out
}

func deref(s *string) string {
	if s == nil {
		return ""
	}
	return *s
}

// reverseZoneFor finds the primary reverse zone for addr in a view.
func reverseZoneFor(st *model.State, viewID int64, addr netip.Addr) (*model.Zone, string) {
	name := dnsname.ReverseName(addr)
	var best *model.Zone
	for _, z := range st.ZonesInView(viewID) {
		if z.Type == model.ZonePrimary && dnsname.IsSubdomain(name, z.Name) && (best == nil || len(z.Name) > len(best.Name)) {
			best = z
		}
	}
	return best, name
}

func addrOf(p *rr.Parsed) (netip.Addr, bool) {
	switch v := p.RR.(type) {
	case *dns.A:
		a, ok := netip.AddrFromSlice(v.A.To4())
		return a, ok
	case *dns.AAAA:
		a, ok := netip.AddrFromSlice(v.AAAA)
		return a, ok
	}
	return netip.Addr{}, false
}

// PTR records follow address records per view (docs/reverse.md): after a
// request's operations (and those keeping linked zones in step), ptrSync
// compares each touched A or AAAA set before and after, in every view it
// is in, and changes the PTR records of that view's reverse zone to match.
// So a record local to one view of a linked zone changes PTR records in
// that view only, and an address that goes from one view keeps its PTR
// record in the views that still have it.

// ptrForce marks a name and type whose PTR records the request asked to
// update (ptr: true), in its zone and the zones linked with it.
func (x *expander) ptrForce(z *model.Zone, name, typ string) {
	if x.ptrForced == nil {
		x.ptrForced = map[rrKey]bool{}
	}
	x.ptrForced[rrKey{z.ID, name, typ}] = true
	for _, o := range x.st.LinkedWith(z) {
		x.ptrForced[rrKey{o.ID, name, typ}] = true
	}
}

// Whether a set has an address: none, only in disabled records, enabled.
const (
	addrNone = iota
	addrDisabled
	addrEnabled
)

// addrStates returns the addresses of a zone's A or AAAA set.
func addrStates(st *model.State, k rrKey) map[netip.Addr]int {
	out := map[netip.Addr]int{}
	for _, r := range st.RRset(k.zone, k.name, k.typ) {
		a, err := netip.ParseAddr(r.Data)
		if err != nil {
			continue
		}
		s := addrDisabled
		if !r.Disabled {
			s = addrEnabled
		}
		out[a.Unmap()] = max(out[a.Unmap()], s)
	}
	return out
}

// ptrSync returns ops followed by the PTR changes they call for: for the
// zone's auto_ptr, or because the request asked (ptrForce).
func (x *expander) ptrSync(ops []model.Op) ([]model.Op, error) {
	forced := x.ptrForced
	x.ptrForced = nil
	work := x.st.Clone()
	c := &applyCtx{p: x.p, now: x.now}
	for _, op := range ops {
		if err := applyOp(work, op, c); err != nil {
			return nil, err
		}
	}
	keys := affectedKeys(x.st, work, ops)
	for _, k := range sortedForced(forced) {
		if !slices.Contains(keys, k) {
			keys = append(keys, k)
		}
	}
	var extra []model.Op
	for _, k := range keys {
		z := work.Zones[k.zone]
		if z == nil || (k.typ != "A" && k.typ != "AAAA") || strings.HasPrefix(k.name, "*.") {
			continue
		}
		force := forced[k]
		if !force && !z.AutoPTR {
			continue
		}
		before, after := addrStates(x.st, k), addrStates(work, k)
		var addrs []netip.Addr
		for _, m := range []map[netip.Addr]int{before, after} {
			for a := range m {
				if !slices.Contains(addrs, a) {
					addrs = append(addrs, a)
				}
			}
		}
		slices.SortFunc(addrs, func(a, b netip.Addr) int { return a.Compare(b) })
		for _, a := range addrs {
			was, is := before[a], after[a]
			if !force && (was == is || was == addrNone && is == addrDisabled) {
				continue
			}
			rz, ptrName := reverseZoneFor(work, z.ViewID, a)
			if rz == nil {
				if force && is == addrEnabled {
					x.warnings = append(x.warnings, fmt.Sprintf("no reverse zone for %s in %s, so no PTR record was added there (create one: jarl zone create %s/%d%s)",
						a, viewOrServer(work, z.ViewID), a, a.BitLen(), viewFlag(work, z.ViewID)))
				}
				continue
			}
			more, err := x.ptrChange(work, rz, ptrName, k.name, is, !force)
			if err != nil {
				return nil, err
			}
			for _, op := range more {
				if err := applyOp(work, op, c); err != nil {
					return nil, err
				}
			}
			extra = append(extra, more...)
		}
	}
	if len(extra) == 0 {
		return ops, nil
	}
	// The PTR records are local (see ptrChange), so this only keeps a
	// linked reverse zone consistent.
	extra, err := x.linkSync(extra)
	if err != nil {
		return nil, err
	}
	return append(ops, extra...), nil
}

func sortedForced(m map[rrKey]bool) []rrKey {
	var out []rrKey
	for k := range m {
		out = append(out, k)
	}
	slices.SortFunc(out, func(a, b rrKey) int {
		if a.zone != b.zone {
			return int(a.zone - b.zone)
		}
		if a.name != b.name {
			return strings.Compare(a.name, b.name)
		}
		return strings.Compare(a.typ, b.typ)
	})
	return out
}

func viewFlag(st *model.State, viewID int64) string {
	if v := st.Views[viewID]; v != nil {
		return " --view " + v.Name
	}
	return ""
}

// ptrChange returns the operations that give reverse zone rz's PTR
// records at ptrName for host owner the state of its address: none
// (deleted), disabled, or enabled (added when missing).
//
// In a linked reverse zone the PTR records are local to each view, since
// each view's follow its own address records: a shared set at ptrName
// is made local in every view of the link first, as each view has it.
func (x *expander) ptrChange(st *model.State, rz *model.Zone, ptrName, owner string, state int, auto bool) ([]model.Op, error) {
	nwarn := len(x.warnings)
	ops, err := x.ptrChangeIn(st, rz, ptrName, owner, state, auto)
	if err != nil || len(ops) == 0 || rz.LinkGroup == 0 {
		return ops, err
	}
	var local []model.Op
	for _, m := range st.LinkMembers(rz.LinkGroup) {
		for _, r := range st.RRset(m.ID, ptrName, "PTR") {
			if r.SharedID != 0 {
				local = append(local, newOp(OpRecordUpdate, r.ID, r.Version, RecordInput{SharedID: model.Ptr(int64(0))},
					fmt.Sprintf("linked: %s PTR %s becomes local to %s (PTR records follow each view's own address records)", r.Name, r.Data, zoneDesc(st, m))))
			}
		}
	}
	if len(local) == 0 {
		return ops, nil
	}
	// Again on the local records (their versions changed).
	scratch := st.Clone()
	c := &applyCtx{p: x.p, now: x.now}
	for _, op := range local {
		if err := applyOp(scratch, op, c); err != nil {
			return nil, err
		}
	}
	x.warnings = x.warnings[:nwarn]
	ops, err = x.ptrChangeIn(scratch, rz, ptrName, owner, state, auto)
	if err != nil {
		return nil, err
	}
	return append(local, ops...), nil
}

func (x *expander) ptrChangeIn(st *model.State, rz *model.Zone, ptrName, owner string, state int, auto bool) ([]model.Op, error) {
	var ops []model.Op
	switch state {
	case addrNone:
		for _, r := range st.RRset(rz.ID, ptrName, "PTR") {
			if strings.EqualFold(r.Data, owner) {
				ops = append(ops, newOp(OpRecordDelete, r.ID, r.Version, nil, fmt.Sprintf("delete %s PTR %s", r.Name, r.Data)))
			}
		}
	case addrDisabled:
		for _, r := range st.RRset(rz.ID, ptrName, "PTR") {
			if strings.EqualFold(r.Data, owner) && !r.Disabled {
				ops = append(ops, newOp(OpRecordUpdate, r.ID, r.Version, RecordInput{Disabled: model.Ptr(true)}, fmt.Sprintf("disable %s PTR %s", r.Name, r.Data)))
			}
		}
	default:
		return x.ptrCreateIn(st, rz, ptrName, owner, auto)
	}
	return ops, nil
}

// ptrCreateIn returns operations creating the PTR record ptrName -> owner
// in reverse zone rz (none when it is there; enabling it when disabled).
// auto is set when the zone's auto_ptr asked rather than the request: an
// address whose PTR record names another host keeps it then.
func (x *expander) ptrCreateIn(st *model.State, rz *model.Zone, ptrName, owner string, auto bool) ([]model.Op, error) {
	var other string
	for _, r := range st.RRset(rz.ID, ptrName, "PTR") {
		if strings.EqualFold(r.Data, owner) {
			if r.Disabled {
				in := RecordInput{Disabled: model.Ptr(false)}
				return []model.Op{newOp(OpRecordUpdate, r.ID, r.Version, in, fmt.Sprintf("enable %s PTR %s", r.Name, r.Data))}, nil
			}
			return nil, nil // already there
		}
		if !r.Disabled {
			other = r.Data
		}
	}
	if other != "" {
		if auto {
			// One name per address: the one it has stays.
			return nil, nil
		}
		x.warnings = append(x.warnings, fmt.Sprintf("%s already has a PTR record (%s); adding another one", ptrName, other))
	}
	ids, err := x.ids(1)
	if err != nil {
		return nil, err
	}
	in := RecordInput{ZoneID: rz.ID, Name: model.Ptr(ptrName), Type: model.Ptr("PTR"), Data: model.Ptr(owner)}
	if rz.LinkGroup != 0 {
		in.SharedID = model.Ptr(int64(0))
	}
	return []model.Op{newOp(OpRecordCreate, ids[0], 0, in, fmt.Sprintf("add %s IN PTR %s", ptrName, owner))}, nil
}

func enableWord(disabled bool) string {
	if disabled {
		return "disable"
	}
	return "enable"
}

// parseWarnings keeps what parsing noticed (e.g. a name read as absolute).
// The stored operation holds the canonical data, so applying it doesn't
// notice again.
func (x *expander) parseWarnings(owner string, p *rr.Parsed) {
	for _, w := range p.Warnings {
		x.warnings = append(x.warnings, fmt.Sprintf("%s %s: %s", dnsname.Display(owner), p.Type, w))
	}
}

func (x *expander) recordCreate(req Request) ([]model.Op, error) {
	var in RecordInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	z, err := x.resolveZone(in.ZoneID, in.Zone, in.View)
	if err != nil {
		return nil, err
	}
	if in.Name == nil || in.Type == nil || in.Data == nil {
		return nil, errf(KindBadRequest, "a record needs a name, a type and data")
	}
	owner, p, err := parseRecord(z, *in.Name, *in.Type, *in.Data)
	if err != nil {
		return nil, err
	}
	x.parseWarnings(owner, p)
	if in.PTR {
		if _, ok := addrOf(p); !ok {
			return nil, errf(KindBadRequest, "ptr only applies to A and AAAA records")
		}
		x.ptrForce(z, owner, p.Type)
	}
	in.ZoneID, in.Zone, in.View, in.PTR = z.ID, "", "", false
	in.Name, in.Type, in.Data = &owner, &p.Type, &p.Data
	ids, err := x.ids(1)
	if err != nil {
		return nil, err
	}
	summary := fmt.Sprintf("add %s%s IN %s %s", owner, ttlText(in.TTL), p.Type, p.Data)
	in.SharedID = nil
	if z.LinkGroup != 0 {
		local, err := x.localFor(z, owner, p.Type, in.Local)
		if err != nil {
			return nil, err
		}
		if local {
			in.SharedID = model.Ptr(int64(0))
			summary += " (local to view " + x.st.ViewName(z) + ")"
		} else {
			if x.st.HasLocal(z.ID, owner, p.Type) {
				return nil, errf(KindConflict, "%s %s is local in view %s; share the set first (jarl record update ID --shared) or add this one as local", dnsname.Display(owner), p.Type, x.st.ViewName(z))
			}
			in.SharedID = &ids[0]
		}
	} else if in.Local != nil && !*in.Local {
		return nil, notLinked(x.st, z)
	}
	// local on a zone that isn't linked: its records are local anyway.
	in.Local = nil
	return []model.Op{newOp(OpRecordCreate, ids[0], 0, in, summary)}, nil
}

func (x *expander) recordUpdate(req Request) ([]model.Op, error) {
	r := x.st.Records[req.ID]
	if r == nil {
		return nil, errf(KindNotFound, "record %d does not exist", req.ID)
	}
	z := x.st.Zones[r.ZoneID]
	var in RecordInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	ptr := in.PTR
	in.PTR = false
	in.Zone, in.View = "", ""
	if in.SharedID != nil {
		return nil, errf(KindBadRequest, "shared_id is managed by Jarl; use local: true or false to make a record local to its view or shared")
	}
	var pre []model.Op
	if in.Local != nil {
		if z.LinkGroup == 0 && !*in.Local {
			return nil, notLinked(x.st, z)
		}
		if want := *in.Local; z.LinkGroup != 0 && want != (r.SharedID == 0) {
			// The whole set of this name and type changes sides.
			for _, o := range x.st.RRset(z.ID, r.Name, r.Type) {
				id := int64(0)
				what := fmt.Sprintf("make %s %s local to view %s", o.Name, o.Type, x.st.ViewName(z))
				if !want {
					id = o.ID
					what = fmt.Sprintf("share %s %s %s with the linked views", o.Name, o.Type, o.Data)
				}
				pre = append(pre, newOp(OpRecordUpdate, o.ID, o.Version, RecordInput{SharedID: model.Ptr(id)}, what))
			}
		}
		if z.LinkGroup != 0 && !*in.Local {
			// Sharing a version makes it every view's, also when it is
			// shared already and another view overrides it.
			pre = append(pre, x.dropOverrides(z, r.Name, r.Type)...)
		}
		in.Local = nil
		if string(mustJSON(in)) == "{}" {
			return pre, nil
		}
	}
	name, typ, data := r.Name, r.Type, r.Data
	if in.Name != nil {
		name = *in.Name
	}
	if in.Type != nil {
		typ = *in.Type
	}
	if in.Data != nil {
		data = *in.Data
	}
	owner, p, err := parseRecord(z, name, typ, data)
	if err != nil {
		return nil, err
	}
	x.parseWarnings(owner, p)
	if in.Name != nil {
		in.Name = &owner
	}
	if in.Type != nil {
		in.Type = &p.Type
	}
	if in.Data != nil {
		in.Data = &p.Data
	}
	var changes []string
	if owner != r.Name {
		changes = append(changes, "name "+r.Name+" → "+owner)
	}
	if p.Type != r.Type {
		changes = append(changes, "type "+r.Type+" → "+p.Type)
	}
	if p.Data != r.Data {
		changes = append(changes, "data "+r.Data+" → "+p.Data)
	}
	if in.TTL.Set {
		old := "default"
		if r.TTL != nil {
			old = fmt.Sprint(*r.TTL)
		}
		nw := "default"
		if !in.TTL.Null {
			nw = fmt.Sprint(in.TTL.Value)
		}
		if old != nw {
			changes = append(changes, "ttl "+old+" → "+nw)
		}
	}
	if in.Comment != nil && *in.Comment != r.Comment {
		changes = append(changes, "comment")
	}
	toggled := in.Disabled != nil && *in.Disabled != r.Disabled
	summary := fmt.Sprintf("change %s %s %s", r.Name, r.Type, r.Data)
	switch {
	case toggled && len(changes) == 0:
		summary = fmt.Sprintf("%s %s %s %s", enableWord(*in.Disabled), r.Name, r.Type, r.Data)
	case toggled:
		changes = append(changes, enableWord(*in.Disabled)+"d")
		fallthrough
	case len(changes) > 0:
		summary += ": " + strings.Join(changes, ", ")
	}
	if z.LinkGroup != 0 && r.SharedID != 0 && len(pre) == 0 && (owner != r.Name || p.Type != r.Type) && x.st.HasLocal(z.ID, owner, p.Type) {
		return nil, errf(KindConflict, "%s %s is local in view %s, so a shared record can't move there", dnsname.Display(owner), p.Type, x.st.ViewName(z))
	}
	base := req.BaseVersion
	if base == 0 {
		base = r.Version
	}
	if len(pre) > 0 {
		base = 0 // the record was just updated by pre
	}
	ops := pre
	if string(mustJSON(in)) != "{}" || !ptr {
		ops = append(ops, newOp(OpRecordUpdate, r.ID, base, in, summary))
	}
	if ptr {
		// The PTR records of the old and the new record, whichever is an
		// address (ptrSync).
		_, isAddr := addrOf(p)
		if old, err := rr.Parse(z.Name, r.Name, r.Type, r.Data); err == nil {
			if _, ok := addrOf(old); ok {
				isAddr = true
				x.ptrForce(z, r.Name, r.Type)
			}
		}
		if !isAddr {
			return nil, errf(KindBadRequest, "ptr only applies to A and AAAA records")
		}
		if _, ok := addrOf(p); ok {
			x.ptrForce(z, owner, p.Type)
		}
	}
	return ops, nil
}

func (x *expander) recordDelete(req Request) ([]model.Op, error) {
	var in RecordInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	if req.ID != 0 {
		r := x.st.Records[req.ID]
		if r == nil {
			if in.MissingOK {
				return nil, nil
			}
			return nil, errf(KindNotFound, "record %d does not exist", req.ID)
		}
		base := req.BaseVersion
		if base == 0 {
			base = r.Version
		}
		ops := []model.Op{newOp(OpRecordDelete, r.ID, base, nil, fmt.Sprintf("delete %s %s %s", r.Name, r.Type, r.Data))}
		if in.PTR {
			x.ptrForce(x.st.Zones[r.ZoneID], r.Name, r.Type)
		}
		return ops, nil
	}
	z, err := x.resolveZone(in.ZoneID, in.Zone, in.View)
	if err != nil {
		return nil, err
	}
	if in.Name == nil || in.Type == nil {
		return nil, errf(KindBadRequest, "deleting by match needs a name and a type (or give the record id)")
	}
	owner, err := dnsname.Owner(*in.Name, z.Name)
	if err != nil {
		return nil, errf(KindBadRequest, "%v", err)
	}
	typ, _, err := rr.NormalizeType(*in.Type)
	if err != nil {
		return nil, errf(KindBadRequest, "%v", err)
	}
	what := owner + " " + typ
	var parsed *rr.Parsed
	if in.Data != nil && strings.TrimSpace(*in.Data) != "" {
		_, p, err := parseRecord(z, owner, typ, *in.Data)
		if err != nil {
			return nil, err
		}
		in.Data = &p.Data
		what += " " + p.Data
		parsed = p
	} else {
		in.Data = nil
		what += " (all)"
	}
	if in.MissingOK {
		what += " (if present)"
	}
	if in.PTR && parsed != nil {
		x.ptrForce(z, owner, typ)
	}
	in.ZoneID, in.Zone, in.View, in.PTR = z.ID, "", "", false
	in.Name, in.Type = &owner, &typ
	return []model.Op{newOp(OpRecordDelete, 0, 0, in, "delete "+what)}, nil
}

// recordSetDisabled expands record.disable and record.enable: the record
// with the request's ID, or the records matching zone, name, type and
// (optionally) data.
func (x *expander) recordSetDisabled(req Request, disabled bool) ([]model.Op, error) {
	var in RecordInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	var recs []*model.Record
	if req.ID != 0 {
		r := x.st.Records[req.ID]
		if r == nil {
			return nil, errf(KindNotFound, "record %d does not exist", req.ID)
		}
		recs = append(recs, r)
	} else {
		z, err := x.resolveZone(in.ZoneID, in.Zone, in.View)
		if err != nil {
			return nil, err
		}
		if in.Name == nil || in.Type == nil {
			return nil, errf(KindBadRequest, "finding records needs a name and a type (or give the record id)")
		}
		owner, err := dnsname.Owner(*in.Name, z.Name)
		if err != nil {
			return nil, errf(KindBadRequest, "%v", err)
		}
		typ, _, err := rr.NormalizeType(*in.Type)
		if err != nil {
			return nil, errf(KindBadRequest, "%v", err)
		}
		data, what := "", owner+" "+typ
		if in.Data != nil && strings.TrimSpace(*in.Data) != "" {
			_, p, err := parseRecord(z, owner, typ, *in.Data)
			if err != nil {
				return nil, err
			}
			data, what = p.Data, what+" "+p.Data
		}
		for _, r := range x.st.ZoneRecords(z.ID) {
			if r.Name == owner && r.Type == typ && (data == "" || strings.EqualFold(r.Data, data)) {
				recs = append(recs, r)
			}
		}
		if len(recs) == 0 {
			if in.MissingOK {
				return nil, nil
			}
			return nil, errf(KindNotFound, "no record %s in zone %s", dnsname.Display(what), dnsname.Display(z.Name))
		}
	}
	var ops []model.Op
	for _, r := range recs {
		if r.Disabled == disabled {
			continue // already so
		}
		base := 0
		if req.ID != 0 {
			base = req.BaseVersion
		}
		more, err := x.recordUpdate(Request{Op: OpRecordUpdate, ID: r.ID, BaseVersion: base, Data: mustJSON(RecordInput{Disabled: model.Ptr(disabled), PTR: in.PTR})})
		if err != nil {
			return nil, err
		}
		ops = append(ops, more...)
	}
	if len(ops) == 0 && !in.MissingOK {
		what := fmt.Sprintf("%s %s %s is", recs[0].Name, recs[0].Type, recs[0].Data)
		if len(recs) > 1 {
			what = fmt.Sprintf("all %d %s %s records are", len(recs), recs[0].Name, recs[0].Type)
		}
		return nil, errf(KindConflict, "%s already %sd", what, enableWord(disabled))
	}
	return ops, nil
}

func (x *expander) rrsetReplace(req Request) ([]model.Op, error) {
	var in RRSetInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	z, err := x.resolveZone(in.ZoneID, in.Zone, in.View)
	if err != nil {
		return nil, err
	}
	owner, err := dnsname.Owner(in.Name, z.Name)
	if err != nil {
		return nil, errf(KindBadRequest, "%v", err)
	}
	typ, _, err := rr.NormalizeType(in.Type)
	if err != nil {
		return nil, errf(KindBadRequest, "%v", err)
	}
	var canon []string
	for _, d := range in.Data {
		_, p, err := parseRecord(z, owner, typ, d)
		if err != nil {
			return nil, err
		}
		x.parseWarnings(owner, p)
		canon = append(canon, p.Data)
	}
	in.ZoneID, in.Zone, in.View, in.Name, in.Type, in.Data = z.ID, "", "", owner, typ, canon
	where := ""
	var pre []model.Op
	if z.LinkGroup != 0 {
		local, err := x.localFor(z, owner, typ, in.Local)
		if err != nil {
			return nil, err
		}
		in.Shared = model.Ptr(!local)
		if local {
			where = " (local to view " + x.st.ViewName(z) + ")"
		} else if in.Local != nil {
			// Explicitly shared: this version becomes every view's.
			pre = x.dropOverrides(z, owner, typ)
		}
	} else if in.Local != nil && !*in.Local {
		return nil, notLinked(x.st, z)
	}
	in.Local = nil
	if len(canon) > 0 {
		in.NewIDs, err = x.ids(len(canon))
		if err != nil {
			return nil, err
		}
	}
	summary := fmt.Sprintf("set %s%s IN %s to [%s]%s", owner, ttlText(in.TTL), typ, strings.Join(canon, ", "), where)
	if len(canon) == 0 {
		summary = fmt.Sprintf("delete all %s records of %s%s", typ, owner, where)
	}
	return append(pre, newOp(OpRRSetReplace, 0, 0, in, summary)), nil
}

func (x *expander) viewCreate(req Request) ([]model.Op, error) {
	var in ViewInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	if in.Name == nil || strings.TrimSpace(*in.Name) == "" {
		return nil, errf(KindBadRequest, "a view needs a name")
	}
	adopt := in.AdoptZones
	in.AdoptZones = false
	ids, err := x.ids(1)
	if err != nil {
		return nil, err
	}
	ops := []model.Op{newOp(OpViewCreate, ids[0], 0, in, "create view "+*in.Name)}
	if adopt {
		for _, z := range x.st.ZonesInView(0) {
			ops = append(ops, newOp(OpZoneUpdate, z.ID, z.Version, ZoneInput{ViewID: model.Ptr(ids[0])}, "move zone "+dnsname.Display(z.Name)+" into view "+*in.Name))
		}
	}
	return ops, nil
}

func (x *expander) tsigCreate(req Request) ([]model.Op, error) {
	var in TSIGInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	if in.Name == nil {
		return nil, errf(KindBadRequest, "a TSIG key needs a name")
	}
	alg := "hmac-sha256"
	if in.Algorithm != nil {
		alg = strings.ToLower(*in.Algorithm)
	}
	in.Algorithm = &alg
	if in.Secret == nil || *in.Secret == "" {
		n := validate.TSIGAlgorithms[alg]
		if n == 0 {
			return nil, errf(KindBadRequest, "unsupported TSIG algorithm %q", alg)
		}
		in.Secret = model.Ptr(auth.GenerateTSIGSecret(n))
	}
	ids, err := x.ids(1)
	if err != nil {
		return nil, err
	}
	return []model.Op{newOp(OpTSIGCreate, ids[0], 0, in, "create TSIG key "+model.NormalizeKeyName(*in.Name)+" ("+alg+")")}, nil
}

func (x *expander) optionCreate(req Request) ([]model.Op, error) {
	var in OptionInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	if in.Scope == nil || in.Name == nil {
		return nil, errf(KindBadRequest, "an option needs a scope and a name")
	}
	scopeID := int64(0)
	if in.ScopeID != nil {
		scopeID = *in.ScopeID
	}
	val := ""
	if in.Value != nil {
		val = *in.Value
	}
	n, v, err := NormalizeOption(x.st, *in.Scope, scopeID, *in.Name, val)
	if err != nil {
		return nil, err
	}
	in.Name, in.Value = &n, &v
	ids, err := x.ids(1)
	if err != nil {
		return nil, err
	}
	o := &model.Option{Scope: *in.Scope, ScopeID: scopeID, Name: n}
	return []model.Op{newOp(OpOptionCreate, ids[0], 0, in, "set "+optionLabel(x.st, o)+" "+v)}, nil
}

// RedactOps hides TSIG secrets in operation data.
func RedactOps(ops []model.Op) []model.Op {
	out := make([]model.Op, len(ops))
	for i, op := range ops {
		out[i] = op
		if op.Kind != OpTSIGCreate && op.Kind != OpTSIGUpdate || len(op.Data) == 0 {
			continue
		}
		var m map[string]any
		if json.Unmarshal(op.Data, &m) == nil {
			if _, ok := m["secret"]; ok {
				m["secret"] = "(hidden)"
				out[i].Data = mustJSON(m)
			}
		}
	}
	return out
}

// zoneToggle returns the new disabled state when a zone update only
// disables or enables the zone (nil otherwise).
func zoneToggle(req Request, z *model.Zone) *bool {
	var in ZoneInput
	if decode(req.Data, &in) != nil || in.Disabled == nil || *in.Disabled == z.Disabled {
		return nil
	}
	only := ZoneInput{Disabled: in.Disabled}
	if string(mustJSON(in)) != string(mustJSON(only)) {
		return nil
	}
	return in.Disabled
}

// disabledZoneEffect says what clients get once named no longer loads a
// zone: in a view that offers recursion, answers from recursion (the
// internet's version of the zone, if it has one); elsewhere, REFUSED.
func disabledZoneEffect(st *model.State, z *model.Zone) string {
	where := "this server"
	if v := st.ViewName(z); v != "" {
		where = "view " + v
	}
	if st.RecursionOn(z.ViewID) {
		return fmt.Sprintf("once zone %s is disabled, clients of %s that may use recursion get its names from recursion: the internet's version of the zone, if there is one", dnsname.Display(z.Name), where)
	}
	return fmt.Sprintf("once zone %s is disabled, %s answers REFUSED for its names", dnsname.Display(z.Name), where)
}

// exposureAck acknowledges an exposure finding of a view or the server,
// or takes the acknowledgement back: the view's (or the settings')
// acknowledgements are updated as a whole.
func (x *expander) exposureAck(req Request, ack bool) ([]model.Op, error) {
	var in AckInput
	if err := decode(req.Data, &in); err != nil {
		return nil, err
	}
	in.Code = strings.TrimSpace(in.Code)
	if !validate.Ackable(in.Code) {
		return nil, errf(KindBadRequest, "%q is not an exposure finding that can be acknowledged (exposure_... or security_open_...)", in.Code)
	}
	if ack && strings.TrimSpace(in.Reason) == "" {
		return nil, errf(KindBadRequest, "say why %s is accepted (a reason is required)", in.Code)
	}
	var v *model.View
	switch {
	case in.ViewID != 0:
		v = x.st.Views[in.ViewID]
	case in.View != "":
		v = x.st.ViewByName(in.View)
	}
	if (in.ViewID != 0 || in.View != "") && v == nil {
		return nil, errf(KindNotFound, "no view %s", firstNonEmptyStr(in.View, fmt.Sprint(in.ViewID)))
	}
	acks := x.st.Settings.Acknowledged
	where := "the server"
	if v != nil {
		acks, where = v.Acknowledged, "view "+v.Name
	}
	var out []model.Acknowledgement
	for _, a := range acks {
		if a.Code != in.Code {
			out = append(out, a)
		}
	}
	summary := "acknowledge " + in.Code + " for " + where + ": " + strings.TrimSpace(in.Reason)
	if ack {
		out = append(out, model.Acknowledgement{Code: in.Code, Reason: strings.TrimSpace(in.Reason), By: x.p.Name(), At: x.now})
	} else {
		if len(out) == len(acks) {
			return nil, errf(KindConflict, "%s isn't acknowledged for %s", in.Code, where)
		}
		summary = "take back the acknowledgement of " + in.Code + " for " + where
	}
	if out == nil {
		out = []model.Acknowledgement{}
	}
	if v != nil {
		return []model.Op{newOp(OpViewUpdate, v.ID, v.Version, ViewInput{Acknowledged: &out}, summary)}, nil
	}
	return []model.Op{newOp(OpSettingsUpdate, 0, 0, SettingsInput{Acknowledged: &out}, summary)}, nil
}

func firstNonEmptyStr(a, b string) string {
	if a != "" {
		return a
	}
	return b
}

// notLinked refuses sharing a record of a zone that isn't linked.
func notLinked(st *model.State, z *model.Zone) error {
	return errf(KindBadRequest, "zone %s isn't linked with other views, so there is nothing to share its records with (link it first: jarl zone link)", zoneDesc(st, z))
}

// zoneUnchanged reports whether an update would leave the zone as it is.
// Errors are left for applying the update to report.
func zoneUnchanged(st *model.State, z *model.Zone, in *ZoneInput) bool {
	if len(in.Nameservers) > 0 || len(in.Records) > 0 || in.CloneFrom != 0 || len(in.Options) > 0 {
		return false
	}
	c := st.Clone()
	n := c.Zones[z.ID]
	if err := setZoneFields(c, n, in, false); err != nil {
		return false
	}
	return reflect.DeepEqual(n, z)
}