// New creates a new WebhookAuthorizer from the provided kubeconfig file.
//
// The config's cluster field is used to refer to the remote service, user refers to the returned authorizer.
//
//     # clusters refers to the remote service.
//     clusters:
//     - name: name-of-remote-authz-service
//       cluster:
//         certificate-authority: /path/to/ca.pem      # CA for verifying the remote service.
//         server: https://authz.example.com/authorize # URL of remote service to query. Must use 'https'.
//
//     # users refers to the API server's webhook configuration.
//     users:
//     - name: name-of-api-server
//       user:
//         client-certificate: /path/to/cert.pem # cert for the webhook plugin to use
//         client-key: /path/to/key.pem          # key matching the cert
//
// For additional HTTP configuration, refer to the kubeconfig documentation
// http://kubernetes.io/v1.1/docs/user-guide/kubeconfig-file.html.
func New(kubeConfigFile string) (*WebhookAuthorizer, error) {

	for _, groupVersion := range requireEnabled {
		if !registered.IsEnabledVersion(groupVersion) {
			return nil, fmt.Errorf("webhook authz plugin requires enabling extension resource: %s", groupVersion)
		}
	}

	loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
	loadingRules.ExplicitPath = kubeConfigFile
	loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, &clientcmd.ConfigOverrides{})

	clientConfig, err := loader.ClientConfig()
	if err != nil {
		return nil, err
	}
	serializer := json.NewSerializer(json.DefaultMetaFactory, api.Scheme, runtime.ObjectTyperToTyper(api.Scheme), false)
	clientConfig.ContentConfig.Codec = versioning.NewCodecForScheme(api.Scheme, serializer, serializer, encodeVersions, decodeVersions)

	restClient, err := restclient.UnversionedRESTClientFor(clientConfig)
	if err != nil {
		return nil, err
	}

	// TODO(ericchiang): Can we ensure remote service is reachable?

	return &WebhookAuthorizer{restClient}, nil
}

// NewGenericWebhook creates a new GenericWebhook from the provided kubeconfig file.
func NewGenericWebhook(kubeConfigFile string, groupVersions []unversioned.GroupVersion, initialBackoff time.Duration) (*GenericWebhook, error) {
	for _, groupVersion := range groupVersions {
		if !registered.IsEnabledVersion(groupVersion) {
			return nil, fmt.Errorf("webhook plugin requires enabling extension resource: %s", groupVersion)
		}
	}

	loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
	loadingRules.ExplicitPath = kubeConfigFile
	loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, &clientcmd.ConfigOverrides{})

	clientConfig, err := loader.ClientConfig()
	if err != nil {
		return nil, err
	}
	codec := api.Codecs.LegacyCodec(groupVersions...)
	clientConfig.ContentConfig.NegotiatedSerializer = runtimeserializer.NegotiatedSerializerWrapper(
		runtime.SerializerInfo{Serializer: codec},
		runtime.StreamSerializerInfo{},
	)

	restClient, err := restclient.UnversionedRESTClientFor(clientConfig)
	if err != nil {
		return nil, err
	}

	// TODO(ericchiang): Can we ensure remote service is reachable?

	return &GenericWebhook{restClient, initialBackoff}, nil
}

// NewDiscoveryClientForConfig creates a new DiscoveryClient for the given config. This client
// can be used to discover supported resources in the API server.
func NewDiscoveryClientForConfig(c *restclient.Config) (*DiscoveryClient, error) {
	config := *c
	if err := setDiscoveryDefaults(&config); err != nil {
		return nil, err
	}
	client, err := restclient.UnversionedRESTClientFor(&config)
	return &DiscoveryClient{restClient: client, LegacyPrefix: "/api"}, err
}