/*
Copyright 2014 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 gce_pd

import (
	"fmt"
	"path"
	"path/filepath"
	"strings"
	"time"

	"github.com/golang/glog"
	"k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/util/sets"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	"k8s.io/kubernetes/pkg/cloudprovider"
	gcecloud "k8s.io/kubernetes/pkg/cloudprovider/providers/gce"
	"k8s.io/kubernetes/pkg/features"
	kubeletapis "k8s.io/kubernetes/pkg/kubelet/apis"
	"k8s.io/kubernetes/pkg/volume"
	volumeutil "k8s.io/kubernetes/pkg/volume/util"
	"k8s.io/utils/exec"
)

const (
	diskByIdPath         = "/dev/disk/by-id/"
	diskGooglePrefix     = "google-"
	diskScsiGooglePrefix = "scsi-0Google_PersistentDisk_"
	diskPartitionSuffix  = "-part"
	diskSDPath           = "/dev/sd"
	diskSDPattern        = "/dev/sd*"
	maxRetries           = 10
	checkSleepDuration   = time.Second
	maxRegionalPDZones   = 2

	// Replication type constants must be lower case.
	replicationTypeNone       = "none"
	replicationTypeRegionalPD = "regional-pd"
)

// These variables are modified only in unit tests and should be constant
// otherwise.
var (
	errorSleepDuration time.Duration = 5 * time.Second
)

type GCEDiskUtil struct{}

func (util *GCEDiskUtil) DeleteVolume(d *gcePersistentDiskDeleter) error {
	cloud, err := getCloudProvider(d.gcePersistentDisk.plugin.host.GetCloudProvider())
	if err != nil {
		return err
	}

	if err = cloud.DeleteDisk(d.pdName); err != nil {
		glog.V(2).Infof("Error deleting GCE PD volume %s: %v", d.pdName, err)
		// GCE cloud provider returns volume.deletedVolumeInUseError when
		// necessary, no handling needed here.
		return err
	}
	glog.V(2).Infof("Successfully deleted GCE PD volume %s", d.pdName)
	return nil
}

// CreateVolume creates a GCE PD.
// Returns: gcePDName, volumeSizeGB, labels, fsType, error
func (gceutil *GCEDiskUtil) CreateVolume(c *gcePersistentDiskProvisioner) (string, int, map[string]string, string, error) {
	cloud, err := getCloudProvider(c.gcePersistentDisk.plugin.host.GetCloudProvider())
	if err != nil {
		return "", 0, nil, "", err
	}

	name := volumeutil.GenerateVolumeName(c.options.ClusterName, c.options.PVName, 63) // GCE PD name can have up to 63 characters
	capacity := c.options.PVC.Spec.Resources.Requests[v1.ResourceName(v1.ResourceStorage)]
	// GCE PDs are allocated in chunks of GBs (not GiBs)
	requestGB := volumeutil.RoundUpToGB(capacity)

	// Apply Parameters.
	// Values for parameter "replication-type" are canonicalized to lower case.
	// Values for other parameters are case-insensitive, and we leave validation of these values
	// to the cloud provider.
	diskType := ""
	configuredZone := ""
	configuredZones := ""
	zonePresent := false
	zonesPresent := false
	replicationType := replicationTypeNone
	fstype := ""
	for k, v := range c.options.Parameters {
		switch strings.ToLower(k) {
		case "type":
			diskType = v
		case "zone":
			zonePresent = true
			configuredZone = v
		case "zones":
			zonesPresent = true
			configuredZones = v
		case "replication-type":
			if !utilfeature.DefaultFeatureGate.Enabled(features.GCERegionalPersistentDisk) {
				return "", 0, nil, "",
					fmt.Errorf("the %q option for volume plugin %v is only supported with the %q Kubernetes feature gate enabled",
						k, c.plugin.GetPluginName(), features.GCERegionalPersistentDisk)
			}
			replicationType = strings.ToLower(v)
		case volume.VolumeParameterFSType:
			fstype = v
		default:
			return "", 0, nil, "", fmt.Errorf("invalid option %q for volume plugin %s", k, c.plugin.GetPluginName())
		}
	}

	if zonePresent && zonesPresent {
		return "", 0, nil, "", fmt.Errorf("the 'zone' and 'zones' StorageClass parameters must not be used at the same time")
	}

	if replicationType == replicationTypeRegionalPD && zonePresent {
		// If a user accidentally types 'zone' instead of 'zones', we want to throw an error
		// instead of assuming that 'zones' is empty and proceed by randomly selecting zones.
		return "", 0, nil, "", fmt.Errorf("the '%s' replication type does not support the 'zone' parameter; use 'zones' instead", replicationTypeRegionalPD)
	}

	// TODO: implement PVC.Selector parsing
	if c.options.PVC.Spec.Selector != nil {
		return "", 0, nil, "", fmt.Errorf("claim.Spec.Selector is not supported for dynamic provisioning on GCE")
	}

	switch replicationType {
	case replicationTypeRegionalPD:
		err = createRegionalPD(
			name,
			c.options.PVC.Name,
			diskType,
			configuredZones,
			requestGB,
			c.options.CloudTags,
			cloud)
		if err != nil {
			glog.V(2).Infof("Error creating regional GCE PD volume: %v", err)
			return "", 0, nil, "", err
		}

		glog.V(2).Infof("Successfully created Regional GCE PD volume %s", name)

	case replicationTypeNone:
		var zones sets.String
		if !zonePresent && !zonesPresent {
			// 00 - neither "zone" or "zones" specified
			// Pick a zone randomly selected from all active zones where
			// Kubernetes cluster has a node.
			zones, err = cloud.GetAllCurrentZones()
			if err != nil {
				glog.V(2).Infof("error getting zone information from GCE: %v", err)
				return "", 0, nil, "", err
			}
		} else if !zonePresent && zonesPresent {
			// 01 - "zones" specified
			// Pick a zone randomly selected from specified set.
			if zones, err = volumeutil.ZonesToSet(configuredZones); err != nil {
				return "", 0, nil, "", err
			}
		} else if zonePresent && !zonesPresent {
			// 10 - "zone" specified
			// Use specified zone
			if err := volumeutil.ValidateZone(configuredZone); err != nil {
				return "", 0, nil, "", err
			}
			zones = make(sets.String)
			zones.Insert(configuredZone)
		}
		zone := volumeutil.ChooseZoneForVolume(zones, c.options.PVC.Name)

		if err := cloud.CreateDisk(
			name,
			diskType,
			zone,
			int64(requestGB),
			*c.options.CloudTags); err != nil {
			glog.V(2).Infof("Error creating single-zone GCE PD volume: %v", err)
			return "", 0, nil, "", err
		}

		glog.V(2).Infof("Successfully created single-zone GCE PD volume %s", name)

	default:
		return "", 0, nil, "", fmt.Errorf("replication-type of '%s' is not supported", replicationType)
	}

	labels, err := cloud.GetAutoLabelsForPD(name, "" /* zone */)
	if err != nil {
		// We don't really want to leak the volume here...
		glog.Errorf("error getting labels for volume %q: %v", name, err)
	}

	return name, int(requestGB), labels, fstype, nil
}

// Creates a Regional PD
func createRegionalPD(
	diskName string,
	pvcName string,
	diskType string,
	zonesString string,
	requestGB int64,
	cloudTags *map[string]string,
	cloud *gcecloud.GCECloud) error {

	var replicaZones sets.String
	var err error

	if zonesString == "" {
		// Consider all zones
		replicaZones, err = cloud.GetAllCurrentZones()
		if err != nil {
			glog.V(2).Infof("error getting zone information from GCE: %v", err)
			return err
		}
	} else {
		replicaZones, err = volumeutil.ZonesToSet(zonesString)
		if err != nil {
			return err
		}
	}

	zoneCount := replicaZones.Len()
	var selectedReplicaZones sets.String
	if zoneCount < maxRegionalPDZones {
		return fmt.Errorf("cannot specify only %d zone(s) for Regional PDs.", zoneCount)
	} else if zoneCount == maxRegionalPDZones {
		selectedReplicaZones = replicaZones
	} else {
		// Must randomly select zones
		selectedReplicaZones = volumeutil.ChooseZonesForVolume(
			replicaZones, pvcName, maxRegionalPDZones)
	}

	if err = cloud.CreateRegionalDisk(
		diskName,
		diskType,
		selectedReplicaZones,
		int64(requestGB),
		*cloudTags); err != nil {
		return err
	}

	return nil
}

// Returns the first path that exists, or empty string if none exist.
func verifyDevicePath(devicePaths []string, sdBeforeSet sets.String) (string, error) {
	if err := udevadmChangeToNewDrives(sdBeforeSet); err != nil {
		// udevadm errors should not block disk detachment, log and continue
		glog.Errorf("udevadmChangeToNewDrives failed with: %v", err)
	}

	for _, path := range devicePaths {
		if pathExists, err := volumeutil.PathExists(path); err != nil {
			return "", fmt.Errorf("Error checking if path exists: %v", err)
		} else if pathExists {
			return path, nil
		}
	}

	return "", nil
}

// Returns the first path that exists, or empty string if none exist.
func verifyAllPathsRemoved(devicePaths []string) (bool, error) {
	allPathsRemoved := true
	for _, path := range devicePaths {
		if err := udevadmChangeToDrive(path); err != nil {
			// udevadm errors should not block disk detachment, log and continue
			glog.Errorf("%v", err)
		}
		if exists, err := volumeutil.PathExists(path); err != nil {
			return false, fmt.Errorf("Error checking if path exists: %v", err)
		} else {
			allPathsRemoved = allPathsRemoved && !exists
		}
	}

	return allPathsRemoved, nil
}

// Returns list of all /dev/disk/by-id/* paths for given PD.
func getDiskByIdPaths(pdName string, partition string) []string {
	devicePaths := []string{
		path.Join(diskByIdPath, diskGooglePrefix+pdName),
		path.Join(diskByIdPath, diskScsiGooglePrefix+pdName),
	}

	if partition != "" {
		for i, path := range devicePaths {
			devicePaths[i] = path + diskPartitionSuffix + partition
		}
	}

	return devicePaths
}

// Return cloud provider
func getCloudProvider(cloudProvider cloudprovider.Interface) (*gcecloud.GCECloud, error) {
	var err error
	for numRetries := 0; numRetries < maxRetries; numRetries++ {
		gceCloudProvider, ok := cloudProvider.(*gcecloud.GCECloud)
		if !ok || gceCloudProvider == nil {
			// Retry on error. See issue #11321
			glog.Errorf("Failed to get GCE Cloud Provider. plugin.host.GetCloudProvider returned %v instead", cloudProvider)
			time.Sleep(errorSleepDuration)
			continue
		}

		return gceCloudProvider, nil
	}

	return nil, fmt.Errorf("Failed to get GCE GCECloudProvider with error %v", err)
}

// Triggers the application of udev rules by calling "udevadm trigger
// --action=change" for newly created "/dev/sd*" drives (exist only in
// after set). This is workaround for Issue #7972. Once the underlying
// issue has been resolved, this may be removed.
func udevadmChangeToNewDrives(sdBeforeSet sets.String) error {
	sdAfter, err := filepath.Glob(diskSDPattern)
	if err != nil {
		return fmt.Errorf("Error filepath.Glob(\"%s\"): %v\r\n", diskSDPattern, err)
	}

	for _, sd := range sdAfter {
		if !sdBeforeSet.Has(sd) {
			return udevadmChangeToDrive(sd)
		}
	}

	return nil
}

// Calls "udevadm trigger --action=change" on the specified drive.
// drivePath must be the block device path to trigger on, in the format "/dev/sd*", or a symlink to it.
// This is workaround for Issue #7972. Once the underlying issue has been resolved, this may be removed.
func udevadmChangeToDrive(drivePath string) error {
	glog.V(5).Infof("udevadmChangeToDrive: drive=%q", drivePath)

	// Evaluate symlink, if any
	drive, err := filepath.EvalSymlinks(drivePath)
	if err != nil {
		return fmt.Errorf("udevadmChangeToDrive: filepath.EvalSymlinks(%q) failed with %v.", drivePath, err)
	}
	glog.V(5).Infof("udevadmChangeToDrive: symlink path is %q", drive)

	// Check to make sure input is "/dev/sd*"
	if !strings.Contains(drive, diskSDPath) {
		return fmt.Errorf("udevadmChangeToDrive: expected input in the form \"%s\" but drive is %q.", diskSDPattern, drive)
	}

	// Call "udevadm trigger --action=change --property-match=DEVNAME=/dev/sd..."
	_, err = exec.New().Command(
		"udevadm",
		"trigger",
		"--action=change",
		fmt.Sprintf("--property-match=DEVNAME=%s", drive)).CombinedOutput()
	if err != nil {
		return fmt.Errorf("udevadmChangeToDrive: udevadm trigger failed for drive %q with %v.", drive, err)
	}
	return nil
}

// Checks whether the given GCE PD volume spec is associated with a regional PD.
func isRegionalPD(spec *volume.Spec) bool {
	if spec.PersistentVolume != nil {
		zonesLabel := spec.PersistentVolume.Labels[kubeletapis.LabelZoneFailureDomain]
		zones := strings.Split(zonesLabel, kubeletapis.LabelMultiZoneDelimiter)
		return len(zones) > 1
	}
	return false
}