package clientcmd

import (
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/emicklei/go-restful/swagger"
	"github.com/golang/glog"
	"github.com/spf13/pflag"

	"k8s.io/kubernetes/pkg/api"
	kerrors "k8s.io/kubernetes/pkg/api/errors"
	"k8s.io/kubernetes/pkg/api/meta"
	"k8s.io/kubernetes/pkg/api/unversioned"
	"k8s.io/kubernetes/pkg/apimachinery/registered"
	"k8s.io/kubernetes/pkg/client/restclient"
	kclient "k8s.io/kubernetes/pkg/client/unversioned"
	kclientcmd "k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
	kclientcmdapi "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
	"k8s.io/kubernetes/pkg/kubectl"
	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
	"k8s.io/kubernetes/pkg/kubectl/resource"
	"k8s.io/kubernetes/pkg/labels"
	"k8s.io/kubernetes/pkg/runtime"
	"k8s.io/kubernetes/pkg/util/homedir"
	"k8s.io/kubernetes/pkg/util/sets"

	"github.com/openshift/origin/pkg/api/latest"
	authorizationapi "github.com/openshift/origin/pkg/authorization/api"
	authorizationreaper "github.com/openshift/origin/pkg/authorization/reaper"
	buildapi "github.com/openshift/origin/pkg/build/api"
	buildreaper "github.com/openshift/origin/pkg/build/reaper"
	buildutil "github.com/openshift/origin/pkg/build/util"
	"github.com/openshift/origin/pkg/client"
	"github.com/openshift/origin/pkg/cmd/cli/describe"
	deployapi "github.com/openshift/origin/pkg/deploy/api"
	deploygen "github.com/openshift/origin/pkg/deploy/generator"
	deployreaper "github.com/openshift/origin/pkg/deploy/reaper"
	deployscaler "github.com/openshift/origin/pkg/deploy/scaler"
	deployutil "github.com/openshift/origin/pkg/deploy/util"
	routegen "github.com/openshift/origin/pkg/route/generator"
	userapi "github.com/openshift/origin/pkg/user/api"
	authenticationreaper "github.com/openshift/origin/pkg/user/reaper"
)

// New creates a default Factory for commands that should share identical server
// connection behavior. Most commands should use this method to get a factory.
func New(flags *pflag.FlagSet) *Factory {
	// TODO refactor this upstream:
	// DefaultCluster should not be a global
	// A call to ClientConfig() should always return the best clientCfg possible
	// even if an error was returned, and let the caller decide what to do
	kclientcmd.DefaultCluster.Server = ""

	// TODO: there should be two client configs, one for OpenShift, and one for Kubernetes
	clientConfig := DefaultClientConfig(flags)
	clientConfig = defaultingClientConfig{clientConfig}
	f := NewFactory(clientConfig)
	f.BindFlags(flags)

	return f
}

// defaultingClientConfig detects whether the provided config is the default, and if
// so returns an error that indicates the user should set up their config.
type defaultingClientConfig struct {
	nested kclientcmd.ClientConfig
}

// RawConfig calls the nested method
func (c defaultingClientConfig) RawConfig() (kclientcmdapi.Config, error) {
	return c.nested.RawConfig()
}

// Namespace calls the nested method, and if an empty config error is returned
// it checks for the same default as kubectl - the value of POD_NAMESPACE or
// "default".
func (c defaultingClientConfig) Namespace() (string, bool, error) {
	namespace, ok, err := c.nested.Namespace()
	if err == nil {
		return namespace, ok, nil
	}
	if !kclientcmd.IsEmptyConfig(err) {
		return "", false, err
	}

	// This way assumes you've set the POD_NAMESPACE environment variable using the downward API.
	// This check has to be done first for backwards compatibility with the way InClusterConfig was originally set up
	if ns := os.Getenv("POD_NAMESPACE"); ns != "" {
		return ns, true, nil
	}

	// Fall back to the namespace associated with the service account token, if available
	if data, err := ioutil.ReadFile("/var/run/secrets/kubernetes.io/serviceaccount/namespace"); err == nil {
		if ns := strings.TrimSpace(string(data)); len(ns) > 0 {
			return ns, true, nil
		}
	}

	return api.NamespaceDefault, false, nil
}

// ClientConfig returns a complete client config
func (c defaultingClientConfig) ClientConfig() (*restclient.Config, error) {
	cfg, err := c.nested.ClientConfig()
	if err == nil {
		return cfg, nil
	}

	if !kclientcmd.IsEmptyConfig(err) {
		return nil, err
	}

	// TODO: need to expose inClusterConfig upstream and use that
	if icc, err := restclient.InClusterConfig(); err == nil {
		glog.V(4).Infof("Using in-cluster configuration")
		return icc, nil
	}

	return nil, fmt.Errorf(`No configuration file found, please login or point to an existing file:

  1. Via the command-line flag --config
  2. Via the KUBECONFIG environment variable
  3. In your home directory as ~/.kube/config

To view or setup config directly use the 'config' command.`)
}

// Factory provides common options for OpenShift commands
type Factory struct {
	*cmdutil.Factory
	OpenShiftClientConfig kclientcmd.ClientConfig
	clients               *clientCache
}

func DefaultGenerators(cmdName string) map[string]kubectl.Generator {
	generators := map[string]map[string]kubectl.Generator{}
	generators["run"] = map[string]kubectl.Generator{
		"run/v1":            deploygen.BasicDeploymentConfigController{},
		"run-controller/v1": kubectl.BasicReplicationController{},
	}
	generators["expose"] = map[string]kubectl.Generator{
		"route/v1": routegen.RouteGenerator{},
	}

	return generators[cmdName]
}

// NewFactory creates an object that holds common methods across all OpenShift commands
func NewFactory(clientConfig kclientcmd.ClientConfig) *Factory {
	var restMapper meta.MultiRESTMapper
	seenGroups := sets.String{}
	for _, gv := range registered.EnabledVersions() {
		if seenGroups.Has(gv.Group) {
			continue
		}
		seenGroups.Insert(gv.Group)

		groupMeta, err := registered.Group(gv.Group)
		if err != nil {
			continue
		}
		restMapper = meta.MultiRESTMapper(append(restMapper, groupMeta.RESTMapper))
	}

	clients := &clientCache{
		clients: make(map[string]*client.Client),
		configs: make(map[string]*restclient.Config),
		loader:  clientConfig,
	}

	w := &Factory{
		Factory:               cmdutil.NewFactory(clientConfig),
		OpenShiftClientConfig: clientConfig,
		clients:               clients,
	}

	w.Object = func() (meta.RESTMapper, runtime.ObjectTyper) {

		defaultMapper := ShortcutExpander{RESTMapper: kubectl.ShortcutExpander{RESTMapper: restMapper}}
		defaultTyper := api.Scheme

		// Output using whatever version was negotiated in the client cache. The
		// version we decode with may not be the same as what the server requires.
		cfg, err := clients.ClientConfigForVersion(nil)
		if err != nil {
			return defaultMapper, defaultTyper
		}

		cmdApiVersion := unversioned.GroupVersion{}
		if cfg.GroupVersion != nil {
			cmdApiVersion = *cfg.GroupVersion
		}

		// at this point we've negotiated and can get the client
		oclient, err := clients.ClientForVersion(nil)
		if err != nil {
			return defaultMapper, defaultTyper
		}

		cacheDir := computeDiscoverCacheDir(filepath.Join(homedir.HomeDir(), ".kube"), cfg.Host)
		cachedDiscoverClient := NewCachedDiscoveryClient(client.NewDiscoveryClient(oclient.RESTClient), cacheDir, time.Duration(10*time.Minute))
		mapper := NewShortcutExpander(cachedDiscoverClient, kubectl.ShortcutExpander{RESTMapper: restMapper})
		return kubectl.OutputVersionMapper{RESTMapper: mapper, OutputVersions: []unversioned.GroupVersion{cmdApiVersion}}, api.Scheme
	}

	kClientForMapping := w.Factory.ClientForMapping
	w.ClientForMapping = func(mapping *meta.RESTMapping) (resource.RESTClient, error) {
		if latest.OriginKind(mapping.GroupVersionKind) {
			mappingVersion := mapping.GroupVersionKind.GroupVersion()
			client, err := clients.ClientForVersion(&mappingVersion)
			if err != nil {
				return nil, err
			}
			return client.RESTClient, nil
		}
		return kClientForMapping(mapping)
	}

	// Save original Describer function
	kDescriberFunc := w.Factory.Describer
	w.Describer = func(mapping *meta.RESTMapping) (kubectl.Describer, error) {
		if latest.OriginKind(mapping.GroupVersionKind) {
			oClient, kClient, err := w.Clients()
			if err != nil {
				return nil, fmt.Errorf("unable to create client %s: %v", mapping.GroupVersionKind.Kind, err)
			}

			mappingVersion := mapping.GroupVersionKind.GroupVersion()
			cfg, err := clients.ClientConfigForVersion(&mappingVersion)
			if err != nil {
				return nil, fmt.Errorf("unable to load a client %s: %v", mapping.GroupVersionKind.Kind, err)
			}

			describer, ok := describe.DescriberFor(mapping.GroupVersionKind.GroupKind(), oClient, kClient, cfg.Host)
			if !ok {
				return nil, fmt.Errorf("no description has been implemented for %q", mapping.GroupVersionKind.Kind)
			}
			return describer, nil
		}
		return kDescriberFunc(mapping)
	}
	kScalerFunc := w.Factory.Scaler
	w.Scaler = func(mapping *meta.RESTMapping) (kubectl.Scaler, error) {
		oc, kc, err := w.Clients()
		if err != nil {
			return nil, err
		}

		if mapping.GroupVersionKind.GroupKind() == deployapi.Kind("DeploymentConfig") {
			return deployscaler.NewDeploymentConfigScaler(oc, kc), nil
		}
		return kScalerFunc(mapping)
	}
	kReaperFunc := w.Factory.Reaper
	w.Reaper = func(mapping *meta.RESTMapping) (kubectl.Reaper, error) {
		oc, kc, err := w.Clients()
		if err != nil {
			return nil, err
		}

		switch mapping.GroupVersionKind.GroupKind() {
		case deployapi.Kind("DeploymentConfig"):
			return deployreaper.NewDeploymentConfigReaper(oc, kc), nil
		case authorizationapi.Kind("Role"):
			return authorizationreaper.NewRoleReaper(oc, oc), nil
		case authorizationapi.Kind("ClusterRole"):
			return authorizationreaper.NewClusterRoleReaper(oc, oc, oc), nil
		case userapi.Kind("User"):
			return authenticationreaper.NewUserReaper(
				client.UsersInterface(oc),
				client.GroupsInterface(oc),
				client.ClusterRoleBindingsInterface(oc),
				client.RoleBindingsNamespacer(oc),
				kclient.SecurityContextConstraintsInterface(kc),
			), nil
		case userapi.Kind("Group"):
			return authenticationreaper.NewGroupReaper(
				client.GroupsInterface(oc),
				client.ClusterRoleBindingsInterface(oc),
				client.RoleBindingsNamespacer(oc),
				kclient.SecurityContextConstraintsInterface(kc),
			), nil
		case buildapi.Kind("BuildConfig"):
			return buildreaper.NewBuildConfigReaper(oc), nil
		}
		return kReaperFunc(mapping)
	}
	kGenerators := w.Factory.Generators
	w.Generators = func(cmdName string) map[string]kubectl.Generator {
		originGenerators := DefaultGenerators(cmdName)
		kubeGenerators := kGenerators(cmdName)

		ret := map[string]kubectl.Generator{}
		for k, v := range kubeGenerators {
			ret[k] = v
		}
		for k, v := range originGenerators {
			ret[k] = v
		}
		return ret
	}
	kPodSelectorForObjectFunc := w.Factory.PodSelectorForObject
	w.PodSelectorForObject = func(object runtime.Object) (string, error) {
		switch t := object.(type) {
		case *deployapi.DeploymentConfig:
			return kubectl.MakeLabels(t.Spec.Selector), nil
		default:
			return kPodSelectorForObjectFunc(object)
		}
	}

	kMapBasedSelectorForObjectFunc := w.Factory.MapBasedSelectorForObject
	w.MapBasedSelectorForObject = func(object runtime.Object) (string, error) {
		switch t := object.(type) {
		case *deployapi.DeploymentConfig:
			return kubectl.MakeLabels(t.Spec.Selector), nil
		default:
			return kMapBasedSelectorForObjectFunc(object)
		}

	}

	kPortsForObjectFunc := w.Factory.PortsForObject
	w.PortsForObject = func(object runtime.Object) ([]string, error) {
		switch t := object.(type) {
		case *deployapi.DeploymentConfig:
			return getPorts(t.Spec.Template.Spec), nil
		default:
			return kPortsForObjectFunc(object)
		}
	}
	kLogsForObjectFunc := w.Factory.LogsForObject
	w.LogsForObject = func(object, options runtime.Object) (*restclient.Request, error) {
		oc, _, err := w.Clients()
		if err != nil {
			return nil, err
		}

		switch t := object.(type) {
		case *deployapi.DeploymentConfig:
			dopts, ok := options.(*deployapi.DeploymentLogOptions)
			if !ok {
				return nil, errors.New("provided options object is not a DeploymentLogOptions")
			}
			return oc.DeploymentLogs(t.Namespace).Get(t.Name, *dopts), nil
		case *buildapi.Build:
			bopts, ok := options.(*buildapi.BuildLogOptions)
			if !ok {
				return nil, errors.New("provided options object is not a BuildLogOptions")
			}
			if bopts.Version != nil {
				return nil, errors.New("cannot specify a version and a build")
			}
			return oc.BuildLogs(t.Namespace).Get(t.Name, *bopts), nil
		case *buildapi.BuildConfig:
			bopts, ok := options.(*buildapi.BuildLogOptions)
			if !ok {
				return nil, errors.New("provided options object is not a BuildLogOptions")
			}
			builds, err := oc.Builds(t.Namespace).List(api.ListOptions{})
			if err != nil {
				return nil, err
			}
			builds.Items = buildapi.FilterBuilds(builds.Items, buildapi.ByBuildConfigLabelPredicate(t.Name))
			if len(builds.Items) == 0 {
				return nil, fmt.Errorf("no builds found for %q", t.Name)
			}
			if bopts.Version != nil {
				// If a version has been specified, try to get the logs from that build.
				desired := buildutil.BuildNameForConfigVersion(t.Name, int(*bopts.Version))
				return oc.BuildLogs(t.Namespace).Get(desired, *bopts), nil
			}
			sort.Sort(sort.Reverse(buildapi.BuildSliceByCreationTimestamp(builds.Items)))
			return oc.BuildLogs(t.Namespace).Get(builds.Items[0].Name, *bopts), nil
		default:
			return kLogsForObjectFunc(object, options)
		}
	}
	w.Printer = func(mapping *meta.RESTMapping, noHeaders, withNamespace, wide bool, showAll bool, showLabels, absoluteTimestamps bool, columnLabels []string) (kubectl.ResourcePrinter, error) {
		return describe.NewHumanReadablePrinter(noHeaders, withNamespace, wide, showAll, showLabels, absoluteTimestamps, columnLabels), nil
	}
	kCanBeExposed := w.Factory.CanBeExposed
	w.CanBeExposed = func(kind unversioned.GroupKind) error {
		if kind == deployapi.Kind("DeploymentConfig") {
			return nil
		}
		return kCanBeExposed(kind)
	}
	kCanBeAutoscaled := w.Factory.CanBeAutoscaled
	w.CanBeAutoscaled = func(kind unversioned.GroupKind) error {
		if kind == deployapi.Kind("DeploymentConfig") {
			return nil
		}
		return kCanBeAutoscaled(kind)
	}
	kAttachablePodForObjectFunc := w.Factory.AttachablePodForObject
	w.AttachablePodForObject = func(object runtime.Object) (*api.Pod, error) {
		oc, kc, err := w.Clients()
		if err != nil {
			return nil, err
		}
		switch t := object.(type) {
		case *deployapi.DeploymentConfig:
			var err error
			var pods *api.PodList
			for pods == nil || len(pods.Items) == 0 {
				if t.Status.LatestVersion == 0 {
					time.Sleep(2 * time.Second)
				}
				if t, err = oc.DeploymentConfigs(t.Namespace).Get(t.Name); err != nil {
					return nil, err
				}
				latestDeploymentName := deployutil.LatestDeploymentNameForConfig(t)
				deployment, err := kc.ReplicationControllers(t.Namespace).Get(latestDeploymentName)
				if err != nil {
					if kerrors.IsNotFound(err) {
						continue
					}
					return nil, err
				}
				pods, err = kc.Pods(deployment.Namespace).List(api.ListOptions{LabelSelector: labels.SelectorFromSet(deployment.Spec.Selector)})
				if err != nil {
					return nil, err
				}
				if len(pods.Items) == 0 {
					time.Sleep(2 * time.Second)
				}
			}
			var oldestPod *api.Pod
			for i := range pods.Items {
				pod := &pods.Items[i]
				if oldestPod == nil || pod.CreationTimestamp.Before(oldestPod.CreationTimestamp) {
					oldestPod = pod
				}
			}
			return oldestPod, nil
		default:
			return kAttachablePodForObjectFunc(object)
		}
	}
	kSwaggerSchemaFunc := w.Factory.SwaggerSchema
	w.Factory.SwaggerSchema = func(gvk unversioned.GroupVersionKind) (*swagger.ApiDeclaration, error) {
		if !latest.OriginKind(gvk) {
			return kSwaggerSchemaFunc(gvk)
		}
		// TODO: we need to register the OpenShift API under the Kube group, and start returning the OpenShift
		// group from the scheme.
		oc, _, err := w.Clients()
		if err != nil {
			return nil, err
		}
		return w.OriginSwaggerSchema(oc.RESTClient, gvk.GroupVersion())
	}

	w.EditorEnvs = func() []string {
		return []string{"OC_EDITOR", "EDITOR"}
	}

	return w
}

// overlyCautiousIllegalFileCharacters matches characters that *might* not be supported.  Windows is really restrictive, so this is really restrictive
var overlyCautiousIllegalFileCharacters = regexp.MustCompile(`[^(\w/\.)]`)

// computeDiscoverCacheDir takes the parentDir and the host and comes up with a "usually non-colliding" name.
func computeDiscoverCacheDir(parentDir, host string) string {
	// strip the optional scheme from host if its there:
	schemelessHost := strings.Replace(strings.Replace(host, "https://", "", 1), "http://", "", 1)
	// now do a simple collapse of non-AZ09 characters.  Collisions are possible but unlikely.  Even if we do collide the problem is short lived
	safeHost := overlyCautiousIllegalFileCharacters.ReplaceAllString(schemelessHost, "_")

	return filepath.Join(parentDir, safeHost)
}

func getPorts(spec api.PodSpec) []string {
	result := []string{}
	for _, container := range spec.Containers {
		for _, port := range container.Ports {
			result = append(result, strconv.Itoa(port.ContainerPort))
		}
	}
	return result
}

// UpdateObjectEnvironment update the environment variables in object specification.
func (f *Factory) UpdateObjectEnvironment(obj runtime.Object, fn func(*[]api.EnvVar) error) (bool, error) {
	switch t := obj.(type) {
	case *buildapi.BuildConfig:
		if t.Spec.Strategy.CustomStrategy != nil {
			return true, fn(&t.Spec.Strategy.CustomStrategy.Env)
		}
		if t.Spec.Strategy.SourceStrategy != nil {
			return true, fn(&t.Spec.Strategy.SourceStrategy.Env)
		}
		if t.Spec.Strategy.DockerStrategy != nil {
			return true, fn(&t.Spec.Strategy.DockerStrategy.Env)
		}
	}
	return false, fmt.Errorf("object does not contain any environment variables")
}

// UpdatePodSpecForObject update the pod specification for the provided object
// TODO: move to upstream
func (f *Factory) UpdatePodSpecForObject(obj runtime.Object, fn func(*api.PodSpec) error) (bool, error) {
	// TODO: replace with a swagger schema based approach (identify pod template via schema introspection)
	switch t := obj.(type) {
	case *api.Pod:
		return true, fn(&t.Spec)
	case *api.PodTemplate:
		return true, fn(&t.Template.Spec)
	case *api.ReplicationController:
		if t.Spec.Template == nil {
			t.Spec.Template = &api.PodTemplateSpec{}
		}
		return true, fn(&t.Spec.Template.Spec)
	case *deployapi.DeploymentConfig:
		template := t.Spec.Template
		if template == nil {
			template = &api.PodTemplateSpec{}
		}
		return true, fn(&template.Spec)
	default:
		return false, fmt.Errorf("the object is not a pod or does not have a pod template")
	}
}

// ApproximatePodTemplateForObject returns a pod template object for the provided source.
// It may return both an error and a object. It attempt to return the best possible template
// avaliable at the current time.
func (w *Factory) ApproximatePodTemplateForObject(object runtime.Object) (*api.PodTemplateSpec, error) {
	switch t := object.(type) {
	case *deployapi.DeploymentConfig:
		fallback := t.Spec.Template

		_, kc, err := w.Clients()
		if err != nil {
			return fallback, err
		}

		latestDeploymentName := deployutil.LatestDeploymentNameForConfig(t)
		deployment, err := kc.ReplicationControllers(t.Namespace).Get(latestDeploymentName)
		if err != nil {
			return fallback, err
		}

		fallback = deployment.Spec.Template

		pods, err := kc.Pods(deployment.Namespace).List(api.ListOptions{LabelSelector: labels.SelectorFromSet(deployment.Spec.Selector)})
		if err != nil {
			return fallback, err
		}

		for i := range pods.Items {
			pod := &pods.Items[i]
			if fallback == nil || pod.CreationTimestamp.Before(fallback.CreationTimestamp) {
				fallback = &api.PodTemplateSpec{
					ObjectMeta: pod.ObjectMeta,
					Spec:       pod.Spec,
				}
			}
		}
		return fallback, nil

	default:
		pod, err := w.AttachablePodForObject(object)
		if pod != nil {
			return &api.PodTemplateSpec{
				ObjectMeta: pod.ObjectMeta,
				Spec:       pod.Spec,
			}, err
		}
		return nil, err
	}
}

// Clients returns an OpenShift and Kubernetes client.
func (f *Factory) Clients() (*client.Client, *kclient.Client, error) {
	kClient, err := f.Client()
	if err != nil {
		return nil, nil, err
	}
	osClient, err := f.clients.ClientForVersion(nil)
	if err != nil {
		return nil, nil, err
	}
	return osClient, kClient, nil
}

// OriginSwaggerSchema returns a swagger API doc for an Origin schema under the /oapi prefix.
func (f *Factory) OriginSwaggerSchema(client *restclient.RESTClient, version unversioned.GroupVersion) (*swagger.ApiDeclaration, error) {
	if version.IsEmpty() {
		return nil, fmt.Errorf("groupVersion cannot be empty")
	}
	body, err := client.Get().AbsPath("/").Suffix("swaggerapi", "oapi", version.Version).Do().Raw()
	if err != nil {
		return nil, err
	}
	var schema swagger.ApiDeclaration
	err = json.Unmarshal(body, &schema)
	if err != nil {
		return nil, fmt.Errorf("got '%s': %v", string(body), err)
	}
	return &schema, nil
}

// clientCache caches previously loaded clients for reuse. This is largely
// copied from upstream (because of typing) but reuses the negotiation logic.
// TODO: Consolidate this entire concept with upstream's ClientCache.
type clientCache struct {
	loader        kclientcmd.ClientConfig
	clients       map[string]*client.Client
	configs       map[string]*restclient.Config
	defaultConfig *restclient.Config
	// negotiatingClient is used only for negotiating versions with the server.
	negotiatingClient *kclient.Client
}

// ClientConfigForVersion returns the correct config for a server
func (c *clientCache) ClientConfigForVersion(version *unversioned.GroupVersion) (*restclient.Config, error) {
	if c.defaultConfig == nil {
		config, err := c.loader.ClientConfig()
		if err != nil {
			return nil, err
		}
		c.defaultConfig = config
	}
	// TODO: have a better config copy method
	cacheKey := ""
	if version != nil {
		cacheKey = version.String()
	}
	if config, ok := c.configs[cacheKey]; ok {
		return config, nil
	}
	if c.negotiatingClient == nil {
		// TODO: We want to reuse the upstream negotiation logic, which is coupled
		// to a concrete kube Client. The negotiation will ultimately try and
		// build an unversioned URL using the config prefix to ask for supported
		// server versions. If we use the default kube client config, the prefix
		// will be /api, while we need to use the OpenShift prefix to ask for the
		// OpenShift server versions. For now, set OpenShift defaults on the
		// config to ensure the right prefix gets used. The client cache and
		// negotiation logic should be refactored upstream to support downstream
		// reuse so that we don't need to do any of this cache or negotiation
		// duplication.
		negotiatingConfig := *c.defaultConfig
		client.SetOpenShiftDefaults(&negotiatingConfig)
		negotiatingClient, err := kclient.New(&negotiatingConfig)
		if err != nil {
			return nil, err
		}
		c.negotiatingClient = negotiatingClient
	}
	config := *c.defaultConfig
	negotiatedVersion, err := negotiateVersion(c.negotiatingClient, &config, version, latest.Versions)
	if err != nil {
		return nil, err
	}
	config.GroupVersion = negotiatedVersion
	client.SetOpenShiftDefaults(&config)
	c.configs[cacheKey] = &config

	// `version` does not necessarily equal `config.Version`.  However, we know that we call this method again with
	// `config.Version`, we should get the the config we've just built.
	configCopy := config
	c.configs[config.GroupVersion.String()] = &configCopy

	return &config, nil
}

// ClientForVersion initializes or reuses a client for the specified version, or returns an
// error if that is not possible
func (c *clientCache) ClientForVersion(version *unversioned.GroupVersion) (*client.Client, error) {
	cacheKey := ""
	if version != nil {
		cacheKey = version.String()
	}
	if client, ok := c.clients[cacheKey]; ok {
		return client, nil
	}
	config, err := c.ClientConfigForVersion(version)
	if err != nil {
		return nil, err
	}
	client, err := client.New(config)
	if err != nil {
		return nil, err
	}

	c.clients[config.GroupVersion.String()] = client
	return client, nil
}