/*
Copyright 2018 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 options

import (
	"fmt"
	"net"
	"os"
	"strconv"
	"time"

	corev1 "k8s.io/api/core/v1"
	apimachineryconfig "k8s.io/apimachinery/pkg/apis/config"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/uuid"
	apiserveroptions "k8s.io/apiserver/pkg/server/options"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	apiserverflag "k8s.io/apiserver/pkg/util/flag"
	"k8s.io/client-go/informers"
	clientset "k8s.io/client-go/kubernetes"
	v1core "k8s.io/client-go/kubernetes/typed/core/v1"
	restclient "k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
	"k8s.io/client-go/tools/leaderelection"
	"k8s.io/client-go/tools/leaderelection/resourcelock"
	"k8s.io/client-go/tools/record"
	"k8s.io/klog"
	kubeschedulerconfigv1alpha1 "k8s.io/kube-scheduler/config/v1alpha1"
	schedulerappconfig "k8s.io/kubernetes/cmd/kube-scheduler/app/config"
	"k8s.io/kubernetes/pkg/api/legacyscheme"
	"k8s.io/kubernetes/pkg/client/leaderelectionconfig"
	"k8s.io/kubernetes/pkg/master/ports"
	kubeschedulerconfig "k8s.io/kubernetes/pkg/scheduler/apis/config"
	kubeschedulerscheme "k8s.io/kubernetes/pkg/scheduler/apis/config/scheme"
	"k8s.io/kubernetes/pkg/scheduler/apis/config/validation"
	"k8s.io/kubernetes/pkg/scheduler/factory"
)

// Options has all the params needed to run a Scheduler
type Options struct {
	// The default values. These are overridden if ConfigFile is set or by values in InsecureServing.
	ComponentConfig kubeschedulerconfig.KubeSchedulerConfiguration

	SecureServing           *apiserveroptions.SecureServingOptionsWithLoopback
	CombinedInsecureServing *CombinedInsecureServingOptions
	Authentication          *apiserveroptions.DelegatingAuthenticationOptions
	Authorization           *apiserveroptions.DelegatingAuthorizationOptions
	Deprecated              *DeprecatedOptions

	// ConfigFile is the location of the scheduler server's configuration file.
	ConfigFile string

	// WriteConfigTo is the path where the default configuration will be written.
	WriteConfigTo string

	Master string
}

// NewOptions returns default scheduler app options.
func NewOptions() (*Options, error) {
	cfg, err := newDefaultComponentConfig()
	if err != nil {
		return nil, err
	}

	hhost, hport, err := splitHostIntPort(cfg.HealthzBindAddress)
	if err != nil {
		return nil, err
	}

	o := &Options{
		ComponentConfig: *cfg,
		SecureServing:   apiserveroptions.NewSecureServingOptions().WithLoopback(),
		CombinedInsecureServing: &CombinedInsecureServingOptions{
			Healthz: (&apiserveroptions.DeprecatedInsecureServingOptions{
				BindNetwork: "tcp",
			}).WithLoopback(),
			Metrics: (&apiserveroptions.DeprecatedInsecureServingOptions{
				BindNetwork: "tcp",
			}).WithLoopback(),
			BindPort:    hport,
			BindAddress: hhost,
		},
		Authentication: apiserveroptions.NewDelegatingAuthenticationOptions(),
		Authorization:  apiserveroptions.NewDelegatingAuthorizationOptions(),
		Deprecated: &DeprecatedOptions{
			UseLegacyPolicyConfig:    false,
			PolicyConfigMapNamespace: metav1.NamespaceSystem,
		},
	}

	o.Authentication.TolerateInClusterLookupFailure = true
	o.Authentication.RemoteKubeConfigFileOptional = true
	o.Authorization.RemoteKubeConfigFileOptional = true
	o.Authorization.AlwaysAllowPaths = []string{"/healthz"}

	// Set the PairName but leave certificate directory blank to generate in-memory by default
	o.SecureServing.ServerCert.CertDirectory = ""
	o.SecureServing.ServerCert.PairName = "kube-scheduler"
	o.SecureServing.BindPort = ports.KubeSchedulerPort

	return o, nil
}

func splitHostIntPort(s string) (string, int, error) {
	host, port, err := net.SplitHostPort(s)
	if err != nil {
		return "", 0, err
	}
	portInt, err := strconv.Atoi(port)
	if err != nil {
		return "", 0, err
	}
	return host, portInt, err
}

func newDefaultComponentConfig() (*kubeschedulerconfig.KubeSchedulerConfiguration, error) {
	cfgv1alpha1 := kubeschedulerconfigv1alpha1.KubeSchedulerConfiguration{}
	kubeschedulerscheme.Scheme.Default(&cfgv1alpha1)
	cfg := kubeschedulerconfig.KubeSchedulerConfiguration{}
	if err := kubeschedulerscheme.Scheme.Convert(&cfgv1alpha1, &cfg, nil); err != nil {
		return nil, err
	}
	return &cfg, nil
}

// Flags returns flags for a specific scheduler by section name
func (o *Options) Flags() (nfs apiserverflag.NamedFlagSets) {
	fs := nfs.FlagSet("misc")
	fs.StringVar(&o.ConfigFile, "config", o.ConfigFile, "The path to the configuration file. Flags override values in this file.")
	fs.StringVar(&o.WriteConfigTo, "write-config-to", o.WriteConfigTo, "If set, write the configuration values to this file and exit.")
	fs.StringVar(&o.Master, "master", o.Master, "The address of the Kubernetes API server (overrides any value in kubeconfig)")

	o.SecureServing.AddFlags(nfs.FlagSet("secure serving"))
	o.CombinedInsecureServing.AddFlags(nfs.FlagSet("insecure serving"))
	o.Authentication.AddFlags(nfs.FlagSet("authentication"))
	o.Authorization.AddFlags(nfs.FlagSet("authorization"))
	o.Deprecated.AddFlags(nfs.FlagSet("deprecated"), &o.ComponentConfig)

	leaderelectionconfig.BindFlags(&o.ComponentConfig.LeaderElection.LeaderElectionConfiguration, nfs.FlagSet("leader election"))
	utilfeature.DefaultFeatureGate.AddFlag(nfs.FlagSet("feature gate"))

	return nfs
}

// ApplyTo applies the scheduler options to the given scheduler app configuration.
func (o *Options) ApplyTo(c *schedulerappconfig.Config) error {
	if len(o.ConfigFile) == 0 {
		c.ComponentConfig = o.ComponentConfig

		// only apply deprecated flags if no config file is loaded (this is the old behaviour).
		if err := o.Deprecated.ApplyTo(&c.ComponentConfig); err != nil {
			return err
		}
		if err := o.CombinedInsecureServing.ApplyTo(c, &c.ComponentConfig); err != nil {
			return err
		}
	} else {
		cfg, err := loadConfigFromFile(o.ConfigFile)
		if err != nil {
			return err
		}

		// use the loaded config file only, with the exception of --address and --port. This means that
		// none of the deprectated flags in o.Deprecated are taken into consideration. This is the old
		// behaviour of the flags we have to keep.
		c.ComponentConfig = *cfg

		if err := o.CombinedInsecureServing.ApplyToFromLoadedConfig(c, &c.ComponentConfig); err != nil {
			return err
		}
	}

	if err := o.SecureServing.ApplyTo(&c.SecureServing, &c.LoopbackClientConfig); err != nil {
		return err
	}
	if o.SecureServing != nil && (o.SecureServing.BindPort != 0 || o.SecureServing.Listener != nil) {
		if err := o.Authentication.ApplyTo(&c.Authentication, c.SecureServing); err != nil {
			return err
		}
		if err := o.Authorization.ApplyTo(&c.Authorization); err != nil {
			return err
		}
	}

	return nil
}

// Validate validates all the required options.
func (o *Options) Validate() []error {
	var errs []error

	if err := validation.ValidateKubeSchedulerConfiguration(&o.ComponentConfig).ToAggregate(); err != nil {
		errs = append(errs, err.Errors()...)
	}
	errs = append(errs, o.SecureServing.Validate()...)
	errs = append(errs, o.CombinedInsecureServing.Validate()...)
	errs = append(errs, o.Authentication.Validate()...)
	errs = append(errs, o.Authorization.Validate()...)
	errs = append(errs, o.Deprecated.Validate()...)

	return errs
}

// Config return a scheduler config object
func (o *Options) Config() (*schedulerappconfig.Config, error) {
	if o.SecureServing != nil {
		if err := o.SecureServing.MaybeDefaultWithSelfSignedCerts("localhost", nil, []net.IP{net.ParseIP("127.0.0.1")}); err != nil {
			return nil, fmt.Errorf("error creating self-signed certificates: %v", err)
		}
	}

	c := &schedulerappconfig.Config{}
	if err := o.ApplyTo(c); err != nil {
		return nil, err
	}

	// Prepare kube clients.
	client, leaderElectionClient, eventClient, err := createClients(c.ComponentConfig.ClientConnection, o.Master, c.ComponentConfig.LeaderElection.RenewDeadline.Duration)
	if err != nil {
		return nil, err
	}

	// Prepare event clients.
	eventBroadcaster := record.NewBroadcaster()
	recorder := eventBroadcaster.NewRecorder(legacyscheme.Scheme, corev1.EventSource{Component: c.ComponentConfig.SchedulerName})

	// Set up leader election if enabled.
	var leaderElectionConfig *leaderelection.LeaderElectionConfig
	if c.ComponentConfig.LeaderElection.LeaderElect {
		leaderElectionConfig, err = makeLeaderElectionConfig(c.ComponentConfig.LeaderElection, leaderElectionClient, recorder)
		if err != nil {
			return nil, err
		}
	}

	c.Client = client
	c.InformerFactory = informers.NewSharedInformerFactory(client, 0)
	c.PodInformer = factory.NewPodInformer(client, 0)
	c.EventClient = eventClient
	c.Recorder = recorder
	c.Broadcaster = eventBroadcaster
	c.LeaderElection = leaderElectionConfig

	return c, nil
}

// makeLeaderElectionConfig builds a leader election configuration. It will
// create a new resource lock associated with the configuration.
func makeLeaderElectionConfig(config kubeschedulerconfig.KubeSchedulerLeaderElectionConfiguration, client clientset.Interface, recorder record.EventRecorder) (*leaderelection.LeaderElectionConfig, error) {
	hostname, err := os.Hostname()
	if err != nil {
		return nil, fmt.Errorf("unable to get hostname: %v", err)
	}
	// add a uniquifier so that two processes on the same host don't accidentally both become active
	id := hostname + "_" + string(uuid.NewUUID())

	rl, err := resourcelock.New(config.ResourceLock,
		config.LockObjectNamespace,
		config.LockObjectName,
		client.CoreV1(),
		resourcelock.ResourceLockConfig{
			Identity:      id,
			EventRecorder: recorder,
		})
	if err != nil {
		return nil, fmt.Errorf("couldn't create resource lock: %v", err)
	}

	return &leaderelection.LeaderElectionConfig{
		Lock:          rl,
		LeaseDuration: config.LeaseDuration.Duration,
		RenewDeadline: config.RenewDeadline.Duration,
		RetryPeriod:   config.RetryPeriod.Duration,
		WatchDog:      leaderelection.NewLeaderHealthzAdaptor(time.Second * 20),
		Name:          "kube-scheduler",
	}, nil
}

// createClients creates a kube client and an event client from the given config and masterOverride.
// TODO remove masterOverride when CLI flags are removed.
func createClients(config apimachineryconfig.ClientConnectionConfiguration, masterOverride string, timeout time.Duration) (clientset.Interface, clientset.Interface, v1core.EventsGetter, error) {
	if len(config.Kubeconfig) == 0 && len(masterOverride) == 0 {
		klog.Warningf("Neither --kubeconfig nor --master was specified. Using default API client. This might not work.")
	}

	// This creates a client, first loading any specified kubeconfig
	// file, and then overriding the Master flag, if non-empty.
	kubeConfig, err := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
		&clientcmd.ClientConfigLoadingRules{ExplicitPath: config.Kubeconfig},
		&clientcmd.ConfigOverrides{ClusterInfo: clientcmdapi.Cluster{Server: masterOverride}}).ClientConfig()
	if err != nil {
		return nil, nil, nil, err
	}

	kubeConfig.AcceptContentTypes = config.AcceptContentTypes
	kubeConfig.ContentType = config.ContentType
	kubeConfig.QPS = config.QPS
	//TODO make config struct use int instead of int32?
	kubeConfig.Burst = int(config.Burst)

	client, err := clientset.NewForConfig(restclient.AddUserAgent(kubeConfig, "scheduler"))
	if err != nil {
		return nil, nil, nil, err
	}

	// shallow copy, do not modify the kubeConfig.Timeout.
	restConfig := *kubeConfig
	restConfig.Timeout = timeout
	leaderElectionClient, err := clientset.NewForConfig(restclient.AddUserAgent(&restConfig, "leader-election"))
	if err != nil {
		return nil, nil, nil, err
	}

	eventClient, err := clientset.NewForConfig(kubeConfig)
	if err != nil {
		return nil, nil, nil, err
	}

	return client, leaderElectionClient, eventClient.CoreV1(), nil
}