/*
Copyright 2016 The Kubernetes Authors.
Copyright 2020 Authors of Arktos - file modified.

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 validation

import (
	"fmt"

	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/kubernetes/pkg/apis/certificates"
	apivalidation "k8s.io/kubernetes/pkg/apis/core/validation"
)

// validateCSR validates the signature and formatting of a base64-wrapped,
// PEM-encoded PKCS#10 certificate signing request. If this is invalid, we must
// not accept the CSR for further processing.
func validateCSR(obj *certificates.CertificateSigningRequest) error {
	csr, err := certificates.ParseCSR(obj)
	if err != nil {
		return err
	}
	// check that the signature is valid
	err = csr.CheckSignature()
	if err != nil {
		return err
	}
	return nil
}

// We don't care what you call your certificate requests.
func ValidateCertificateRequestName(name string, prefix bool) []string {
	return nil
}

func ValidateCertificateSigningRequest(csr *certificates.CertificateSigningRequest) field.ErrorList {
	isTenanted := true
	isNamespaced := false
	allErrs := apivalidation.ValidateObjectMeta(&csr.ObjectMeta, isTenanted, isNamespaced, ValidateCertificateRequestName, field.NewPath("metadata"))
	err := validateCSR(csr)

	specPath := field.NewPath("spec")

	if err != nil {
		allErrs = append(allErrs, field.Invalid(specPath.Child("request"), csr.Spec.Request, fmt.Sprintf("%v", err)))
	}
	if len(csr.Spec.Usages) == 0 {
		allErrs = append(allErrs, field.Required(specPath.Child("usages"), "usages must be provided"))
	}
	return allErrs
}

func ValidateCertificateSigningRequestUpdate(newCSR, oldCSR *certificates.CertificateSigningRequest) field.ErrorList {
	validationErrorList := ValidateCertificateSigningRequest(newCSR)
	metaUpdateErrorList := apivalidation.ValidateObjectMetaUpdate(&newCSR.ObjectMeta, &oldCSR.ObjectMeta, field.NewPath("metadata"))
	return append(validationErrorList, metaUpdateErrorList...)
}
