/*
Copyright 2015 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 pod

import (
	"strings"

	"k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	clientset "k8s.io/client-go/kubernetes"
	"k8s.io/klog"
	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
)

// MirrorClient knows how to create/delete a mirror pod in the API server.
type MirrorClient interface {
	// CreateMirrorPod creates a mirror pod in the API server for the given
	// pod or returns an error.  The mirror pod will have the same annotations
	// as the given pod as well as an extra annotation containing the hash of
	// the static pod.
	CreateMirrorPod(pod *v1.Pod) error
	// DeleteMirrorPod deletes the mirror pod with the given full name from
	// the API server or returns an error.
	DeleteMirrorPod(podFullName string) error
}

// basicMirrorClient is a functional MirrorClient.  Mirror pods are stored in
// the kubelet directly because they need to be in sync with the internal
// pods.
type basicMirrorClient struct {
	apiserverClient clientset.Interface
}

// NewBasicMirrorClient returns a new MirrorClient.
func NewBasicMirrorClient(apiserverClient clientset.Interface) MirrorClient {
	return &basicMirrorClient{apiserverClient: apiserverClient}
}

func (mc *basicMirrorClient) CreateMirrorPod(pod *v1.Pod) error {
	if mc.apiserverClient == nil {
		return nil
	}
	// Make a copy of the pod.
	copyPod := *pod
	copyPod.Annotations = make(map[string]string)

	for k, v := range pod.Annotations {
		copyPod.Annotations[k] = v
	}
	hash := getPodHash(pod)
	copyPod.Annotations[kubetypes.ConfigMirrorAnnotationKey] = hash
	apiPod, err := mc.apiserverClient.CoreV1().PodsWithMultiTenancy(copyPod.Namespace, copyPod.Tenant).Create(&copyPod)
	if err != nil && errors.IsAlreadyExists(err) {
		// Check if the existing pod is the same as the pod we want to create.
		if h, ok := apiPod.Annotations[kubetypes.ConfigMirrorAnnotationKey]; ok && h == hash {
			return nil
		}
	}
	return err
}

func (mc *basicMirrorClient) DeleteMirrorPod(podFullName string) error {
	if mc.apiserverClient == nil {
		return nil
	}
	name, namespace, tenant, err := kubecontainer.ParsePodFullName(podFullName)
	if err != nil {
		klog.Errorf("Failed to parse a pod full name %q", podFullName)
		return err
	}
	klog.V(2).Infof("Deleting a mirror pod %q", podFullName)
	// TODO(random-liu): Delete the mirror pod with uid precondition in mirror pod manager
	if err := mc.apiserverClient.CoreV1().PodsWithMultiTenancy(namespace, tenant).Delete(name, metav1.NewDeleteOptions(0)); err != nil && !errors.IsNotFound(err) {
		klog.Errorf("Failed deleting a mirror pod %q: %v", podFullName, err)
	}
	return nil
}

// IsStaticPod returns true if the pod is a static pod.
func IsStaticPod(pod *v1.Pod) bool {
	source, err := kubetypes.GetPodSource(pod)
	return err == nil && !strings.HasPrefix(source, kubetypes.ApiserverSource)
}

// IsMirrorPod returns true if the pod is a mirror pod.
func IsMirrorPod(pod *v1.Pod) bool {
	_, ok := pod.Annotations[kubetypes.ConfigMirrorAnnotationKey]
	return ok
}

func getHashFromMirrorPod(pod *v1.Pod) (string, bool) {
	hash, ok := pod.Annotations[kubetypes.ConfigMirrorAnnotationKey]
	return hash, ok
}

func getPodHash(pod *v1.Pod) string {
	// The annotation exists for all static pods.
	return pod.Annotations[kubetypes.ConfigHashAnnotationKey]
}
