// Copyright 2020 Copyright (c) 2020 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file.
//
// 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 framework

import (
	"fmt"
	"io/ioutil"
	"time"

	"github.com/gardener/gardener/pkg/client/kubernetes"
	"github.com/gardener/gardener/pkg/mock/go/context"

	"github.com/sirupsen/logrus"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

// RootPodExecutor enables the execution of command on the operating system of a node.
// The executor deploys a pod with root privileged on a specified node.
// This pod is then used to execute commands on the host operating system.
type RootPodExecutor interface {
	Execute(ctx context.Context, command string) ([]byte, error)
	Clean(ctx context.Context) error
}

// rootPodExecutor is the RootPodExecutor implementation
type rootPodExecutor struct {
	logger   *logrus.Logger
	client   kubernetes.Interface
	executor PodExecutor

	nodeName  *string
	namespace string

	Pod *corev1.Pod
}

// NewRootPodExecutor creates a new root pod executor to run commands on a node.
func NewRootPodExecutor(logger *logrus.Logger, c kubernetes.Interface, nodeName *string, namespace string) RootPodExecutor {
	executor := NewPodExecutor(c)
	return &rootPodExecutor{
		logger:    logger,
		client:    c,
		executor:  executor,
		nodeName:  nodeName,
		namespace: namespace,
	}
}

// Clean delete the deployed pod
func (e *rootPodExecutor) Clean(ctx context.Context) error {
	if e.Pod == nil {
		return nil
	}

	return DeleteAndWaitForResource(ctx, e.client, e.Pod, 2*time.Minute)
}

// Execute executes a command on the node the root pod is running
func (e *rootPodExecutor) Execute(ctx context.Context, command string) ([]byte, error) {
	isRunning, err := e.checkPodRunning(ctx)
	if err != nil {
		return nil, err
	}
	if !isRunning {
		if err := e.deploy(ctx); err != nil {
			return nil, err
		}
	}

	command = fmt.Sprintf("chroot /hostroot %s", command)
	reader, err := e.executor.Execute(ctx, e.Pod.Namespace, e.Pod.Name, e.Pod.Spec.Containers[0].Name, command)
	if err != nil {
		return nil, err
	}
	response, err := ioutil.ReadAll(reader)
	if err != nil {
		return nil, err
	}
	return response, nil
}

// deploy deploys a root pod on the specified node and waits until it is running
func (e *rootPodExecutor) deploy(ctx context.Context) error {
	rootPod, err := DeployRootPod(ctx, e.client.Client(), e.namespace, e.nodeName)
	if err != nil {
		return err
	}
	if err := WaitUntilPodIsRunning(ctx, e.logger, rootPod.Name, rootPod.Namespace, e.client); err != nil {
		return err
	}

	e.Pod = rootPod
	return nil
}

// checkPodRunning checks if the root pod is still running.
func (e *rootPodExecutor) checkPodRunning(ctx context.Context) (bool, error) {
	if e.Pod == nil {
		return false, nil
	}

	pod := e.Pod.DeepCopy()
	key, err := client.ObjectKeyFromObject(e.Pod)
	if err != nil {
		return false, err
	}
	if err := e.client.Client().Get(ctx, key, pod); err != nil {
		if apierrors.IsNotFound(err) {
			return false, nil
		}
		return false, err
	}

	return true, nil
}