// Copyright 2020-2021 Clastix Labs
// SPDX-License-Identifier: Apache-2.0

package registry

import (
	"context"
	"net/http"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/client-go/tools/record"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"

	capsulev1alpha1 "github.com/clastix/capsule/api/v1alpha1"
	"github.com/clastix/capsule/api/v1alpha1/domain"
	capsulewebhook "github.com/clastix/capsule/pkg/webhook"
)

// +kubebuilder:webhook:path=/validating-v1-registry,mutating=false,sideEffects=None,admissionReviewVersions=v1,failurePolicy=ignore,groups="",resources=pods,verbs=create,versions=v1,name=pod.capsule.clastix.io

type webhook struct {
	handler capsulewebhook.Handler
}

func Webhook(handler capsulewebhook.Handler) capsulewebhook.Webhook {
	return &webhook{handler: handler}
}

func (w *webhook) GetName() string {
	return "registry"
}

func (w *webhook) GetPath() string {
	return "/validating-v1-registry"
}

func (w *webhook) GetHandler() capsulewebhook.Handler {
	return w.handler
}

type handler struct {
}

func Handler() capsulewebhook.Handler {
	return &handler{}
}

func (h *handler) OnCreate(c client.Client, decoder *admission.Decoder, recorder record.EventRecorder) capsulewebhook.Func {
	return func(ctx context.Context, req admission.Request) admission.Response {
		pod := &corev1.Pod{}
		if err := decoder.Decode(req, pod); err != nil {
			return admission.Errored(http.StatusBadRequest, err)
		}

		tntList := &capsulev1alpha1.TenantList{}
		if err := c.List(ctx, tntList, client.MatchingFieldsSelector{
			Selector: fields.OneTermEqualSelector(".status.namespaces", pod.Namespace),
		}); err != nil {
			return admission.Errored(http.StatusBadRequest, err)
		}
		if len(tntList.Items) == 0 {
			return admission.Allowed("")
		}

		tnt := tntList.Items[0]

		if tnt.Spec.ContainerRegistries != nil {
			var valid, matched bool
			for _, container := range pod.Spec.Containers {
				registry := domain.NewRegistry(container.Image)
				valid = tnt.Spec.ContainerRegistries.ExactMatch(registry.Registry())
				matched = tnt.Spec.ContainerRegistries.RegexMatch(registry.Registry())
				if !valid && !matched {
					recorder.Eventf(&tnt, corev1.EventTypeWarning, "ForbiddenContainerRegistry", "Pod %s/%s is using a forbidden registry %s is forbidden for the current Tenant", req.Namespace, req.Name, registry.Registry())

					return admission.Errored(http.StatusBadRequest, NewContainerRegistryForbidden(container.Image, *tnt.Spec.ContainerRegistries))
				}
			}
		}

		return admission.Allowed("")
	}
}

func (h *handler) OnDelete(client.Client, *admission.Decoder, record.EventRecorder) capsulewebhook.Func {
	return func(ctx context.Context, req admission.Request) admission.Response {
		return admission.Allowed("")
	}
}

func (h *handler) OnUpdate(client.Client, *admission.Decoder, record.EventRecorder) capsulewebhook.Func {
	return func(ctx context.Context, req admission.Request) admission.Response {
		return admission.Allowed("")
	}
}