/*
Copyright The Velero 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 kube

import (
	"context"
	"fmt"
	"io"
	"os"
	"strings"
	"time"

	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	corev1api "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/wait"
	corev1client "k8s.io/client-go/kubernetes/typed/core/v1"
)

type LoadAffinity struct {
	// NodeSelector specifies the label selector to match nodes
	NodeSelector metav1.LabelSelector `json:"nodeSelector"`

	// StorageClass specifies the VGDPs the LoadAffinity applied to. If the StorageClass doesn't have value, it applies to all. If not, it applies to only the VGDPs that use this StorageClass.
	StorageClass string `json:"storageClass"`
}

type PodResources struct {
	CPURequest              string `json:"cpuRequest,omitempty"`
	CPULimit                string `json:"cpuLimit,omitempty"`
	MemoryRequest           string `json:"memoryRequest,omitempty"`
	MemoryLimit             string `json:"memoryLimit,omitempty"`
	EphemeralStorageRequest string `json:"ephemeralStorageRequest,omitempty"`
	EphemeralStorageLimit   string `json:"ephemeralStorageLimit,omitempty"`
}

// IsPodRunning does a well-rounded check to make sure the specified pod is running stably.
// If not, return the error found
func IsPodRunning(pod *corev1api.Pod) error {
	return isPodScheduledInStatus(pod, func(pod *corev1api.Pod) error {
		if pod.Status.Phase != corev1api.PodRunning {
			return errors.New("pod is not running")
		}

		return nil
	})
}

// IsPodScheduled does a well-rounded check to make sure the specified pod has been scheduled into a node and in a stable status.
// If not, return the error found
func IsPodScheduled(pod *corev1api.Pod) error {
	return isPodScheduledInStatus(pod, func(pod *corev1api.Pod) error {
		if pod.Status.Phase != corev1api.PodRunning && pod.Status.Phase != corev1api.PodPending {
			return errors.New("pod is not running or pending")
		}

		return nil
	})
}

func isPodScheduledInStatus(pod *corev1api.Pod, statusCheckFunc func(*corev1api.Pod) error) error {
	if pod == nil {
		return errors.New("invalid input pod")
	}

	if pod.Spec.NodeName == "" {
		return errors.Errorf("pod is not scheduled, name=%s, namespace=%s, phase=%s", pod.Name, pod.Namespace, pod.Status.Phase)
	}

	if err := statusCheckFunc(pod); err != nil {
		return errors.Wrapf(err, "pod is not in the expected status, name=%s, namespace=%s, phase=%s", pod.Name, pod.Namespace, pod.Status.Phase)
	}

	if pod.DeletionTimestamp != nil {
		return errors.Errorf("pod is being terminated, name=%s, namespace=%s, phase=%s", pod.Name, pod.Namespace, pod.Status.Phase)
	}

	return nil
}

// DeletePodIfAny deletes a pod by name if it exists, and log an error when the deletion fails
func DeletePodIfAny(ctx context.Context, podGetter corev1client.CoreV1Interface, podName string, podNamespace string, log logrus.FieldLogger) {
	err := podGetter.Pods(podNamespace).Delete(ctx, podName, metav1.DeleteOptions{})
	if err != nil {
		if apierrors.IsNotFound(err) {
			log.WithError(err).Debugf("Abort deleting pod, it doesn't exist %s/%s", podNamespace, podName)
		} else {
			log.WithError(err).Errorf("Failed to delete pod %s/%s", podNamespace, podName)
		}
	}
}

// EnsureDeletePod asserts the existence of a pod by name, deletes it and waits for its disappearance and returns errors on any failure
func EnsureDeletePod(ctx context.Context, podGetter corev1client.CoreV1Interface, pod string, namespace string, timeout time.Duration) error {
	err := podGetter.Pods(namespace).Delete(ctx, pod, metav1.DeleteOptions{})
	if err != nil {
		return errors.Wrapf(err, "error to delete pod %s", pod)
	}

	var updated *corev1api.Pod
	err = wait.PollUntilContextTimeout(ctx, waitInternal, timeout, true, func(ctx context.Context) (bool, error) {
		po, err := podGetter.Pods(namespace).Get(ctx, pod, metav1.GetOptions{})
		if err != nil {
			if apierrors.IsNotFound(err) {
				return true, nil
			}

			return false, errors.Wrapf(err, "error to get pod %s", pod)
		}

		updated = po
		return false, nil
	})

	if err != nil {
		if errors.Is(err, context.DeadlineExceeded) {
			return errors.Errorf("timeout to assure pod %s is deleted, finalizers in pod %v", pod, updated.Finalizers)
		} else {
			return errors.Wrapf(err, "error to assure pod is deleted, %s", pod)
		}
	}

	return nil
}

// IsPodUnrecoverable checks if the pod is in an abnormal state and could not be recovered
// It could not cover all the cases but we could add more cases in the future
func IsPodUnrecoverable(pod *corev1api.Pod, log logrus.FieldLogger) (bool, string) {
	// Check the Phase field
	if pod.Status.Phase == corev1api.PodFailed || pod.Status.Phase == corev1api.PodUnknown {
		message := ""
		if pod.Status.Message != "" {
			message += pod.Status.Message + "/"
		}

		message += GetPodTerminateMessage(pod)

		log.Warnf("Pod is in abnormal state %s, message [%s]", pod.Status.Phase, message)
		return true, fmt.Sprintf("Pod is in abnormal state [%s], message [%s]", pod.Status.Phase, message)
	}

	// removed "Unschedulable" check since unschedulable condition isn't always permanent

	// Check the Status field
	for _, containerStatus := range pod.Status.ContainerStatuses {
		// If the container's image state is ImagePullBackOff, it indicates an image pull failure
		if containerStatus.State.Waiting != nil && (containerStatus.State.Waiting.Reason == "ImagePullBackOff" || containerStatus.State.Waiting.Reason == "ErrImageNeverPull") {
			log.Warnf("Container %s in Pod %s/%s is in pull image failed with reason %s", containerStatus.Name, pod.Namespace, pod.Name, containerStatus.State.Waiting.Reason)
			return true, fmt.Sprintf("Container %s in Pod %s/%s is in pull image failed with reason %s", containerStatus.Name, pod.Namespace, pod.Name, containerStatus.State.Waiting.Reason)
		}
	}
	return false, ""
}

// GetPodContainerTerminateMessage returns the terminate message for a specific container of a pod
func GetPodContainerTerminateMessage(pod *corev1api.Pod, container string) string {
	message := ""
	for _, containerStatus := range pod.Status.ContainerStatuses {
		if containerStatus.Name == container {
			if containerStatus.State.Terminated != nil {
				message = containerStatus.State.Terminated.Message
			}
			break
		}
	}

	return message
}

// GetPodTerminateMessage returns the terminate message for all containers of a pod
func GetPodTerminateMessage(pod *corev1api.Pod) string {
	//message := ""
	var message strings.Builder
	for _, containerStatus := range pod.Status.ContainerStatuses {
		if containerStatus.State.Terminated != nil {
			if containerStatus.State.Terminated.Message != "" {
				_, _ = fmt.Fprintf(&message, "%s/", containerStatus.State.Terminated.Message)
			}
		}
	}

	return message.String()
}

func getPodLogReader(ctx context.Context, podGetter corev1client.CoreV1Interface, pod string, namespace string, logOptions *corev1api.PodLogOptions) (io.ReadCloser, error) {
	request := podGetter.Pods(namespace).GetLogs(pod, logOptions)
	return request.Stream(ctx)
}

var podLogReaderGetter = getPodLogReader

// CollectPodLogs collects logs of the specified container of a pod and write to the output
func CollectPodLogs(ctx context.Context, podGetter corev1client.CoreV1Interface, pod string, namespace string, container string, output io.Writer) error {
	logIndicator := fmt.Sprintf("***************************begin pod logs[%s/%s]***************************\n", pod, container)

	if _, err := output.Write([]byte(logIndicator)); err != nil {
		return errors.Wrap(err, "error to write begin pod log indicator")
	}

	logOptions := &corev1api.PodLogOptions{
		Container: container,
	}

	if input, err := podLogReaderGetter(ctx, podGetter, pod, namespace, logOptions); err != nil {
		logIndicator = fmt.Sprintf("No present log retrieved, err: %v\n", err)
	} else {
		if _, err := io.Copy(output, input); err != nil {
			return errors.Wrap(err, "error to copy input")
		}

		logIndicator = ""
	}

	logIndicator += fmt.Sprintf("***************************end pod logs[%s/%s]***************************\n", pod, container)
	if _, err := output.Write([]byte(logIndicator)); err != nil {
		return errors.Wrap(err, "error to write end pod log indicator")
	}

	return nil
}

func ToSystemAffinity(loadAffinity *LoadAffinity, volumeTopology *corev1api.NodeSelector) *corev1api.Affinity {
	requirements := []corev1api.NodeSelectorRequirement{}
	if loadAffinity != nil {
		for k, v := range loadAffinity.NodeSelector.MatchLabels {
			requirements = append(requirements, corev1api.NodeSelectorRequirement{
				Key:      k,
				Values:   []string{v},
				Operator: corev1api.NodeSelectorOpIn,
			})
		}

		for _, exp := range loadAffinity.NodeSelector.MatchExpressions {
			requirements = append(requirements, corev1api.NodeSelectorRequirement{
				Key:      exp.Key,
				Values:   exp.Values,
				Operator: corev1api.NodeSelectorOperator(exp.Operator),
			})
		}
	}

	result := new(corev1api.Affinity)
	result.NodeAffinity = new(corev1api.NodeAffinity)
	result.NodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution = new(corev1api.NodeSelector)

	if volumeTopology != nil {
		result.NodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms = append(result.NodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms, volumeTopology.NodeSelectorTerms...)
	} else if len(requirements) > 0 {
		result.NodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms = make([]corev1api.NodeSelectorTerm, 1)
	} else {
		return nil
	}

	for i := range result.NodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms {
		result.NodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms[i].MatchExpressions = append(result.NodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms[i].MatchExpressions, requirements...)
	}

	return result
}

func DiagnosePod(pod *corev1api.Pod, events *corev1api.EventList) string {
	var diag strings.Builder
	_, _ = fmt.Fprintf(&diag, "Pod %s/%s, phase %s, node name %s, message %s\n", pod.Namespace, pod.Name, pod.Status.Phase, pod.Spec.NodeName, pod.Status.Message)

	for _, condition := range pod.Status.Conditions {
		_, _ = fmt.Fprintf(&diag, "Pod condition %s, status %s, reason %s, message %s\n", condition.Type, condition.Status, condition.Reason, condition.Message)
	}

	if events != nil {
		for _, e := range events.Items {
			if e.InvolvedObject.UID == pod.UID && e.Type == corev1api.EventTypeWarning {
				_, _ = fmt.Fprintf(&diag, "Pod event reason %s, message %s\n", e.Reason, e.Message)
			}
		}
	}

	return diag.String()
}

var funcExit = os.Exit
var funcCreateFile = os.Create

func ExitPodWithMessage(logger logrus.FieldLogger, succeed bool, message string, a ...any) {
	exitCode := 0
	if !succeed {
		exitCode = 1
	}

	toWrite := fmt.Sprintf(message, a...)

	podFile, err := funcCreateFile("/dev/termination-log")
	if err != nil {
		logger.WithError(err).Error("Failed to create termination log file")
		exitCode = 1
	} else {
		if _, err := podFile.WriteString(toWrite); err != nil {
			logger.WithError(err).Error("Failed to write error to termination log file")
			exitCode = 1
		}

		podFile.Close()
	}

	funcExit(exitCode)
}

// GetLoadAffinityByStorageClass retrieves the LoadAffinity from the parameter affinityList.
// The function first try to find by the scName. If there is no such LoadAffinity,
// it will try to get the LoadAffinity whose StorageClass has no value.
func GetLoadAffinityByStorageClass(
	affinityList []*LoadAffinity,
	scName string,
	logger logrus.FieldLogger,
) *LoadAffinity {
	var globalAffinity *LoadAffinity

	for _, affinity := range affinityList {
		if affinity.StorageClass == scName {
			logger.WithField("StorageClass", scName).Info("Found pod's affinity setting per StorageClass.")
			return affinity
		}

		if affinity.StorageClass == "" && globalAffinity == nil {
			globalAffinity = affinity
		}
	}

	if globalAffinity != nil {
		logger.Info("Use the Global affinity for pod.")
	} else {
		logger.Info("No Affinity is found for pod.")
	}

	return globalAffinity
}
