/*
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 (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path"

	"github.com/golang/glog"
	grpctx "golang.org/x/net/context"
	api "k8s.io/api/core/v1"
	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/kubernetes"
	kstrings "k8s.io/kubernetes/pkg/util/strings"
	"k8s.io/kubernetes/pkg/volume"
	"k8s.io/kubernetes/pkg/volume/util"
)

const defaultFSType = "ext4"

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

type csiMountMgr struct {
	k8s          kubernetes.Interface
	csiClient    csiClient
	plugin       *csiPlugin
	driverName   string
	volumeID     string
	specVolumeID string
	readOnly     bool
	spec         *volume.Spec
	pod          *api.Pod
	podUID       types.UID
	options      volume.VolumeOptions
	volumeInfo   map[string]string
	volume.MetricsNil
}

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

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

func getTargetPath(uid types.UID, specVolumeID string, host volume.VolumeHost) string {
	specVolID := kstrings.EscapeQualifiedNameForDisk(specVolumeID)
	return host.GetPodVolumeDir(uid, kstrings.EscapeQualifiedNameForDisk(csiPluginName), specVolID)
}

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

func (c *csiMountMgr) CanMount() error {
	//TODO (vladimirvivien) use this method to probe controller using CSI.NodeProbe() call
	// to ensure Node service is ready in the CSI plugin
	return nil
}

func (c *csiMountMgr) SetUp(fsGroup *int64) error {
	return c.SetUpAt(c.GetPath(), fsGroup)
}

func (c *csiMountMgr) SetUpAt(dir string, fsGroup *int64) error {
	glog.V(4).Infof(log("Mounter.SetUpAt(%s)", dir))

	mounted, err := isDirMounted(c.plugin, dir)
	if err != nil {
		glog.Error(log("mounter.SetUpAt failed while checking mount status for dir [%s]", dir))
		return err
	}

	if mounted {
		glog.V(4).Info(log("mounter.SetUpAt skipping mount, dir already mounted [%s]", dir))
		return nil
	}

	csiSource, err := getCSISourceFromSpec(c.spec)
	if err != nil {
		glog.Error(log("mounter.SetupAt failed to get CSI persistent source: %v", err))
		return err
	}

	ctx, cancel := grpctx.WithTimeout(grpctx.Background(), csiTimeout)
	defer cancel()

	csi := c.csiClient
	nodeName := string(c.plugin.host.GetNodeName())
	attachID := getAttachmentName(csiSource.VolumeHandle, csiSource.Driver, nodeName)

	// ensure version is supported
	if err := csi.AssertSupportedVersion(ctx, csiVersion); err != nil {
		glog.Error(log("mounter.SetUpAt failed to assert version: %v", err))
		return err
	}

	// probe driver
	// TODO (vladimirvivien) move probe call where it is done only when it is needed.
	if err := csi.NodeProbe(ctx, csiVersion); err != nil {
		glog.Error(log("mounter.SetUpAt failed to probe driver: %v", err))
		return err
	}

	// search for attachment by VolumeAttachment.Spec.Source.PersistentVolumeName
	if c.volumeInfo == nil {
		attachment, err := c.k8s.StorageV1alpha1().VolumeAttachments().Get(attachID, meta.GetOptions{})
		if err != nil {
			glog.Error(log("mounter.SetupAt failed while getting volume attachment [id=%v]: %v", attachID, err))
			return err
		}

		if attachment == nil {
			glog.Error(log("unable to find VolumeAttachment [id=%s]", attachID))
			return errors.New("no existing VolumeAttachment found")
		}
		c.volumeInfo = attachment.Status.AttachmentMetadata
	}

	// get volume attributes
	// TODO: for alpha vol atttributes are passed via PV.Annotations
	// Beta will fix that
	attribs, err := getVolAttribsFromSpec(c.spec)
	if err != nil {
		glog.Error(log("mounter.SetUpAt failed to extract volume attributes from PV annotations: %v", err))
		return err
	}

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

	// persist volume info data for teardown
	volData := map[string]string{
		volDataKey.specVolID:    c.spec.Name(),
		volDataKey.volHandle:    csiSource.VolumeHandle,
		volDataKey.driverName:   csiSource.Driver,
		volDataKey.nodeName:     nodeName,
		volDataKey.attachmentID: attachID,
	}

	if err := saveVolumeData(c.plugin, c.podUID, c.spec.Name(), volData); err != nil {
		glog.Error(log("mounter.SetUpAt failed to save volume info data: %v", err))
		if err := removeMountDir(c.plugin, dir); err != nil {
			glog.Error(log("mounter.SetUpAt failed to remove mount dir after a saveVolumeData() error [%s]: %v", dir, err))
			return err
		}
		return err
	}

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

	fsType := csiSource.FSType
	if len(fsType) == 0 {
		fsType = defaultFSType
	}

	err = csi.NodePublishVolume(
		ctx,
		c.volumeID,
		c.readOnly,
		dir,
		accessMode,
		c.volumeInfo,
		attribs,
		fsType,
	)

	if err != nil {
		glog.Errorf(log("mounter.SetupAt failed: %v", err))
		if err := removeMountDir(c.plugin, dir); err != nil {
			glog.Error(log("mounter.SetuAt failed to remove mount dir after a NodePublish() error [%s]: %v", dir, err))
			return err
		}
		return err
	}

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

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

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

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

	// is dir even mounted ?
	// TODO (vladimirvivien) this check may not work for an emptyDir or local storage
	// see https://github.com/kubernetes/kubernetes/pull/56836#discussion_r155834524
	mounted, err := isDirMounted(c.plugin, dir)
	if err != nil {
		glog.Error(log("unmounter.Teardown failed while checking mount status for dir [%s]: %v", dir, err))
		return err
	}

	if !mounted {
		glog.V(4).Info(log("unmounter.Teardown skipping unmout, dir not mounted [%s]", dir))
		return nil
	}

	// load volume info from file
	dataDir := path.Dir(dir) // dropoff /mount at end
	data, err := loadVolumeData(dataDir, volDataFileName)
	if err != nil {
		glog.Error(log("unmounter.Teardown failed to load volume data file using dir [%s]: %v", dir, err))
		return err
	}

	volID := data[volDataKey.volHandle]
	driverName := data[volDataKey.driverName]

	if c.csiClient == nil {
		addr := fmt.Sprintf(csiAddrTemplate, driverName)
		client := newCsiDriverClient("unix", addr)
		glog.V(4).Infof(log("unmounter csiClient setup [volume=%v,driver=%v]", volID, driverName))
		c.csiClient = client
	}

	ctx, cancel := grpctx.WithTimeout(grpctx.Background(), csiTimeout)
	defer cancel()

	csi := c.csiClient

	// TODO make all assertion calls private within the client itself
	if err := csi.AssertSupportedVersion(ctx, csiVersion); err != nil {
		glog.Errorf(log("mounter.TearDownAt failed to assert version: %v", err))
		return err
	}

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

	// clean mount point dir
	if err := removeMountDir(c.plugin, dir); err != nil {
		glog.Error(log("mounter.TearDownAt failed to clean mount dir [%s]: %v", dir, err))
		return err
	}
	glog.V(4).Infof(log("mounte.TearDownAt successfully unmounted dir [%s]", dir))

	return nil
}

// getVolAttribsFromSpec exracts CSI VolumeAttributes information from PV.Annotations
// using key csi.kubernetes.io/volume-attributes.  The annotation value is expected
// to be a JSON-encoded object of form {"key0":"val0",...,"keyN":"valN"}
func getVolAttribsFromSpec(spec *volume.Spec) (map[string]string, error) {
	if spec == nil {
		return nil, errors.New("missing volume spec")
	}
	annotations := spec.PersistentVolume.GetAnnotations()
	if annotations == nil {
		return nil, nil // no annotations found
	}
	jsonAttribs := annotations[csiVolAttribsAnnotationKey]
	if jsonAttribs == "" {
		return nil, nil // csi annotation not found
	}
	attribs := map[string]string{}
	if err := json.Unmarshal([]byte(jsonAttribs), &attribs); err != nil {
		glog.Error(log("error parsing csi PV.Annotation [%s]=%s: %v", csiVolAttribsAnnotationKey, jsonAttribs, err))
		return nil, err
	}
	return attribs, nil
}

// saveVolumeData persists parameter data as json file using the locagion
// generated by /var/lib/kubelet/pods/<podID>/volumes/kubernetes.io~csi/<specVolId>/volume_data.json
func saveVolumeData(p *csiPlugin, podUID types.UID, specVolID string, data map[string]string) error {
	dir := getTargetPath(podUID, specVolID, p.host)
	dataFilePath := path.Join(dir, volDataFileName)

	file, err := os.Create(dataFilePath)
	if err != nil {
		glog.Error(log("failed to save volume data file %s: %v", dataFilePath, err))
		return err
	}
	defer file.Close()
	if err := json.NewEncoder(file).Encode(data); err != nil {
		glog.Error(log("failed to save volume data file %s: %v", dataFilePath, err))
		return err
	}
	glog.V(4).Info(log("volume data file saved successfully [%s]", dataFilePath))
	return nil
}

// loadVolumeData uses the directory returned by mounter.GetPath with value
// /var/lib/kubelet/pods/<podID>/volumes/kubernetes.io~csi/<specVolumeId>/mount.
// The function extracts specVolumeID and uses it to load the json data file from dir
// /var/lib/kubelet/pods/<podID>/volumes/kubernetes.io~csi/<specVolId>/volume_data.json
func loadVolumeData(dir string, fileName string) (map[string]string, error) {
	// remove /mount at the end
	dataFileName := path.Join(dir, fileName)
	glog.V(4).Info(log("loading volume data file [%s]", dataFileName))

	file, err := os.Open(dataFileName)
	if err != nil {
		glog.Error(log("failed to open volume data file [%s]: %v", dataFileName, err))
		return nil, err
	}
	defer file.Close()
	data := map[string]string{}
	if err := json.NewDecoder(file).Decode(&data); err != nil {
		glog.Error(log("failed to parse volume data file [%s]: %v", dataFileName, err))
		return nil, err
	}

	return data, nil
}

// 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) {
		glog.Error(log("isDirMounted IsLikelyNotMountPoint test failed for dir [%v]", dir))
		return false, err
	}
	return !notMnt, nil
}

// 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 {
	glog.V(4).Info(log("removing mount path [%s]", mountPath))
	if pathExists, pathErr := util.PathExists(mountPath); pathErr != nil {
		glog.Error(log("failed while checking mount path stat [%s]", pathErr))
		return pathErr
	} else if !pathExists {
		glog.Warning(log("skipping mount dir removal, path does not exist [%v]", mountPath))
		return nil
	}

	mounter := plug.host.GetMounter(plug.GetPluginName())
	notMnt, err := mounter.IsLikelyNotMountPoint(mountPath)
	if err != nil {
		glog.Error(log("mount dir removal failed [%s]: %v", mountPath, err))
		return err
	}
	if notMnt {
		glog.V(4).Info(log("dir not mounted, deleting it [%s]", mountPath))
		if err := os.Remove(mountPath); err != nil && !os.IsNotExist(err) {
			glog.Error(log("failed to remove dir [%s]: %v", mountPath, err))
			return err
		}
		// remove volume data file as well
		dataFile := path.Join(path.Dir(mountPath), volDataFileName)
		glog.V(4).Info(log("also deleting volume info data file [%s]", dataFile))
		if err := os.Remove(dataFile); err != nil && !os.IsNotExist(err) {
			glog.Error(log("failed to delete volume data file [%s]: %v", dataFile, err))
			return err
		}
	}
	return nil
}