/*
Copyright 2016 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 certificates

import (
	"context"
	"fmt"
	"io"

	"github.com/spf13/cobra"

	certificatesv1 "k8s.io/api/certificates/v1"
	certificatesv1beta1 "k8s.io/api/certificates/v1beta1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/cli-runtime/pkg/genericclioptions"
	"k8s.io/cli-runtime/pkg/printers"
	"k8s.io/cli-runtime/pkg/resource"
	clientset "k8s.io/client-go/kubernetes"
	cmdutil "k8s.io/kubectl/pkg/cmd/util"
	"k8s.io/kubectl/pkg/scheme"
	"k8s.io/kubectl/pkg/util/i18n"
	"k8s.io/kubectl/pkg/util/templates"
)

func NewCmdCertificate(f cmdutil.Factory, ioStreams genericclioptions.IOStreams) *cobra.Command {
	cmd := &cobra.Command{
		Use:                   "certificate SUBCOMMAND",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Modify certificate resources."),
		Long:                  i18n.T("Modify certificate resources."),
		Run: func(cmd *cobra.Command, args []string) {
			cmd.Help()
		},
	}

	cmd.AddCommand(NewCmdCertificateApprove(f, ioStreams))
	cmd.AddCommand(NewCmdCertificateDeny(f, ioStreams))

	return cmd
}

type CertificateOptions struct {
	resource.FilenameOptions

	PrintFlags *genericclioptions.PrintFlags
	PrintObj   printers.ResourcePrinterFunc

	csrNames    []string
	outputStyle string

	clientSet clientset.Interface
	builder   *resource.Builder

	genericclioptions.IOStreams
}

// NewCertificateOptions creates the options for certificate
func NewCertificateOptions(ioStreams genericclioptions.IOStreams, operation string) *CertificateOptions {
	return &CertificateOptions{
		PrintFlags: genericclioptions.NewPrintFlags(operation).WithTypeSetter(scheme.Scheme),
		IOStreams:  ioStreams,
	}
}

func (o *CertificateOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []string) error {
	o.csrNames = args
	o.outputStyle = cmdutil.GetFlagString(cmd, "output")

	printer, err := o.PrintFlags.ToPrinter()
	if err != nil {
		return err
	}

	o.PrintObj = func(obj runtime.Object, out io.Writer) error {
		return printer.PrintObj(obj, out)
	}

	o.builder = f.NewBuilder()

	o.clientSet, err = f.KubernetesClientSet()
	if err != nil {
		return err
	}

	return nil
}

func (o *CertificateOptions) Validate() error {
	if len(o.csrNames) < 1 && cmdutil.IsFilenameSliceEmpty(o.Filenames, o.Kustomize) {
		return fmt.Errorf("one or more CSRs must be specified as <name> or -f <filename>")
	}
	return nil
}

func NewCmdCertificateApprove(f cmdutil.Factory, ioStreams genericclioptions.IOStreams) *cobra.Command {
	o := NewCertificateOptions(ioStreams, "approved")

	cmd := &cobra.Command{
		Use:                   "approve (-f FILENAME | NAME)",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Approve a certificate signing request"),
		Long: templates.LongDesc(i18n.T(`
		Approve a certificate signing request.

		kubectl certificate approve allows a cluster admin to approve a certificate
		signing request (CSR). This action tells a certificate signing controller to
		issue a certificate to the requestor with the attributes requested in the CSR.

		SECURITY NOTICE: Depending on the requested attributes, the issued certificate
		can potentially grant a requester access to cluster resources or to authenticate
		as a requested identity. Before approving a CSR, ensure you understand what the
		signed certificate can do.
		`)),
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(o.Complete(f, cmd, args))
			cmdutil.CheckErr(o.Validate())
			cmdutil.CheckErr(o.RunCertificateApprove(cmdutil.GetFlagBool(cmd, "force")))
		},
	}

	o.PrintFlags.AddFlags(cmd)

	cmd.Flags().Bool("force", false, "Update the CSR even if it is already approved.")
	cmdutil.AddFilenameOptionFlags(cmd, &o.FilenameOptions, "identifying the resource to update")

	return cmd
}

func (o *CertificateOptions) RunCertificateApprove(force bool) error {
	return o.modifyCertificateCondition(
		o.builder,
		o.clientSet,
		force,
		addConditionIfNeeded(string(certificatesv1.CertificateDenied), string(certificatesv1.CertificateApproved), "KubectlApprove", "This CSR was approved by kubectl certificate approve."),
	)
}

func NewCmdCertificateDeny(f cmdutil.Factory, ioStreams genericclioptions.IOStreams) *cobra.Command {
	o := NewCertificateOptions(ioStreams, "denied")

	cmd := &cobra.Command{
		Use:                   "deny (-f FILENAME | NAME)",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Deny a certificate signing request"),
		Long: templates.LongDesc(i18n.T(`
		Deny a certificate signing request.

		kubectl certificate deny allows a cluster admin to deny a certificate
		signing request (CSR). This action tells a certificate signing controller to
		not to issue a certificate to the requestor.
		`)),
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(o.Complete(f, cmd, args))
			cmdutil.CheckErr(o.Validate())
			cmdutil.CheckErr(o.RunCertificateDeny(cmdutil.GetFlagBool(cmd, "force")))
		},
	}

	o.PrintFlags.AddFlags(cmd)

	cmd.Flags().Bool("force", false, "Update the CSR even if it is already denied.")
	cmdutil.AddFilenameOptionFlags(cmd, &o.FilenameOptions, "identifying the resource to update")

	return cmd
}

func (o *CertificateOptions) RunCertificateDeny(force bool) error {
	return o.modifyCertificateCondition(
		o.builder,
		o.clientSet,
		force,
		addConditionIfNeeded(string(certificatesv1.CertificateApproved), string(certificatesv1.CertificateDenied), "KubectlDeny", "This CSR was denied by kubectl certificate deny."),
	)
}

func (o *CertificateOptions) modifyCertificateCondition(builder *resource.Builder, clientSet clientset.Interface, force bool, modify func(csr runtime.Object) (runtime.Object, bool, error)) error {
	var found int
	r := builder.
		Unstructured().
		ContinueOnError().
		FilenameParam(false, &o.FilenameOptions).
		ResourceNames("certificatesigningrequests", o.csrNames...).
		RequireObject(true).
		Flatten().
		Latest().
		Do()
	err := r.Visit(func(info *resource.Info, err error) error {
		if err != nil {
			return err
		}
		for i := 0; ; i++ {
			obj, ok := info.Object.(*unstructured.Unstructured)
			if !ok {
				return fmt.Errorf("expected *unstructured.Unstructured, got %T", obj)
			}
			if want, got := certificatesv1.Kind("CertificateSigningRequest"), obj.GetObjectKind().GroupVersionKind().GroupKind(); want != got {
				return fmt.Errorf("can only handle %s objects, got %s", want.String(), got.String())
			}
			var csr runtime.Object
			// get a typed object
			// first try v1
			csr, err = clientSet.CertificatesV1().CertificateSigningRequests().Get(context.TODO(), obj.GetName(), metav1.GetOptions{})
			if apierrors.IsNotFound(err) {
				// fall back to v1beta1
				csr, err = clientSet.CertificatesV1beta1().CertificateSigningRequests().Get(context.TODO(), obj.GetName(), metav1.GetOptions{})
			}
			if apierrors.IsNotFound(err) {
				return fmt.Errorf("could not find v1 or v1beta1 version of %s: %v", obj.GetName(), err)
			}
			if err != nil {
				return err
			}

			modifiedCSR, hasCondition, err := modify(csr)
			if err != nil {
				return err
			}
			if !hasCondition || force {
				switch modifiedCSR := modifiedCSR.(type) {
				case *certificatesv1.CertificateSigningRequest:
					_, err = clientSet.CertificatesV1().CertificateSigningRequests().UpdateApproval(context.TODO(), modifiedCSR.Name, modifiedCSR, metav1.UpdateOptions{})
				case *certificatesv1beta1.CertificateSigningRequest:
					_, err = clientSet.CertificatesV1beta1().CertificateSigningRequests().UpdateApproval(context.TODO(), modifiedCSR, metav1.UpdateOptions{})
				default:
					return fmt.Errorf("can only handle certificates.k8s.io CertificateSigningRequest objects, got %T", modifiedCSR)
				}
				if errors.IsConflict(err) && i < 10 {
					if err := info.Get(); err != nil {
						return err
					}
					continue
				}
				if err != nil {
					return err
				}
			}
			break
		}
		found++

		return o.PrintObj(info.Object, o.Out)
	})
	if found == 0 && err == nil {
		fmt.Fprintf(o.Out, "No resources found\n")
	}
	return err
}

func addConditionIfNeeded(mustNotHaveConditionType, conditionType, reason, message string) func(runtime.Object) (runtime.Object, bool, error) {
	return func(csr runtime.Object) (runtime.Object, bool, error) {
		switch csr := csr.(type) {
		case *certificatesv1.CertificateSigningRequest:
			var alreadyHasCondition bool
			for _, c := range csr.Status.Conditions {
				if string(c.Type) == mustNotHaveConditionType {
					return nil, false, fmt.Errorf("certificate signing request %q is already %s", csr.Name, c.Type)
				}
				if string(c.Type) == conditionType {
					alreadyHasCondition = true
				}
			}
			if alreadyHasCondition {
				return csr, true, nil
			}
			csr.Status.Conditions = append(csr.Status.Conditions, certificatesv1.CertificateSigningRequestCondition{
				Type:           certificatesv1.RequestConditionType(conditionType),
				Status:         corev1.ConditionTrue,
				Reason:         reason,
				Message:        message,
				LastUpdateTime: metav1.Now(),
			})
			return csr, false, nil

		case *certificatesv1beta1.CertificateSigningRequest:
			var alreadyHasCondition bool
			for _, c := range csr.Status.Conditions {
				if string(c.Type) == mustNotHaveConditionType {
					return nil, false, fmt.Errorf("certificate signing request %q is already %s", csr.Name, c.Type)
				}
				if string(c.Type) == conditionType {
					alreadyHasCondition = true
				}
			}
			if alreadyHasCondition {
				return csr, true, nil
			}
			csr.Status.Conditions = append(csr.Status.Conditions, certificatesv1beta1.CertificateSigningRequestCondition{
				Type:           certificatesv1beta1.RequestConditionType(conditionType),
				Status:         corev1.ConditionTrue,
				Reason:         reason,
				Message:        message,
				LastUpdateTime: metav1.Now(),
			})
			return csr, false, nil

		default:
			return csr, false, nil
		}
	}
}
