/*
Copyright 2021 The Karmada 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 karmada

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	corev1 "k8s.io/api/core/v1"
	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
	"k8s.io/apiextensions-apiserver/pkg/client/clientset/clientset"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/klog/v2"
	apiregistrationv1 "k8s.io/kube-aggregator/pkg/apis/apiregistration/v1"
	"sigs.k8s.io/yaml"

	clusterv1alpha1 "github.com/karmada-io/karmada/pkg/apis/cluster/v1alpha1"
	bootstrapagent "github.com/karmada-io/karmada/pkg/karmadactl/cmdinit/bootstraptoken/agent"
	"github.com/karmada-io/karmada/pkg/karmadactl/cmdinit/bootstraptoken/clusterinfo"
	"github.com/karmada-io/karmada/pkg/karmadactl/cmdinit/options"
	"github.com/karmada-io/karmada/pkg/karmadactl/cmdinit/utils"
	"github.com/karmada-io/karmada/pkg/karmadactl/util"
	"github.com/karmada-io/karmada/pkg/karmadactl/util/apiclient"
	tokenutil "github.com/karmada-io/karmada/pkg/karmadactl/util/bootstraptoken"
)

const (
	clusterProxyAdminRole = "cluster-proxy-admin"
	clusterProxyAdminUser = "system:admin"

	aggregatedApiserverServiceName = "karmada-aggregated-apiserver"
)

// InitKarmadaResources Initialize karmada resource
func InitKarmadaResources(dir, caBase64, systemNamespace string) error {
	restConfig, err := apiclient.RestConfig("", filepath.Join(dir, options.KarmadaKubeConfigName))
	if err != nil {
		return err
	}

	clientSet, err := apiclient.NewClientSet(restConfig)
	if err != nil {
		return err
	}

	// create namespace
	if err := util.CreateOrUpdateNamespace(clientSet, util.NewNamespace(systemNamespace)); err != nil {
		klog.Exitln(err)
	}

	// New CRDsClient
	crdClient, err := apiclient.NewCRDsClient(restConfig)
	if err != nil {
		return err
	}

	// Initialize crd
	basesCRDsFiles := utils.ListFiles(dir + "/crds/bases")
	klog.Infof("Initialize karmada bases crd resource `%s/crds/bases`", dir)
	for _, v := range basesCRDsFiles {
		if path.Ext(v) != ".yaml" {
			continue
		}
		if err := createCRDs(crdClient, v); err != nil {
			return err
		}
	}

	patchesCRDsFiles := utils.ListFiles(dir + "/crds/patches")
	klog.Infof("Initialize karmada patches crd resource `%s/crds/patches`", dir)
	for _, v := range patchesCRDsFiles {
		if path.Ext(v) != ".yaml" {
			continue
		}
		if err := patchCRDs(crdClient, caBase64, v); err != nil {
			return err
		}
	}

	// create webhook configuration
	// https://github.com/karmada-io/karmada/blob/master/artifacts/deploy/webhook-configuration.yaml
	klog.Info("Create MutatingWebhookConfiguration mutating-config.")
	if err = createOrUpdateMutatingWebhookConfiguration(clientSet, mutatingConfig(caBase64, systemNamespace)); err != nil {
		klog.Exitln(err)
	}

	klog.Info("Create ValidatingWebhookConfiguration validating-config.")
	if err = createOrUpdateValidatingWebhookConfiguration(clientSet, validatingConfig(caBase64, systemNamespace)); err != nil {
		klog.Exitln(err)
	}

	// karmada-aggregated-apiserver
	klog.Info("Create Service 'karmada-aggregated-apiserver' and APIService 'v1alpha1.cluster.karmada.io'.")
	if err = initAggregatedAPIService(clientSet, restConfig, systemNamespace, caBase64); err != nil {
		klog.Exitln(err)
	}

	if err = createExtraResources(clientSet, dir); err != nil {
		klog.Exitln(err)
	}

	return nil
}

// InitKarmadaBootstrapToken create initial bootstrap token
func InitKarmadaBootstrapToken(dir string) (string, error) {
	restConfig, err := apiclient.RestConfig("", filepath.Join(dir, options.KarmadaKubeConfigName))
	if err != nil {
		return "", err
	}

	clientSet, err := apiclient.NewClientSet(restConfig)
	if err != nil {
		return "", err
	}
	// Create initial bootstrap token
	klog.Info("Initialize karmada bootstrap token")
	bootstrapToken, err := tokenutil.GenerateRandomBootstrapToken(&metav1.Duration{Duration: tokenutil.DefaultTokenDuration}, "", tokenutil.DefaultGroups, tokenutil.DefaultUsages)
	if err != nil {
		return "", err
	}

	if err := tokenutil.CreateNewToken(clientSet, bootstrapToken); err != nil {
		return "", err
	}

	tokenStr := bootstrapToken.Token.ID + "." + bootstrapToken.Token.Secret

	registerCommand, err := tokenutil.GenerateRegisterCommand(filepath.Join(dir, options.KarmadaKubeConfigName), "", tokenStr, "")
	if err != nil {
		return "", fmt.Errorf("failed to get register command, err: %w", err)
	}

	return registerCommand, nil
}

func createExtraResources(clientSet *kubernetes.Clientset, dir string) error {
	// grant view clusterrole with karmada resource permission
	if err := grantKarmadaPermissionToViewClusterRole(clientSet); err != nil {
		return err
	}

	// grant edit clusterrole with karmada resource permission
	if err := grantKarmadaPermissionToEditClusterRole(clientSet); err != nil {
		return err
	}

	// grant proxy permission to "system:admin".
	if err := grantProxyPermissionToAdmin(clientSet); err != nil {
		return err
	}

	// Create the cluster-info ConfigMap with the associated RBAC rules
	if err := clusterinfo.CreateBootstrapConfigMapIfNotExists(clientSet, filepath.Join(dir, options.KarmadaKubeConfigName)); err != nil {
		return fmt.Errorf("error creating bootstrap ConfigMap: %v", err)
	}

	if err := clusterinfo.CreateClusterInfoRBACRules(clientSet); err != nil {
		return fmt.Errorf("error creating clusterinfo RBAC rules: %v", err)
	}

	// grant limited access permission to 'karmada-agent'
	if err := grantAccessPermissionToAgent(clientSet); err != nil {
		return err
	}

	if err := bootstrapagent.AllowBootstrapTokensToPostCSRs(clientSet); err != nil {
		return err
	}

	if err := bootstrapagent.AutoApproveKarmadaAgentBootstrapTokens(clientSet); err != nil {
		return err
	}

	if err := bootstrapagent.AutoApproveAgentCertificateRotation(clientSet); err != nil {
		return err
	}

	return nil
}

func crdPatchesResources(filename, caBundle string) ([]byte, error) {
	data, err := os.ReadFile(filename)
	if err != nil {
		return nil, err
	}

	re, err := regexp.Compile("{{caBundle}}")
	if err != nil {
		return nil, err
	}
	repl := re.ReplaceAllString(string(data), caBundle)

	return []byte(repl), nil
}

// createCRDs create crd resource
func createCRDs(crdClient *clientset.Clientset, filename string) error {
	obj := apiextensionsv1.CustomResourceDefinition{}
	data, err := os.ReadFile(filename)
	if err != nil {
		return err
	}
	jsonByte, err := yaml.YAMLToJSON(data)
	if err != nil {
		return err
	}

	if err := json.Unmarshal(jsonByte, &obj); err != nil {
		klog.Errorln("Error convert json byte to apiExtensionsV1 CustomResourceDefinition struct.")
		return err
	}

	klog.Infof("Attempting to create CRD")
	crd := crdClient.ApiextensionsV1().CustomResourceDefinitions()
	if _, err := crd.Create(context.TODO(), &obj, metav1.CreateOptions{}); err != nil {
		if !apierrors.IsAlreadyExists(err) {
			return err
		}
		klog.Infof("CRD %s already exists, skipping.", obj.Name)
		return nil
	}

	klog.Infof("Create CRD %s successfully.", obj.Name)
	return nil
}

// patchCRDs patch crd resource
func patchCRDs(crdClient *clientset.Clientset, caBundle, filename string) error {
	data, err := crdPatchesResources(filename, caBundle)
	if err != nil {
		return err
	}
	jsonByte, err := yaml.YAMLToJSON(data)
	if err != nil {
		return err
	}
	name := getName(path.Base(filename), "_", ".") + ".work.karmada.io"
	crd := crdClient.ApiextensionsV1().CustomResourceDefinitions()
	if _, err := crd.Patch(context.TODO(), name, types.StrategicMergePatchType, jsonByte, metav1.PatchOptions{}); err != nil {
		return err
	}
	return nil
}

func getName(str, start, end string) string {
	n := strings.LastIndex(str, start) + 1
	str = string([]byte(str)[n:])
	m := strings.Index(str, end)
	str = string([]byte(str)[:m])
	return str
}

func initAggregatedAPIService(clientSet *kubernetes.Clientset, restConfig *rest.Config, systemNamespace, caBase64 string) error {
	// https://github.com/karmada-io/karmada/blob/master/artifacts/deploy/karmada-aggregated-apiserver-apiservice.yaml
	caBytes, err := base64.StdEncoding.DecodeString(caBase64)
	if err != nil {
		return fmt.Errorf("failed to decode caBase64: %+v", err)
	}
	aaService := &corev1.Service{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Service",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      aggregatedApiserverServiceName,
			Namespace: systemNamespace,
		},
		Spec: corev1.ServiceSpec{
			Type:         corev1.ServiceTypeExternalName,
			ExternalName: fmt.Sprintf("%s.%s.svc", aggregatedApiserverServiceName, systemNamespace),
		},
	}
	if err := util.CreateOrUpdateService(clientSet, aaService); err != nil {
		return err
	}

	// new apiRegistrationClient
	apiRegistrationClient, err := apiclient.NewAPIRegistrationClient(restConfig)
	if err != nil {
		return err
	}

	aaAPIServiceObjName := "v1alpha1.cluster.karmada.io"
	aaAPIService := &apiregistrationv1.APIService{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "APIService",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:   aaAPIServiceObjName,
			Labels: map[string]string{"app": "karmada-aggregated-apiserver", "apiserver": "true"},
		},
		Spec: apiregistrationv1.APIServiceSpec{
			CABundle:             caBytes,
			Group:                clusterv1alpha1.GroupName,
			GroupPriorityMinimum: 2000,
			Service: &apiregistrationv1.ServiceReference{
				Name:      aaService.Name,
				Namespace: aaService.Namespace,
			},
			Version:         clusterv1alpha1.GroupVersion.Version,
			VersionPriority: 10,
		},
	}

	if err = util.CreateOrUpdateAPIService(apiRegistrationClient, aaAPIService); err != nil {
		return err
	}

	if err := WaitAPIServiceReady(apiRegistrationClient, aaAPIServiceObjName, 120*time.Second); err != nil {
		return err
	}
	return nil
}