/*
Copyright 2014 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 namespace

import (
	"context"
	"fmt"

	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/apiserver/pkg/registry/generic"
	apistorage "k8s.io/apiserver/pkg/storage"
	"k8s.io/apiserver/pkg/storage/names"
	"k8s.io/kubernetes/pkg/api/legacyscheme"
	api "k8s.io/kubernetes/pkg/apis/core"
	"k8s.io/kubernetes/pkg/apis/core/validation"
)

// namespaceStrategy implements behavior for Namespaces
type namespaceStrategy struct {
	runtime.ObjectTyper
	names.NameGenerator
}

// Strategy is the default logic that applies when creating and updating Namespace
// objects via the REST API.
var Strategy = namespaceStrategy{legacyscheme.Scheme, names.SimpleNameGenerator}

// NamespaceScoped is false for namespaces.
func (namespaceStrategy) NamespaceScoped() bool {
	return false
}

//TenantScoped is true as this resource need to be under a given tenant
func (namespaceStrategy) TenantScoped() bool {
	return true
}

// PrepareForCreate clears fields that are not allowed to be set by end users on creation.
func (namespaceStrategy) PrepareForCreate(ctx context.Context, obj runtime.Object) {
	// on create, status is active
	namespace := obj.(*api.Namespace)
	namespace.Status = api.NamespaceStatus{
		Phase: api.NamespaceActive,
	}
	// on create, we require the kubernetes value
	// we cannot use this in defaults conversion because we let it get removed over life of object
	hasKubeFinalizer := false
	for i := range namespace.Spec.Finalizers {
		if namespace.Spec.Finalizers[i] == api.FinalizerKubernetes {
			hasKubeFinalizer = true
			break
		}
	}
	if !hasKubeFinalizer {
		if len(namespace.Spec.Finalizers) == 0 {
			namespace.Spec.Finalizers = []api.FinalizerName{api.FinalizerKubernetes}
		} else {
			namespace.Spec.Finalizers = append(namespace.Spec.Finalizers, api.FinalizerKubernetes)
		}
	}
}

// PrepareForUpdate clears fields that are not allowed to be set by end users on update.
func (namespaceStrategy) PrepareForUpdate(ctx context.Context, obj, old runtime.Object) {
	newNamespace := obj.(*api.Namespace)
	oldNamespace := old.(*api.Namespace)
	newNamespace.Spec.Finalizers = oldNamespace.Spec.Finalizers
	newNamespace.Status = oldNamespace.Status
}

// Validate validates a new namespace.
func (namespaceStrategy) Validate(ctx context.Context, obj runtime.Object) field.ErrorList {
	namespace := obj.(*api.Namespace)
	return validation.ValidateNamespace(namespace)
}

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

// AllowCreateOnUpdate is false for namespaces.
func (namespaceStrategy) AllowCreateOnUpdate() bool {
	return false
}

// ValidateUpdate is the default update validation for an end user.
func (namespaceStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
	errorList := validation.ValidateNamespace(obj.(*api.Namespace))
	return append(errorList, validation.ValidateNamespaceUpdate(obj.(*api.Namespace), old.(*api.Namespace))...)
}

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

type namespaceStatusStrategy struct {
	namespaceStrategy
}

var StatusStrategy = namespaceStatusStrategy{Strategy}

func (namespaceStatusStrategy) PrepareForUpdate(ctx context.Context, obj, old runtime.Object) {
	newNamespace := obj.(*api.Namespace)
	oldNamespace := old.(*api.Namespace)
	newNamespace.Spec = oldNamespace.Spec
}

func (namespaceStatusStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
	return validation.ValidateNamespaceStatusUpdate(obj.(*api.Namespace), old.(*api.Namespace))
}

type namespaceFinalizeStrategy struct {
	namespaceStrategy
}

var FinalizeStrategy = namespaceFinalizeStrategy{Strategy}

func (namespaceFinalizeStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
	return validation.ValidateNamespaceFinalizeUpdate(obj.(*api.Namespace), old.(*api.Namespace))
}

// PrepareForUpdate clears fields that are not allowed to be set by end users on update.
func (namespaceFinalizeStrategy) PrepareForUpdate(ctx context.Context, obj, old runtime.Object) {
	newNamespace := obj.(*api.Namespace)
	oldNamespace := old.(*api.Namespace)
	newNamespace.Status = oldNamespace.Status
}

// GetAttrs returns labels and fields of a given object for filtering purposes.
func GetAttrs(obj runtime.Object) (labels.Set, fields.Set, error) {
	namespaceObj, ok := obj.(*api.Namespace)
	if !ok {
		return nil, nil, fmt.Errorf("not a namespace")
	}
	return labels.Set(namespaceObj.Labels), NamespaceToSelectableFields(namespaceObj), nil
}

// MatchNamespace returns a generic matcher for a given label and field selector.
func MatchNamespace(label labels.Selector, field fields.Selector) apistorage.SelectionPredicate {
	return apistorage.SelectionPredicate{
		Label:    label,
		Field:    field,
		GetAttrs: GetAttrs,
	}
}

// NamespaceToSelectableFields returns a field set that represents the object
func NamespaceToSelectableFields(namespace *api.Namespace) fields.Set {
	objectMetaFieldsSet := generic.ObjectMetaFieldsSet(&namespace.ObjectMeta, false)
	specificFieldsSet := fields.Set{
		"status.phase": string(namespace.Status.Phase),
		// This is a bug, but we need to support it for backward compatibility.
		"name": namespace.Name,
	}
	return generic.MergeFieldsSets(objectMetaFieldsSet, specificFieldsSet)
}
