/*
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 driver

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

	"github.com/yandex-cloud/k8s-csi-s3/pkg/mounter"
	"github.com/yandex-cloud/k8s-csi-s3/pkg/s3"
	"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"

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

type nodeServer struct {
	*csicommon.DefaultNodeServer
}

func getMeta(bucketName, prefix string, context map[string]string) *s3.FSMeta {
	mountOptions := make([]string, 0)
	mountOptStr := context[mounter.OptionsKey]
	if mountOptStr != "" {
		re, _ := regexp.Compile(`([^\s"]+|"([^"\\]+|\\")*")+`)
		re2, _ := regexp.Compile(`"([^"\\]+|\\")*"`)
		re3, _ := regexp.Compile(`\\(.)`)
		for _, opt := range re.FindAll([]byte(mountOptStr), -1) {
			// Unquote options
			opt = re2.ReplaceAllFunc(opt, func(q []byte) []byte {
				return re3.ReplaceAll(q[1 : len(q)-1], []byte("$1"))
			})
			mountOptions = append(mountOptions, string(opt))
		}
	}
	capacity, _ := strconv.ParseInt(context["capacity"], 10, 64)
	return &s3.FSMeta{
		BucketName:    bucketName,
		Prefix:        prefix,
		Mounter:       context[mounter.TypeKey],
		MountOptions:  mountOptions,
		CapacityBytes: capacity,
	}
}

func (ns *nodeServer) NodePublishVolume(ctx context.Context, req *csi.NodePublishVolumeRequest) (*csi.NodePublishVolumeResponse, error) {
	volumeID := req.GetVolumeId()
	targetPath := req.GetTargetPath()
	stagingTargetPath := req.GetStagingTargetPath()

	// Check arguments
	if req.GetVolumeCapability() == nil {
		return nil, status.Error(codes.InvalidArgument, "Volume capability missing in request")
	}
	if len(volumeID) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Volume ID missing in request")
	}
	if len(stagingTargetPath) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Staging Target path missing in request")
	}
	if len(targetPath) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Target path missing in request")
	}

	notMnt, err := checkMount(targetPath)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	if !notMnt {
		return &csi.NodePublishVolumeResponse{}, nil
	}

	// TODO: Implement readOnly & mountFlags
	readOnly := req.GetReadonly()
	mountFlags := req.GetVolumeCapability().GetMount().GetMountFlags()
	attrib := req.GetVolumeContext()

	glog.V(4).Infof("target %v\nreadonly %v\nvolumeId %v\nattributes %v\nmountflags %v\n",
		targetPath, readOnly, volumeID, attrib, mountFlags)

	cmd := exec.Command("mount", "--bind", stagingTargetPath, targetPath)
	cmd.Stderr = os.Stderr
	glog.V(3).Infof("Binding volume %v from %v to %v", volumeID, stagingTargetPath, targetPath)
	out, err := cmd.Output()
	if err != nil {
		return nil, fmt.Errorf("Error running mount --bind %v %v: %s", stagingTargetPath, targetPath, out)
	}

	glog.V(4).Infof("s3: volume %s successfully mounted to %s", volumeID, targetPath)

	return &csi.NodePublishVolumeResponse{}, nil
}

func (ns *nodeServer) NodeUnpublishVolume(ctx context.Context, req *csi.NodeUnpublishVolumeRequest) (*csi.NodeUnpublishVolumeResponse, error) {
	volumeID := req.GetVolumeId()
	targetPath := req.GetTargetPath()

	// Check arguments
	if len(volumeID) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Volume ID missing in request")
	}
	if len(targetPath) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Target path missing in request")
	}

	if err := mounter.Unmount(targetPath); err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	glog.V(4).Infof("s3: volume %s has been unmounted.", volumeID)

	return &csi.NodeUnpublishVolumeResponse{}, nil
}

func (ns *nodeServer) NodeStageVolume(ctx context.Context, req *csi.NodeStageVolumeRequest) (*csi.NodeStageVolumeResponse, error) {
	volumeID := req.GetVolumeId()
	stagingTargetPath := req.GetStagingTargetPath()
	bucketName, prefix := volumeIDToBucketPrefix(volumeID)

	// Check arguments
	if len(volumeID) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Volume ID missing in request")
	}

	if len(stagingTargetPath) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Target path missing in request")
	}

	if req.VolumeCapability == nil {
		return nil, status.Error(codes.InvalidArgument, "NodeStageVolume Volume Capability must be provided")
	}

	notMnt, err := checkMount(stagingTargetPath)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}
	if !notMnt {
		return &csi.NodeStageVolumeResponse{}, nil
	}
	client, err := s3.NewClientFromSecret(req.GetSecrets())
	if err != nil {
		return nil, fmt.Errorf("failed to initialize S3 client: %s", err)
	}

	meta := getMeta(bucketName, prefix, req.VolumeContext)
	mounter, err := mounter.New(meta, client.Config)
	if err != nil {
		return nil, err
	}
	if err := mounter.Mount(stagingTargetPath, volumeID); err != nil {
		return nil, err
	}

	return &csi.NodeStageVolumeResponse{}, nil
}

func (ns *nodeServer) NodeUnstageVolume(ctx context.Context, req *csi.NodeUnstageVolumeRequest) (*csi.NodeUnstageVolumeResponse, error) {
	volumeID := req.GetVolumeId()
	stagingTargetPath := req.GetStagingTargetPath()

	// Check arguments
	if len(volumeID) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Volume ID missing in request")
	}
	if len(stagingTargetPath) == 0 {
		return nil, status.Error(codes.InvalidArgument, "Target path missing in request")
	}

	proc, err := mounter.FindFuseMountProcess(stagingTargetPath)
	if err != nil {
		return nil, err
	}
	exists := false
	if proc == nil {
		exists, err = mounter.SystemdUnmount(volumeID)
		if exists && err != nil {
			return nil, err
		}
	}
	if !exists {
		err = mounter.FuseUnmount(stagingTargetPath)
	}
	glog.V(4).Infof("s3: volume %s has been unmounted from stage path %v.", volumeID, stagingTargetPath)

	return &csi.NodeUnstageVolumeResponse{}, nil
}

// NodeGetCapabilities returns the supported capabilities of the node server
func (ns *nodeServer) NodeGetCapabilities(ctx context.Context, req *csi.NodeGetCapabilitiesRequest) (*csi.NodeGetCapabilitiesResponse, error) {
	// currently there is a single NodeServer capability according to the spec
	nscap := &csi.NodeServiceCapability{
		Type: &csi.NodeServiceCapability_Rpc{
			Rpc: &csi.NodeServiceCapability_RPC{
				Type: csi.NodeServiceCapability_RPC_STAGE_UNSTAGE_VOLUME,
			},
		},
	}

	return &csi.NodeGetCapabilitiesResponse{
		Capabilities: []*csi.NodeServiceCapability{
			nscap,
		},
	}, nil
}

func (ns *nodeServer) NodeExpandVolume(ctx context.Context, req *csi.NodeExpandVolumeRequest) (*csi.NodeExpandVolumeResponse, error) {
	return &csi.NodeExpandVolumeResponse{}, status.Error(codes.Unimplemented, "NodeExpandVolume is not implemented")
}

func checkMount(targetPath string) (bool, error) {
	notMnt, err := mount.New("").IsLikelyNotMountPoint(targetPath)
	if err != nil {
		if os.IsNotExist(err) {
			if err = os.MkdirAll(targetPath, 0750); err != nil {
				return false, err
			}
			notMnt = true
		} else {
			return false, err
		}
	}
	return notMnt, nil
}