/*
Copyright 2017 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 phases

import (
	"fmt"
	"strings"

	"github.com/spf13/cobra"

	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
	kubeadmscheme "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/scheme"
	kubeadmapiv1alpha3 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha3"
	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
	certscmdphase "k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/certs"
	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
	certsphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/certs"
	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
	configutil "k8s.io/kubernetes/cmd/kubeadm/app/util/config"
	"k8s.io/kubernetes/pkg/util/normalizer"
)

var (
	allCertsLongDesc = normalizer.LongDesc(`
		Generates a self-signed CA to provision identities for each component in the cluster (including nodes)
		and client certificates to be used by various components.

		If a given certificate and private key pair both exist, kubeadm skips the generation step and
		existing files will be used.
		` + cmdutil.AlphaDisclaimer)

	allCertsExample = normalizer.Examples(`
		# Creates all PKI assets necessary to establish the control plane,
		# functionally equivalent to what generated by kubeadm init.
		kubeadm alpha phase certs all

		# Creates all PKI assets using options read from a configuration file.
		kubeadm alpha phase certs all --config masterconfiguration.yaml
		`)

	saKeyLongDesc = fmt.Sprintf(normalizer.LongDesc(`
		Generates the private key for signing service account tokens along with its public key, and saves them into
		%s and %s files.
		If both files already exist, kubeadm skips the generation step and existing files will be used.
		`+cmdutil.AlphaDisclaimer), kubeadmconstants.ServiceAccountPrivateKeyName, kubeadmconstants.ServiceAccountPublicKeyName)

	genericLongDesc = normalizer.LongDesc(`
		Generates the %[1]s, and saves them into %[2]s.cert and %[2]s.key files.%[3]s

		If both files already exist, kubeadm skips the generation step and existing files will be used.
		` + cmdutil.AlphaDisclaimer)
)

// NewCmdCerts returns main command for certs phase
func NewCmdCerts() *cobra.Command {
	cmd := &cobra.Command{
		Use:     "certs",
		Aliases: []string{"certificates"},
		Short:   "Generates certificates for a Kubernetes cluster",
		Long:    cmdutil.MacroCommandLongDescription,
	}

	cmd.AddCommand(getCertsSubCommands("")...)
	return cmd
}

// getCertsSubCommands returns sub commands for certs phase
func getCertsSubCommands(defaultKubernetesVersion string) []*cobra.Command {

	cfg := &kubeadmapiv1alpha3.InitConfiguration{}

	// Default values for the cobra help text
	kubeadmscheme.Scheme.Default(cfg)

	var cfgPath string

	// Special case commands
	// All runs CreatePKIAssets, which isn't a particular certificate
	allCmd := &cobra.Command{
		Use:     "all",
		Short:   "Generates all PKI assets necessary to establish the control plane",
		Long:    allCertsLongDesc,
		Example: allCertsExample,
		Run: func(cmd *cobra.Command, args []string) {
			internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(cfgPath, cfg)
			kubeadmutil.CheckErr(err)

			err = certsphase.CreatePKIAssets(internalcfg)
			kubeadmutil.CheckErr(err)
		},
	}
	addFlags(allCmd, &cfgPath, cfg, true)

	// SA creates the private/public key pair, which doesn't use x509 at all
	saCmd := &cobra.Command{
		Use:   "sa",
		Short: "Generates a private key for signing service account tokens along with its public key",
		Long:  saKeyLongDesc,
		Run: func(cmd *cobra.Command, args []string) {
			internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(cfgPath, cfg)
			kubeadmutil.CheckErr(err)

			err = certsphase.CreateServiceAccountKeyAndPublicKeyFiles(internalcfg)
			kubeadmutil.CheckErr(err)
		},
	}
	addFlags(saCmd, &cfgPath, cfg, false)

	// "renew" command
	renewCmd := certscmdphase.NewCmdCertsRenewal()

	subCmds := []*cobra.Command{allCmd, saCmd, renewCmd}

	certTree, err := certsphase.GetDefaultCertList().AsMap().CertTree()
	kubeadmutil.CheckErr(err)

	for ca, certList := range certTree {
		// Don't use pointers from for loops, they will be rewrittenb
		caCmds := makeCommandsForCA(ca, certList, &cfgPath, cfg)
		subCmds = append(subCmds, caCmds...)
	}

	return subCmds
}

func makeCmd(certSpec *certsphase.KubeadmCert, cfgPath *string, cfg *kubeadmapiv1alpha3.InitConfiguration) *cobra.Command {
	cmd := &cobra.Command{
		Use:   certSpec.Name,
		Short: fmt.Sprintf("Generates the %s", certSpec.LongName),
		Long: fmt.Sprintf(
			genericLongDesc,
			certSpec.LongName,
			certSpec.BaseName,
			getSANDescription(certSpec),
		),
	}
	addFlags(cmd, cfgPath, cfg, certSpec.Name == "apiserver")
	// Add flags to the command
	return cmd
}

func getSANDescription(certSpec *certsphase.KubeadmCert) string {
	//Defaulted config we will use to get SAN certs
	defaultConfig := &kubeadmapiv1alpha3.InitConfiguration{
		APIEndpoint: kubeadmapiv1alpha3.APIEndpoint{
			// GetAPIServerAltNames errors without an AdvertiseAddress; this is as good as any.
			AdvertiseAddress: "127.0.0.1",
		},
	}
	defaultInternalConfig := &kubeadmapi.InitConfiguration{}

	kubeadmscheme.Scheme.Default(defaultConfig)
	kubeadmscheme.Scheme.Convert(defaultConfig, defaultInternalConfig, nil)

	certConfig, err := certSpec.GetConfig(defaultInternalConfig)
	kubeadmutil.CheckErr(err)

	if len(certConfig.AltNames.DNSNames) == 0 && len(certConfig.AltNames.IPs) == 0 {
		return ""
	}
	// This mutates the certConfig, but we're throwing it after we construct the command anyway
	sans := []string{}

	for _, dnsName := range certConfig.AltNames.DNSNames {
		if dnsName != "" {
			sans = append(sans, dnsName)
		}
	}

	for _, ip := range certConfig.AltNames.IPs {
		sans = append(sans, ip.String())
	}
	return fmt.Sprintf("\n\nDefault SANs are %s", strings.Join(sans, ", "))
}

func addFlags(cmd *cobra.Command, cfgPath *string, cfg *kubeadmapiv1alpha3.InitConfiguration, addAPIFlags bool) {
	options.AddCertificateDirFlag(cmd.Flags(), &cfg.CertificatesDir)
	options.AddConfigFlag(cmd.Flags(), cfgPath)
	if addAPIFlags {
		cmd.Flags().StringVar(&cfg.Networking.DNSDomain, "service-dns-domain", cfg.Networking.DNSDomain, "Alternative domain for services, to use for the API server serving cert")
		cmd.Flags().StringVar(&cfg.Networking.ServiceSubnet, "service-cidr", cfg.Networking.ServiceSubnet, "Alternative range of IP address for service VIPs, from which derives the internal API server VIP that will be added to the API Server serving cert")
		cmd.Flags().StringSliceVar(&cfg.APIServerCertSANs, "apiserver-cert-extra-sans", []string{}, "Optional extra altnames to use for the API server serving cert. Can be both IP addresses and DNS names")
		cmd.Flags().StringVar(&cfg.APIEndpoint.AdvertiseAddress, "apiserver-advertise-address", cfg.APIEndpoint.AdvertiseAddress, "The IP address the API server is accessible on, to use for the API server serving cert")
	}
}

func makeCommandsForCA(ca *certsphase.KubeadmCert, certList []*certsphase.KubeadmCert, cfgPath *string, cfg *kubeadmapiv1alpha3.InitConfiguration) []*cobra.Command {
	subCmds := []*cobra.Command{}

	caCmd := makeCmd(ca, cfgPath, cfg)
	caCmd.Run = func(cmd *cobra.Command, args []string) {
		internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(*cfgPath, cfg)
		kubeadmutil.CheckErr(err)

		err = certsphase.CreateCACertAndKeyFiles(ca, internalcfg)
		kubeadmutil.CheckErr(err)
	}

	subCmds = append(subCmds, caCmd)

	for _, cert := range certList {
		certCmd := makeCommandForCert(cert, ca, cfgPath, cfg)
		subCmds = append(subCmds, certCmd)
	}

	return subCmds
}

func makeCommandForCert(cert *certsphase.KubeadmCert, caCert *certsphase.KubeadmCert, cfgPath *string, cfg *kubeadmapiv1alpha3.InitConfiguration) *cobra.Command {
	certCmd := makeCmd(cert, cfgPath, cfg)

	certCmd.Run = func(cmd *cobra.Command, args []string) {
		internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(*cfgPath, cfg)
		kubeadmutil.CheckErr(err)
		err = configutil.VerifyAPIServerBindAddress(internalcfg.APIEndpoint.AdvertiseAddress)
		kubeadmutil.CheckErr(err)

		err = certsphase.CreateCertAndKeyFilesWithCA(cert, caCert, internalcfg)
		kubeadmutil.CheckErr(err)
	}

	return certCmd
}