/*
Copyright 2015 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 glusterfs

import (
	"fmt"
	"os"
	"path"
	"strconv"
	dstrings "strings"

	"runtime"

	"github.com/golang/glog"
	gcli "github.com/heketi/heketi/client/api/go-client"
	gapi "github.com/heketi/heketi/pkg/glusterfs/api"
	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/api/resource"
	"k8s.io/kubernetes/pkg/types"
	"k8s.io/kubernetes/pkg/util/exec"
	"k8s.io/kubernetes/pkg/util/mount"
	"k8s.io/kubernetes/pkg/util/strings"
	"k8s.io/kubernetes/pkg/volume"
	volutil "k8s.io/kubernetes/pkg/volume/util"
)

// This is the primary entrypoint for volume plugins.
func ProbeVolumePlugins() []volume.VolumePlugin {
	return []volume.VolumePlugin{&glusterfsPlugin{nil, exec.New(), new(glusterfsClusterConf)}}
}

type glusterfsPlugin struct {
	host        volume.VolumeHost
	exe         exec.Interface
	clusterconf *glusterfsClusterConf
}

var _ volume.VolumePlugin = &glusterfsPlugin{}
var _ volume.PersistentVolumePlugin = &glusterfsPlugin{}
var _ volume.DeletableVolumePlugin = &glusterfsPlugin{}
var _ volume.ProvisionableVolumePlugin = &glusterfsPlugin{}
var _ volume.Provisioner = &glusterfsVolumeProvisioner{}
var _ volume.Deleter = &glusterfsVolumeDeleter{}

const (
	glusterfsPluginName         = "kubernetes.io/glusterfs"
	volprefix                   = "vol_"
	gciGlusterMountBinariesPath = "/sbin/mount.glusterfs"
)

func (plugin *glusterfsPlugin) Init(host volume.VolumeHost) error {
	plugin.host = host
	return nil
}

func (plugin *glusterfsPlugin) GetPluginName() string {
	return glusterfsPluginName
}

func (plugin *glusterfsPlugin) GetVolumeName(spec *volume.Spec) (string, error) {
	volumeSource, _, err := getVolumeSource(spec)
	if err != nil {
		return "", err
	}

	return fmt.Sprintf(
		"%v:%v",
		volumeSource.EndpointsName,
		volumeSource.Path), nil
}

func (plugin *glusterfsPlugin) CanSupport(spec *volume.Spec) bool {
	if (spec.PersistentVolume != nil && spec.PersistentVolume.Spec.Glusterfs == nil) ||
		(spec.Volume != nil && spec.Volume.Glusterfs == nil) {
		return false
	}

	return true
}

func (plugin *glusterfsPlugin) RequiresRemount() bool {
	return false
}

func (plugin *glusterfsPlugin) GetAccessModes() []api.PersistentVolumeAccessMode {
	return []api.PersistentVolumeAccessMode{
		api.ReadWriteOnce,
		api.ReadOnlyMany,
		api.ReadWriteMany,
	}
}

func (plugin *glusterfsPlugin) NewMounter(spec *volume.Spec, pod *api.Pod, _ volume.VolumeOptions) (volume.Mounter, error) {
	source, _ := plugin.getGlusterVolumeSource(spec)
	ep_name := source.EndpointsName
	ns := pod.Namespace
	ep, err := plugin.host.GetKubeClient().Core().Endpoints(ns).Get(ep_name)
	if err != nil {
		glog.Errorf("glusterfs: failed to get endpoints %s[%v]", ep_name, err)
		return nil, err
	}
	glog.V(1).Infof("glusterfs: endpoints %v", ep)
	return plugin.newMounterInternal(spec, ep, pod, plugin.host.GetMounter(), exec.New())
}

func (plugin *glusterfsPlugin) getGlusterVolumeSource(spec *volume.Spec) (*api.GlusterfsVolumeSource, bool) {
	// Glusterfs volumes used directly in a pod have a ReadOnly flag set by the pod author.
	// Glusterfs volumes used as a PersistentVolume gets the ReadOnly flag indirectly through the persistent-claim volume used to mount the PV
	if spec.Volume != nil && spec.Volume.Glusterfs != nil {
		return spec.Volume.Glusterfs, spec.Volume.Glusterfs.ReadOnly
	} else {
		return spec.PersistentVolume.Spec.Glusterfs, spec.ReadOnly
	}
}

func (plugin *glusterfsPlugin) newMounterInternal(spec *volume.Spec, ep *api.Endpoints, pod *api.Pod, mounter mount.Interface, exe exec.Interface) (volume.Mounter, error) {
	source, readOnly := plugin.getGlusterVolumeSource(spec)
	return &glusterfsMounter{
		glusterfs: &glusterfs{
			volName: spec.Name(),
			mounter: mounter,
			pod:     pod,
			plugin:  plugin,
		},
		hosts:    ep,
		path:     source.Path,
		readOnly: readOnly,
		exe:      exe}, nil
}

func (plugin *glusterfsPlugin) NewUnmounter(volName string, podUID types.UID) (volume.Unmounter, error) {
	return plugin.newUnmounterInternal(volName, podUID, plugin.host.GetMounter())
}

func (plugin *glusterfsPlugin) newUnmounterInternal(volName string, podUID types.UID, mounter mount.Interface) (volume.Unmounter, error) {
	return &glusterfsUnmounter{&glusterfs{
		volName: volName,
		mounter: mounter,
		pod:     &api.Pod{ObjectMeta: api.ObjectMeta{UID: podUID}},
		plugin:  plugin,
	}}, nil
}

func (plugin *glusterfsPlugin) execCommand(command string, args []string) ([]byte, error) {
	cmd := plugin.exe.Command(command, args...)
	return cmd.CombinedOutput()
}

func (plugin *glusterfsPlugin) ConstructVolumeSpec(volumeName, mountPath string) (*volume.Spec, error) {
	glusterfsVolume := &api.Volume{
		Name: volumeName,
		VolumeSource: api.VolumeSource{
			Glusterfs: &api.GlusterfsVolumeSource{
				EndpointsName: volumeName,
				Path:          volumeName,
			},
		},
	}
	return volume.NewSpecFromVolume(glusterfsVolume), nil
}

// Glusterfs volumes represent a bare host file or directory mount of an Glusterfs export.
type glusterfs struct {
	volName string
	pod     *api.Pod
	mounter mount.Interface
	plugin  *glusterfsPlugin
	volume.MetricsNil
}

type glusterfsMounter struct {
	*glusterfs
	hosts    *api.Endpoints
	path     string
	readOnly bool
	exe      exec.Interface
}

var _ volume.Mounter = &glusterfsMounter{}

func (b *glusterfsMounter) GetAttributes() volume.Attributes {
	return volume.Attributes{
		ReadOnly:        b.readOnly,
		Managed:         false,
		SupportsSELinux: false,
	}
}

// Checks prior to mount operations to verify that the required components (binaries, etc.)
// to mount the volume are available on the underlying node.
// If not, it returns an error
func (b *glusterfsMounter) CanMount() error {
	exe := exec.New()
	switch runtime.GOOS {
	case "linux":
		if _, err := exe.Command("/bin/ls", gciGlusterMountBinariesPath).CombinedOutput(); err != nil {
			return fmt.Errorf("Required binary %s is missing", gciGlusterMountBinariesPath)
		}
	}
	return nil
}

// SetUp attaches the disk and bind mounts to the volume path.
func (b *glusterfsMounter) SetUp(fsGroup *int64) error {
	return b.SetUpAt(b.GetPath(), fsGroup)
}

func (b *glusterfsMounter) SetUpAt(dir string, fsGroup *int64) error {
	notMnt, err := b.mounter.IsLikelyNotMountPoint(dir)
	glog.V(4).Infof("glusterfs: mount set up: %s %v %v", dir, !notMnt, err)
	if err != nil && !os.IsNotExist(err) {
		return err
	}
	if !notMnt {
		return nil
	}

	os.MkdirAll(dir, 0750)
	err = b.setUpAtInternal(dir)
	if err == nil {
		return nil
	}

	// Cleanup upon failure.
	volutil.UnmountPath(dir, b.mounter)
	return err
}

func (glusterfsVolume *glusterfs) GetPath() string {
	name := glusterfsPluginName
	return glusterfsVolume.plugin.host.GetPodVolumeDir(glusterfsVolume.pod.UID, strings.EscapeQualifiedNameForDisk(name), glusterfsVolume.volName)
}

type glusterfsUnmounter struct {
	*glusterfs
}

var _ volume.Unmounter = &glusterfsUnmounter{}

func (c *glusterfsUnmounter) TearDown() error {
	return c.TearDownAt(c.GetPath())
}

func (c *glusterfsUnmounter) TearDownAt(dir string) error {
	return volutil.UnmountPath(dir, c.mounter)
}

func (b *glusterfsMounter) setUpAtInternal(dir string) error {
	var errs error

	options := []string{}
	if b.readOnly {
		options = append(options, "ro")
	}

	p := path.Join(b.glusterfs.plugin.host.GetPluginDir(glusterfsPluginName), b.glusterfs.volName)
	if err := os.MkdirAll(p, 0750); err != nil {
		return fmt.Errorf("glusterfs: mkdir failed: %v", err)
	}

	// adding log-level ERROR to remove noise
	// and more specific log path so each pod has
	// it's own log based on PV + Pod
	log := path.Join(p, b.pod.Name+"-glusterfs.log")
	options = append(options, "log-level=ERROR")
	options = append(options, "log-file="+log)

	addr := make(map[string]struct{})
	for _, s := range b.hosts.Subsets {
		for _, a := range s.Addresses {
			addr[a.IP] = struct{}{}
		}
	}

	// Avoid mount storm, pick a host randomly.
	// Iterate all hosts until mount succeeds.
	for hostIP := range addr {
		errs = b.mounter.Mount(hostIP+":"+b.path, dir, "glusterfs", options)
		if errs == nil {
			glog.Infof("glusterfs: successfully mounted %s", dir)
			return nil
		}
	}

	// Failed mount scenario.
	// Since gluster does not return eror text
	// it all goes in a log file, we will read the log file
	logerror := readGlusterLog(log, b.pod.Name)
	if logerror != nil {
		// return fmt.Errorf("glusterfs: mount failed: %v", logerror)
		return fmt.Errorf("glusterfs: mount failed: %v the following error information was pulled from the glusterfs log to help diagnose this issue: %v", errs, logerror)
	}
	return fmt.Errorf("glusterfs: mount failed: %v", errs)
}

func getVolumeSource(
	spec *volume.Spec) (*api.GlusterfsVolumeSource, bool, error) {
	if spec.Volume != nil && spec.Volume.Glusterfs != nil {
		return spec.Volume.Glusterfs, spec.Volume.Glusterfs.ReadOnly, nil
	} else if spec.PersistentVolume != nil &&
		spec.PersistentVolume.Spec.Glusterfs != nil {
		return spec.PersistentVolume.Spec.Glusterfs, spec.ReadOnly, nil
	}

	return nil, false, fmt.Errorf("Spec does not reference a Gluster volume type")
}

func (plugin *glusterfsPlugin) NewProvisioner(options volume.VolumeOptions) (volume.Provisioner, error) {
	if len(options.AccessModes) == 0 {
		options.AccessModes = plugin.GetAccessModes()
	}
	return plugin.newProvisionerInternal(options)
}

func (plugin *glusterfsPlugin) newProvisionerInternal(options volume.VolumeOptions) (volume.Provisioner, error) {
	return &glusterfsVolumeProvisioner{
		glusterfsMounter: &glusterfsMounter{
			glusterfs: &glusterfs{
				plugin: plugin,
			},
		},
		options: options,
	}, nil
}

type glusterfsClusterConf struct {
	glusterep          string
	glusterRestvolpath string
	glusterRestUrl     string
	glusterRestAuth    bool
	glusterRestUser    string
	glusterRestUserKey string
}

type glusterfsVolumeProvisioner struct {
	*glusterfsMounter
	*glusterfsClusterConf
	options volume.VolumeOptions
}

func (plugin *glusterfsPlugin) NewDeleter(spec *volume.Spec) (volume.Deleter, error) {
	return plugin.newDeleterInternal(spec)
}

func (plugin *glusterfsPlugin) newDeleterInternal(spec *volume.Spec) (volume.Deleter, error) {
	if spec.PersistentVolume != nil && spec.PersistentVolume.Spec.Glusterfs == nil {
		return nil, fmt.Errorf("spec.PersistentVolumeSource.Spec.Glusterfs is nil")
	}
	return &glusterfsVolumeDeleter{
		glusterfsMounter: &glusterfsMounter{
			glusterfs: &glusterfs{
				volName: spec.Name(),
				plugin:  plugin,
			},
			path: spec.PersistentVolume.Spec.Glusterfs.Path,
		}}, nil
}

type glusterfsVolumeDeleter struct {
	*glusterfsMounter
	*glusterfsClusterConf
}

func (d *glusterfsVolumeDeleter) GetPath() string {
	name := glusterfsPluginName
	return d.plugin.host.GetPodVolumeDir(d.glusterfsMounter.glusterfs.pod.UID, strings.EscapeQualifiedNameForDisk(name), d.glusterfsMounter.glusterfs.volName)
}

func (d *glusterfsVolumeDeleter) Delete() error {
	var err error
	glog.V(2).Infof("glusterfs: delete volume :%s ", d.glusterfsMounter.path)
	volumetodel := d.glusterfsMounter.path
	d.glusterfsClusterConf = d.plugin.clusterconf
	newvolumetodel := dstrings.TrimPrefix(volumetodel, volprefix)
	cli := gcli.NewClient(d.glusterRestUrl, d.glusterRestUser, d.glusterRestUserKey)
	if cli == nil {
		glog.Errorf("glusterfs: failed to create gluster rest client")
		return fmt.Errorf("glusterfs: failed to create gluster rest client, REST server authentication failed")
	}
	err = cli.VolumeDelete(newvolumetodel)
	if err != nil {
		glog.V(4).Infof("glusterfs: error when deleting the volume :%s", err)
		return err
	}
	glog.V(2).Infof("glusterfs: volume %s deleted successfully", volumetodel)
	return nil

}

func (r *glusterfsVolumeProvisioner) Provision() (*api.PersistentVolume, error) {
	var err error
	if r.options.Selector != nil {
		glog.V(4).Infof("glusterfs: not able to parse your claim Selector")
		return nil, fmt.Errorf("glusterfs: not able to parse your claim Selector")
	}
	glog.V(4).Infof("glusterfs: Provison VolumeOptions %v", r.options)
	for k, v := range r.options.Parameters {
		switch dstrings.ToLower(k) {
		case "endpoint":
			r.plugin.clusterconf.glusterep = v
		case "path":
			r.plugin.clusterconf.glusterRestvolpath = v
		case "resturl":
			r.plugin.clusterconf.glusterRestUrl = v
		case "restauthenabled":
			r.plugin.clusterconf.glusterRestAuth, err = strconv.ParseBool(v)
		case "restuser":
			r.plugin.clusterconf.glusterRestUser = v
		case "restuserkey":
			r.plugin.clusterconf.glusterRestUserKey = v
		default:
			return nil, fmt.Errorf("glusterfs: invalid option %q for volume plugin %s", k, r.plugin.GetPluginName())
		}
	}
	glog.V(4).Infof("glusterfs: storage class parameters in plugin clusterconf %v", r.plugin.clusterconf)
	if !r.plugin.clusterconf.glusterRestAuth {
		r.plugin.clusterconf.glusterRestUser = ""
		r.plugin.clusterconf.glusterRestUserKey = ""
	}
	r.glusterfsClusterConf = r.plugin.clusterconf
	glusterfs, sizeGB, err := r.CreateVolume()
	if err != nil {
		glog.Errorf("glusterfs: create volume err: %s.", err)
		return nil, fmt.Errorf("glusterfs: create volume err: %s.", err)
	}
	pv := new(api.PersistentVolume)
	pv.Spec.PersistentVolumeSource.Glusterfs = glusterfs
	pv.Spec.PersistentVolumeReclaimPolicy = r.options.PersistentVolumeReclaimPolicy
	pv.Spec.AccessModes = r.options.AccessModes
	pv.Spec.Capacity = api.ResourceList{
		api.ResourceName(api.ResourceStorage): resource.MustParse(fmt.Sprintf("%dGi", sizeGB)),
	}
	return pv, nil
}

func (p *glusterfsVolumeProvisioner) CreateVolume() (r *api.GlusterfsVolumeSource, size int, err error) {
	volSizeBytes := p.options.Capacity.Value()
	sz := int(volume.RoundUpSize(volSizeBytes, 1024*1024*1024))
	glog.V(2).Infof("glusterfs: create volume of size:%d bytes", volSizeBytes)
	if p.glusterfsClusterConf.glusterRestUrl == "" {
		glog.Errorf("glusterfs : rest server endpoint is empty")
		return nil, 0, fmt.Errorf("failed to create gluster REST client, REST URL is empty")
	}
	cli := gcli.NewClient(p.glusterRestUrl, p.glusterRestUser, p.glusterRestUserKey)
	if cli == nil {
		glog.Errorf("glusterfs: failed to create gluster rest client")
		return nil, 0, fmt.Errorf("failed to create gluster REST client, REST server authentication failed")
	}
	volumeReq := &gapi.VolumeCreateRequest{Size: sz}
	volume, err := cli.VolumeCreate(volumeReq)
	if err != nil {
		glog.Errorf("glusterfs: error creating volume %s ", err)
		return nil, 0, fmt.Errorf("error creating volume %v", err)
	}
	glog.V(1).Infof("glusterfs: volume with size: %d and name: %s created", volume.Size, volume.Name)
	return &api.GlusterfsVolumeSource{
		EndpointsName: p.glusterfsClusterConf.glusterep,
		Path:          volume.Name,
		ReadOnly:      false,
	}, sz, nil
}