package rclone

import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"strings"

	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/klog"

	"github.com/container-storage-interface/spec/lib/go/csi"
	"golang.org/x/net/context"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/kubernetes/pkg/util/mount"
	"k8s.io/kubernetes/pkg/volume/util"

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

type nodeServer struct {
	*csicommon.DefaultNodeServer
	mounter *mount.SafeFormatAndMount
}

type mountPoint struct {
	VolumeId  string
	MountPath string
}

func (ns *nodeServer) NodePublishVolume(ctx context.Context, req *csi.NodePublishVolumeRequest) (*csi.NodePublishVolumeResponse, error) {
	klog.Infof("NodePublishVolume: called with args %+v", *req)

	targetPath := req.GetTargetPath()

	notMnt, err := mount.New("").IsLikelyNotMountPoint(targetPath)
	if err != nil {
		if os.IsNotExist(err) {
			if err := os.MkdirAll(targetPath, 0750); err != nil {
				return nil, status.Error(codes.Internal, err.Error())
			}
			notMnt = true
		} else {
			return nil, status.Error(codes.Internal, err.Error())
		}
	}

	if !notMnt {
		// testing original mount point, make sure the mount link is valid
		if _, err := ioutil.ReadDir(targetPath); err == nil {
			klog.Infof("already mounted to target %s", targetPath)
			return &csi.NodePublishVolumeResponse{}, nil
		}
		// todo: mount link is invalid, now unmount and remount later (built-in functionality)
		klog.Warningf("ReadDir %s failed with %v, unmount this directory", targetPath, err)

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

		if err := ns.mounter.Unmount(targetPath); err != nil {
			klog.Errorf("Unmount directory %s failed with %v", targetPath, err)
			return nil, err
		}
	}

	mountOptions := req.GetVolumeCapability().GetMount().GetMountFlags()
	if req.GetReadonly() {
		mountOptions = append(mountOptions, "ro")
	}

	remote, remotePath, configData, flags, e := extractFlags(req.GetVolumeContext())
	if e != nil {
		klog.Warningf("storage parameter error: %s", e)
		return nil, e
	}

	e = Mount(remote, remotePath, targetPath, configData, flags)
	if e != nil {
		if os.IsPermission(e) {
			return nil, status.Error(codes.PermissionDenied, e.Error())
		}
		if strings.Contains(e.Error(), "invalid argument") {
			return nil, status.Error(codes.InvalidArgument, e.Error())
		}
		return nil, status.Error(codes.Internal, e.Error())
	}

	return &csi.NodePublishVolumeResponse{}, nil
}

// extractFlags extracts the flags from the given volumeContext
// Retturns: remote, remotePath, configData, flags, error
func extractFlags(volumeContext map[string]string) (string, string, string, map[string]string, error) {
	// Load default connection settings from secret
	var secret *v1.Secret

	if secretName, ok := volumeContext["secretName"]; ok {
		// Load the secret that the PV spec defines
		var e error
		secret, e = getSecret(secretName)
		if e != nil {
			// if the user explicitly requested a secret and there is an error fetching it, bail with an error
			return "", "", "", nil, e
		}
	} else {
		// use rclone-secret as the default secret if none was defined
		secret, _ = getSecret("rclone-secret")
	}

	// Empty argument list
	flags := make(map[string]string)

	// Secret values are default, gets merged and overriden by corresponding PV values
	if secret != nil && secret.Data != nil && len(secret.Data) > 0 {
		// Needs byte to string casting for map values
		for k, v := range secret.Data {
			flags[k] = string(v)
		}
	} else {
		klog.Infof("No csi-rclone connection defaults secret found.")
	}

	if len(volumeContext) > 0 {
		for k, v := range volumeContext {
			flags[k] = v
		}
	}

	if e := validateFlags(flags); e != nil {
		return "", "", "", flags, e
	}

	remote := flags["remote"]
	remotePath := flags["remotePath"]

	if remotePathSuffix, ok := flags["remotePathSuffix"]; ok {
		remotePath = remotePath + remotePathSuffix
		delete(flags, "remotePathSuffix")
	}

	configData := ""
	ok := false

	if configData, ok = flags["configData"]; ok {
		delete(flags, "configData")
	}

	delete(flags, "remote")
	delete(flags, "remotePath")
	delete(flags, "secretName")

	return remote, remotePath, configData, flags, nil
}

func (ns *nodeServer) NodeUnpublishVolume(ctx context.Context, req *csi.NodeUnpublishVolumeRequest) (*csi.NodeUnpublishVolumeResponse, error) {

	klog.Infof("NodeUnPublishVolume: called with args %+v", *req)

	targetPath := req.GetTargetPath()
	if len(targetPath) == 0 {
		return nil, status.Error(codes.InvalidArgument, "NodeUnpublishVolume Target Path must be provided")
	}

	m := mount.New("")

	notMnt, err := m.IsLikelyNotMountPoint(targetPath)
	if err != nil && !mount.IsCorruptedMnt(err) {
		return nil, status.Error(codes.Internal, err.Error())
	}

	if notMnt && !mount.IsCorruptedMnt(err) {
		klog.Infof("Volume not mounted")

	} else {
		err = util.UnmountPath(req.GetTargetPath(), m)
		if err != nil {
			klog.Infof("Error while unmounting path: %s", err)
			// This will exit and fail the NodeUnpublishVolume making it to retry unmount on the next api schedule trigger.
			// Since we mount the volume with allow-non-empty now, we could skip this one too.
			return nil, status.Error(codes.Internal, err.Error())
		}

		klog.Infof("Volume %s unmounted successfully", req.VolumeId)
	}

	return &csi.NodeUnpublishVolumeResponse{}, nil
}

func (ns *nodeServer) NodeUnstageVolume(ctx context.Context, req *csi.NodeUnstageVolumeRequest) (*csi.NodeUnstageVolumeResponse, error) {
	klog.Infof("NodeUnstageVolume: called with args %+v", *req)
	return &csi.NodeUnstageVolumeResponse{}, nil
}

func (ns *nodeServer) NodeStageVolume(ctx context.Context, req *csi.NodeStageVolumeRequest) (*csi.NodeStageVolumeResponse, error) {
	klog.Infof("NodeStageVolume: called with args %+v", *req)
	return &csi.NodeStageVolumeResponse{}, nil
}

func validateFlags(flags map[string]string) error {
	if _, ok := flags["remote"]; !ok {
		return status.Errorf(codes.InvalidArgument, "missing volume context value: remote")
	}
	if _, ok := flags["remotePath"]; !ok {
		return status.Errorf(codes.InvalidArgument, "missing volume context value: remotePath")
	}
	return nil
}

func getSecret(secretName string) (*v1.Secret, error) {
	clientset, e := GetK8sClient()
	if e != nil {
		return nil, status.Errorf(codes.Internal, "can not create kubernetes client: %s", e)
	}

	kubeconfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
		clientcmd.NewDefaultClientConfigLoadingRules(),
		&clientcmd.ConfigOverrides{},
	)

	namespace, _, err := kubeconfig.Namespace()
	if err != nil {
		return nil, status.Errorf(codes.Internal, "can't get current namespace, error %s", secretName, err)
	}

	klog.Infof("Loading csi-rclone connection defaults from secret %s/%s", namespace, secretName)

	secret, e := clientset.CoreV1().
		Secrets(namespace).
		Get(secretName, metav1.GetOptions{})

	if e != nil {
		return nil, status.Errorf(codes.Internal, "can't load csi-rclone settings from secret %s: %s", secretName, e)
	}

	return secret, nil
}

// Mount routine.
func Mount(remote string, remotePath string, targetPath string, configData string, flags map[string]string) error {
	mountCmd := "rclone"
	mountArgs := []string{}

	defaultFlags := map[string]string{}
	defaultFlags["cache-info-age"] = "72h"
	defaultFlags["cache-chunk-clean-interval"] = "15m"
	defaultFlags["dir-cache-time"] = "5s"
	defaultFlags["vfs-cache-mode"] = "writes"
	defaultFlags["allow-non-empty"] = "true"
	defaultFlags["allow-other"] = "true"

	remoteWithPath := fmt.Sprintf(":%s:%s", remote, remotePath)

	if strings.Contains(configData, "["+remote+"]") {
		remoteWithPath = fmt.Sprintf("%s:%s", remote, remotePath)
		klog.Infof("remote %s found in configData, remoteWithPath set to %s", remote, remoteWithPath)
	}

	// rclone mount remote:path /path/to/mountpoint [flags]
	mountArgs = append(
		mountArgs,
		"mount",
		remoteWithPath,
		targetPath,
		"--daemon",
	)

	// If a custom flag configData is defined,
	// create a temporary file, fill it with  configData content,
	// and run rclone with --config <tmpfile> flag
	if configData != "" {

		configFile, err := ioutil.TempFile("", "rclone.conf")
		if err != nil {
			return err
		}

		// Normally, a defer os.Remove(configFile.Name()) should be placed here.
		// However, due to a rclone mount --daemon flag, rclone forks and creates a race condition
		// with this nodeplugin proceess. As a result, the config file gets deleted
		// before it's reread by a forked process.

		if _, err := configFile.Write([]byte(configData)); err != nil {
			return err
		}
		if err := configFile.Close(); err != nil {
			return err
		}

		mountArgs = append(mountArgs, "--config", configFile.Name())
	}

	// Add default flags
	for k, v := range defaultFlags {
		// Exclude overriden flags
		if _, ok := flags[k]; !ok {
			mountArgs = append(mountArgs, fmt.Sprintf("--%s=%s", k, v))
		}
	}

	// Add user supplied flags
	for k, v := range flags {
		mountArgs = append(mountArgs, fmt.Sprintf("--%s=%s", k, v))
	}

	// create target, os.Mkdirall is noop if it exists
	err := os.MkdirAll(targetPath, 0750)
	if err != nil {
		return err
	}

	klog.Infof("executing mount command cmd=%s, remote=%s, targetpath=%s", mountCmd, remoteWithPath, targetPath)

	out, err := exec.Command(mountCmd, mountArgs...).CombinedOutput()
	if err != nil {
		return fmt.Errorf("mounting failed: %v cmd: '%s' remote: '%s' targetpath: %s output: %q",
			err, mountCmd, remoteWithPath, targetPath, string(out))
	}

	return nil
}