// Copyright © 2017 The virtual-kubelet 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 root

import (
	"context"
	"os"

	"github.com/cpuguy83/strongerrors"
	"github.com/pkg/errors"
	"github.com/spf13/cobra"
	"github.com/virtual-kubelet/virtual-kubelet/log"
	"github.com/virtual-kubelet/virtual-kubelet/manager"
	"github.com/virtual-kubelet/virtual-kubelet/providers"
	"github.com/virtual-kubelet/virtual-kubelet/providers/register"
	"github.com/virtual-kubelet/virtual-kubelet/vkubelet"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/fields"
	kubeinformers "k8s.io/client-go/informers"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
)

// NewCommand creates a new top-level command.
// This command is used to start the virtual-kubelet daemon
func NewCommand(ctx context.Context, name string, c Opts) *cobra.Command {
	cmd := &cobra.Command{
		Use:   name,
		Short: name + " provides a virtual kubelet interface for your kubernetes cluster.",
		Long: name + ` implements the Kubelet interface with a pluggable
backend implementation allowing users to create kubernetes nodes without running the kubelet.
This allows users to schedule kubernetes workloads on nodes that aren't running Kubernetes.`,
		RunE: func(cmd *cobra.Command, args []string) error {
			return runRootCommand(ctx, c)
		},
	}

	installFlags(cmd.Flags(), &c)
	return cmd
}

func runRootCommand(ctx context.Context, c Opts) error {
	if ok := providers.ValidOperatingSystems[c.OperatingSystem]; !ok {
		return strongerrors.InvalidArgument(errors.Errorf("operating system %q is not supported", c.OperatingSystem))
	}

	if c.PodSyncWorkers == 0 {
		return strongerrors.InvalidArgument(errors.New("pod sync workers must be greater than 0"))
	}

	var taint *corev1.Taint
	if !c.DisableTaint {
		var err error
		taint, err = getTaint(c)
		if err != nil {
			return err
		}
	}

	client, err := newClient(c.KubeConfigPath)
	if err != nil {
		return err
	}

	// Create a shared informer factory for Kubernetes pods in the current namespace (if specified) and scheduled to the current node.
	podInformerFactory := kubeinformers.NewSharedInformerFactoryWithOptions(
		client,
		c.InformerResyncPeriod,
		kubeinformers.WithNamespace(c.KubeNamespace),
		kubeinformers.WithTweakListOptions(func(options *metav1.ListOptions) {
			options.FieldSelector = fields.OneTermEqualSelector("spec.nodeName", c.NodeName).String()
		}))
	// Create a pod informer so we can pass its lister to the resource manager.
	podInformer := podInformerFactory.Core().V1().Pods()

	// Create another shared informer factory for Kubernetes secrets and configmaps (not subject to any selectors).
	scmInformerFactory := kubeinformers.NewSharedInformerFactoryWithOptions(client, c.InformerResyncPeriod)
	// Create a secret informer and a config map informer so we can pass their listers to the resource manager.
	secretInformer := scmInformerFactory.Core().V1().Secrets()
	configMapInformer := scmInformerFactory.Core().V1().ConfigMaps()
	serviceInformer := scmInformerFactory.Core().V1().Services()

	go podInformerFactory.Start(ctx.Done())
	go scmInformerFactory.Start(ctx.Done())

	rm, err := manager.NewResourceManager(podInformer.Lister(), secretInformer.Lister(), configMapInformer.Lister(), serviceInformer.Lister())
	if err != nil {
		return errors.Wrap(err, "could not create resource manager")
	}

	apiConfig, err := getAPIConfig(c)
	if err != nil {
		return err
	}

	if err := setupTracing(ctx, c); err != nil {
		return err
	}

	initConfig := register.InitConfig{
		ConfigPath:      c.ProviderConfigPath,
		NodeName:        c.NodeName,
		OperatingSystem: c.OperatingSystem,
		ResourceManager: rm,
		DaemonPort:      int32(c.ListenPort),
		InternalIP:      os.Getenv("VKUBELET_POD_IP"),
	}

	p, err := register.GetProvider(c.Provider, initConfig)
	if err != nil {
		return err
	}

	ctx = log.WithLogger(ctx, log.G(ctx).WithFields(log.Fields{
		"provider":         c.Provider,
		"operatingSystem":  c.OperatingSystem,
		"node":             c.NodeName,
		"watchedNamespace": c.KubeNamespace,
	}))

	pNode := NodeFromProvider(ctx, c.NodeName, taint, p)
	node, err := vkubelet.NewNode(
		vkubelet.NaiveNodeProvider{},
		pNode,
		client.CoordinationV1beta1().Leases(corev1.NamespaceNodeLease),
		client.CoreV1().Nodes(),
		vkubelet.WithNodeDisableLease(!c.EnableNodeLease),
	)
	if err != nil {
		log.G(ctx).Fatal(err)
	}

	vk := vkubelet.New(vkubelet.Config{
		Client:          client,
		Namespace:       c.KubeNamespace,
		NodeName:        pNode.Name,
		Provider:        p,
		ResourceManager: rm,
		PodSyncWorkers:  c.PodSyncWorkers,
		PodInformer:     podInformer,
	})

	cancelHTTP, err := setupHTTPServer(ctx, p, apiConfig)
	if err != nil {
		return err
	}
	defer cancelHTTP()

	go func() {
		if err := vk.Run(ctx); err != nil && errors.Cause(err) != context.Canceled {
			log.G(ctx).Fatal(err)
		}
	}()

	go func() {
		if err := node.Run(ctx); err != nil {
			log.G(ctx).Fatal(err)
		}
	}()

	log.G(ctx).Info("Initialized")

	<-ctx.Done()
	return nil
}

func newClient(configPath string) (*kubernetes.Clientset, error) {
	var config *rest.Config

	// Check if the kubeConfig file exists.
	if _, err := os.Stat(configPath); !os.IsNotExist(err) {
		// Get the kubeconfig from the filepath.
		config, err = clientcmd.BuildConfigFromFlags("", configPath)
		if err != nil {
			return nil, errors.Wrap(err, "error building client config")
		}
	} else {
		// Set to in-cluster config.
		config, err = rest.InClusterConfig()
		if err != nil {
			return nil, errors.Wrap(err, "error building in cluster config")
		}
	}

	if masterURI := os.Getenv("MASTER_URI"); masterURI != "" {
		config.Host = masterURI
	}

	return kubernetes.NewForConfig(config)
}