/*
Copyright 2018 The Ceph-CSI 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 (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/ceph/ceph-csi/pkg/util"

	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/klog"
)

const (
	rbdTonbd  = "rbd-nbd"
	moduleNbd = "nbd"

	accessTypeKRbd = "krbd"
	accessTypeNbd  = "nbd"

	rbd = "rbd"

	// Output strings returned during invocation of "rbd unmap --device-type... <imageSpec>" when
	// image is not found to be mapped. Used to ignore errors when attempting to unmap such images.
	// The %s format specifier should contain the <imageSpec> string
	// NOTE: When using devicePath instead of imageSpec, the error strings are different
	rbdUnmapCmdkRbdMissingMap = "rbd: %s: not a mapped image or snapshot"
	rbdUnmapCmdNbdMissingMap  = "rbd-nbd: %s is not mapped"
	rbdMapConnectionTimeout   = "Connection timed out"
)

var hasNBD = false

func init() {
	hasNBD = checkRbdNbdTools()
}

// rbdDeviceInfo strongly typed JSON spec for rbd device list output (of type krbd)
type rbdDeviceInfo struct {
	ID     string `json:"id"`
	Pool   string `json:"pool"`
	Name   string `json:"name"`
	Device string `json:"device"`
}

// nbdDeviceInfo strongly typed JSON spec for rbd-nbd device list output (of type nbd)
// NOTE: There is a bug in rbd output that returns id as number for nbd, and string for krbd, thus
// requiring 2 different JSON structures to unmarshal the output.
// NOTE: image key is "name" in krbd output and "image" in nbd output, which is another difference
type nbdDeviceInfo struct {
	ID     int64  `json:"id"`
	Pool   string `json:"pool"`
	Name   string `json:"image"`
	Device string `json:"device"`
}

// rbdGetDeviceList queries rbd about mapped devices and returns a list of rbdDeviceInfo
// It will selectively list devices mapped using krbd or nbd as specified by accessType
func rbdGetDeviceList(accessType string) ([]rbdDeviceInfo, error) {
	// rbd device list --format json --device-type [krbd|nbd]
	var (
		rbdDeviceList []rbdDeviceInfo
		nbdDeviceList []nbdDeviceInfo
	)

	stdout, _, err := util.ExecCommand(rbd, "device", "list", "--format="+"json", "--device-type", accessType)
	if err != nil {
		return nil, fmt.Errorf("error getting device list from rbd for devices of type (%s): (%v)", accessType, err)
	}

	if accessType == accessTypeKRbd {
		err = json.Unmarshal(stdout, &rbdDeviceList)
	} else {
		err = json.Unmarshal(stdout, &nbdDeviceList)
	}
	if err != nil {
		return nil, fmt.Errorf("error to parse JSON output of device list for devices of type (%s): (%v)", accessType, err)
	}

	// convert output to a rbdDeviceInfo list for consumers
	if accessType == accessTypeNbd {
		for _, device := range nbdDeviceList {
			rbdDeviceList = append(
				rbdDeviceList,
				rbdDeviceInfo{
					ID:     strconv.FormatInt(device.ID, 10),
					Pool:   device.Pool,
					Name:   device.Name,
					Device: device.Device,
				})
		}
	}

	return rbdDeviceList, nil
}

// findDeviceMappingImage finds a devicePath, if available, based on image spec (pool/image) on the node.
func findDeviceMappingImage(ctx context.Context, pool, image string, useNbdDriver bool) (string, bool) {
	accessType := accessTypeKRbd
	if useNbdDriver {
		accessType = accessTypeNbd
	}

	rbdDeviceList, err := rbdGetDeviceList(accessType)
	if err != nil {
		klog.Warningf(util.Log(ctx, "failed to determine if image (%s/%s) is mapped to a device (%v)"), pool, image, err)
		return "", false
	}

	for _, device := range rbdDeviceList {
		if device.Name == image && device.Pool == pool {
			return device.Device, true
		}
	}

	return "", false
}

// Stat a path, if it doesn't exist, retry maxRetries times.
func waitForPath(ctx context.Context, pool, image string, maxRetries int, useNbdDriver bool) (string, bool) {
	for i := 0; i < maxRetries; i++ {
		if i != 0 {
			time.Sleep(time.Second)
		}

		device, found := findDeviceMappingImage(ctx, pool, image, useNbdDriver)
		if found {
			return device, found
		}
	}

	return "", false
}

// Check if rbd-nbd tools are installed.
func checkRbdNbdTools() bool {
	// check if the module is loaded or compiled in
	_, err := os.Stat(fmt.Sprintf("/sys/module/%s", moduleNbd))
	if os.IsNotExist(err) {
		// try to load the module
		_, err = execCommand("modprobe", []string{moduleNbd})
		if err != nil {
			klog.V(3).Infof("rbd-nbd: nbd modprobe failed with error %v", err)
			return false
		}
	}
	if _, err := execCommand(rbdTonbd, []string{"--version"}); err != nil {
		klog.V(3).Infof("rbd-nbd: running rbd-nbd --version failed with error %v", err)
		return false
	}
	klog.V(3).Infof("rbd-nbd tools were found.")
	return true
}

func attachRBDImage(ctx context.Context, volOptions *rbdVolume, cr *util.Credentials) (string, error) {
	var err error

	image := volOptions.RbdImageName
	useNBD := false
	if volOptions.Mounter == rbdTonbd && hasNBD {
		useNBD = true
	}

	devicePath, found := waitForPath(ctx, volOptions.Pool, image, 1, useNBD)
	if !found {
		backoff := wait.Backoff{
			Duration: rbdImageWatcherInitDelay,
			Factor:   rbdImageWatcherFactor,
			Steps:    rbdImageWatcherSteps,
		}

		err = waitForrbdImage(ctx, backoff, volOptions, cr)

		if err != nil {
			return "", err
		}
		devicePath, err = createPath(ctx, volOptions, cr)
	}

	return devicePath, err
}

func createPath(ctx context.Context, volOpt *rbdVolume, cr *util.Credentials) (string, error) {
	isNbd := false
	image := volOpt.RbdImageName
	imagePath := fmt.Sprintf("%s/%s", volOpt.Pool, image)

	klog.V(5).Infof(util.Log(ctx, "rbd: map mon %s"), volOpt.Monitors)

	// Map options
	mapOptions := []string{
		"--id", cr.ID,
		"-m", volOpt.Monitors,
		"--keyfile=" + cr.KeyFile,
		"map", imagePath,
	}

	// Choose access protocol
	accessType := accessTypeKRbd
	if volOpt.Mounter == rbdTonbd && hasNBD {
		isNbd = true
		accessType = accessTypeNbd
	}

	// Update options with device type selection
	mapOptions = append(mapOptions, "--device-type", accessType)

	// Execute map
	output, err := execCommand(rbd, mapOptions)
	if err != nil {
		klog.Warningf(util.Log(ctx, "rbd: map error %v, rbd output: %s"), err, string(output))
		// unmap rbd image if connection timeout
		if strings.Contains(err.Error(), rbdMapConnectionTimeout) {
			detErr := detachRBDImageOrDeviceSpec(ctx, imagePath, true, isNbd, volOpt.Encrypted, volOpt.VolID)
			if detErr != nil {
				klog.Warningf(util.Log(ctx, "rbd: %s unmap error %v"), imagePath, detErr)
			}
		}
		return "", fmt.Errorf("rbd: map failed %v, rbd output: %s", err, string(output))
	}
	devicePath := strings.TrimSuffix(string(output), "\n")

	return devicePath, nil
}

func waitForrbdImage(ctx context.Context, backoff wait.Backoff, volOptions *rbdVolume, cr *util.Credentials) error {
	image := volOptions.RbdImageName
	imagePath := fmt.Sprintf("%s/%s", volOptions.Pool, image)

	err := wait.ExponentialBackoff(backoff, func() (bool, error) {
		used, rbdOutput, err := rbdStatus(ctx, volOptions, cr)
		if err != nil {
			return false, fmt.Errorf("fail to check rbd image status with: (%v), rbd output: (%s)", err, rbdOutput)
		}
		if (volOptions.DisableInUseChecks) && (used) {
			klog.V(2).Info(util.Log(ctx, "valid multi-node attach requested, ignoring watcher in-use result"))
			return used, nil
		}
		return !used, nil
	})
	// return error if rbd image has not become available for the specified timeout
	if err == wait.ErrWaitTimeout {
		return fmt.Errorf("rbd image %s is still being used", imagePath)
	}
	// return error if any other errors were encountered during waiting for the image to become available
	return err
}

func detachRBDDevice(ctx context.Context, devicePath, volumeID string, encrypted bool) error {
	nbdType := false
	if strings.HasPrefix(devicePath, "/dev/nbd") {
		nbdType = true
	}

	return detachRBDImageOrDeviceSpec(ctx, devicePath, false, nbdType, encrypted, volumeID)
}

// detachRBDImageOrDeviceSpec detaches an rbd imageSpec or devicePath, with additional checking
// when imageSpec is used to decide if image is already unmapped
func detachRBDImageOrDeviceSpec(ctx context.Context, imageOrDeviceSpec string, isImageSpec, ndbType, encrypted bool, volumeID string) error {
	var output []byte

	if encrypted {
		mapperFile, mapperPath := util.VolumeMapper(volumeID)
		mappedDevice, mapper, err := util.DeviceEncryptionStatus(ctx, mapperPath)
		if err != nil {
			klog.Errorf(util.Log(ctx, "error determining LUKS device on %s, %s: %s"),
				mapperPath, imageOrDeviceSpec, err)
			return err
		}
		if len(mapper) > 0 {
			// mapper found, so it is open Luks device
			err = util.CloseEncryptedVolume(ctx, mapperFile)
			if err != nil {
				klog.Errorf(util.Log(ctx, "error closing LUKS device on %s, %s: %s"),
					mapperPath, imageOrDeviceSpec, err)
				return err
			}
			imageOrDeviceSpec = mappedDevice
		}
	}

	accessType := accessTypeKRbd
	if ndbType {
		accessType = accessTypeNbd
	}
	options := []string{"unmap", "--device-type", accessType, imageOrDeviceSpec}

	output, err := execCommand(rbd, options)
	if err != nil {
		// Messages for krbd and nbd differ, hence checking either of them for missing mapping
		// This is not applicable when a device path is passed in
		if isImageSpec &&
			(strings.Contains(string(output), fmt.Sprintf(rbdUnmapCmdkRbdMissingMap, imageOrDeviceSpec)) ||
				strings.Contains(string(output), fmt.Sprintf(rbdUnmapCmdNbdMissingMap, imageOrDeviceSpec))) {
			// Devices found not to be mapped are treated as a successful detach
			klog.V(5).Infof(util.Log(ctx, "image or device spec (%s) not mapped"), imageOrDeviceSpec)
			return nil
		}
		return fmt.Errorf("rbd: unmap for spec (%s) failed (%v): (%s)", imageOrDeviceSpec, err, string(output))
	}

	return nil
}