/*
Copyright 2020 The Flux CD contributors.

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 main

import (
	"bytes"
	"context"
	"fmt"

	"github.com/spf13/cobra"
	corev1 "k8s.io/api/core/v1"
	rbacv1 "k8s.io/api/rbac/v1"
	"k8s.io/apimachinery/pkg/api/equality"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/yaml"
)

var createTenantCmd = &cobra.Command{
	Use:   "tenant",
	Short: "Create or update a tenant",
	Long: `
The create tenant command generates a namespace and a role binding to limit the
reconcilers scope to the tenant namespace.`,
	RunE: createTenantCmdRun,
}

func init() {
	createCmd.AddCommand(createTenantCmd)
}

func createTenantCmdRun(cmd *cobra.Command, args []string) error {
	if len(args) < 1 {
		return fmt.Errorf("tenant name is required")
	}
	tenant := args[0]

	objLabels, err := parseLabels()
	if err != nil {
		return err
	}

	namespace := corev1.Namespace{
		ObjectMeta: metav1.ObjectMeta{
			Name:   tenant,
			Labels: objLabels,
		},
	}

	roleBinding := rbacv1.RoleBinding{
		ObjectMeta: metav1.ObjectMeta{
			Name:      "gotk-reconciler",
			Namespace: tenant,
			Labels:    objLabels,
		},
		Subjects: []rbacv1.Subject{
			{
				APIGroup: "rbac.authorization.k8s.io",
				Kind:     "User",
				Name:     fmt.Sprintf("gotk:%s:reconciler", tenant),
			},
		},
		RoleRef: rbacv1.RoleRef{
			APIGroup: "rbac.authorization.k8s.io",
			Kind:     "ClusterRole",
			Name:     "cluster-admin",
		},
	}

	if export {
		return exportTenant(namespace, roleBinding)
	}

	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()

	kubeClient, err := utils.kubeClient(kubeconfig)
	if err != nil {
		return err
	}

	logger.Actionf("applying namespace %s", namespace.Name)
	if err := upsertNamespace(ctx, kubeClient, namespace); err != nil {
		return err
	}

	logger.Actionf("applying role binding %s", roleBinding.Name)
	if err := upsertRoleBinding(ctx, kubeClient, roleBinding); err != nil {
		return err
	}

	logger.Successf("tenant setup completed")
	return nil
}

func upsertNamespace(ctx context.Context, kubeClient client.Client, namespace corev1.Namespace) error {
	namespacedName := types.NamespacedName{
		Namespace: namespace.GetNamespace(),
		Name:      namespace.GetName(),
	}

	var existing corev1.Namespace
	err := kubeClient.Get(ctx, namespacedName, &existing)
	if err != nil {
		if errors.IsNotFound(err) {
			if err := kubeClient.Create(ctx, &namespace); err != nil {
				return err
			} else {
				return nil
			}
		}
		return err
	}

	if !equality.Semantic.DeepDerivative(namespace.Labels, existing.Labels) {
		existing.Labels = namespace.Labels
		if err := kubeClient.Update(ctx, &existing); err != nil {
			return err
		}
	}

	return nil
}

func upsertRoleBinding(ctx context.Context, kubeClient client.Client, roleBinding rbacv1.RoleBinding) error {
	namespacedName := types.NamespacedName{
		Namespace: roleBinding.GetNamespace(),
		Name:      roleBinding.GetName(),
	}

	var existing rbacv1.RoleBinding
	err := kubeClient.Get(ctx, namespacedName, &existing)
	if err != nil {
		if errors.IsNotFound(err) {
			if err := kubeClient.Create(ctx, &roleBinding); err != nil {
				return err
			} else {
				return nil
			}
		}
		return err
	}

	if !equality.Semantic.DeepDerivative(roleBinding.Subjects, existing.Subjects) ||
		!equality.Semantic.DeepDerivative(roleBinding.RoleRef, existing.RoleRef) ||
		!equality.Semantic.DeepDerivative(roleBinding.Labels, existing.Labels) {
		if err := kubeClient.Delete(ctx, &existing); err != nil {
			return err
		}
		if err := kubeClient.Create(ctx, &roleBinding); err != nil {
			return err
		}
	}

	return nil
}

func exportTenant(namespace corev1.Namespace, roleBinding rbacv1.RoleBinding) error {
	namespace.TypeMeta = metav1.TypeMeta{
		APIVersion: "v1",
		Kind:       "Namespace",
	}
	data, err := yaml.Marshal(namespace)
	if err != nil {
		return err
	}

	fmt.Println("---")
	data = bytes.Replace(data, []byte("spec: {}\n"), []byte(""), 1)
	fmt.Println(resourceToString(data))

	roleBinding.TypeMeta = metav1.TypeMeta{
		APIVersion: "rbac.authorization.k8s.io/v1",
		Kind:       "RoleBinding",
	}
	data, err = yaml.Marshal(roleBinding)
	if err != nil {
		return err
	}

	fmt.Println("---")
	fmt.Println(resourceToString(data))

	return nil
}