/*
Copyright 2014 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 service

import (
	"context"
	"fmt"

	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/apiserver/pkg/storage/names"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	"k8s.io/kubernetes/pkg/api/legacyscheme"
	api "k8s.io/kubernetes/pkg/apis/core"
	"k8s.io/kubernetes/pkg/apis/core/validation"
	"k8s.io/kubernetes/pkg/features"
)

// svcStrategy implements behavior for Services
type svcStrategy struct {
	runtime.ObjectTyper
	names.NameGenerator
}

// Services is the default logic that applies when creating and updating Service
// objects.
var Strategy = svcStrategy{legacyscheme.Scheme, names.SimpleNameGenerator}

// NamespaceScoped is true for services.
func (svcStrategy) NamespaceScoped() bool {
	return true
}

// PrepareForCreate clears fields that are not allowed to be set by end users on creation.
func (svcStrategy) PrepareForCreate(ctx context.Context, obj runtime.Object) {
	service := obj.(*api.Service)
	service.Status = api.ServiceStatus{}

	dropServiceDisabledFields(service, nil)
}

// PrepareForUpdate clears fields that are not allowed to be set by end users on update.
func (svcStrategy) PrepareForUpdate(ctx context.Context, obj, old runtime.Object) {
	newService := obj.(*api.Service)
	oldService := old.(*api.Service)
	newService.Status = oldService.Status

	dropServiceDisabledFields(newService, oldService)
}

// Validate validates a new service.
func (svcStrategy) Validate(ctx context.Context, obj runtime.Object) field.ErrorList {
	service := obj.(*api.Service)
	allErrs := validation.ValidateServiceCreate(service)
	allErrs = append(allErrs, validation.ValidateConditionalService(service, nil)...)
	return allErrs
}

// Canonicalize normalizes the object after validation.
func (svcStrategy) Canonicalize(obj runtime.Object) {
}

func (svcStrategy) AllowCreateOnUpdate() bool {
	return true
}

func (svcStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
	allErrs := validation.ValidateServiceUpdate(obj.(*api.Service), old.(*api.Service))
	allErrs = append(allErrs, validation.ValidateConditionalService(obj.(*api.Service), old.(*api.Service))...)
	return allErrs
}

func (svcStrategy) AllowUnconditionalUpdate() bool {
	return true
}

func (svcStrategy) Export(ctx context.Context, obj runtime.Object, exact bool) error {
	t, ok := obj.(*api.Service)
	if !ok {
		// unexpected programmer error
		return fmt.Errorf("unexpected object: %v", obj)
	}
	// TODO: service does not yet have a prepare create strategy (see above)
	t.Status = api.ServiceStatus{}
	if exact {
		return nil
	}
	if t.Spec.ClusterIP != api.ClusterIPNone {
		t.Spec.ClusterIP = ""
	}
	if t.Spec.Type == api.ServiceTypeNodePort {
		for i := range t.Spec.Ports {
			t.Spec.Ports[i].NodePort = 0
		}
	}
	return nil
}

// dropServiceDisabledFields drops fields that are not used if their associated feature gates
// are not enabled.  The typical pattern is:
//     if !utilfeature.DefaultFeatureGate.Enabled(features.MyFeature) && !myFeatureInUse(oldSvc) {
//         newSvc.Spec.MyFeature = nil
//     }
func dropServiceDisabledFields(newSvc *api.Service, oldSvc *api.Service) {
	// Drop IPFamily if DualStack is not enabled
	if !utilfeature.DefaultFeatureGate.Enabled(features.IPv6DualStack) && !serviceIPFamilyInUse(oldSvc) {
		newSvc.Spec.IPFamily = nil
	}
	// Drop TopologyKeys if ServiceTopology is not enabled
	if !utilfeature.DefaultFeatureGate.Enabled(features.ServiceTopology) && !topologyKeysInUse(oldSvc) {
		newSvc.Spec.TopologyKeys = nil
	}
}

// returns true if svc.Spec.ServiceIPFamily field is in use
func serviceIPFamilyInUse(svc *api.Service) bool {
	if svc == nil {
		return false
	}
	if svc.Spec.IPFamily != nil {
		return true
	}
	return false
}

// returns true if svc.Spec.TopologyKeys field is in use
func topologyKeysInUse(svc *api.Service) bool {
	if svc == nil {
		return false
	}
	return len(svc.Spec.TopologyKeys) > 0
}

type serviceStatusStrategy struct {
	svcStrategy
}

// StatusStrategy is the default logic invoked when updating service status.
var StatusStrategy = serviceStatusStrategy{Strategy}

// PrepareForUpdate clears fields that are not allowed to be set by end users on update of status
func (serviceStatusStrategy) PrepareForUpdate(ctx context.Context, obj, old runtime.Object) {
	newService := obj.(*api.Service)
	oldService := old.(*api.Service)
	// status changes are not allowed to update spec
	newService.Spec = oldService.Spec
}

// ValidateUpdate is the default update validation for an end user updating status
func (serviceStatusStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
	return validation.ValidateServiceStatusUpdate(obj.(*api.Service), old.(*api.Service))
}
