/*
Copyright 2018 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 rbd

import (
	"fmt"
	"os"
	"os/exec"
	"regexp"
	"strings"

	"github.com/golang/glog"
	"golang.org/x/net/context"

	"github.com/container-storage-interface/spec/lib/go/csi"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	"k8s.io/kubernetes/pkg/util/mount"

	"github.com/kubernetes-csi/drivers/pkg/csi-common"
)

// NodeServer struct of ceph rbd driver with supported methods of CSI
// node server spec
type NodeServer struct {
	*csicommon.DefaultNodeServer
	mounter mount.Interface
}

//TODO remove both stage and unstage methods
//once https://github.com/kubernetes-csi/drivers/pull/145 is merged

// NodeStageVolume returns unimplemented response
func (ns *NodeServer) NodeStageVolume(ctx context.Context, req *csi.NodeStageVolumeRequest) (*csi.NodeStageVolumeResponse, error) {
	return nil, status.Error(codes.Unimplemented, "")
}

// NodeUnstageVolume returns unimplemented response
func (ns *NodeServer) NodeUnstageVolume(ctx context.Context, req *csi.NodeUnstageVolumeRequest) (*csi.NodeUnstageVolumeResponse, error) {
	return nil, status.Error(codes.Unimplemented, "")
}

// NodePublishVolume mounts the volume mounted to the device path to the target
// path
func (ns *NodeServer) NodePublishVolume(ctx context.Context, req *csi.NodePublishVolumeRequest) (*csi.NodePublishVolumeResponse, error) {
	targetPath := req.GetTargetPath()
	targetPathMutex.LockKey(targetPath)

	defer func() {
		if err := targetPathMutex.UnlockKey(targetPath); err != nil {
			glog.Warningf("failed to unlock mutex targetpath:%s %v", targetPath, err)
		}
	}()

	volName, err := ns.getVolumeName(req)
	if err != nil {
		return nil, err
	}

	isBlock := req.GetVolumeCapability().GetBlock() != nil
	// Check if that target path exists properly
	notMnt, err := ns.createTargetPath(targetPath, isBlock)
	if err != nil {
		return nil, err
	}

	if !notMnt {
		return &csi.NodePublishVolumeResponse{}, nil
	}
	volOptions, err := getRBDVolumeOptions(req.GetVolumeContext())
	if err != nil {
		return nil, err
	}
	volOptions.VolName = volName
	// Mapping RBD image
	devicePath, err := attachRBDImage(volOptions, volOptions.UserID, req.GetSecrets())
	if err != nil {
		return nil, err
	}
	glog.V(4).Infof("rbd image: %s/%s was successfully mapped at %s\n", req.GetVolumeId(), volOptions.Pool, devicePath)

	// Publish Path
	err = ns.mountVolume(req, devicePath)
	if err != nil {
		return nil, err
	}
	return &csi.NodePublishVolumeResponse{}, nil
}

func (ns *NodeServer) getVolumeName(req *csi.NodePublishVolumeRequest) (string, error) {
	var volName string
	isBlock := req.GetVolumeCapability().GetBlock() != nil
	targetPath := req.GetTargetPath()
	if isBlock {
		// Get volName from targetPath
		s := strings.Split(targetPath, "/")
		volName = s[len(s)-1]
	} else {
		// Get volName from targetPath
		if !strings.HasSuffix(targetPath, "/mount") {
			return "", fmt.Errorf("rbd: malformed the value of target path: %s", targetPath)
		}
		s := strings.Split(strings.TrimSuffix(targetPath, "/mount"), "/")
		volName = s[len(s)-1]
	}
	return volName, nil
}

func (ns *NodeServer) mountVolume(req *csi.NodePublishVolumeRequest, devicePath string) error {
	// Publish Path
	fsType := req.GetVolumeCapability().GetMount().GetFsType()
	readOnly := req.GetReadonly()
	attrib := req.GetVolumeContext()
	mountFlags := req.GetVolumeCapability().GetMount().GetMountFlags()
	isBlock := req.GetVolumeCapability().GetBlock() != nil
	targetPath := req.GetTargetPath()

	glog.V(4).Infof("target %v\nisBlock %v\nfstype %v\ndevice %v\nreadonly %v\nattributes %v\n mountflags %v\n",
		targetPath, isBlock, fsType, devicePath, readOnly, attrib, mountFlags)

	diskMounter := &mount.SafeFormatAndMount{Interface: ns.mounter, Exec: mount.NewOsExec()}
	if isBlock {
		options := []string{"bind"}
		if err := diskMounter.Mount(devicePath, targetPath, fsType, options); err != nil {
			return err
		}
	} else {
		options := []string{}
		if readOnly {
			options = append(options, "ro")
		}

		if err := diskMounter.FormatAndMount(devicePath, targetPath, fsType, options); err != nil {
			return err
		}
	}
	return nil
}

func (ns *NodeServer) createTargetPath(targetPath string, isBlock bool) (bool, error) {
	// Check if that target path exists properly
	notMnt, err := ns.mounter.IsNotMountPoint(targetPath)
	if err != nil {
		if os.IsNotExist(err) {
			if isBlock {
				// create an empty file
				// #nosec
				targetPathFile, e := os.OpenFile(targetPath, os.O_CREATE|os.O_RDWR, 0750)
				if e != nil {
					glog.V(4).Infof("Failed to create targetPath:%s with error: %v", targetPath, err)
					return notMnt, status.Error(codes.Internal, e.Error())
				}
				if err = targetPathFile.Close(); err != nil {
					glog.V(4).Infof("Failed to close targetPath:%s with error: %v", targetPath, err)
					return notMnt, status.Error(codes.Internal, err.Error())
				}
			} else {
				// Create a directory
				if err = os.MkdirAll(targetPath, 0750); err != nil {
					return notMnt, status.Error(codes.Internal, err.Error())
				}
			}
			notMnt = true
		} else {
			return false, status.Error(codes.Internal, err.Error())
		}
	}
	return notMnt, err

}

// NodeUnpublishVolume unmounts the volume from the target path
func (ns *NodeServer) NodeUnpublishVolume(ctx context.Context, req *csi.NodeUnpublishVolumeRequest) (*csi.NodeUnpublishVolumeResponse, error) {
	targetPath := req.GetTargetPath()
	targetPathMutex.LockKey(targetPath)

	defer func() {
		if err := targetPathMutex.UnlockKey(targetPath); err != nil {
			glog.Warningf("failed to unlock mutex targetpath:%s %v", targetPath, err)
		}
	}()

	notMnt, err := ns.mounter.IsNotMountPoint(targetPath)
	if err != nil {
		if os.IsNotExist(err) {
			// targetPath has already been deleted
			glog.V(4).Infof("targetPath: %s has already been deleted", targetPath)
			return &csi.NodeUnpublishVolumeResponse{}, nil
		}
		return nil, status.Error(codes.NotFound, err.Error())
	}
	if notMnt {
		// TODO should consider deleting path instead of returning error,
		// once all codes become ready for csi 1.0.
		return nil, status.Error(codes.NotFound, "Volume not mounted")
	}

	devicePath, cnt, err := mount.GetDeviceNameFromMount(ns.mounter, targetPath)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	// Bind mounted device needs to be resolved by using resolveBindMountedBlockDevice
	if devicePath == "devtmpfs" {
		devicePath, err = resolveBindMountedBlockDevice(targetPath)
		if err != nil {
			return nil, status.Error(codes.Internal, err.Error())
		}
		glog.V(4).Infof("NodeUnpublishVolume: devicePath: %s, (original)cnt: %d\n", devicePath, cnt)
		// cnt for GetDeviceNameFromMount is broken for bind mouted device,
		// it counts total number of mounted "devtmpfs", instead of counting this device.
		// So, forcibly setting cnt to 1 here.
		// TODO : fix this properly
		cnt = 1
	}

	glog.V(4).Infof("NodeUnpublishVolume: targetPath: %s, devicePath: %s\n", targetPath, devicePath)

	// Unmounting the image
	err = ns.mounter.Unmount(targetPath)
	if err != nil {
		glog.V(3).Infof("failed to unmount targetPath: %s with error: %v", targetPath, err)
		return nil, status.Error(codes.Internal, err.Error())
	}

	cnt--
	if cnt != 0 {
		// TODO should this be fixed not to success, so that driver can retry unmounting?
		return &csi.NodeUnpublishVolumeResponse{}, nil
	}

	// Unmapping rbd device
	if err = detachRBDDevice(devicePath); err != nil {
		glog.V(3).Infof("failed to unmap rbd device: %s with error: %v", devicePath, err)
		return nil, err
	}

	// Remove targetPath
	if err = os.RemoveAll(targetPath); err != nil {
		glog.V(3).Infof("failed to remove targetPath: %s with error: %v", targetPath, err)
		return nil, err
	}

	return &csi.NodeUnpublishVolumeResponse{}, nil
}

func resolveBindMountedBlockDevice(mountPath string) (string, error) {
	// #nosec
	cmd := exec.Command("findmnt", "-n", "-o", "SOURCE", "--first-only", "--target", mountPath)
	out, err := cmd.CombinedOutput()
	if err != nil {
		glog.V(2).Infof("Failed findmnt command for path %s: %s %v", mountPath, out, err)
		return "", err
	}
	return parseFindMntResolveSource(string(out))
}

// parse output of "findmnt -o SOURCE --first-only --target" and return just the SOURCE
func parseFindMntResolveSource(out string) (string, error) {
	// cut trailing newline
	out = strings.TrimSuffix(out, "\n")
	// Check if out is a mounted device
	reMnt := regexp.MustCompile(`^(/[^/]+(?:/[^/]*)*)$`)
	if match := reMnt.FindStringSubmatch(out); match != nil {
		return match[1], nil
	}
	// Check if out is a block device
	reBlk := regexp.MustCompile(`^devtmpfs\\[(/[^/]+(?:/[^/]*)*)\\]$`)
	if match := reBlk.FindStringSubmatch(out); match != nil {
		return fmt.Sprintf("/dev%s", match[1]), nil
	}
	return "", fmt.Errorf("parseFindMntResolveSource: %s doesn't match to any expected findMnt output", out)
}