package route

import (
	"context"
	"errors"
	"net"
	"net/netip"
	"os"
	"runtime"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/sagernet/sing-box/adapter"
	"github.com/sagernet/sing-box/common/settings"
	"github.com/sagernet/sing-box/common/taskmonitor"
	C "github.com/sagernet/sing-box/constant"
	"github.com/sagernet/sing-box/option"
	"github.com/sagernet/sing-tun"
	"github.com/sagernet/sing/common"
	"github.com/sagernet/sing/common/control"
	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/winpowrprof"
	"github.com/sagernet/sing/service"
	"github.com/sagernet/sing/service/pause"

	"golang.org/x/exp/slices"
)

var _ adapter.NetworkManager = (*NetworkManager)(nil)

type NetworkManager struct {
	logger            logger.ContextLogger
	interfaceFinder   *control.DefaultInterfaceFinder
	networkInterfaces common.TypedValue[[]adapter.NetworkInterface]

	autoDetectInterface    bool
	defaultOptions         adapter.NetworkOptions
	autoRedirectOutputMark uint32
	networkMonitor         tun.NetworkUpdateMonitor
	interfaceMonitor       tun.DefaultInterfaceMonitor
	packageManager         tun.PackageManager
	powerListener          winpowrprof.EventListener
	pauseManager           pause.Manager
	platformInterface      adapter.PlatformInterface
	connectionManager      adapter.ConnectionManager
	endpoint               adapter.EndpointManager
	inbound                adapter.InboundManager
	outbound               adapter.OutboundManager
	needWIFIState          bool
	wifiMonitor            settings.WIFIMonitor
	wifiState              adapter.WIFIState
	wifiStateMutex         sync.RWMutex
	started                bool
}

func NewNetworkManager(ctx context.Context, logger logger.ContextLogger, options option.RouteOptions, dnsOptions option.DNSOptions) (*NetworkManager, error) {
	defaultDomainResolver := common.PtrValueOrDefault(options.DefaultDomainResolver)
	if options.AutoDetectInterface && !(C.IsLinux || C.IsDarwin || C.IsWindows) {
		return nil, E.New("`auto_detect_interface` is only supported on Linux, Windows and macOS")
	} else if options.OverrideAndroidVPN && !C.IsAndroid {
		return nil, E.New("`override_android_vpn` is only supported on Android")
	} else if options.DefaultInterface != "" && !(C.IsLinux || C.IsDarwin || C.IsWindows) {
		return nil, E.New("`default_interface` is only supported on Linux, Windows and macOS")
	} else if options.DefaultMark != 0 && !C.IsLinux {
		return nil, E.New("`default_mark` is only supported on linux")
	}
	nm := &NetworkManager{
		logger:              logger,
		interfaceFinder:     control.NewDefaultInterfaceFinder(),
		autoDetectInterface: options.AutoDetectInterface,
		defaultOptions: adapter.NetworkOptions{
			BindInterface:  options.DefaultInterface,
			RoutingMark:    uint32(options.DefaultMark),
			DomainResolver: defaultDomainResolver.Server,
			DomainResolveOptions: adapter.DNSQueryOptions{
				Strategy:               C.DomainStrategy(defaultDomainResolver.Strategy),
				DisableCache:           defaultDomainResolver.DisableCache,
				DisableOptimisticCache: defaultDomainResolver.DisableOptimisticCache,
				RewriteTTL:             defaultDomainResolver.RewriteTTL,
				ClientSubnet:           defaultDomainResolver.ClientSubnet.Build(netip.Prefix{}),
			},
			NetworkStrategy:     (*C.NetworkStrategy)(options.DefaultNetworkStrategy),
			NetworkType:         common.Map(options.DefaultNetworkType, option.InterfaceType.Build),
			FallbackNetworkType: common.Map(options.DefaultFallbackNetworkType, option.InterfaceType.Build),
			FallbackDelay:       time.Duration(options.DefaultFallbackDelay),
		},
		pauseManager:      service.FromContext[pause.Manager](ctx),
		platformInterface: service.FromContext[adapter.PlatformInterface](ctx),
		connectionManager: service.FromContext[adapter.ConnectionManager](ctx),
		endpoint:          service.FromContext[adapter.EndpointManager](ctx),
		inbound:           service.FromContext[adapter.InboundManager](ctx),
		outbound:          service.FromContext[adapter.OutboundManager](ctx),
		needWIFIState:     hasRule(options.Rules, isWIFIRule) || hasDNSRule(dnsOptions.Rules, isWIFIDNSRule),
	}
	if options.DefaultNetworkStrategy != nil {
		if options.DefaultInterface != "" {
			return nil, E.New("`default_network_strategy` is conflict with `default_interface`")
		}
		if !options.AutoDetectInterface {
			return nil, E.New("`auto_detect_interface` is required by `default_network_strategy`")
		}
	}
	usePlatformDefaultInterfaceMonitor := nm.platformInterface != nil
	enforceInterfaceMonitor := options.AutoDetectInterface
	if !usePlatformDefaultInterfaceMonitor {
		networkMonitor, err := tun.NewNetworkUpdateMonitor(logger)
		if !((err != nil && !enforceInterfaceMonitor) || errors.Is(err, os.ErrInvalid)) {
			if err != nil {
				return nil, E.Cause(err, "create network monitor")
			}
			nm.networkMonitor = networkMonitor
			interfaceMonitor, err := tun.NewDefaultInterfaceMonitor(nm.networkMonitor, logger, tun.DefaultInterfaceMonitorOptions{
				InterfaceFinder:       nm.interfaceFinder,
				OverrideAndroidVPN:    options.OverrideAndroidVPN,
				UnderNetworkExtension: nm.platformInterface != nil && nm.platformInterface.UnderNetworkExtension(),
			})
			if err != nil {
				return nil, E.New("auto_detect_interface unsupported on current platform")
			}
			interfaceMonitor.RegisterCallback(nm.notifyInterfaceUpdate)
			nm.interfaceMonitor = interfaceMonitor
		}
	} else {
		interfaceMonitor := nm.platformInterface.CreateDefaultInterfaceMonitor(logger)
		interfaceMonitor.RegisterCallback(nm.notifyInterfaceUpdate)
		nm.interfaceMonitor = interfaceMonitor
	}
	return nm, nil
}

func (r *NetworkManager) Start(stage adapter.StartStage) error {
	monitor := taskmonitor.New(r.logger, C.StartTimeout)
	switch stage {
	case adapter.StartStateInitialize:
		if r.networkMonitor != nil {
			monitor.Start("initialize network monitor")
			err := r.networkMonitor.Start()
			monitor.Finish()
			if err != nil {
				return err
			}
		}
		if r.interfaceMonitor != nil {
			monitor.Start("initialize interface monitor")
			err := r.interfaceMonitor.Start()
			monitor.Finish()
			if err != nil {
				return err
			}
		}
	case adapter.StartStateStart:
		if runtime.GOOS == "windows" {
			powerListener, err := winpowrprof.NewEventListener(r.notifyWindowsPowerEvent)
			if err == nil {
				r.powerListener = powerListener
			} else {
				r.logger.Warn("initialize power listener: ", err)
			}
		}
		if r.powerListener != nil {
			monitor.Start("start power listener")
			err := r.powerListener.Start()
			monitor.Finish()
			if err != nil {
				return E.Cause(err, "start power listener")
			}
		}
		if C.IsAndroid && r.platformInterface == nil {
			monitor.Start("initialize package manager")
			packageManager, err := tun.NewPackageManager(tun.PackageManagerOptions{
				Callback: r,
				Logger:   r.logger,
			})
			monitor.Finish()
			if err != nil {
				return E.Cause(err, "create package manager")
			}
			monitor.Start("start package manager")
			err = packageManager.Start()
			monitor.Finish()
			if err != nil {
				r.logger.Warn("initialize package manager: ", err)
			} else {
				r.packageManager = packageManager
			}
		}
	case adapter.StartStatePostStart:
		if r.needWIFIState && !(r.platformInterface != nil && r.platformInterface.UsePlatformWIFIMonitor()) {
			wifiMonitor, err := settings.NewWIFIMonitor(r.onWIFIStateChanged)
			if err != nil {
				if err != os.ErrInvalid {
					r.logger.Warn(E.Cause(err, "create WIFI monitor"))
				}
			} else {
				r.wifiMonitor = wifiMonitor
				err = r.wifiMonitor.Start()
				if err != nil {
					r.logger.Warn(E.Cause(err, "start WIFI monitor"))
				}
			}
		}
		r.started = true
	}
	return nil
}

func (r *NetworkManager) Initialize(ruleSets []adapter.RuleSet) {
	for _, ruleSet := range ruleSets {
		metadata := ruleSet.Metadata()
		if metadata.ContainsWIFIRule {
			r.needWIFIState = true
			break
		}
	}
}

func (r *NetworkManager) Close() error {
	monitor := taskmonitor.New(r.logger, C.StopTimeout)
	var err error
	if r.packageManager != nil {
		monitor.Start("close package manager")
		err = E.Append(err, r.packageManager.Close(), func(err error) error {
			return E.Cause(err, "close package manager")
		})
		monitor.Finish()
	}
	if r.powerListener != nil {
		monitor.Start("close power listener")
		err = E.Append(err, r.powerListener.Close(), func(err error) error {
			return E.Cause(err, "close power listener")
		})
		monitor.Finish()
	}
	if r.interfaceMonitor != nil {
		monitor.Start("close interface monitor")
		err = E.Append(err, r.interfaceMonitor.Close(), func(err error) error {
			return E.Cause(err, "close interface monitor")
		})
		monitor.Finish()
	}
	if r.networkMonitor != nil {
		monitor.Start("close network monitor")
		err = E.Append(err, r.networkMonitor.Close(), func(err error) error {
			return E.Cause(err, "close network monitor")
		})
		monitor.Finish()
	}
	if r.wifiMonitor != nil {
		monitor.Start("close WIFI monitor")
		err = E.Append(err, r.wifiMonitor.Close(), func(err error) error {
			return E.Cause(err, "close WIFI monitor")
		})
		monitor.Finish()
	}
	return err
}

func (r *NetworkManager) InterfaceFinder() control.InterfaceFinder {
	return r.interfaceFinder
}

func (r *NetworkManager) UpdateInterfaces() error {
	if r.platformInterface == nil || !r.platformInterface.UsePlatformNetworkInterfaces() {
		return r.interfaceFinder.Update()
	} else {
		interfaces, err := r.platformInterface.NetworkInterfaces()
		if err != nil {
			return err
		}
		if C.IsDarwin {
			err = r.interfaceFinder.Update()
			if err != nil {
				return err
			}
			// NEInterface only provides name,index and type
			interfaces = common.Map(interfaces, func(it adapter.NetworkInterface) adapter.NetworkInterface {
				iif, _ := r.interfaceFinder.ByIndex(it.Index)
				if iif != nil {
					it.Interface = *iif
				}
				return it
			})
		} else {
			r.interfaceFinder.UpdateInterfaces(common.Map(interfaces, func(it adapter.NetworkInterface) control.Interface { return it.Interface }))
		}
		oldInterfaces := r.networkInterfaces.Load()
		newInterfaces := common.Filter(interfaces, func(it adapter.NetworkInterface) bool {
			return it.Flags&net.FlagUp != 0
		})
		r.networkInterfaces.Store(newInterfaces)
		if len(newInterfaces) > 0 && !slices.EqualFunc(oldInterfaces, newInterfaces, func(oldInterface adapter.NetworkInterface, newInterface adapter.NetworkInterface) bool {
			return oldInterface.Interface.Index == newInterface.Interface.Index &&
				oldInterface.Interface.Name == newInterface.Interface.Name &&
				oldInterface.Interface.Flags == newInterface.Interface.Flags &&
				oldInterface.Type == newInterface.Type &&
				oldInterface.Expensive == newInterface.Expensive &&
				oldInterface.Constrained == newInterface.Constrained
		}) {
			r.logger.Info("updated available networks: ", strings.Join(common.Map(newInterfaces, func(it adapter.NetworkInterface) string {
				var options []string
				options = append(options, F.ToString(it.Type))
				if it.Expensive {
					options = append(options, "expensive")
				}
				if it.Constrained {
					options = append(options, "constrained")
				}
				return F.ToString(it.Name, " (", strings.Join(options, ", "), ")")
			}), ", "))
		}
		return nil
	}
}

func (r *NetworkManager) DefaultNetworkInterface() *adapter.NetworkInterface {
	iif := r.interfaceMonitor.DefaultInterface()
	if iif == nil {
		return nil
	}
	for _, it := range r.networkInterfaces.Load() {
		if it.Interface.Index == iif.Index {
			return &it
		}
	}
	return &adapter.NetworkInterface{Interface: *iif}
}

func (r *NetworkManager) NetworkInterfaces() []adapter.NetworkInterface {
	return r.networkInterfaces.Load()
}

func (r *NetworkManager) AutoDetectInterface() bool {
	return r.autoDetectInterface
}

func (r *NetworkManager) AutoDetectInterfaceFunc() control.Func {
	if r.platformInterface != nil && r.platformInterface.UsePlatformAutoDetectInterfaceControl() {
		return func(network, address string, conn syscall.RawConn) error {
			return control.Raw(conn, func(fd uintptr) error {
				return r.platformInterface.AutoDetectInterfaceControl(int(fd))
			})
		}
	} else {
		if r.interfaceMonitor == nil {
			return nil
		}
		return control.BindToInterfaceFunc(r.interfaceFinder, func(network string, address string) (interfaceName string, interfaceIndex int, err error) {
			remoteAddr := M.ParseSocksaddr(address).Addr
			if remoteAddr.IsValid() {
				iif, err := r.interfaceFinder.ByAddr(remoteAddr)
				if err == nil {
					return iif.Name, iif.Index, nil
				}
			}
			defaultInterface := r.interfaceMonitor.DefaultInterface()
			if defaultInterface == nil {
				return "", -1, tun.ErrNoRoute
			}
			return defaultInterface.Name, defaultInterface.Index, nil
		})
	}
}

func (r *NetworkManager) ProtectFunc() control.Func {
	if r.platformInterface != nil && r.platformInterface.UsePlatformAutoDetectInterfaceControl() {
		return func(network, address string, conn syscall.RawConn) error {
			return control.Raw(conn, func(fd uintptr) error {
				return r.platformInterface.AutoDetectInterfaceControl(int(fd))
			})
		}
	}
	return nil
}

func (r *NetworkManager) DefaultOptions() adapter.NetworkOptions {
	return r.defaultOptions
}

func (r *NetworkManager) RegisterAutoRedirectOutputMark(mark uint32) error {
	if r.autoRedirectOutputMark > 0 {
		return E.New("only one auto-redirect can be configured")
	}
	r.autoRedirectOutputMark = mark
	return nil
}

func (r *NetworkManager) AutoRedirectOutputMark() uint32 {
	return r.autoRedirectOutputMark
}

func (r *NetworkManager) AutoRedirectOutputMarkFunc() control.Func {
	return func(network, address string, conn syscall.RawConn) error {
		if r.autoRedirectOutputMark == 0 {
			return nil
		}
		return control.RoutingMark(r.autoRedirectOutputMark)(network, address, conn)
	}
}

func (r *NetworkManager) NetworkMonitor() tun.NetworkUpdateMonitor {
	return r.networkMonitor
}

func (r *NetworkManager) InterfaceMonitor() tun.DefaultInterfaceMonitor {
	return r.interfaceMonitor
}

func (r *NetworkManager) PackageManager() tun.PackageManager {
	return r.packageManager
}

func (r *NetworkManager) NeedWIFIState() bool {
	return r.needWIFIState
}

func (r *NetworkManager) WIFIState() adapter.WIFIState {
	r.wifiStateMutex.RLock()
	defer r.wifiStateMutex.RUnlock()
	return r.wifiState
}

func (r *NetworkManager) onWIFIStateChanged(state adapter.WIFIState) {
	r.wifiStateMutex.Lock()
	if state != r.wifiState {
		r.wifiState = state
		r.wifiStateMutex.Unlock()
		if state.SSID != "" {
			r.logger.Info("WIFI state changed: SSID=", state.SSID, ", BSSID=", state.BSSID)
		} else {
			r.logger.Info("WIFI disconnected")
		}
	} else {
		r.wifiStateMutex.Unlock()
	}
}

func (r *NetworkManager) UpdateWIFIState() {
	var state adapter.WIFIState
	if r.wifiMonitor != nil {
		state = r.wifiMonitor.ReadWIFIState()
	} else if r.platformInterface != nil && r.platformInterface.UsePlatformWIFIMonitor() {
		state = r.platformInterface.ReadWIFIState()
	} else {
		return
	}
	r.onWIFIStateChanged(state)
}

func (r *NetworkManager) ResetNetwork() {
	if r.connectionManager != nil {
		r.connectionManager.CloseAll()
	}

	for _, endpoint := range r.endpoint.Endpoints() {
		listener, isListener := endpoint.(adapter.InterfaceUpdateListener)
		if isListener {
			listener.InterfaceUpdated()
		}
	}

	for _, inbound := range r.inbound.Inbounds() {
		listener, isListener := inbound.(adapter.InterfaceUpdateListener)
		if isListener {
			listener.InterfaceUpdated()
		}
	}

	for _, outbound := range r.outbound.Outbounds() {
		listener, isListener := outbound.(adapter.InterfaceUpdateListener)
		if isListener {
			listener.InterfaceUpdated()
		}
	}
}

func (r *NetworkManager) notifyInterfaceUpdate(defaultInterface *control.Interface, flags int) {
	if defaultInterface == nil {
		r.pauseManager.NetworkPause()
		r.logger.Error("missing default interface")
		return
	}

	r.pauseManager.NetworkWake()
	var options []string
	options = append(options, F.ToString("index ", defaultInterface.Index))
	if C.IsAndroid && r.platformInterface == nil {
		var vpnStatus string
		if r.interfaceMonitor.AndroidVPNEnabled() {
			vpnStatus = "enabled"
		} else {
			vpnStatus = "disabled"
		}
		options = append(options, "vpn "+vpnStatus)
	} else if r.platformInterface != nil {
		networkInterface := common.Find(r.networkInterfaces.Load(), func(it adapter.NetworkInterface) bool {
			return it.Interface.Index == defaultInterface.Index
		})
		if networkInterface.Name == "" {
			// race
			return
		}
		options = append(options, F.ToString("type ", networkInterface.Type))
		if networkInterface.Expensive {
			options = append(options, "expensive")
		}
		if networkInterface.Constrained {
			options = append(options, "constrained")
		}
	}
	r.logger.Info("updated default interface ", defaultInterface.Name, ", ", strings.Join(options, ", "))
	r.UpdateWIFIState()

	if !r.started {
		return
	}
	r.ResetNetwork()
}

func (r *NetworkManager) notifyWindowsPowerEvent(event int) {
	switch event {
	case winpowrprof.EVENT_SUSPEND:
		r.pauseManager.DevicePause()
		r.ResetNetwork()
	case winpowrprof.EVENT_RESUME:
		if !r.pauseManager.IsDevicePaused() {
			return
		}
		fallthrough
	case winpowrprof.EVENT_RESUME_AUTOMATIC:
		r.pauseManager.DeviceWake()
		r.ResetNetwork()
	}
}

func (r *NetworkManager) OnPackagesUpdated(packages int, sharedUsers int) {
	r.logger.Info("updated packages list: ", packages, " packages, ", sharedUsers, " shared users")
}