/*
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 validation

import (
	"fmt"
	"strings"

	genericvalidation "k8s.io/apimachinery/pkg/api/validation"
	metav1validation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/apimachinery/pkg/util/validation"
	utilvalidation "k8s.io/apimachinery/pkg/util/validation"
	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/apiserver/pkg/util/webhook"
	"k8s.io/kubernetes/pkg/apis/admissionregistration"
	"k8s.io/kubernetes/pkg/apis/admissionregistration/v1beta1"
)

func hasWildcard(slice []string) bool {
	for _, s := range slice {
		if s == "*" {
			return true
		}
	}
	return false
}

func validateResources(resources []string, fldPath *field.Path) field.ErrorList {
	var allErrors field.ErrorList
	if len(resources) == 0 {
		allErrors = append(allErrors, field.Required(fldPath, ""))
	}

	// */x
	resourcesWithWildcardSubresoures := sets.String{}
	// x/*
	subResourcesWithWildcardResource := sets.String{}
	// */*
	hasDoubleWildcard := false
	// *
	hasSingleWildcard := false
	// x
	hasResourceWithoutSubresource := false

	for i, resSub := range resources {
		if resSub == "" {
			allErrors = append(allErrors, field.Required(fldPath.Index(i), ""))
			continue
		}
		if resSub == "*/*" {
			hasDoubleWildcard = true
		}
		if resSub == "*" {
			hasSingleWildcard = true
		}
		parts := strings.SplitN(resSub, "/", 2)
		if len(parts) == 1 {
			hasResourceWithoutSubresource = resSub != "*"
			continue
		}
		res, sub := parts[0], parts[1]
		if _, ok := resourcesWithWildcardSubresoures[res]; ok {
			allErrors = append(allErrors, field.Invalid(fldPath.Index(i), resSub, fmt.Sprintf("if '%s/*' is present, must not specify %s", res, resSub)))
		}
		if _, ok := subResourcesWithWildcardResource[sub]; ok {
			allErrors = append(allErrors, field.Invalid(fldPath.Index(i), resSub, fmt.Sprintf("if '*/%s' is present, must not specify %s", sub, resSub)))
		}
		if sub == "*" {
			resourcesWithWildcardSubresoures[res] = struct{}{}
		}
		if res == "*" {
			subResourcesWithWildcardResource[sub] = struct{}{}
		}
	}
	if len(resources) > 1 && hasDoubleWildcard {
		allErrors = append(allErrors, field.Invalid(fldPath, resources, "if '*/*' is present, must not specify other resources"))
	}
	if hasSingleWildcard && hasResourceWithoutSubresource {
		allErrors = append(allErrors, field.Invalid(fldPath, resources, "if '*' is present, must not specify other resources without subresources"))
	}
	return allErrors
}

func validateResourcesNoSubResources(resources []string, fldPath *field.Path) field.ErrorList {
	var allErrors field.ErrorList
	if len(resources) == 0 {
		allErrors = append(allErrors, field.Required(fldPath, ""))
	}
	for i, resource := range resources {
		if resource == "" {
			allErrors = append(allErrors, field.Required(fldPath.Index(i), ""))
		}
		if strings.Contains(resource, "/") {
			allErrors = append(allErrors, field.Invalid(fldPath.Index(i), resource, "must not specify subresources"))
		}
	}
	if len(resources) > 1 && hasWildcard(resources) {
		allErrors = append(allErrors, field.Invalid(fldPath, resources, "if '*' is present, must not specify other resources"))
	}
	return allErrors
}

var validScopes = sets.NewString(
	string(admissionregistration.ClusterScope),
	string(admissionregistration.NamespacedScope),
	string(admissionregistration.AllScopes),
)

func validateRule(rule *admissionregistration.Rule, fldPath *field.Path, allowSubResource bool) field.ErrorList {
	var allErrors field.ErrorList
	if len(rule.APIGroups) == 0 {
		allErrors = append(allErrors, field.Required(fldPath.Child("apiGroups"), ""))
	}
	if len(rule.APIGroups) > 1 && hasWildcard(rule.APIGroups) {
		allErrors = append(allErrors, field.Invalid(fldPath.Child("apiGroups"), rule.APIGroups, "if '*' is present, must not specify other API groups"))
	}
	// Note: group could be empty, e.g., the legacy "v1" API
	if len(rule.APIVersions) == 0 {
		allErrors = append(allErrors, field.Required(fldPath.Child("apiVersions"), ""))
	}
	if len(rule.APIVersions) > 1 && hasWildcard(rule.APIVersions) {
		allErrors = append(allErrors, field.Invalid(fldPath.Child("apiVersions"), rule.APIVersions, "if '*' is present, must not specify other API versions"))
	}
	for i, version := range rule.APIVersions {
		if version == "" {
			allErrors = append(allErrors, field.Required(fldPath.Child("apiVersions").Index(i), ""))
		}
	}
	if allowSubResource {
		allErrors = append(allErrors, validateResources(rule.Resources, fldPath.Child("resources"))...)
	} else {
		allErrors = append(allErrors, validateResourcesNoSubResources(rule.Resources, fldPath.Child("resources"))...)
	}
	if rule.Scope != nil && !validScopes.Has(string(*rule.Scope)) {
		allErrors = append(allErrors, field.NotSupported(fldPath.Child("scope"), *rule.Scope, validScopes.List()))
	}
	return allErrors
}

var AcceptedAdmissionReviewVersions = []string{v1beta1.SchemeGroupVersion.Version}

func isAcceptedAdmissionReviewVersion(v string) bool {
	for _, version := range AcceptedAdmissionReviewVersions {
		if v == version {
			return true
		}
	}
	return false
}

func validateAdmissionReviewVersions(versions []string, requireRecognizedVersion bool, fldPath *field.Path) field.ErrorList {
	allErrors := field.ErrorList{}

	// Currently only v1beta1 accepted in AdmissionReviewVersions
	if len(versions) < 1 {
		allErrors = append(allErrors, field.Required(fldPath, ""))
	} else {
		seen := map[string]bool{}
		hasAcceptedVersion := false
		for i, v := range versions {
			if seen[v] {
				allErrors = append(allErrors, field.Invalid(fldPath.Index(i), v, "duplicate version"))
				continue
			}
			seen[v] = true
			for _, errString := range utilvalidation.IsDNS1035Label(v) {
				allErrors = append(allErrors, field.Invalid(fldPath.Index(i), v, errString))
			}
			if isAcceptedAdmissionReviewVersion(v) {
				hasAcceptedVersion = true
			}
		}
		if requireRecognizedVersion && !hasAcceptedVersion {
			allErrors = append(allErrors, field.Invalid(
				fldPath, versions,
				fmt.Sprintf("none of the versions accepted by this server. accepted version(s) are %v",
					strings.Join(AcceptedAdmissionReviewVersions, ", "))))
		}
	}
	return allErrors
}

func ValidateValidatingWebhookConfiguration(e *admissionregistration.ValidatingWebhookConfiguration) field.ErrorList {
	return validateValidatingWebhookConfiguration(e, true)
}

func validateValidatingWebhookConfiguration(e *admissionregistration.ValidatingWebhookConfiguration, requireRecognizedVersion bool) field.ErrorList {
	allErrors := genericvalidation.ValidateObjectMeta(&e.ObjectMeta, false, genericvalidation.NameIsDNSSubdomain, field.NewPath("metadata"))
	for i, hook := range e.Webhooks {
		allErrors = append(allErrors, validateWebhook(&hook, field.NewPath("webhooks").Index(i))...)
		allErrors = append(allErrors, validateAdmissionReviewVersions(hook.AdmissionReviewVersions, requireRecognizedVersion, field.NewPath("webhooks").Index(i).Child("admissionReviewVersions"))...)
	}
	return allErrors
}

func ValidateMutatingWebhookConfiguration(e *admissionregistration.MutatingWebhookConfiguration) field.ErrorList {
	return validateMutatingWebhookConfiguration(e, true)
}

func validateMutatingWebhookConfiguration(e *admissionregistration.MutatingWebhookConfiguration, requireRecognizedVersion bool) field.ErrorList {
	allErrors := genericvalidation.ValidateObjectMeta(&e.ObjectMeta, false, genericvalidation.NameIsDNSSubdomain, field.NewPath("metadata"))
	for i, hook := range e.Webhooks {
		allErrors = append(allErrors, validateWebhook(&hook, field.NewPath("webhooks").Index(i))...)
		allErrors = append(allErrors, validateAdmissionReviewVersions(hook.AdmissionReviewVersions, requireRecognizedVersion, field.NewPath("webhooks").Index(i).Child("admissionReviewVersions"))...)
	}
	return allErrors
}

func validateWebhook(hook *admissionregistration.Webhook, fldPath *field.Path) field.ErrorList {
	var allErrors field.ErrorList
	// hook.Name must be fully qualified
	allErrors = append(allErrors, validation.IsFullyQualifiedName(fldPath.Child("name"), hook.Name)...)

	for i, rule := range hook.Rules {
		allErrors = append(allErrors, validateRuleWithOperations(&rule, fldPath.Child("rules").Index(i))...)
	}
	if hook.FailurePolicy != nil && !supportedFailurePolicies.Has(string(*hook.FailurePolicy)) {
		allErrors = append(allErrors, field.NotSupported(fldPath.Child("failurePolicy"), *hook.FailurePolicy, supportedFailurePolicies.List()))
	}
	if hook.SideEffects != nil && !supportedSideEffectClasses.Has(string(*hook.SideEffects)) {
		allErrors = append(allErrors, field.NotSupported(fldPath.Child("sideEffects"), *hook.SideEffects, supportedSideEffectClasses.List()))
	}
	if hook.TimeoutSeconds != nil && (*hook.TimeoutSeconds > 30 || *hook.TimeoutSeconds < 1) {
		allErrors = append(allErrors, field.Invalid(fldPath.Child("timeoutSeconds"), *hook.TimeoutSeconds, "the timeout value must be between 1 and 30 seconds"))
	}

	if hook.NamespaceSelector != nil {
		allErrors = append(allErrors, metav1validation.ValidateLabelSelector(hook.NamespaceSelector, fldPath.Child("namespaceSelector"))...)
	}

	cc := hook.ClientConfig
	switch {
	case (cc.URL == nil) == (cc.Service == nil):
		allErrors = append(allErrors, field.Required(fldPath.Child("clientConfig"), "exactly one of url or service is required"))
	case cc.URL != nil:
		allErrors = append(allErrors, webhook.ValidateWebhookURL(fldPath.Child("clientConfig").Child("url"), *cc.URL, true)...)
	case cc.Service != nil:
		allErrors = append(allErrors, webhook.ValidateWebhookService(fldPath.Child("clientConfig").Child("service"), cc.Service.Name, cc.Service.Namespace, cc.Service.Path)...)
	}
	return allErrors
}

var supportedFailurePolicies = sets.NewString(
	string(admissionregistration.Ignore),
	string(admissionregistration.Fail),
)

var supportedSideEffectClasses = sets.NewString(
	string(admissionregistration.SideEffectClassUnknown),
	string(admissionregistration.SideEffectClassNone),
	string(admissionregistration.SideEffectClassSome),
	string(admissionregistration.SideEffectClassNoneOnDryRun),
)

var supportedOperations = sets.NewString(
	string(admissionregistration.OperationAll),
	string(admissionregistration.Create),
	string(admissionregistration.Update),
	string(admissionregistration.Delete),
	string(admissionregistration.Connect),
)

func hasWildcardOperation(operations []admissionregistration.OperationType) bool {
	for _, o := range operations {
		if o == admissionregistration.OperationAll {
			return true
		}
	}
	return false
}

func validateRuleWithOperations(ruleWithOperations *admissionregistration.RuleWithOperations, fldPath *field.Path) field.ErrorList {
	var allErrors field.ErrorList
	if len(ruleWithOperations.Operations) == 0 {
		allErrors = append(allErrors, field.Required(fldPath.Child("operations"), ""))
	}
	if len(ruleWithOperations.Operations) > 1 && hasWildcardOperation(ruleWithOperations.Operations) {
		allErrors = append(allErrors, field.Invalid(fldPath.Child("operations"), ruleWithOperations.Operations, "if '*' is present, must not specify other operations"))
	}
	for i, operation := range ruleWithOperations.Operations {
		if !supportedOperations.Has(string(operation)) {
			allErrors = append(allErrors, field.NotSupported(fldPath.Child("operations").Index(i), operation, supportedOperations.List()))
		}
	}
	allowSubResource := true
	allErrors = append(allErrors, validateRule(&ruleWithOperations.Rule, fldPath, allowSubResource)...)
	return allErrors
}

// hasAcceptedAdmissionReviewVersions returns true if all webhooks have at least one
// admission review version this apiserver accepts.
func hasAcceptedAdmissionReviewVersions(webhooks []admissionregistration.Webhook) bool {
	for _, hook := range webhooks {
		hasRecognizedVersion := false
		for _, version := range hook.AdmissionReviewVersions {
			if isAcceptedAdmissionReviewVersion(version) {
				hasRecognizedVersion = true
				break
			}
		}
		if !hasRecognizedVersion && len(hook.AdmissionReviewVersions) > 0 {
			return false
		}
	}
	return true
}

func ValidateValidatingWebhookConfigurationUpdate(newC, oldC *admissionregistration.ValidatingWebhookConfiguration) field.ErrorList {
	return validateValidatingWebhookConfiguration(newC, hasAcceptedAdmissionReviewVersions(oldC.Webhooks))
}

func ValidateMutatingWebhookConfigurationUpdate(newC, oldC *admissionregistration.MutatingWebhookConfiguration) field.ErrorList {
	return validateMutatingWebhookConfiguration(newC, hasAcceptedAdmissionReviewVersions(oldC.Webhooks))
}