/*
Copyright © 2020 The OpenEBS 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 zfs

import (
	"fmt"
	"os"
	"os/exec"

	apis "github.com/openebs/zfs-localpv/pkg/apis/openebs.io/zfs/v1"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"k8s.io/klog"
	"k8s.io/kubernetes/pkg/util/mount"
)

// FormatAndMountZvol formats and mounts the created volume to the desired mount path
func FormatAndMountZvol(devicePath string, mountInfo *apis.MountInfo) error {
	mounter := &mount.SafeFormatAndMount{Interface: mount.New(""), Exec: mount.NewOsExec()}

	err := mounter.FormatAndMount(devicePath, mountInfo.MountPath, mountInfo.FSType, mountInfo.MountOptions)
	if err != nil {
		klog.Errorf(
			"zfspv: failed to mount volume %s [%s] to %s, error %v",
			devicePath, mountInfo.FSType, mountInfo.MountPath, err,
		)
		return err
	}

	return nil
}

// UmountVolume unmounts the volume and the corresponding mount path is removed
func UmountVolume(vol *apis.ZFSVolume, targetPath string,
) error {
	mounter := &mount.SafeFormatAndMount{Interface: mount.New(""), Exec: mount.NewOsExec()}

	dev, ref, err := mount.GetDeviceNameFromMount(mounter, targetPath)
	if err != nil {
		klog.Errorf(
			"zfspv umount volume: failed to get device from mnt: %s\nError: %v",
			targetPath, err,
		)
		return err
	}

	// device has already been un-mounted, return successful
	if len(dev) == 0 || ref == 0 {
		klog.Warningf(
			"Warning: Unmount skipped because volume %s not mounted: %v",
			vol.Name, targetPath,
		)
		return nil
	}

	if pathExists, pathErr := mount.PathExists(targetPath); pathErr != nil {
		return fmt.Errorf("Error checking if path exists: %v", pathErr)
	} else if !pathExists {
		klog.Warningf(
			"Warning: Unmount skipped because path does not exist: %v",
			targetPath,
		)
		return nil
	}

	if err = mounter.Unmount(targetPath); err != nil {
		klog.Errorf(
			"zfs: failed to unmount %s: path %s err: %v",
			vol.Name, targetPath, err,
		)
		return err
	}

	if err = SetDatasetLegacyMount(vol); err != nil {
		// ignoring the failure as the volume has already
		// been umounted, now the new pod can mount it
		klog.Warningf(
			"zfs: failed to set legacy mountpoint: %s err: %v",
			vol.Name, err,
		)
	}

	if err := os.Remove(targetPath); err != nil {
		klog.Errorf("zfspv: failed to remove mount path vol %s err : %v", vol.Name, err)
	}

	klog.Infof("umount done %s path %v", vol.Name, targetPath)

	return nil
}

// GetMounts gets mountpoints for the specified volume
func GetMounts(dev string) ([]string, error) {

	var (
		currentMounts []string
		err           error
		mountList     []mount.MountPoint
	)

	mounter := mount.New("")
	// Get list of mounted paths present with the node
	if mountList, err = mounter.List(); err != nil {
		return nil, err
	}
	for _, mntInfo := range mountList {
		if mntInfo.Device == dev {
			currentMounts = append(currentMounts, mntInfo.Path)
		}
	}
	return currentMounts, nil
}

// IsMountPath returns true if path is a mount path
func IsMountPath(path string) bool {

	var (
		err       error
		mountList []mount.MountPoint
	)

	mounter := mount.New("")
	// Get list of mounted paths present with the node
	if mountList, err = mounter.List(); err != nil {
		return false
	}
	for _, mntInfo := range mountList {
		if mntInfo.Path == path {
			return true
		}
	}
	return false
}

func verifyMountRequest(vol *apis.ZFSVolume, mountpath string) error {
	if len(mountpath) == 0 {
		return status.Error(codes.InvalidArgument, "verifyMount: mount path missing in request")
	}

	if len(vol.Spec.OwnerNodeID) > 0 &&
		vol.Spec.OwnerNodeID != NodeID {
		return status.Error(codes.Internal, "verifyMount: volume is owned by different node")
	}
	if vol.Finalizers == nil {
		return status.Error(codes.Internal, "verifyMount: volume is not ready to be mounted")
	}

	devicePath, err := GetVolumeDevPath(vol)
	if err != nil {
		klog.Errorf("can not get device for volume:%s dev %s err: %v",
			vol.Name, devicePath, err.Error())
		return status.Errorf(codes.Internal, "verifyMount: GetVolumePath failed %s", err.Error())
	}

	// if it is not a shared volume, then make sure it is not mounted to more than one path
	if vol.Spec.Shared != "yes" {
		/*
		 * This check is the famous *Wall Of North*
		 * It will not let the volume to be mounted
		 * at more than two places. The volume should
		 * be unmounted before proceeding to the mount
		 * operation.
		 */
		currentMounts, err := GetMounts(devicePath)
		if err != nil {
			klog.Errorf("can not get mounts for volume:%s dev %s err: %v",
				vol.Name, devicePath, err.Error())
			return status.Errorf(codes.Internal, "verifyMount: Getmounts failed %s", err.Error())
		} else if len(currentMounts) >= 1 {
			klog.Errorf(
				"can not mount, volume:%s already mounted dev %s mounts: %v",
				vol.Name, devicePath, currentMounts,
			)
			return status.Errorf(codes.Internal, "verifyMount: device already mounted at %s", currentMounts)
		}
	}
	return nil
}

// MountZvol mounts the disk to the specified path
func MountZvol(vol *apis.ZFSVolume, mount *apis.MountInfo) error {
	volume := vol.Spec.PoolName + "/" + vol.Name
	err := verifyMountRequest(vol, mount.MountPath)
	if err != nil {
		return err
	}

	devicePath := ZFSDevPath + volume

	err = FormatAndMountZvol(devicePath, mount)
	if err != nil {
		return status.Error(codes.Internal, "not able to format and mount the zvol")
	}

	klog.Infof("zvol %v mounted %v fs %v", volume, mount.MountPath, mount.FSType)

	return err
}

// MountDataset mounts the zfs dataset to the specified path
func MountDataset(vol *apis.ZFSVolume, mount *apis.MountInfo) error {
	volume := vol.Spec.PoolName + "/" + vol.Name
	err := verifyMountRequest(vol, mount.MountPath)
	if err != nil {
		return err
	}

	val, err := GetVolumeProperty(vol, "mountpoint")
	if err != nil {
		return err
	}

	if val == "legacy" {
		var MountVolArg []string
		var mntopt string

		for _, option := range mount.MountOptions {
			mntopt += option + ","
		}

		MountVolArg = append(MountVolArg, "-o", mntopt, "-t", "zfs", volume, mount.MountPath)
		cmd := exec.Command("mount", MountVolArg...)
		out, err := cmd.CombinedOutput()
		if err != nil {
			klog.Errorf("zfs: could not mount the dataset %v cmd %v error: %s",
				volume, MountVolArg, string(out))
			return status.Errorf(codes.Internal, "dataset: mount failed err : %s", string(out))
		}
		klog.Infof("dataset : legacy mounted %s => %s", volume, mount.MountPath)
	} else {
		/*
		 * We might have created volumes and then upgraded the node agent before
		 * getting the mount request for that volume. In this case volume will
		 * not be created with mountpoint as legacy. Handling the mount in old way.
		 */
		err = MountZFSDataset(vol, mount.MountPath)
		if err != nil {
			return status.Errorf(codes.Internal, "zfs: mount failed err : %s", err.Error())
		}
		klog.Infof("dataset : mounted %s => %s", volume, mount.MountPath)
	}

	return nil
}

// MountFilesystem mounts the disk to the specified path
func MountFilesystem(vol *apis.ZFSVolume, mount *apis.MountInfo) error {
	switch vol.Spec.VolumeType {
	case VolTypeDataset:
		return MountDataset(vol, mount)
	default:
		return MountZvol(vol, mount)
	}
}

// MountBlock mounts the block disk to the specified path
func MountBlock(vol *apis.ZFSVolume, mountinfo *apis.MountInfo) error {
	target := mountinfo.MountPath
	devicePath := ZFSDevPath + vol.Spec.PoolName + "/" + vol.Name
	mountopt := []string{"bind"}

	mounter := &mount.SafeFormatAndMount{Interface: mount.New(""), Exec: mount.NewOsExec()}

	// Create the mount point as a file since bind mount device node requires it to be a file
	err := mounter.MakeFile(target)
	if err != nil {
		return status.Errorf(codes.Internal, "Could not create target file %q: %v", target, err)
	}

	// do the bind mount of the zvol device at the target path
	if err := mounter.Mount(devicePath, target, "", mountopt); err != nil {
		if removeErr := os.Remove(target); removeErr != nil {
			return status.Errorf(codes.Internal, "Could not remove mount target %q: %v", target, removeErr)
		}
		return status.Errorf(codes.Internal, "mount failed at %v err : %v", target, err)
	}

	klog.Infof("NodePublishVolume mounted block device %s at %s", devicePath, target)

	return nil
}