// +build windows

/*
Copyright 2014 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// Package app does all of the work necessary to configure and run a
// Kubernetes app process.
package app

import (
	"errors"
	"fmt"
	"net"

	// Enable pprof HTTP handlers.
	_ "net/http/pprof"

	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/types"
	utilnet "k8s.io/apimachinery/pkg/util/net"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	"k8s.io/client-go/tools/record"
	"k8s.io/component-base/configz"
	"k8s.io/component-base/metrics"
	"k8s.io/klog/v2"
	"k8s.io/kubernetes/pkg/features"
	"k8s.io/kubernetes/pkg/proxy"
	proxyconfigapi "k8s.io/kubernetes/pkg/proxy/apis/config"
	proxyconfigscheme "k8s.io/kubernetes/pkg/proxy/apis/config/scheme"
	"k8s.io/kubernetes/pkg/proxy/healthcheck"
	"k8s.io/kubernetes/pkg/proxy/winkernel"
	"k8s.io/kubernetes/pkg/proxy/winuserspace"
	utilnetsh "k8s.io/kubernetes/pkg/util/netsh"
	utilnode "k8s.io/kubernetes/pkg/util/node"
	"k8s.io/utils/exec"
	utilsnet "k8s.io/utils/net"
)

// NewProxyServer returns a new ProxyServer.
func NewProxyServer(o *Options) (*ProxyServer, error) {
	return newProxyServer(o.config, o.CleanupAndExit, o.master)
}

func newProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExit bool, master string) (*ProxyServer, error) {
	if config == nil {
		return nil, errors.New("config is required")
	}

	if c, err := configz.New(proxyconfigapi.GroupName); err == nil {
		c.Set(config)
	} else {
		return nil, fmt.Errorf("unable to register configz: %s", err)
	}

	// We omit creation of pretty much everything if we run in cleanup mode
	if cleanupAndExit {
		return &ProxyServer{}, nil
	}

	if len(config.ShowHiddenMetricsForVersion) > 0 {
		metrics.SetShowHidden()
	}

	client, eventClient, err := createClients(config.ClientConnection, master)
	if err != nil {
		return nil, err
	}

	// Create event recorder
	hostname, err := utilnode.GetHostname(config.HostnameOverride)
	if err != nil {
		return nil, err
	}
	eventBroadcaster := record.NewBroadcaster()
	recorder := eventBroadcaster.NewRecorder(proxyconfigscheme.Scheme, v1.EventSource{Component: "kube-proxy", Host: hostname})

	nodeRef := &v1.ObjectReference{
		Kind:      "Node",
		Name:      hostname,
		UID:       types.UID(hostname),
		Namespace: "",
	}

	var healthzServer healthcheck.ProxierHealthUpdater
	if len(config.HealthzBindAddress) > 0 {
		healthzServer = healthcheck.NewProxierHealthServer(config.HealthzBindAddress, 2*config.IPTables.SyncPeriod.Duration, recorder, nodeRef)
	}

	var proxier proxy.Provider

	proxyMode := getProxyMode(string(config.Mode), winkernel.WindowsKernelCompatTester{})
	if proxyMode == proxyModeKernelspace {
		klog.V(0).Info("Using Kernelspace Proxier.")
		isIPv6DualStackEnabled := utilfeature.DefaultFeatureGate.Enabled(features.IPv6DualStack)
		if isIPv6DualStackEnabled {
			klog.V(0).Info("creating dualStackProxier for Windows kernel.")

			proxier, err = winkernel.NewDualStackProxier(
				config.IPTables.SyncPeriod.Duration,
				config.IPTables.MinSyncPeriod.Duration,
				config.IPTables.MasqueradeAll,
				int(*config.IPTables.MasqueradeBit),
				config.ClusterCIDR,
				hostname,
				nodeIPTuple(config.BindAddress),
				recorder,
				healthzServer,
				config.Winkernel,
			)
		} else {

			proxier, err = winkernel.NewProxier(
				config.IPTables.SyncPeriod.Duration,
				config.IPTables.MinSyncPeriod.Duration,
				config.IPTables.MasqueradeAll,
				int(*config.IPTables.MasqueradeBit),
				config.ClusterCIDR,
				hostname,
				utilnode.GetNodeIP(client, hostname),
				recorder,
				healthzServer,
				config.Winkernel,
			)

		}

		if err != nil {
			return nil, fmt.Errorf("unable to create proxier: %v", err)
		}
	} else {
		klog.V(0).Info("Using userspace Proxier.")
		execer := exec.New()
		var netshInterface utilnetsh.Interface
		netshInterface = utilnetsh.New(execer)

		proxier, err = winuserspace.NewProxier(
			winuserspace.NewLoadBalancerRR(),
			net.ParseIP(config.BindAddress),
			netshInterface,
			*utilnet.ParsePortRangeOrDie(config.PortRange),
			// TODO @pires replace below with default values, if applicable
			config.IPTables.SyncPeriod.Duration,
			config.UDPIdleTimeout.Duration,
		)
		if err != nil {
			return nil, fmt.Errorf("unable to create proxier: %v", err)
		}
	}

	return &ProxyServer{
		Client:              client,
		EventClient:         eventClient,
		Proxier:             proxier,
		Broadcaster:         eventBroadcaster,
		Recorder:            recorder,
		ProxyMode:           proxyMode,
		NodeRef:             nodeRef,
		MetricsBindAddress:  config.MetricsBindAddress,
		BindAddressHardFail: config.BindAddressHardFail,
		EnableProfiling:     config.EnableProfiling,
		OOMScoreAdj:         config.OOMScoreAdj,
		ConfigSyncPeriod:    config.ConfigSyncPeriod.Duration,
		HealthzServer:       healthzServer,
		UseEndpointSlices:   utilfeature.DefaultFeatureGate.Enabled(features.WindowsEndpointSliceProxying),
	}, nil
}

func getProxyMode(proxyMode string, kcompat winkernel.KernelCompatTester) string {
	if proxyMode == proxyModeUserspace {
		return proxyModeUserspace
	} else if proxyMode == proxyModeKernelspace {
		return tryWinKernelSpaceProxy(kcompat)
	}
	return proxyModeUserspace
}

func tryWinKernelSpaceProxy(kcompat winkernel.KernelCompatTester) string {
	// Check for Windows Kernel Version if we can support Kernel Space proxy
	// Check for Windows Version

	// guaranteed false on error, error only necessary for debugging
	useWinKernelProxy, err := winkernel.CanUseWinKernelProxier(kcompat)
	if err != nil {
		klog.Errorf("Can't determine whether to use windows kernel proxy, using userspace proxier: %v", err)
		return proxyModeUserspace
	}
	if useWinKernelProxy {
		return proxyModeKernelspace
	}
	// Fallback.
	klog.V(1).Infof("Can't use winkernel proxy, using userspace proxier")
	return proxyModeUserspace
}

// nodeIPTuple takes an addresses and return a tuple (ipv4,ipv6)
// The returned tuple is guaranteed to have the order (ipv4,ipv6). The address NOT of the passed address
// will have "any" address (0.0.0.0 or ::) inserted.
func nodeIPTuple(bindAddress string) [2]net.IP {
	nodes := [2]net.IP{net.IPv4zero, net.IPv6zero}

	adr := net.ParseIP(bindAddress)
	if utilsnet.IsIPv6(adr) {
		nodes[1] = adr
	} else {
		nodes[0] = adr
	}

	return nodes
}
