/*
Copyright 2017 The Kubernetes 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 csi

import (
	"crypto/sha256"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"

	authenticationv1 "k8s.io/api/authentication/v1"
	api "k8s.io/api/core/v1"
	storage "k8s.io/api/storage/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/types"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	"k8s.io/client-go/kubernetes"
	"k8s.io/klog/v2"
	"k8s.io/kubernetes/pkg/features"
	"k8s.io/kubernetes/pkg/volume"
	"k8s.io/kubernetes/pkg/volume/util"
	volumetypes "k8s.io/kubernetes/pkg/volume/util/types"
	"k8s.io/mount-utils"
	utilstrings "k8s.io/utils/strings"
)

// TODO (vladimirvivien) move this in a central loc later
var (
	volDataKey = struct {
		specVolID,
		volHandle,
		driverName,
		nodeName,
		attachmentID,
		volumeLifecycleMode,
		seLinuxMountContext string
	}{
		"specVolID",
		"volumeHandle",
		"driverName",
		"nodeName",
		"attachmentID",
		"volumeLifecycleMode",
		"seLinuxMountContext",
	}
)

type csiMountMgr struct {
	csiClientGetter
	k8s                 kubernetes.Interface
	plugin              *csiPlugin
	driverName          csiDriverName
	volumeLifecycleMode storage.VolumeLifecycleMode
	volumeID            string
	specVolumeID        string
	readOnly            bool
	needSELinuxRelabel  bool
	spec                *volume.Spec
	pod                 *api.Pod
	podUID              types.UID
	publishContext      map[string]string
	kubeVolHost         volume.KubeletVolumeHost
	volume.MetricsProvider
}

// volume.Volume methods
var _ volume.Volume = &csiMountMgr{}

func (c *csiMountMgr) GetPath() string {
	dir := GetCSIMounterPath(filepath.Join(getTargetPath(c.podUID, c.specVolumeID, c.plugin.host)))
	klog.V(4).Info(log("mounter.GetPath generated [%s]", dir))
	return dir
}

func getTargetPath(uid types.UID, specVolumeID string, host volume.VolumeHost) string {
	specVolID := utilstrings.EscapeQualifiedName(specVolumeID)
	return host.GetPodVolumeDir(uid, utilstrings.EscapeQualifiedName(CSIPluginName), specVolID)
}

// volume.Mounter methods
var _ volume.Mounter = &csiMountMgr{}

func (c *csiMountMgr) SetUp(mounterArgs volume.MounterArgs) error {
	return c.SetUpAt(c.GetPath(), mounterArgs)
}

func (c *csiMountMgr) SetUpAt(dir string, mounterArgs volume.MounterArgs) error {
	klog.V(4).Infof(log("Mounter.SetUpAt(%s)", dir))

	csi, err := c.csiClientGetter.Get()
	if err != nil {
		// Treat the absence of the CSI driver as a transient error
		// See https://github.com/kubernetes/kubernetes/issues/120268
		return volumetypes.NewTransientOperationFailure(log("mounter.SetUpAt failed to get CSI client: %v", err))
	}

	ctx, cancel := createCSIOperationContext(c.spec, csiTimeout)
	defer cancel()

	volSrc, pvSrc, err := getSourceFromSpec(c.spec)
	if err != nil {
		return errors.New(log("mounter.SetupAt failed to get CSI persistent source: %v", err))
	}

	// Check CSIDriver.Spec.Mode to ensure that the CSI driver
	// supports the current volumeLifecycleMode.
	if err := c.supportsVolumeLifecycleMode(); err != nil {
		return volumetypes.NewTransientOperationFailure(log("mounter.SetupAt failed to check volume lifecycle mode: %s", err))
	}

	fsGroupPolicy, err := c.getFSGroupPolicy()
	if err != nil {
		return volumetypes.NewTransientOperationFailure(log("mounter.SetupAt failed to check fsGroup policy: %s", err))
	}

	driverName := c.driverName
	volumeHandle := c.volumeID
	readOnly := c.readOnly
	accessMode := api.ReadWriteOnce

	var (
		fsType             string
		volAttribs         map[string]string
		nodePublishSecrets map[string]string
		publishContext     map[string]string
		mountOptions       []string
		deviceMountPath    string
		secretRef          *api.SecretReference
	)

	switch {
	case volSrc != nil:
		if c.volumeLifecycleMode != storage.VolumeLifecycleEphemeral {
			return fmt.Errorf("unexpected volume mode: %s", c.volumeLifecycleMode)
		}
		if volSrc.FSType != nil {
			fsType = *volSrc.FSType
		}

		volAttribs = volSrc.VolumeAttributes

		if volSrc.NodePublishSecretRef != nil {
			secretName := volSrc.NodePublishSecretRef.Name
			ns := c.pod.Namespace
			secretRef = &api.SecretReference{Name: secretName, Namespace: ns}
		}
	case pvSrc != nil:
		if c.volumeLifecycleMode != storage.VolumeLifecyclePersistent {
			return fmt.Errorf("unexpected driver mode: %s", c.volumeLifecycleMode)
		}

		fsType = pvSrc.FSType

		volAttribs = pvSrc.VolumeAttributes

		if pvSrc.NodePublishSecretRef != nil {
			secretRef = pvSrc.NodePublishSecretRef
		}

		//TODO (vladimirvivien) implement better AccessModes mapping between k8s and CSI
		if c.spec.PersistentVolume.Spec.AccessModes != nil {
			accessMode = c.spec.PersistentVolume.Spec.AccessModes[0]
		}

		mountOptions = c.spec.PersistentVolume.Spec.MountOptions

		// Check for STAGE_UNSTAGE_VOLUME set and populate deviceMountPath if so
		stageUnstageSet, err := csi.NodeSupportsStageUnstage(ctx)
		if err != nil {
			return errors.New(log("mounter.SetUpAt failed to check for STAGE_UNSTAGE_VOLUME capability: %v", err))
		}

		if stageUnstageSet {
			deviceMountPath, err = makeDeviceMountPath(c.plugin, c.spec)
			if err != nil {
				return errors.New(log("mounter.SetUpAt failed to make device mount path: %v", err))
			}
		}

		// search for attachment by VolumeAttachment.Spec.Source.PersistentVolumeName
		if c.publishContext == nil {
			nodeName := string(c.plugin.host.GetNodeName())
			c.publishContext, err = c.plugin.getPublishContext(c.k8s, volumeHandle, string(driverName), nodeName)
			if err != nil {
				// we could have a transient error associated with fetching publish context
				return volumetypes.NewTransientOperationFailure(log("mounter.SetUpAt failed to fetch publishContext: %v", err))
			}
			publishContext = c.publishContext
		}

	default:
		return fmt.Errorf("volume source not found in volume.Spec")
	}

	// create target_dir before call to NodePublish
	parentDir := filepath.Dir(dir)
	if err := os.MkdirAll(parentDir, 0750); err != nil {
		return errors.New(log("mounter.SetUpAt failed to create dir %#v:  %v", parentDir, err))
	}
	klog.V(4).Info(log("created target path successfully [%s]", parentDir))

	nodePublishSecrets = map[string]string{}
	if secretRef != nil {
		nodePublishSecrets, err = getCredentialsFromSecret(c.k8s, secretRef)
		if err != nil {
			return volumetypes.NewTransientOperationFailure(fmt.Sprintf("fetching NodePublishSecretRef %s/%s failed: %v",
				secretRef.Namespace, secretRef.Name, err))
		}

	}

	// Inject pod information into volume_attributes
	podInfoEnabled, err := c.plugin.podInfoEnabled(string(c.driverName))
	if err != nil {
		return volumetypes.NewTransientOperationFailure(log("mounter.SetUpAt failed to assemble volume attributes: %v", err))
	}
	if podInfoEnabled {
		volAttribs = mergeMap(volAttribs, getPodInfoAttrs(c.pod, c.volumeLifecycleMode))
	}

	// Inject pod service account token into volume attributes
	serviceAccountTokenAttrs, err := c.podServiceAccountTokenAttrs()
	if err != nil {
		return volumetypes.NewTransientOperationFailure(log("mounter.SetUpAt failed to get service accoount token attributes: %v", err))
	}
	volAttribs = mergeMap(volAttribs, serviceAccountTokenAttrs)

	driverSupportsCSIVolumeMountGroup := false
	var nodePublishFSGroupArg *int64
	driverSupportsCSIVolumeMountGroup, err = csi.NodeSupportsVolumeMountGroup(ctx)
	if err != nil {
		return volumetypes.NewTransientOperationFailure(log("mounter.SetUpAt failed to determine if the node service has VOLUME_MOUNT_GROUP capability: %v", err))
	}

	if driverSupportsCSIVolumeMountGroup {
		klog.V(3).Infof("Driver %s supports applying FSGroup (has VOLUME_MOUNT_GROUP node capability). Delegating FSGroup application to the driver through NodePublishVolume.", c.driverName)
		nodePublishFSGroupArg = mounterArgs.FsGroup
	}

	var selinuxLabelMount bool
	if utilfeature.DefaultFeatureGate.Enabled(features.SELinuxMountReadWriteOncePod) {
		support, err := c.plugin.SupportsSELinuxContextMount(c.spec)
		if err != nil {
			return errors.New(log("failed to query for SELinuxMount support: %s", err))
		}
		if support && mounterArgs.SELinuxLabel != "" {
			mountOptions = util.AddSELinuxMountOption(mountOptions, mounterArgs.SELinuxLabel)
			selinuxLabelMount = true
		}
	}

	// Save volume info in pod dir
	// persist volume info data for teardown
	nodeName := string(c.plugin.host.GetNodeName())
	volData := map[string]string{
		volDataKey.specVolID:           c.spec.Name(),
		volDataKey.volHandle:           volumeHandle,
		volDataKey.driverName:          string(c.driverName),
		volDataKey.nodeName:            nodeName,
		volDataKey.volumeLifecycleMode: string(c.volumeLifecycleMode),
		volDataKey.attachmentID:        getAttachmentName(volumeHandle, string(c.driverName), nodeName),
	}

	if utilfeature.DefaultFeatureGate.Enabled(features.SELinuxMountReadWriteOncePod) && selinuxLabelMount {
		volData[volDataKey.seLinuxMountContext] = mounterArgs.SELinuxLabel
	}

	err = saveVolumeData(parentDir, volDataFileName, volData)
	defer func() {
		// Only if there was an error and volume operation was considered
		// finished, we should remove the directory.
		if err != nil && volumetypes.IsOperationFinishedError(err) {
			// attempt to cleanup volume mount dir
			if removeerr := removeMountDir(c.plugin, dir); removeerr != nil {
				klog.Error(log("mounter.SetUpAt failed to remove mount dir after error [%s]: %v", dir, removeerr))
			}
		}
	}()
	if err != nil {
		errorMsg := log("mounter.SetUpAt failed to save volume info data: %v", err)
		klog.Error(errorMsg)
		return volumetypes.NewTransientOperationFailure(errorMsg)
	}

	err = csi.NodePublishVolume(
		ctx,
		volumeHandle,
		readOnly,
		deviceMountPath,
		dir,
		accessMode,
		publishContext,
		volAttribs,
		nodePublishSecrets,
		fsType,
		mountOptions,
		nodePublishFSGroupArg,
	)

	if err != nil {
		// If operation finished with error then we can remove the mount directory.
		if volumetypes.IsOperationFinishedError(err) {
			if removeMountDirErr := removeMountDir(c.plugin, dir); removeMountDirErr != nil {
				klog.Error(log("mounter.SetupAt failed to remove mount dir after a NodePublish() error [%s]: %v", dir, removeMountDirErr))
			}
		}
		return err
	}

	if !selinuxLabelMount {
		c.needSELinuxRelabel, err = c.kubeVolHost.GetHostUtil().GetSELinuxSupport(dir)
		if err != nil {
			// The volume is mounted. Return UncertainProgressError, so kubelet will unmount it when user deletes the pod.
			return volumetypes.NewUncertainProgressError(fmt.Sprintf("error checking for SELinux support: %s", err))
		}
	}

	if !driverSupportsCSIVolumeMountGroup && c.supportsFSGroup(fsType, mounterArgs.FsGroup, fsGroupPolicy) {
		// Driver doesn't support applying FSGroup. Kubelet must apply it instead.

		// fullPluginName helps to distinguish different driver from csi plugin
		err := volume.SetVolumeOwnership(c, dir, mounterArgs.FsGroup, mounterArgs.FSGroupChangePolicy, util.FSGroupCompleteHook(c.plugin, c.spec))
		if err != nil {
			// At this point mount operation is successful:
			//   1. Since volume can not be used by the pod because of invalid permissions, we must return error
			//   2. Since mount is successful, we must record volume as mounted in uncertain state, so it can be
			//      cleaned up.
			return volumetypes.NewUncertainProgressError(fmt.Sprintf("applyFSGroup failed for vol %s: %v", c.volumeID, err))
		}
		klog.V(4).Info(log("mounter.SetupAt fsGroup [%d] applied successfully to %s", *mounterArgs.FsGroup, c.volumeID))
	}

	klog.V(4).Infof(log("mounter.SetUp successfully requested NodePublish [%s]", dir))
	return nil
}

func (c *csiMountMgr) podServiceAccountTokenAttrs() (map[string]string, error) {
	if c.plugin.serviceAccountTokenGetter == nil {
		return nil, errors.New("ServiceAccountTokenGetter is nil")
	}

	csiDriver, err := c.plugin.csiDriverLister.Get(string(c.driverName))
	if err != nil {
		if apierrors.IsNotFound(err) {
			klog.V(5).Infof(log("CSIDriver %q not found, not adding service account token information", c.driverName))
			return nil, nil
		}
		return nil, err
	}

	if len(csiDriver.Spec.TokenRequests) == 0 {
		return nil, nil
	}

	outputs := map[string]authenticationv1.TokenRequestStatus{}
	for _, tokenRequest := range csiDriver.Spec.TokenRequests {
		audience := tokenRequest.Audience
		audiences := []string{audience}
		if audience == "" {
			audiences = []string{}
		}
		tr, err := c.plugin.serviceAccountTokenGetter(c.pod.Namespace, c.pod.Spec.ServiceAccountName, &authenticationv1.TokenRequest{
			Spec: authenticationv1.TokenRequestSpec{
				Audiences:         audiences,
				ExpirationSeconds: tokenRequest.ExpirationSeconds,
				BoundObjectRef: &authenticationv1.BoundObjectReference{
					APIVersion: "v1",
					Kind:       "Pod",
					Name:       c.pod.Name,
					UID:        c.pod.UID,
				},
			},
		})
		if err != nil {
			return nil, err
		}

		outputs[audience] = tr.Status
	}

	klog.V(4).Infof(log("Fetched service account token attrs for CSIDriver %q", c.driverName))
	tokens, _ := json.Marshal(outputs)
	return map[string]string{
		"csi.storage.k8s.io/serviceAccount.tokens": string(tokens),
	}, nil
}

func (c *csiMountMgr) GetAttributes() volume.Attributes {
	return volume.Attributes{
		ReadOnly:       c.readOnly,
		Managed:        !c.readOnly,
		SELinuxRelabel: c.needSELinuxRelabel,
	}
}

// volume.Unmounter methods
var _ volume.Unmounter = &csiMountMgr{}

func (c *csiMountMgr) TearDown() error {
	return c.TearDownAt(c.GetPath())
}
func (c *csiMountMgr) TearDownAt(dir string) error {
	klog.V(4).Infof(log("Unmounter.TearDownAt(%s)", dir))

	volID := c.volumeID
	csi, err := c.csiClientGetter.Get()
	if err != nil {
		// Treat the absence of the CSI driver as a transient error
		// See https://github.com/kubernetes/kubernetes/issues/120268
		return volumetypes.NewTransientOperationFailure(log("Unmounter.TearDownAt failed to get CSI client: %v", err))
	}

	// Could not get spec info on whether this is a migrated operation because c.spec is nil
	ctx, cancel := createCSIOperationContext(c.spec, csiTimeout)
	defer cancel()

	if err := csi.NodeUnpublishVolume(ctx, volID, dir); err != nil {
		return errors.New(log("Unmounter.TearDownAt failed: %v", err))
	}

	// Removal of target_path provided in the NodePublish RPC call
	// (in this case location `dir`) MUST be done by the CSI plugin according
	// to the spec.
	//
	// Kubelet should only be responsible for removal of json data files it
	// creates and parent directories.
	//
	// However, some CSI plugins maybe buggy and don't adhere to the standard,
	// so we still need to remove the target_path here if it's unmounted and
	// empty.
	if err := removeMountDir(c.plugin, dir); err != nil {
		return errors.New(log("Unmounter.TearDownAt failed to clean mount dir [%s]: %v", dir, err))
	}
	klog.V(4).Infof(log("Unmounter.TearDownAt successfully unmounted dir [%s]", dir))

	return nil
}

func (c *csiMountMgr) supportsFSGroup(fsType string, fsGroup *int64, driverPolicy storage.FSGroupPolicy) bool {
	if fsGroup == nil || driverPolicy == storage.NoneFSGroupPolicy || c.readOnly {
		return false
	}

	if driverPolicy == storage.FileFSGroupPolicy {
		return true
	}

	if fsType == "" {
		klog.V(4).Info(log("mounter.SetupAt WARNING: skipping fsGroup, fsType not provided"))
		return false
	}

	if c.spec.PersistentVolume != nil {
		if c.spec.PersistentVolume.Spec.AccessModes == nil {
			klog.V(4).Info(log("mounter.SetupAt WARNING: skipping fsGroup, access modes not provided"))
			return false
		}
		if !hasReadWriteOnce(c.spec.PersistentVolume.Spec.AccessModes) {
			klog.V(4).Info(log("mounter.SetupAt WARNING: skipping fsGroup, only support ReadWriteOnce access mode"))
			return false
		}
		return true
	} else if c.spec.Volume != nil && c.spec.Volume.CSI != nil {
		// Inline CSI volumes are always mounted with RWO AccessMode by SetUpAt
		return true
	}

	klog.V(4).Info(log("mounter.SetupAt WARNING: skipping fsGroup, unsupported volume type"))
	return false
}

// getFSGroupPolicy returns if the CSI driver supports a volume in the given mode.
// An error indicates that it isn't supported and explains why.
func (c *csiMountMgr) getFSGroupPolicy() (storage.FSGroupPolicy, error) {
	// Retrieve CSIDriver. It's not an error if that isn't
	// possible (we don't have the lister if CSIDriverRegistry is
	// disabled) or the driver isn't found (CSIDriver is
	// optional)
	var csiDriver *storage.CSIDriver
	driver := string(c.driverName)
	if c.plugin.csiDriverLister != nil {
		c, err := c.plugin.getCSIDriver(driver)
		if err != nil && !apierrors.IsNotFound(err) {
			// Some internal error.
			return storage.ReadWriteOnceWithFSTypeFSGroupPolicy, err
		}
		csiDriver = c
	}

	// If the csiDriver isn't defined, return the default behavior
	if csiDriver == nil {
		return storage.ReadWriteOnceWithFSTypeFSGroupPolicy, nil
	}
	// If the csiDriver exists but the fsGroupPolicy isn't defined, return an error
	if csiDriver.Spec.FSGroupPolicy == nil || *csiDriver.Spec.FSGroupPolicy == "" {
		return storage.ReadWriteOnceWithFSTypeFSGroupPolicy, errors.New(log("expected valid fsGroupPolicy, received nil value or empty string"))
	}
	return *csiDriver.Spec.FSGroupPolicy, nil
}

// supportsVolumeMode checks whether the CSI driver supports a volume in the given mode.
// An error indicates that it isn't supported and explains why.
func (c *csiMountMgr) supportsVolumeLifecycleMode() error {
	// Retrieve CSIDriver. It's not an error if that isn't
	// possible (we don't have the lister if CSIDriverRegistry is
	// disabled) or the driver isn't found (CSIDriver is
	// optional), but then only persistent volumes are supported.
	var csiDriver *storage.CSIDriver
	driver := string(c.driverName)
	if c.plugin.csiDriverLister != nil {
		c, err := c.plugin.getCSIDriver(driver)
		if err != nil && !apierrors.IsNotFound(err) {
			// Some internal error.
			return err
		}
		csiDriver = c
	}

	// The right response depends on whether we have information
	// about the driver and the volume mode.
	switch {
	case csiDriver == nil && c.volumeLifecycleMode == storage.VolumeLifecyclePersistent:
		// No information, but that's okay for persistent volumes (and only those).
		return nil
	case csiDriver == nil:
		return fmt.Errorf("volume mode %q not supported by driver %s (no CSIDriver object)", c.volumeLifecycleMode, driver)
	case containsVolumeMode(csiDriver.Spec.VolumeLifecycleModes, c.volumeLifecycleMode):
		// Explicitly listed.
		return nil
	default:
		return fmt.Errorf("volume mode %q not supported by driver %s (only supports %q)", c.volumeLifecycleMode, driver, csiDriver.Spec.VolumeLifecycleModes)
	}
}

// containsVolumeMode checks whether the given volume mode is listed.
func containsVolumeMode(modes []storage.VolumeLifecycleMode, mode storage.VolumeLifecycleMode) bool {
	for _, m := range modes {
		if m == mode {
			return true
		}
	}
	return false
}

// isDirMounted returns the !notMounted result from IsLikelyNotMountPoint check
func isDirMounted(plug *csiPlugin, dir string) (bool, error) {
	mounter := plug.host.GetMounter(plug.GetPluginName())
	notMnt, err := mounter.IsLikelyNotMountPoint(dir)
	if err != nil && !os.IsNotExist(err) {
		klog.Error(log("isDirMounted IsLikelyNotMountPoint test failed for dir [%v]", dir))
		return false, err
	}
	return !notMnt, nil
}

func isCorruptedDir(dir string) bool {
	_, pathErr := mount.PathExists(dir)
	return pathErr != nil && mount.IsCorruptedMnt(pathErr)
}

// removeMountDir cleans the mount dir when dir is not mounted and removed the volume data file in dir
func removeMountDir(plug *csiPlugin, mountPath string) error {
	klog.V(4).Info(log("removing mount path [%s]", mountPath))

	mnt, err := isDirMounted(plug, mountPath)
	if err != nil {
		return err
	}
	if !mnt {
		klog.V(4).Info(log("dir not mounted, deleting it [%s]", mountPath))
		if err := os.Remove(mountPath); err != nil && !os.IsNotExist(err) {
			return errors.New(log("failed to remove dir [%s]: %v", mountPath, err))
		}
		// remove volume data file as well
		volPath := filepath.Dir(mountPath)
		dataFile := filepath.Join(volPath, volDataFileName)
		klog.V(4).Info(log("also deleting volume info data file [%s]", dataFile))
		if err := os.Remove(dataFile); err != nil && !os.IsNotExist(err) {
			return errors.New(log("failed to delete volume data file [%s]: %v", dataFile, err))
		}
		// remove volume path
		klog.V(4).Info(log("deleting volume path [%s]", volPath))
		if err := os.Remove(volPath); err != nil && !os.IsNotExist(err) {
			return errors.New(log("failed to delete volume path [%s]: %v", volPath, err))
		}
	}
	return nil
}

// makeVolumeHandle returns csi-<sha256(podUID,volSourceSpecName)>
func makeVolumeHandle(podUID, volSourceSpecName string) string {
	result := sha256.Sum256([]byte(fmt.Sprintf("%s%s", podUID, volSourceSpecName)))
	return fmt.Sprintf("csi-%x", result)
}

func mergeMap(first, second map[string]string) map[string]string {
	if first == nil {
		return second
	}
	for k, v := range second {
		first[k] = v
	}
	return first
}