//go:build !no_embedded_executor
// +build !no_embedded_executor

package executor

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"runtime"

	"github.com/k3s-io/k3s/pkg/cli/cmds"
	daemonconfig "github.com/k3s-io/k3s/pkg/daemons/config"
	"github.com/k3s-io/k3s/pkg/version"
	"github.com/sirupsen/logrus"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/apimachinery/pkg/watch"
	"k8s.io/apiserver/pkg/authentication/authenticator"
	typedcorev1 "k8s.io/client-go/kubernetes/typed/core/v1"
	"k8s.io/client-go/tools/clientcmd"
	ccm "k8s.io/cloud-provider"
	cloudprovider "k8s.io/cloud-provider"
	cloudproviderapi "k8s.io/cloud-provider/api"
	ccmapp "k8s.io/cloud-provider/app"
	cloudcontrollerconfig "k8s.io/cloud-provider/app/config"
	ccmopt "k8s.io/cloud-provider/options"
	cliflag "k8s.io/component-base/cli/flag"
	"k8s.io/kubernetes/cmd/kube-apiserver/app"
	cmapp "k8s.io/kubernetes/cmd/kube-controller-manager/app"
	proxy "k8s.io/kubernetes/cmd/kube-proxy/app"
	sapp "k8s.io/kubernetes/cmd/kube-scheduler/app"
	kubelet "k8s.io/kubernetes/cmd/kubelet/app"

	// registering k3s cloud provider
	_ "github.com/k3s-io/k3s/pkg/cloudprovider"
)

func init() {
	executor = &Embedded{}
}

func (e *Embedded) Bootstrap(ctx context.Context, nodeConfig *daemonconfig.Node, cfg cmds.Agent) error {
	e.nodeConfig = nodeConfig
	return nil
}

func (*Embedded) Kubelet(ctx context.Context, args []string) error {
	command := kubelet.NewKubeletCommand(context.Background())
	command.SetArgs(args)

	go func() {
		defer func() {
			if err := recover(); err != nil {
				logrus.Fatalf("kubelet panic: %v", err)
			}
		}()
		logrus.Fatalf("kubelet exited: %v", command.ExecuteContext(ctx))
	}()

	return nil
}

func (*Embedded) KubeProxy(ctx context.Context, args []string) error {
	command := proxy.NewProxyCommand()
	command.SetArgs(args)

	go func() {
		defer func() {
			if err := recover(); err != nil {
				logrus.Fatalf("kube-proxy panic: %v", err)
			}
		}()
		logrus.Fatalf("kube-proxy exited: %v", command.ExecuteContext(ctx))
	}()

	return nil
}

func (*Embedded) APIServerHandlers(ctx context.Context) (authenticator.Request, http.Handler, error) {
	startupConfig := <-app.StartupConfig
	return startupConfig.Authenticator, startupConfig.Handler, nil
}

func (*Embedded) APIServer(ctx context.Context, etcdReady <-chan struct{}, args []string) error {
	command := app.NewAPIServerCommand(ctx.Done())
	command.SetArgs(args)

	go func() {
		<-etcdReady
		defer func() {
			if err := recover(); err != nil {
				logrus.Fatalf("apiserver panic: %v", err)
			}
		}()
		logrus.Fatalf("apiserver exited: %v", command.ExecuteContext(ctx))
	}()

	return nil
}

func (e *Embedded) Scheduler(ctx context.Context, apiReady <-chan struct{}, args []string) error {
	command := sapp.NewSchedulerCommand()
	command.SetArgs(args)

	go func() {
		<-apiReady
		// wait for Bootstrap to set nodeConfig
		for e.nodeConfig == nil {
			runtime.Gosched()
		}
		// If we're running the embedded cloud controller, wait for it to untaint at least one
		// node (usually, the local node) before starting the scheduler to ensure that it
		// finds a node that is ready to run pods during its initial scheduling loop.
		if !e.nodeConfig.AgentConfig.DisableCCM {
			if err := waitForUntaintedNode(ctx, e.nodeConfig.AgentConfig.KubeConfigKubelet); err != nil {
				logrus.Fatalf("failed to wait for untained node: %v", err)
			}
		}
		defer func() {
			if err := recover(); err != nil {
				logrus.Fatalf("scheduler panic: %v", err)
			}
		}()
		logrus.Fatalf("scheduler exited: %v", command.ExecuteContext(ctx))
	}()

	return nil
}

func (*Embedded) ControllerManager(ctx context.Context, apiReady <-chan struct{}, args []string) error {
	command := cmapp.NewControllerManagerCommand()
	command.SetArgs(args)

	go func() {
		<-apiReady
		defer func() {
			if err := recover(); err != nil {
				logrus.Fatalf("controller-manager panic: %v", err)
			}
		}()
		logrus.Fatalf("controller-manager exited: %v", command.ExecuteContext(ctx))
	}()

	return nil
}

func (*Embedded) CloudControllerManager(ctx context.Context, ccmRBACReady <-chan struct{}, args []string) error {
	ccmOptions, err := ccmopt.NewCloudControllerManagerOptions()
	if err != nil {
		logrus.Fatalf("unable to initialize command options: %v", err)
	}

	cloudInitializer := func(config *cloudcontrollerconfig.CompletedConfig) cloudprovider.Interface {
		cloud, err := ccm.InitCloudProvider(version.Program, "")
		if err != nil {
			logrus.Fatalf("Cloud provider could not be initialized: %v", err)
		}
		if cloud == nil {
			logrus.Fatalf("Cloud provider is nil")
		}

		cloud.Initialize(config.ClientBuilder, make(chan struct{}))
		if informerUserCloud, ok := cloud.(ccm.InformerUser); ok {
			informerUserCloud.SetInformers(config.SharedInformers)
		}

		return cloud
	}

	controllerInitializers := ccmapp.DefaultInitFuncConstructors
	delete(controllerInitializers, "service")
	delete(controllerInitializers, "route")

	command := ccmapp.NewCloudControllerManagerCommand(ccmOptions, cloudInitializer, controllerInitializers, cliflag.NamedFlagSets{}, wait.NeverStop)
	command.SetArgs(args)

	go func() {
		<-ccmRBACReady
		defer func() {
			if err := recover(); err != nil {
				logrus.Fatalf("cloud-controller-manager panic: %v", err)
			}
		}()
		logrus.Errorf("cloud-controller-manager exited: %v", command.ExecuteContext(ctx))
	}()

	return nil
}

func (e *Embedded) CurrentETCDOptions() (InitialOptions, error) {
	return InitialOptions{}, nil
}

// waitForUntaintedNode watches nodes, waiting to find one not tainted as
// uninitialized by the external cloud provider.
func waitForUntaintedNode(ctx context.Context, kubeConfig string) error {
	restConfig, err := clientcmd.BuildConfigFromFlags("", kubeConfig)
	if err != nil {
		return err
	}
	coreClient, err := typedcorev1.NewForConfig(restConfig)
	if err != nil {
		return err
	}

	// List first, to see if there's an existing node that will do
	nodes, err := coreClient.Nodes().List(ctx, metav1.ListOptions{})
	if err != nil {
		return err
	}
	for _, node := range nodes.Items {
		if taint := getCloudTaint(node.Spec.Taints); taint == nil {
			return nil
		}
	}

	// List didn't give us an existing node, start watching at whatever ResourceVersion the list left off at.
	watcher, err := coreClient.Nodes().Watch(ctx, metav1.ListOptions{ResourceVersion: nodes.ListMeta.ResourceVersion})
	if err != nil {
		return err
	}
	defer watcher.Stop()

	for ev := range watcher.ResultChan() {
		if ev.Type == watch.Added || ev.Type == watch.Modified {
			node, ok := ev.Object.(*corev1.Node)
			if !ok {
				return fmt.Errorf("could not convert event object to node: %v", ev)
			}
			if taint := getCloudTaint(node.Spec.Taints); taint == nil {
				return nil
			}
		}
	}

	return errors.New("watch channel closed")
}

// getCloudTaint returns the external cloud provider taint, if present.
// Cribbed from k8s.io/cloud-provider/controllers/node/node_controller.go
func getCloudTaint(taints []corev1.Taint) *corev1.Taint {
	for _, taint := range taints {
		if taint.Key == cloudproviderapi.TaintExternalCloudProvider {
			return &taint
		}
	}
	return nil
}