package dns

import (
	"context"
	"errors"
	"net/netip"
	"strings"
	"time"

	"github.com/sagernet/sing-box/adapter"
	"github.com/sagernet/sing-box/common/taskmonitor"
	C "github.com/sagernet/sing-box/constant"
	"github.com/sagernet/sing-box/experimental/deprecated"
	"github.com/sagernet/sing-box/log"
	"github.com/sagernet/sing-box/option"
	R "github.com/sagernet/sing-box/route/rule"
	"github.com/sagernet/sing-tun"
	"github.com/sagernet/sing/common"
	E "github.com/sagernet/sing/common/exceptions"
	F "github.com/sagernet/sing/common/format"
	"github.com/sagernet/sing/common/logger"
	M "github.com/sagernet/sing/common/metadata"
	"github.com/sagernet/sing/common/task"
	"github.com/sagernet/sing/contrab/freelru"
	"github.com/sagernet/sing/contrab/maphash"
	"github.com/sagernet/sing/service"

	mDNS "github.com/miekg/dns"
)

var _ adapter.DNSRouter = (*Router)(nil)

type Router struct {
	ctx                     context.Context
	logger                  logger.ContextLogger
	transport               adapter.DNSTransportManager
	outbound                adapter.OutboundManager
	client                  adapter.DNSClient
	rules                   []adapter.DNSRule
	defaultDomainStrategy   C.DomainStrategy
	dnsReverseMapping       freelru.Cache[netip.Addr, string]
	platformInterface       adapter.PlatformInterface
	legacyAddressFilterMode bool
}

func NewRouter(ctx context.Context, logFactory log.Factory, options option.DNSOptions) *Router {
	router := &Router{
		ctx:                   ctx,
		logger:                logFactory.NewLogger("dns"),
		transport:             service.FromContext[adapter.DNSTransportManager](ctx),
		outbound:              service.FromContext[adapter.OutboundManager](ctx),
		rules:                 make([]adapter.DNSRule, 0, len(options.Rules)),
		defaultDomainStrategy: C.DomainStrategy(options.Strategy),
	}
	router.client = NewClient(ClientOptions{
		DisableCache:     options.DNSClientOptions.DisableCache,
		DisableExpire:    options.DNSClientOptions.DisableExpire,
		IndependentCache: options.DNSClientOptions.IndependentCache,
		CacheCapacity:    options.DNSClientOptions.CacheCapacity,
		ClientSubnet:     options.DNSClientOptions.ClientSubnet.Build(netip.Prefix{}),
		RDRC: func() adapter.RDRCStore {
			cacheFile := service.FromContext[adapter.CacheFile](ctx)
			if cacheFile == nil {
				return nil
			}
			if !cacheFile.StoreRDRC() {
				return nil
			}
			return cacheFile
		},
		Logger: router.logger,
	})
	if options.ReverseMapping {
		router.dnsReverseMapping = common.Must1(freelru.NewSharded[netip.Addr, string](1024, maphash.NewHasher[netip.Addr]().Hash32))
	}
	return router
}

func (r *Router) Initialize(rules []option.DNSRule) error {
	r.legacyAddressFilterMode = !hasNonLegacyAddressFilterItems(rules)
	if !r.legacyAddressFilterMode {
		err := validateNonLegacyAddressFilterRules(rules)
		if err != nil {
			return err
		}
	}
	for i, ruleOptions := range rules {
		dnsRule, err := R.NewDNSRule(r.ctx, r.logger, ruleOptions, true, r.legacyAddressFilterMode)
		if err != nil {
			return E.Cause(err, "parse dns rule[", i, "]")
		}
		r.rules = append(r.rules, dnsRule)
	}
	return nil
}

func (r *Router) Start(stage adapter.StartStage) error {
	monitor := taskmonitor.New(r.logger, C.StartTimeout)
	switch stage {
	case adapter.StartStateStart:
		monitor.Start("initialize DNS client")
		r.client.Start()
		monitor.Finish()

		for i, rule := range r.rules {
			monitor.Start("initialize DNS rule[", i, "]")
			err := rule.Start()
			monitor.Finish()
			if err != nil {
				return E.Cause(err, "initialize DNS rule[", i, "]")
			}
		}
		if r.legacyAddressFilterMode && common.Any(r.rules, func(rule adapter.DNSRule) bool { return rule.WithAddressLimit() }) {
			deprecated.Report(r.ctx, deprecated.OptionLegacyDNSAddressFilter)
		}
	}
	return nil
}

func (r *Router) Close() error {
	monitor := taskmonitor.New(r.logger, C.StopTimeout)
	var err error
	for i, rule := range r.rules {
		monitor.Start("close dns rule[", i, "]")
		err = E.Append(err, rule.Close(), func(err error) error {
			return E.Cause(err, "close dns rule[", i, "]")
		})
		monitor.Finish()
	}
	return err
}

func (r *Router) matchDNS(ctx context.Context, allowFakeIP bool, ruleIndex int, isAddressQuery bool, options *adapter.DNSQueryOptions) (adapter.DNSTransport, adapter.DNSRule, int) {
	metadata := adapter.ContextFrom(ctx)
	if metadata == nil {
		panic("no context")
	}
	var currentRuleIndex int
	if ruleIndex != -1 {
		currentRuleIndex = ruleIndex + 1
	}
	for ; currentRuleIndex < len(r.rules); currentRuleIndex++ {
		currentRule := r.rules[currentRuleIndex]
		if currentRule.WithAddressLimit() && !isAddressQuery {
			continue
		}
		metadata.ResetRuleCache()
		metadata.DestinationAddressMatchFromResponse = false
		if currentRule.Match(metadata) {
			displayRuleIndex := currentRuleIndex
			if displayRuleIndex != -1 {
				displayRuleIndex += displayRuleIndex + 1
			}
			ruleDescription := currentRule.String()
			if ruleDescription != "" {
				r.logger.DebugContext(ctx, "match[", displayRuleIndex, "] ", currentRule, " => ", currentRule.Action())
			} else {
				r.logger.DebugContext(ctx, "match[", displayRuleIndex, "] => ", currentRule.Action())
			}
			switch action := currentRule.Action().(type) {
			case *R.RuleActionDNSRoute:
				transport, loaded := r.transport.Transport(action.Server)
				if !loaded {
					r.logger.ErrorContext(ctx, "transport not found: ", action.Server)
					continue
				}
				isFakeIP := transport.Type() == C.DNSTypeFakeIP
				if isFakeIP && !allowFakeIP {
					continue
				}
				if action.Strategy != C.DomainStrategyAsIS {
					options.Strategy = action.Strategy
				}
				if isFakeIP || action.DisableCache {
					options.DisableCache = true
				}
				if action.RewriteTTL != nil {
					options.RewriteTTL = action.RewriteTTL
				}
				if action.ClientSubnet.IsValid() {
					options.ClientSubnet = action.ClientSubnet
				}
				if legacyTransport, isLegacy := transport.(adapter.LegacyDNSTransport); isLegacy {
					if options.Strategy == C.DomainStrategyAsIS {
						options.Strategy = legacyTransport.LegacyStrategy()
					}
					if !options.ClientSubnet.IsValid() {
						options.ClientSubnet = legacyTransport.LegacyClientSubnet()
					}
				}
				return transport, currentRule, currentRuleIndex
			case *R.RuleActionDNSRouteOptions:
				if action.Strategy != C.DomainStrategyAsIS {
					options.Strategy = action.Strategy
				}
				if action.DisableCache {
					options.DisableCache = true
				}
				if action.RewriteTTL != nil {
					options.RewriteTTL = action.RewriteTTL
				}
				if action.ClientSubnet.IsValid() {
					options.ClientSubnet = action.ClientSubnet
				}
			case *R.RuleActionReject:
				return nil, currentRule, currentRuleIndex
			case *R.RuleActionPredefined:
				return nil, currentRule, currentRuleIndex
			}
		}
	}
	transport := r.transport.Default()
	if legacyTransport, isLegacy := transport.(adapter.LegacyDNSTransport); isLegacy {
		if options.Strategy == C.DomainStrategyAsIS {
			options.Strategy = legacyTransport.LegacyStrategy()
		}
		if !options.ClientSubnet.IsValid() {
			options.ClientSubnet = legacyTransport.LegacyClientSubnet()
		}
	}
	return transport, nil, -1
}

func (r *Router) applyTransportDefaults(transport adapter.DNSTransport, options *adapter.DNSQueryOptions) {
	if legacyTransport, isLegacy := transport.(adapter.LegacyDNSTransport); isLegacy {
		if options.Strategy == C.DomainStrategyAsIS {
			options.Strategy = legacyTransport.LegacyStrategy()
		}
		if !options.ClientSubnet.IsValid() {
			options.ClientSubnet = legacyTransport.LegacyClientSubnet()
		}
	}
}

func (r *Router) applyDNSRouteOptions(options *adapter.DNSQueryOptions, routeOptions R.RuleActionDNSRouteOptions) {
	if routeOptions.Strategy != C.DomainStrategyAsIS {
		options.Strategy = routeOptions.Strategy
	}
	if routeOptions.DisableCache {
		options.DisableCache = true
	}
	if routeOptions.RewriteTTL != nil {
		options.RewriteTTL = routeOptions.RewriteTTL
	}
	if routeOptions.ClientSubnet.IsValid() {
		options.ClientSubnet = routeOptions.ClientSubnet
	}
}

func (r *Router) resolveDNSRoute(action *R.RuleActionDNSRoute, allowFakeIP bool, options *adapter.DNSQueryOptions) (adapter.DNSTransport, bool) {
	transport, loaded := r.transport.Transport(action.Server)
	if !loaded {
		return nil, false
	}
	isFakeIP := transport.Type() == C.DNSTypeFakeIP
	if isFakeIP && !allowFakeIP {
		return transport, false
	}
	r.applyDNSRouteOptions(options, action.RuleActionDNSRouteOptions)
	if isFakeIP {
		options.DisableCache = true
	}
	r.applyTransportDefaults(transport, options)
	return transport, true
}

func (r *Router) logRuleMatch(ctx context.Context, ruleIndex int, currentRule adapter.DNSRule) {
	displayRuleIndex := ruleIndex
	if displayRuleIndex != -1 {
		displayRuleIndex += displayRuleIndex + 1
	}
	if ruleDescription := currentRule.String(); ruleDescription != "" {
		r.logger.DebugContext(ctx, "match[", displayRuleIndex, "] ", currentRule, " => ", currentRule.Action())
	} else {
		r.logger.DebugContext(ctx, "match[", displayRuleIndex, "] => ", currentRule.Action())
	}
}

func (r *Router) exchangeWithRules(ctx context.Context, message *mDNS.Msg, options adapter.DNSQueryOptions, allowFakeIP bool) (*mDNS.Msg, adapter.DNSTransport, adapter.DNSQueryOptions, error) {
	metadata := adapter.ContextFrom(ctx)
	if metadata == nil {
		panic("no context")
	}
	effectiveOptions := options
	var savedResponse *mDNS.Msg
	for currentRuleIndex, currentRule := range r.rules {
		metadata.ResetRuleCache()
		metadata.DNSResponse = savedResponse
		metadata.DestinationAddressMatchFromResponse = false
		if !currentRule.Match(metadata) {
			continue
		}
		r.logRuleMatch(ctx, currentRuleIndex, currentRule)
		switch action := currentRule.Action().(type) {
		case *R.RuleActionDNSRouteOptions:
			r.applyDNSRouteOptions(&effectiveOptions, *action)
		case *R.RuleActionEvaluate:
			queryOptions := effectiveOptions
			transport, loaded := r.resolveDNSRoute(&R.RuleActionDNSRoute{
				Server:                    action.Server,
				RuleActionDNSRouteOptions: action.RuleActionDNSRouteOptions,
			}, allowFakeIP, &queryOptions)
			if !loaded {
				if transport == nil {
					r.logger.ErrorContext(ctx, "transport not found: ", action.Server)
				}
				savedResponse = nil
				continue
			}
			if queryOptions.Strategy == C.DomainStrategyAsIS {
				queryOptions.Strategy = r.defaultDomainStrategy
			}
			response, err := r.client.Exchange(adapter.OverrideContext(ctx), transport, message, queryOptions, nil)
			if err != nil {
				r.logger.ErrorContext(ctx, E.Cause(err, "exchange failed for ", FormatQuestion(message.Question[0].String())))
				savedResponse = nil
				continue
			}
			savedResponse = response
		case *R.RuleActionDNSRoute:
			queryOptions := effectiveOptions
			transport, loaded := r.resolveDNSRoute(action, allowFakeIP, &queryOptions)
			if !loaded {
				if transport == nil {
					r.logger.ErrorContext(ctx, "transport not found: ", action.Server)
				}
				continue
			}
			if queryOptions.Strategy == C.DomainStrategyAsIS {
				queryOptions.Strategy = r.defaultDomainStrategy
			}
			response, err := r.client.Exchange(adapter.OverrideContext(ctx), transport, message, queryOptions, nil)
			return response, transport, queryOptions, err
		case *R.RuleActionReject:
			switch action.Method {
			case C.RuleActionRejectMethodDefault:
				return &mDNS.Msg{
					MsgHdr: mDNS.MsgHdr{
						Id:       message.Id,
						Rcode:    mDNS.RcodeRefused,
						Response: true,
					},
					Question: []mDNS.Question{message.Question[0]},
				}, nil, effectiveOptions, nil
			case C.RuleActionRejectMethodDrop:
				return nil, nil, effectiveOptions, tun.ErrDrop
			}
		case *R.RuleActionPredefined:
			return action.Response(message), nil, effectiveOptions, nil
		}
	}
	queryOptions := effectiveOptions
	transport := r.transport.Default()
	r.applyTransportDefaults(transport, &queryOptions)
	if queryOptions.Strategy == C.DomainStrategyAsIS {
		queryOptions.Strategy = r.defaultDomainStrategy
	}
	response, err := r.client.Exchange(adapter.OverrideContext(ctx), transport, message, queryOptions, nil)
	return response, transport, queryOptions, err
}

type lookupWithRulesResponse struct {
	addresses []netip.Addr
	strategy  C.DomainStrategy
}

func (r *Router) resolveLookupStrategy(options adapter.DNSQueryOptions, strategies ...C.DomainStrategy) C.DomainStrategy {
	if options.LookupStrategy != C.DomainStrategyAsIS {
		return options.LookupStrategy
	}
	for _, strategy := range strategies {
		if strategy != C.DomainStrategyAsIS {
			return strategy
		}
	}
	if options.Strategy != C.DomainStrategyAsIS {
		return options.Strategy
	}
	return r.defaultDomainStrategy
}

func lookupStrategyAllowsQueryType(strategy C.DomainStrategy, qType uint16) bool {
	switch strategy {
	case C.DomainStrategyIPv4Only:
		return qType == mDNS.TypeA
	case C.DomainStrategyIPv6Only:
		return qType == mDNS.TypeAAAA
	default:
		return true
	}
}

func (r *Router) lookupWithRules(ctx context.Context, domain string, options adapter.DNSQueryOptions) ([]netip.Addr, error) {
	lookupOptions := options
	if options.LookupStrategy != C.DomainStrategyAsIS {
		lookupOptions.Strategy = options.LookupStrategy
	}
	if options.LookupStrategy == C.DomainStrategyIPv4Only {
		response, err := r.lookupWithRulesType(ctx, domain, mDNS.TypeA, lookupOptions)
		return response.addresses, err
	}
	if options.LookupStrategy == C.DomainStrategyIPv6Only {
		response, err := r.lookupWithRulesType(ctx, domain, mDNS.TypeAAAA, lookupOptions)
		return response.addresses, err
	}
	var (
		response4 lookupWithRulesResponse
		response6 lookupWithRulesResponse
	)
	var group task.Group
	group.Append("exchange4", func(ctx context.Context) error {
		result, err := r.lookupWithRulesType(ctx, domain, mDNS.TypeA, lookupOptions)
		response4 = result
		return err
	})
	group.Append("exchange6", func(ctx context.Context) error {
		result, err := r.lookupWithRulesType(ctx, domain, mDNS.TypeAAAA, lookupOptions)
		response6 = result
		return err
	})
	err := group.Run(ctx)
	strategy := r.resolveLookupStrategy(options, response4.strategy, response6.strategy)
	if !lookupStrategyAllowsQueryType(strategy, mDNS.TypeA) {
		response4.addresses = nil
	}
	if !lookupStrategyAllowsQueryType(strategy, mDNS.TypeAAAA) {
		response6.addresses = nil
	}
	if len(response4.addresses) == 0 && len(response6.addresses) == 0 {
		return nil, err
	}
	return sortAddresses(response4.addresses, response6.addresses, strategy), nil
}

func (r *Router) lookupWithRulesType(ctx context.Context, domain string, qType uint16, options adapter.DNSQueryOptions) (lookupWithRulesResponse, error) {
	request := &mDNS.Msg{
		MsgHdr: mDNS.MsgHdr{
			RecursionDesired: true,
		},
		Question: []mDNS.Question{{
			Name:   mDNS.Fqdn(FqdnToDomain(domain)),
			Qtype:  qType,
			Qclass: mDNS.ClassINET,
		}},
	}
	response, _, queryOptions, err := r.exchangeWithRules(adapter.OverrideContext(ctx), request, options, false)
	result := lookupWithRulesResponse{
		strategy: r.resolveLookupStrategy(options, queryOptions.Strategy),
	}
	if err != nil {
		return result, err
	}
	if response.Rcode != mDNS.RcodeSuccess {
		return result, RcodeError(response.Rcode)
	}
	if !lookupStrategyAllowsQueryType(result.strategy, qType) {
		return result, nil
	}
	result.addresses = MessageToAddresses(response)
	return result, nil
}

func (r *Router) Exchange(ctx context.Context, message *mDNS.Msg, options adapter.DNSQueryOptions) (*mDNS.Msg, error) {
	if len(message.Question) != 1 {
		r.logger.WarnContext(ctx, "bad question size: ", len(message.Question))
		responseMessage := mDNS.Msg{
			MsgHdr: mDNS.MsgHdr{
				Id:       message.Id,
				Response: true,
				Rcode:    mDNS.RcodeFormatError,
			},
			Question: message.Question,
		}
		return &responseMessage, nil
	}
	r.logger.DebugContext(ctx, "exchange ", FormatQuestion(message.Question[0].String()))
	var (
		response  *mDNS.Msg
		transport adapter.DNSTransport
		err       error
	)
	var metadata *adapter.InboundContext
	ctx, metadata = adapter.ExtendContext(ctx)
	metadata.Destination = M.Socksaddr{}
	metadata.QueryType = message.Question[0].Qtype
	metadata.DNSResponse = nil
	metadata.DestinationAddressMatchFromResponse = false
	switch metadata.QueryType {
	case mDNS.TypeA:
		metadata.IPVersion = 4
	case mDNS.TypeAAAA:
		metadata.IPVersion = 6
	}
	metadata.Domain = FqdnToDomain(message.Question[0].Name)
	if options.Transport != nil {
		transport = options.Transport
		r.applyTransportDefaults(transport, &options)
		if options.Strategy == C.DomainStrategyAsIS {
			options.Strategy = r.defaultDomainStrategy
		}
		response, err = r.client.Exchange(ctx, transport, message, options, nil)
	} else if !r.legacyAddressFilterMode {
		response, transport, _, err = r.exchangeWithRules(ctx, message, options, true)
	} else {
		var (
			rule      adapter.DNSRule
			ruleIndex int
		)
		ruleIndex = -1
		for {
			dnsCtx := adapter.OverrideContext(ctx)
			dnsOptions := options
			transport, rule, ruleIndex = r.matchDNS(ctx, true, ruleIndex, isAddressQuery(message), &dnsOptions)
			if rule != nil {
				switch action := rule.Action().(type) {
				case *R.RuleActionReject:
					switch action.Method {
					case C.RuleActionRejectMethodDefault:
						return &mDNS.Msg{
							MsgHdr: mDNS.MsgHdr{
								Id:       message.Id,
								Rcode:    mDNS.RcodeRefused,
								Response: true,
							},
							Question: []mDNS.Question{message.Question[0]},
						}, nil
					case C.RuleActionRejectMethodDrop:
						return nil, tun.ErrDrop
					}
				case *R.RuleActionPredefined:
					return action.Response(message), nil
				}
			}
			responseCheck := addressLimitResponseCheck(rule, metadata)
			if dnsOptions.Strategy == C.DomainStrategyAsIS {
				dnsOptions.Strategy = r.defaultDomainStrategy
			}
			response, err = r.client.Exchange(dnsCtx, transport, message, dnsOptions, responseCheck)
			var rejected bool
			if err != nil {
				if errors.Is(err, ErrResponseRejectedCached) {
					rejected = true
					r.logger.DebugContext(ctx, E.Cause(err, "response rejected for ", FormatQuestion(message.Question[0].String())), " (cached)")
				} else if errors.Is(err, ErrResponseRejected) {
					rejected = true
					r.logger.DebugContext(ctx, E.Cause(err, "response rejected for ", FormatQuestion(message.Question[0].String())))
				} else if len(message.Question) > 0 {
					r.logger.ErrorContext(ctx, E.Cause(err, "exchange failed for ", FormatQuestion(message.Question[0].String())))
				} else {
					r.logger.ErrorContext(ctx, E.Cause(err, "exchange failed for <empty query>"))
				}
			}
			if responseCheck != nil && rejected {
				continue
			}
			break
		}
	}
	if err != nil {
		return nil, err
	}
	if r.dnsReverseMapping != nil && len(message.Question) > 0 && response != nil && len(response.Answer) > 0 {
		if transport == nil || transport.Type() != C.DNSTypeFakeIP {
			for _, answer := range response.Answer {
				switch record := answer.(type) {
				case *mDNS.A:
					r.dnsReverseMapping.AddWithLifetime(M.AddrFromIP(record.A), FqdnToDomain(record.Hdr.Name), time.Duration(record.Hdr.Ttl)*time.Second)
				case *mDNS.AAAA:
					r.dnsReverseMapping.AddWithLifetime(M.AddrFromIP(record.AAAA), FqdnToDomain(record.Hdr.Name), time.Duration(record.Hdr.Ttl)*time.Second)
				}
			}
		}
	}
	return response, nil
}

func (r *Router) Lookup(ctx context.Context, domain string, options adapter.DNSQueryOptions) ([]netip.Addr, error) {
	var (
		responseAddrs []netip.Addr
		err           error
	)
	printResult := func() {
		if err == nil && len(responseAddrs) == 0 {
			err = E.New("empty result")
		}
		if err != nil {
			if errors.Is(err, ErrResponseRejectedCached) {
				r.logger.DebugContext(ctx, "response rejected for ", domain, " (cached)")
			} else if errors.Is(err, ErrResponseRejected) {
				r.logger.DebugContext(ctx, "response rejected for ", domain)
			} else {
				r.logger.ErrorContext(ctx, E.Cause(err, "lookup failed for ", domain))
			}
		}
		if err != nil {
			err = E.Cause(err, "lookup ", domain)
		}
	}
	r.logger.DebugContext(ctx, "lookup domain ", domain)
	ctx, metadata := adapter.ExtendContext(ctx)
	metadata.Destination = M.Socksaddr{}
	metadata.Domain = FqdnToDomain(domain)
	metadata.DNSResponse = nil
	metadata.DestinationAddressMatchFromResponse = false
	if options.Transport != nil {
		transport := options.Transport
		r.applyTransportDefaults(transport, &options)
		if options.Strategy == C.DomainStrategyAsIS {
			options.Strategy = r.defaultDomainStrategy
		}
		responseAddrs, err = r.client.Lookup(ctx, transport, domain, options, nil)
	} else if !r.legacyAddressFilterMode {
		responseAddrs, err = r.lookupWithRules(ctx, domain, options)
	} else {
		var (
			transport adapter.DNSTransport
			rule      adapter.DNSRule
			ruleIndex int
		)
		ruleIndex = -1
		for {
			dnsCtx := adapter.OverrideContext(ctx)
			dnsOptions := options
			transport, rule, ruleIndex = r.matchDNS(ctx, false, ruleIndex, true, &dnsOptions)
			if rule != nil {
				switch action := rule.Action().(type) {
				case *R.RuleActionReject:
					return nil, &R.RejectedError{Cause: action.Error(ctx)}
				case *R.RuleActionPredefined:
					responseAddrs = nil
					if action.Rcode != mDNS.RcodeSuccess {
						err = RcodeError(action.Rcode)
					} else {
						err = nil
						for _, answer := range action.Answer {
							switch record := answer.(type) {
							case *mDNS.A:
								responseAddrs = append(responseAddrs, M.AddrFromIP(record.A))
							case *mDNS.AAAA:
								responseAddrs = append(responseAddrs, M.AddrFromIP(record.AAAA))
							}
						}
					}
					goto response
				}
			}
			responseCheck := addressLimitResponseCheck(rule, metadata)
			if dnsOptions.Strategy == C.DomainStrategyAsIS {
				dnsOptions.Strategy = r.defaultDomainStrategy
			}
			responseAddrs, err = r.client.Lookup(dnsCtx, transport, domain, dnsOptions, responseCheck)
			if responseCheck == nil || err == nil {
				break
			}
			printResult()
		}
	}
response:
	printResult()
	if len(responseAddrs) > 0 {
		r.logger.InfoContext(ctx, "lookup succeed for ", domain, ": ", strings.Join(F.MapToString(responseAddrs), " "))
	}
	return responseAddrs, err
}

func isAddressQuery(message *mDNS.Msg) bool {
	for _, question := range message.Question {
		if question.Qtype == mDNS.TypeA || question.Qtype == mDNS.TypeAAAA || question.Qtype == mDNS.TypeHTTPS {
			return true
		}
	}
	return false
}

func addressLimitResponseCheck(rule adapter.DNSRule, metadata *adapter.InboundContext) func(response *mDNS.Msg) bool {
	if rule == nil || !rule.WithAddressLimit() {
		return nil
	}
	responseMetadata := *metadata
	return func(response *mDNS.Msg) bool {
		checkMetadata := responseMetadata
		checkMetadata.DNSResponse = response
		return rule.MatchAddressLimit(&checkMetadata, response)
	}
}

func (r *Router) ClearCache() {
	r.client.ClearCache()
	if r.platformInterface != nil {
		r.platformInterface.ClearDNSCache()
	}
}

func (r *Router) LookupReverseMapping(ip netip.Addr) (string, bool) {
	if r.dnsReverseMapping == nil {
		return "", false
	}
	domain, loaded := r.dnsReverseMapping.Get(ip)
	return domain, loaded
}

func (r *Router) ResetNetwork() {
	r.ClearCache()
	for _, transport := range r.transport.Transports() {
		transport.Reset()
	}
}

func hasNonLegacyAddressFilterItems(rules []option.DNSRule) bool {
	return common.Any(rules, hasNonLegacyAddressFilterItemsInRule)
}

func hasNonLegacyAddressFilterItemsInRule(rule option.DNSRule) bool {
	switch rule.Type {
	case "", C.RuleTypeDefault:
		return hasNonLegacyAddressFilterItemsInDefaultRule(rule.DefaultOptions)
	case C.RuleTypeLogical:
		action := rule.LogicalOptions.Action
		return action == C.RuleActionTypeEvaluate || common.Any(rule.LogicalOptions.Rules, hasNonLegacyAddressFilterItemsInRule)
	default:
		return false
	}
}

func hasNonLegacyAddressFilterItemsInDefaultRule(rule option.DefaultDNSRule) bool {
	action := rule.Action
	return action == C.RuleActionTypeEvaluate ||
		rule.MatchResponse ||
		rule.ResponseRcode != nil ||
		len(rule.ResponseAnswer) > 0 ||
		len(rule.ResponseNs) > 0 ||
		len(rule.ResponseExtra) > 0
}

func validateNonLegacyAddressFilterRules(rules []option.DNSRule) error {
	var seenEvaluate bool
	for i, rule := range rules {
		consumesResponse, err := validateNonLegacyAddressFilterRuleTree(rule)
		if err != nil {
			return E.Cause(err, "validate dns rule[", i, "]")
		}
		action := dnsRuleActionType(rule)
		if action == C.RuleActionTypeEvaluate && consumesResponse {
			return E.New("dns rule[", i, "]: evaluate rule cannot consume response state")
		}
		if consumesResponse && !seenEvaluate {
			return E.New("dns rule[", i, "]: response matching requires a preceding top-level evaluate rule")
		}
		if action == C.RuleActionTypeEvaluate {
			seenEvaluate = true
		}
	}
	return nil
}

func validateNonLegacyAddressFilterRuleTree(rule option.DNSRule) (bool, error) {
	switch rule.Type {
	case "", C.RuleTypeDefault:
		return validateNonLegacyAddressFilterDefaultRule(rule.DefaultOptions)
	case C.RuleTypeLogical:
		var consumesResponse bool
		for i, subRule := range rule.LogicalOptions.Rules {
			subConsumesResponse, err := validateNonLegacyAddressFilterRuleTree(subRule)
			if err != nil {
				return false, E.Cause(err, "sub rule[", i, "]")
			}
			consumesResponse = consumesResponse || subConsumesResponse
		}
		return consumesResponse, nil
	default:
		return false, nil
	}
}

func validateNonLegacyAddressFilterDefaultRule(rule option.DefaultDNSRule) (bool, error) {
	hasResponseRecords := rule.ResponseRcode != nil ||
		len(rule.ResponseAnswer) > 0 ||
		len(rule.ResponseNs) > 0 ||
		len(rule.ResponseExtra) > 0
	if hasResponseRecords && !rule.MatchResponse {
		return false, E.New("response_* items require match_response")
	}
	if (len(rule.IPCIDR) > 0 || rule.IPIsPrivate) && !rule.MatchResponse {
		return false, E.New("ip_cidr and ip_is_private require match_response in DNS evaluate mode")
	}
	if rule.IPAcceptAny {
		return false, E.New("ip_accept_any is removed in DNS evaluate mode, use ip_cidr with match_response")
	}
	if rule.RuleSetIPCIDRAcceptEmpty {
		return false, E.New("rule_set_ip_cidr_accept_empty is removed in DNS evaluate mode")
	}
	return rule.MatchResponse, nil
}

func dnsRuleActionType(rule option.DNSRule) string {
	switch rule.Type {
	case "", C.RuleTypeDefault:
		if rule.DefaultOptions.Action == "" {
			return C.RuleActionTypeRoute
		}
		return rule.DefaultOptions.Action
	case C.RuleTypeLogical:
		if rule.LogicalOptions.Action == "" {
			return C.RuleActionTypeRoute
		}
		return rule.LogicalOptions.Action
	default:
		return ""
	}
}