package proxy

import (
	"fmt"
	"golang.org/x/exp/slices"
	"net"
	"sort"
	"strconv"
	"sync"

	"github.com/Dreamacro/clash/adapter/inbound"
	"github.com/Dreamacro/clash/component/ebpf"
	"github.com/Dreamacro/clash/config"
	C "github.com/Dreamacro/clash/constant"
	"github.com/Dreamacro/clash/listener/autoredir"
	"github.com/Dreamacro/clash/listener/http"
	"github.com/Dreamacro/clash/listener/mixed"
	"github.com/Dreamacro/clash/listener/redir"
	"github.com/Dreamacro/clash/listener/sing_shadowsocks"
	"github.com/Dreamacro/clash/listener/sing_tun"
	"github.com/Dreamacro/clash/listener/sing_vmess"
	"github.com/Dreamacro/clash/listener/socks"
	"github.com/Dreamacro/clash/listener/tproxy"
	"github.com/Dreamacro/clash/listener/tuic"
	"github.com/Dreamacro/clash/listener/tunnel"
	"github.com/Dreamacro/clash/log"
)

var (
	allowLan    = false
	bindAddress = "*"

	socksListener       *socks.Listener
	socksUDPListener    *socks.UDPListener
	httpListener        *http.Listener
	redirListener       *redir.Listener
	redirUDPListener    *tproxy.UDPListener
	tproxyListener      *tproxy.Listener
	tproxyUDPListener   *tproxy.UDPListener
	mixedListener       *mixed.Listener
	mixedUDPLister      *socks.UDPListener
	tunLister           *sing_tun.Listener
	shadowSocksListener C.AdvanceListener
	vmessListener       *sing_vmess.Listener
	tcpTunListener      *tunnel.Listener
	udpTunListener      *tunnel.UdpListener
	tuicListener        *tuic.Listener
	autoRedirListener   *autoredir.Listener
	autoRedirProgram    *ebpf.TcEBpfProgram
	tcProgram           *ebpf.TcEBpfProgram

	// lock for recreate function
	socksMux     sync.Mutex
	httpMux      sync.Mutex
	redirMux     sync.Mutex
	tproxyMux    sync.Mutex
	mixedMux     sync.Mutex
	tunMux       sync.Mutex
	ssMux        sync.Mutex
	vmessMux     sync.Mutex
	tcpTunMux    sync.Mutex
	udpTunMux    sync.Mutex
	tuicMux      sync.Mutex
	autoRedirMux sync.Mutex
	tcMux        sync.Mutex

	LastTunConf  config.Tun
	LastTuicConf config.TuicServer
)

type Ports struct {
	Port              int    `json:"port"`
	SocksPort         int    `json:"socks-port"`
	RedirPort         int    `json:"redir-port"`
	TProxyPort        int    `json:"tproxy-port"`
	MixedPort         int    `json:"mixed-port"`
	ShadowSocksConfig string `json:"ss-config"`
	VmessConfig       string `json:"vmess-config"`
	TcpTunConfig      string `json:"tcptun-config"`
	UdpTunConfig      string `json:"udptun-config"`
}

func GetTunConf() config.Tun {
	if tunLister == nil {
		return config.Tun{
			Enable: false,
		}
	}
	return tunLister.Config()
}

func GetTuicConf() config.TuicServer {
	if tuicListener == nil {
		return config.TuicServer{Enable: false}
	}
	return tuicListener.Config()
}

func AllowLan() bool {
	return allowLan
}

func BindAddress() string {
	return bindAddress
}

func SetAllowLan(al bool) {
	allowLan = al
}

func SetBindAddress(host string) {
	bindAddress = host
}

func ReCreateHTTP(port int, tcpIn chan<- C.ConnContext) {
	httpMux.Lock()
	defer httpMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start HTTP server error: %s", err.Error())
		}
	}()

	addr := genAddr(bindAddress, port, allowLan)

	if httpListener != nil {
		if httpListener.RawAddress() == addr {
			return
		}
		httpListener.Close()
		httpListener = nil
	}

	if portIsZero(addr) {
		return
	}

	httpListener, err = http.New(addr, tcpIn)
	if err != nil {
		log.Errorln("Start HTTP server error: %s", err.Error())
		return
	}

	log.Infoln("HTTP proxy listening at: %s", httpListener.Address())
}

func ReCreateSocks(port int, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	socksMux.Lock()
	defer socksMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start SOCKS server error: %s", err.Error())
		}
	}()

	addr := genAddr(bindAddress, port, allowLan)

	shouldTCPIgnore := false
	shouldUDPIgnore := false

	if socksListener != nil {
		if socksListener.RawAddress() != addr {
			socksListener.Close()
			socksListener = nil
		} else {
			shouldTCPIgnore = true
		}
	}

	if socksUDPListener != nil {
		if socksUDPListener.RawAddress() != addr {
			socksUDPListener.Close()
			socksUDPListener = nil
		} else {
			shouldUDPIgnore = true
		}
	}

	if shouldTCPIgnore && shouldUDPIgnore {
		return
	}

	if portIsZero(addr) {
		return
	}

	tcpListener, err := socks.New(addr, tcpIn)
	if err != nil {
		return
	}

	udpListener, err := socks.NewUDP(addr, udpIn)
	if err != nil {
		tcpListener.Close()
		return
	}

	socksListener = tcpListener
	socksUDPListener = udpListener

	log.Infoln("SOCKS proxy listening at: %s", socksListener.Address())
}

func ReCreateRedir(port int, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	redirMux.Lock()
	defer redirMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start Redir server error: %s", err.Error())
		}
	}()

	addr := genAddr(bindAddress, port, allowLan)

	if redirListener != nil {
		if redirListener.RawAddress() == addr {
			return
		}
		redirListener.Close()
		redirListener = nil
	}

	if redirUDPListener != nil {
		if redirUDPListener.RawAddress() == addr {
			return
		}
		redirUDPListener.Close()
		redirUDPListener = nil
	}

	if portIsZero(addr) {
		return
	}

	redirListener, err = redir.New(addr, tcpIn)
	if err != nil {
		return
	}

	redirUDPListener, err = tproxy.NewUDP(addr, udpIn)
	if err != nil {
		log.Warnln("Failed to start Redir UDP Listener: %s", err)
	}

	log.Infoln("Redirect proxy listening at: %s", redirListener.Address())
}

func ReCreateShadowSocks(shadowSocksConfig string, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	ssMux.Lock()
	defer ssMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start ShadowSocks server error: %s", err.Error())
		}
	}()

	shouldIgnore := false

	if shadowSocksListener != nil {
		if shadowSocksListener.Config() != shadowSocksConfig {
			shadowSocksListener.Close()
			shadowSocksListener = nil
		} else {
			shouldIgnore = true
		}
	}

	if shouldIgnore {
		return
	}

	if len(shadowSocksConfig) == 0 {
		return
	}

	listener, err := sing_shadowsocks.New(shadowSocksConfig, tcpIn, udpIn)
	if err != nil {
		return
	}

	shadowSocksListener = listener

	return
}

func ReCreateVmess(vmessConfig string, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	vmessMux.Lock()
	defer vmessMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start Vmess server error: %s", err.Error())
		}
	}()

	shouldIgnore := false

	if vmessListener != nil {
		if vmessListener.Config() != vmessConfig {
			vmessListener.Close()
			vmessListener = nil
		} else {
			shouldIgnore = true
		}
	}

	if shouldIgnore {
		return
	}

	if len(vmessConfig) == 0 {
		return
	}

	listener, err := sing_vmess.New(vmessConfig, tcpIn, udpIn)
	if err != nil {
		return
	}

	vmessListener = listener

	return
}

func ReCreateTcpTun(config string, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	tcpTunMux.Lock()
	defer tcpTunMux.Unlock()
	shouldIgnore := false

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start TcpTun server error: %s", err.Error())
		}
	}()

	if tcpTunListener != nil {
		if tcpTunListener.Config() != config {
			tcpTunListener.Close()
			tcpTunListener = nil
		} else {
			shouldIgnore = true
		}
	}

	if shouldIgnore {
		return
	}

	tcpListener, err := tunnel.New(config, tcpIn)
	if err != nil {
		return
	}

	tcpTunListener = tcpListener

	return
}

func ReCreateUdpTun(config string, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	udpTunMux.Lock()
	defer udpTunMux.Unlock()
	shouldIgnore := false

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start UdpTun server error: %s", err.Error())
		}
	}()

	if udpTunListener != nil {
		if udpTunListener.Config() != config {
			udpTunListener.Close()
			udpTunListener = nil
		} else {
			shouldIgnore = true
		}
	}

	if shouldIgnore {
		return
	}

	udpListener, err := tunnel.NewUdp(config, udpIn)
	if err != nil {
		return
	}

	udpTunListener = udpListener

	return
}

func ReCreateTuic(config config.TuicServer, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	tuicMux.Lock()
	defer func() {
		LastTuicConf = config
		tuicMux.Unlock()
	}()
	shouldIgnore := false

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start Tuic server error: %s", err.Error())
		}
	}()

	if tuicListener != nil {
		if tuicListener.Config().String() != config.String() {
			tuicListener.Close()
			tuicListener = nil
		} else {
			shouldIgnore = true
		}
	}

	if shouldIgnore {
		return
	}

	if !config.Enable {
		return
	}

	listener, err := tuic.New(config, tcpIn, udpIn)
	if err != nil {
		return
	}

	tuicListener = listener

	return
}

func ReCreateTProxy(port int, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	tproxyMux.Lock()
	defer tproxyMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start TProxy server error: %s", err.Error())
		}
	}()

	addr := genAddr(bindAddress, port, allowLan)

	if tproxyListener != nil {
		if tproxyListener.RawAddress() == addr {
			return
		}
		tproxyListener.Close()
		tproxyListener = nil
	}

	if tproxyUDPListener != nil {
		if tproxyUDPListener.RawAddress() == addr {
			return
		}
		tproxyUDPListener.Close()
		tproxyUDPListener = nil
	}

	if portIsZero(addr) {
		return
	}

	tproxyListener, err = tproxy.New(addr, tcpIn)
	if err != nil {
		return
	}

	tproxyUDPListener, err = tproxy.NewUDP(addr, udpIn)
	if err != nil {
		log.Warnln("Failed to start TProxy UDP Listener: %s", err)
	}

	log.Infoln("TProxy server listening at: %s", tproxyListener.Address())
}

func ReCreateMixed(port int, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	mixedMux.Lock()
	defer mixedMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start Mixed(http+socks) server error: %s", err.Error())
		}
	}()

	addr := genAddr(bindAddress, port, allowLan)

	shouldTCPIgnore := false
	shouldUDPIgnore := false

	if mixedListener != nil {
		if mixedListener.RawAddress() != addr {
			mixedListener.Close()
			mixedListener = nil
		} else {
			shouldTCPIgnore = true
		}
	}
	if mixedUDPLister != nil {
		if mixedUDPLister.RawAddress() != addr {
			mixedUDPLister.Close()
			mixedUDPLister = nil
		} else {
			shouldUDPIgnore = true
		}
	}

	if shouldTCPIgnore && shouldUDPIgnore {
		return
	}

	if portIsZero(addr) {
		return
	}

	mixedListener, err = mixed.New(addr, tcpIn)
	if err != nil {
		return
	}

	mixedUDPLister, err = socks.NewUDP(addr, udpIn)
	if err != nil {
		mixedListener.Close()
		return
	}

	log.Infoln("Mixed(http+socks) proxy listening at: %s", mixedListener.Address())
}

func ReCreateTun(tunConf config.Tun, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) {
	tunMux.Lock()
	defer func() {
		LastTunConf = tunConf
		tunMux.Unlock()
	}()

	var err error
	defer func() {
		if err != nil {
			log.Errorln("Start TUN listening error: %s", err.Error())
			Cleanup(false)
		}
	}()

	if !hasTunConfigChange(&tunConf) {
		if tunLister != nil {
			tunLister.FlushDefaultInterface()
		}
		return
	}

	Cleanup(true)

	if !tunConf.Enable {
		return
	}

	tunLister, err = sing_tun.New(tunConf, tcpIn, udpIn)
}

func ReCreateRedirToTun(ifaceNames []string) {
	tcMux.Lock()
	defer tcMux.Unlock()

	nicArr := ifaceNames
	slices.Sort(nicArr)
	nicArr = slices.Compact(nicArr)

	if tcProgram != nil {
		tcProgram.Close()
		tcProgram = nil
	}

	if len(nicArr) == 0 {
		return
	}

	tunConf := GetTunConf()

	if !tunConf.Enable {
		return
	}

	program, err := ebpf.NewTcEBpfProgram(nicArr, tunConf.Device)
	if err != nil {
		log.Errorln("Attached tc ebpf program error: %v", err)
		return
	}
	tcProgram = program

	log.Infoln("Attached tc ebpf program to interfaces %v", tcProgram.RawNICs())
}

func ReCreateAutoRedir(ifaceNames []string, tcpIn chan<- C.ConnContext, _ chan<- *inbound.PacketAdapter) {
	autoRedirMux.Lock()
	defer autoRedirMux.Unlock()

	var err error
	defer func() {
		if err != nil {
			if autoRedirListener != nil {
				_ = autoRedirListener.Close()
				autoRedirListener = nil
			}
			if autoRedirProgram != nil {
				autoRedirProgram.Close()
				autoRedirProgram = nil
			}
			log.Errorln("Start auto redirect server error: %s", err.Error())
		}
	}()

	nicArr := ifaceNames
	slices.Sort(nicArr)
	nicArr = slices.Compact(nicArr)

	if autoRedirListener != nil && autoRedirProgram != nil {
		_ = autoRedirListener.Close()
		autoRedirProgram.Close()
		autoRedirListener = nil
		autoRedirProgram = nil
	}

	if len(nicArr) == 0 {
		return
	}

	defaultRouteInterfaceName, err := ebpf.GetAutoDetectInterface()
	if err != nil {
		return
	}

	addr := genAddr("*", C.TcpAutoRedirPort, true)

	autoRedirListener, err = autoredir.New(addr, tcpIn)
	if err != nil {
		return
	}

	autoRedirProgram, err = ebpf.NewRedirEBpfProgram(nicArr, autoRedirListener.TCPAddr().Port(), defaultRouteInterfaceName)
	if err != nil {
		return
	}

	autoRedirListener.SetLookupFunc(autoRedirProgram.Lookup)

	log.Infoln("Auto redirect proxy listening at: %s, attached tc ebpf program to interfaces %v", autoRedirListener.Address(), autoRedirProgram.RawNICs())
}

// GetPorts return the ports of proxy servers
func GetPorts() *Ports {
	ports := &Ports{}

	if httpListener != nil {
		_, portStr, _ := net.SplitHostPort(httpListener.Address())
		port, _ := strconv.Atoi(portStr)
		ports.Port = port
	}

	if socksListener != nil {
		_, portStr, _ := net.SplitHostPort(socksListener.Address())
		port, _ := strconv.Atoi(portStr)
		ports.SocksPort = port
	}

	if redirListener != nil {
		_, portStr, _ := net.SplitHostPort(redirListener.Address())
		port, _ := strconv.Atoi(portStr)
		ports.RedirPort = port
	}

	if tproxyListener != nil {
		_, portStr, _ := net.SplitHostPort(tproxyListener.Address())
		port, _ := strconv.Atoi(portStr)
		ports.TProxyPort = port
	}

	if mixedListener != nil {
		_, portStr, _ := net.SplitHostPort(mixedListener.Address())
		port, _ := strconv.Atoi(portStr)
		ports.MixedPort = port
	}

	if shadowSocksListener != nil {
		ports.ShadowSocksConfig = shadowSocksListener.Config()
	}

	if vmessListener != nil {
		ports.VmessConfig = vmessListener.Config()
	}

	if tcpTunListener != nil {
		ports.TcpTunConfig = tcpTunListener.Config()
	}

	if udpTunListener != nil {
		ports.UdpTunConfig = udpTunListener.Config()
	}

	return ports
}

func portIsZero(addr string) bool {
	_, port, err := net.SplitHostPort(addr)
	if port == "0" || port == "" || err != nil {
		return true
	}
	return false
}

func genAddr(host string, port int, allowLan bool) string {
	if allowLan {
		if host == "*" {
			return fmt.Sprintf(":%d", port)
		}
		return fmt.Sprintf("%s:%d", host, port)
	}

	return fmt.Sprintf("127.0.0.1:%d", port)
}

func hasTunConfigChange(tunConf *config.Tun) bool {
	if LastTunConf.Enable != tunConf.Enable ||
		LastTunConf.Device != tunConf.Device ||
		LastTunConf.Stack != tunConf.Stack ||
		LastTunConf.AutoRoute != tunConf.AutoRoute ||
		LastTunConf.AutoDetectInterface != tunConf.AutoDetectInterface ||
		LastTunConf.MTU != tunConf.MTU ||
		LastTunConf.StrictRoute != tunConf.StrictRoute ||
		LastTunConf.EndpointIndependentNat != tunConf.EndpointIndependentNat ||
		LastTunConf.UDPTimeout != tunConf.UDPTimeout {
		return true
	}

	if len(LastTunConf.DNSHijack) != len(tunConf.DNSHijack) {
		return true
	}

	sort.Slice(tunConf.DNSHijack, func(i, j int) bool {
		return tunConf.DNSHijack[i].Addr().Less(tunConf.DNSHijack[j].Addr())
	})

	sort.Slice(tunConf.Inet4Address, func(i, j int) bool {
		return tunConf.Inet4Address[i].Build().String() < tunConf.Inet4Address[j].Build().String()
	})

	sort.Slice(tunConf.Inet6Address, func(i, j int) bool {
		return tunConf.Inet6Address[i].Build().String() < tunConf.Inet6Address[j].Build().String()
	})

	sort.Slice(tunConf.Inet4RouteAddress, func(i, j int) bool {
		return tunConf.Inet4RouteAddress[i].Build().String() < tunConf.Inet4RouteAddress[j].Build().String()
	})

	sort.Slice(tunConf.Inet6RouteAddress, func(i, j int) bool {
		return tunConf.Inet6RouteAddress[i].Build().String() < tunConf.Inet6RouteAddress[j].Build().String()
	})

	sort.Slice(tunConf.IncludeUID, func(i, j int) bool {
		return tunConf.IncludeUID[i] < tunConf.IncludeUID[j]
	})

	sort.Slice(tunConf.IncludeUIDRange, func(i, j int) bool {
		return tunConf.IncludeUIDRange[i] < tunConf.IncludeUIDRange[j]
	})

	sort.Slice(tunConf.ExcludeUID, func(i, j int) bool {
		return tunConf.ExcludeUID[i] < tunConf.ExcludeUID[j]
	})

	sort.Slice(tunConf.ExcludeUIDRange, func(i, j int) bool {
		return tunConf.ExcludeUIDRange[i] < tunConf.ExcludeUIDRange[j]
	})

	sort.Slice(tunConf.IncludeAndroidUser, func(i, j int) bool {
		return tunConf.IncludeAndroidUser[i] < tunConf.IncludeAndroidUser[j]
	})

	sort.Slice(tunConf.IncludePackage, func(i, j int) bool {
		return tunConf.IncludePackage[i] < tunConf.IncludePackage[j]
	})

	sort.Slice(tunConf.ExcludePackage, func(i, j int) bool {
		return tunConf.ExcludePackage[i] < tunConf.ExcludePackage[j]
	})

	if !slices.Equal(tunConf.DNSHijack, LastTunConf.DNSHijack) ||
		!slices.Equal(tunConf.Inet4Address, LastTunConf.Inet4Address) ||
		!slices.Equal(tunConf.Inet6Address, LastTunConf.Inet6Address) ||
		!slices.Equal(tunConf.Inet4RouteAddress, LastTunConf.Inet4RouteAddress) ||
		!slices.Equal(tunConf.Inet6RouteAddress, LastTunConf.Inet6RouteAddress) ||
		!slices.Equal(tunConf.IncludeUID, LastTunConf.IncludeUID) ||
		!slices.Equal(tunConf.IncludeUIDRange, LastTunConf.IncludeUIDRange) ||
		!slices.Equal(tunConf.ExcludeUID, LastTunConf.ExcludeUID) ||
		!slices.Equal(tunConf.ExcludeUIDRange, LastTunConf.ExcludeUIDRange) ||
		!slices.Equal(tunConf.IncludeAndroidUser, LastTunConf.IncludeAndroidUser) ||
		!slices.Equal(tunConf.IncludePackage, LastTunConf.IncludePackage) ||
		!slices.Equal(tunConf.ExcludePackage, LastTunConf.ExcludePackage) {
		return true
	}

	return false
}

func Cleanup(wait bool) {
	if tunLister != nil {
		tunLister.Close()
		tunLister = nil
	}
	LastTunConf = config.Tun{}
}