/*
Copyright 2018 The Volcano 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 validate

import (
	"fmt"

	"k8s.io/api/admission/v1beta1"
	whv1beta1 "k8s.io/api/admissionregistration/v1beta1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/klog"

	schedulingv1beta1 "volcano.sh/volcano/pkg/apis/scheduling/v1beta1"
	"volcano.sh/volcano/pkg/webhooks/router"
	"volcano.sh/volcano/pkg/webhooks/schema"
	"volcano.sh/volcano/pkg/webhooks/util"
)

func init() {
	router.RegisterAdmission(service)
}

var service = &router.AdmissionService{
	Path: "/queues/validate",
	Func: AdmitQueues,

	Config: config,

	ValidatingConfig: &whv1beta1.ValidatingWebhookConfiguration{
		Webhooks: []whv1beta1.ValidatingWebhook{{
			Name: "validatequeue.volcano.sh",
			Rules: []whv1beta1.RuleWithOperations{
				{
					Operations: []whv1beta1.OperationType{whv1beta1.Create, whv1beta1.Update, whv1beta1.Delete},
					Rule: whv1beta1.Rule{
						APIGroups:   []string{schedulingv1beta1.SchemeGroupVersion.Group},
						APIVersions: []string{schedulingv1beta1.SchemeGroupVersion.Version},
						Resources:   []string{"queues"},
					},
				},
			},
		}},
	},
}

var config = &router.AdmissionServiceConfig{}

// AdmitQueues is to admit queues and return response
func AdmitQueues(ar v1beta1.AdmissionReview) *v1beta1.AdmissionResponse {
	klog.V(3).Infof("Admitting %s queue %s.", ar.Request.Operation, ar.Request.Name)

	queue, err := schema.DecodeQueue(ar.Request.Object, ar.Request.Resource)
	if err != nil {
		return util.ToAdmissionResponse(err)
	}

	switch ar.Request.Operation {
	case v1beta1.Create, v1beta1.Update:
		err = validateQueue(queue)

		break
	case v1beta1.Delete:
		err = validateQueueDeleting(ar.Request.Name)

		break
	default:
		return util.ToAdmissionResponse(fmt.Errorf("invalid operation `%s`, "+
			"expect operation to be `CREATE`, `UPDATE` or `DELETE`", ar.Request.Operation))
	}

	if err != nil {
		return &v1beta1.AdmissionResponse{
			Allowed: false,
			Result:  &metav1.Status{Message: err.Error()},
		}
	}

	return &v1beta1.AdmissionResponse{
		Allowed: true,
	}
}

func validateQueue(queue *schedulingv1beta1.Queue) error {
	errs := field.ErrorList{}
	resourcePath := field.NewPath("requestBody")

	errs = append(errs, validateStateOfQueue(queue.Status.State, resourcePath.Child("spec").Child("state"))...)

	if len(errs) > 0 {
		return errs.ToAggregate()
	}

	return nil
}

func validateStateOfQueue(value schedulingv1beta1.QueueState, fldPath *field.Path) field.ErrorList {
	errs := field.ErrorList{}

	if len(value) == 0 {
		return errs
	}

	validQueueStates := []schedulingv1beta1.QueueState{
		schedulingv1beta1.QueueStateOpen,
		schedulingv1beta1.QueueStateClosed,
	}

	for _, validQueue := range validQueueStates {
		if value == validQueue {
			return errs
		}
	}

	return append(errs, field.Invalid(fldPath, value, fmt.Sprintf("queue state must be in %v", validQueueStates)))
}

func validateQueueDeleting(queue string) error {
	if queue == "default" {
		return fmt.Errorf("`%s` queue can not be deleted", "default")
	}

	q, err := config.VolcanoClient.SchedulingV1beta1().Queues().Get(queue, metav1.GetOptions{})
	if err != nil {
		return err
	}

	if q.Status.State != schedulingv1beta1.QueueStateClosed {
		return fmt.Errorf("only queue with state `%s` can be deleted, queue `%s` state is `%s`",
			schedulingv1beta1.QueueStateClosed, q.Name, q.Status.State)
	}

	return nil
}