/*
Copyright 2018 The Rook Authors. All rights reserved.

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 discover to discover unused devices.
package discover

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"os/signal"
	"path"
	"regexp"
	"strings"
	"syscall"
	"time"

	"github.com/coreos/pkg/capnslog"
	"github.com/rook/rook/pkg/clusterd"
	"github.com/rook/rook/pkg/operator/k8sutil"
	"github.com/rook/rook/pkg/util/sys"

	v1 "k8s.io/api/core/v1"
	kerrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

const (
	discoverDaemonUdev = "DISCOVER_DAEMON_UDEV_BLACKLIST"
)

var (
	logger = capnslog.NewPackageLogger("github.com/rook/rook", "rook-discover")
	// AppName is the name of the pod
	AppName = "rook-discover"
	// NodeAttr is the attribute of that node
	NodeAttr = "rook.io/node"
	// LocalDiskCMData is the data name of the config map storing devices
	LocalDiskCMData = "devices"
	// LocalDiskCMName is name of the config map storing devices
	LocalDiskCMName = "local-device-%s"
	nodeName        string
	namespace       string
	lastDevice      string
	cmName          string
	cm              *v1.ConfigMap
	udevEventPeriod = time.Duration(5) * time.Second
	useCVInventory  bool
)

// CephVolumeInventory is the Go struct representation of the json output
type CephVolumeInventory struct {
	Path            string          `json:"path"`
	Available       bool            `json:"available"`
	RejectedReasons json.RawMessage `json:"rejected_reasons"`
	SysAPI          json.RawMessage `json:"sys_api"`
	LVS             json.RawMessage `json:"lvs"`
}

// Run is the entry point of that package execution
func Run(ctx context.Context, context *clusterd.Context, probeInterval time.Duration, useCV bool) error {
	if context == nil {
		return fmt.Errorf("nil context")
	}
	logger.Debugf("device discovery interval is %q", probeInterval.String())
	logger.Debugf("use ceph-volume inventory is %t", useCV)
	nodeName = os.Getenv(k8sutil.NodeNameEnvVar)
	namespace = os.Getenv(k8sutil.PodNamespaceEnvVar)
	cmName = k8sutil.TruncateNodeName(LocalDiskCMName, nodeName)
	useCVInventory = useCV
	sigc := make(chan os.Signal, 1)
	signal.Notify(sigc, syscall.SIGTERM)

	err := updateDeviceCM(ctx, context)
	if err != nil {
		logger.Infof("failed to update device configmap: %v", err)
		return err
	}

	udevEvents := make(chan struct{})
	go udevBlockMonitor(udevEvents, udevEventPeriod)
	for {
		select {
		case <-sigc:
			logger.Infof("shutdown signal received, exiting...")
			return nil
		case <-time.After(probeInterval):
			if err := updateDeviceCM(ctx, context); err != nil {
				logger.Errorf("failed to update device configmap during probe interval. %v", err)
			}
		case _, ok := <-udevEvents:
			if ok {
				logger.Info("trigger probe from udev event")
				if err := updateDeviceCM(ctx, context); err != nil {
					logger.Errorf("failed to update device configmap triggered from udev event. %v", err)
				}
			} else {
				logger.Warningf("disabling udev monitoring")
				udevEvents = nil
			}
		}
	}
}

func matchUdevEvent(text string, matches, exclusions []string) (bool, error) {
	for _, match := range matches {
		matched, err := regexp.MatchString(match, text)
		if err != nil {
			return false, fmt.Errorf("failed to search string: %v", err)
		}
		if matched {
			hasExclusion := false
			for _, exclusion := range exclusions {
				matched, err = regexp.MatchString(exclusion, text)
				if err != nil {
					return false, fmt.Errorf("failed to search string: %v", err)
				}
				if matched {
					hasExclusion = true
					break
				}
			}
			if !hasExclusion {
				logger.Infof("udevadm monitor: matched event: %s", text)
				return true, nil
			}
		}
	}
	return false, nil
}

// Scans `udevadm monitor` output for block sub-system events. Each line of
// output matching a set of substrings is sent to the provided channel. An event
// is returned if it passes any matches tests, and passes all exclusion tests.
func rawUdevBlockMonitor(c chan struct{}, matches, exclusions []string) {
	defer close(c)

	// stdbuf -oL performs line buffered output
	cmd := exec.Command("stdbuf", "-oL", "udevadm", "monitor", "-u", "-s", "block")
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		logger.Warningf("Cannot open udevadm stdout: %v", err)
		return
	}
	defer stdout.Close()

	err = cmd.Start()
	if err != nil {
		logger.Warningf("Cannot start udevadm monitoring: %v", err)
		return
	}

	scanner := bufio.NewScanner(stdout)
	for scanner.Scan() {
		text := scanner.Text()
		logger.Debugf("udevadm monitor: %s", text)
		match, err := matchUdevEvent(text, matches, exclusions)
		if err != nil {
			logger.Warningf("udevadm filtering failed: %v", err)
			return
		}
		if match {
			c <- struct{}{}
		}
	}

	if err := scanner.Err(); err != nil {
		logger.Warningf("udevadm monitor scanner error: %v", err)
	}

	logger.Info("udevadm monitor finished")
}

// Monitors udev for block device changes, and collapses these events such that
// only one event is emitted per period in order to deal with flapping.
func udevBlockMonitor(c chan struct{}, period time.Duration) {
	defer close(c)
	var udevFilter []string

	// return any add or remove events, but none that match device mapper
	// events. string matching is case-insensitive
	events := make(chan struct{})

	// get discoverDaemonUdevBlacklist from the environment variable
	// if user doesn't provide any regex; generate the default regex
	// else use the regex provided by user
	discoverUdev := os.Getenv(discoverDaemonUdev)
	if discoverUdev == "" {
		discoverUdev = "(?i)dm-[0-9]+,(?i)rbd[0-9]+,(?i)nbd[0-9]+"
	}
	udevFilter = strings.Split(discoverUdev, ",")
	logger.Infof("using the regular expressions %q", udevFilter)

	go rawUdevBlockMonitor(events,
		[]string{"(?i)add", "(?i)remove"},
		udevFilter)

	timeout := time.NewTimer(period)
	defer timeout.Stop()
	for {
		_, ok := <-events
		if !ok {
			return
		}
		if !timeout.Stop() {
			<-timeout.C
		}
		timeout.Reset(period)
		for {
			select {
			case <-timeout.C:
			case _, ok := <-events:
				if !ok {
					return
				}
				continue
			}
			break
		}
		c <- struct{}{}
	}
}

func ignoreDevice(dev sys.LocalDisk) bool {
	return strings.Contains(strings.ToUpper(dev.DevLinks), "USB")
}

func checkMatchingDevice(checkDev sys.LocalDisk, devices []sys.LocalDisk) *sys.LocalDisk {
	for i, dev := range devices {
		if ignoreDevice(dev) {
			continue
		}
		// check if devices should be considered the same. the uuid can be
		// unstable, so we also use the reported serial and device name, which
		// appear to be more stable.
		if checkDev.UUID != "" && dev.UUID != "" && checkDev.UUID == dev.UUID {
			return &devices[i]
		}

		// on virt-io devices in libvirt, the serial is reported as an empty
		// string, so also account for that.
		if checkDev.Serial == dev.Serial && checkDev.Serial != "" {
			return &devices[i]
		}

		if checkDev.Name == dev.Name {
			return &devices[i]
		}
	}
	return nil
}

// note that the idea of equality here may not be intuitive. equality of device
// sets refers to a state in which no change has been observed between the sets
// of devices that would warrant changes to their consumption by storage
// daemons. for example, if a device appears to have been wiped vs a device
// appears to now be in use.
func checkDeviceListsEqual(oldDevs, newDevs []sys.LocalDisk) bool {
	for _, oldDev := range oldDevs {
		if ignoreDevice(oldDev) {
			continue
		}
		match := checkMatchingDevice(oldDev, newDevs)
		if match == nil {
			// device has been removed
			return false
		}
		if !oldDev.Empty && match.Empty {
			// device has changed from non-empty to empty
			return false
		}
		if oldDev.Partitions != nil && match.Partitions == nil {
			return false
		}
		if string(oldDev.CephVolumeData) == "" && string(match.CephVolumeData) != "" {
			// return ceph volume inventory data was not enabled before
			return false
		}
	}

	for _, newDev := range newDevs {
		if ignoreDevice(newDev) {
			continue
		}
		match := checkMatchingDevice(newDev, oldDevs)
		if match == nil {
			// device has been added
			return false
		}
		// the matching case is handled in the previous join
	}

	return true
}

// DeviceListsEqual checks whether 2 lists are equal or not
func DeviceListsEqual(old, new string) (bool, error) {
	var oldDevs []sys.LocalDisk
	var newDevs []sys.LocalDisk

	err := json.Unmarshal([]byte(old), &oldDevs)
	if err != nil {
		return false, fmt.Errorf("cannot unmarshal devices: %+v", err)
	}

	err = json.Unmarshal([]byte(new), &newDevs)
	if err != nil {
		return false, fmt.Errorf("cannot unmarshal devices: %+v", err)
	}

	return checkDeviceListsEqual(oldDevs, newDevs), nil
}

func updateDeviceCM(ctx context.Context, clusterdContext *clusterd.Context) error {
	logger.Infof("updating device configmap")
	devices, err := probeDevices(clusterdContext)
	if err != nil {
		logger.Infof("failed to probe devices: %v", err)
		return err
	}
	deviceJSON, err := json.Marshal(devices)
	if err != nil {
		logger.Infof("failed to marshal: %v", err)
		return err
	}

	deviceStr := string(deviceJSON)
	if cm == nil {
		cm, err = clusterdContext.Clientset.CoreV1().ConfigMaps(namespace).Get(ctx, cmName, metav1.GetOptions{})
	}
	if err == nil {
		lastDevice = cm.Data[LocalDiskCMData]
		logger.Debugf("last devices %s", lastDevice)
	} else {
		if !kerrors.IsNotFound(err) {
			logger.Infof("failed to get configmap: %v", err)
			return err
		}

		data := make(map[string]string, 1)
		data[LocalDiskCMData] = deviceStr

		// the map doesn't exist yet, create it now
		cm = &v1.ConfigMap{
			ObjectMeta: metav1.ObjectMeta{
				Name:      cmName,
				Namespace: namespace,
				Labels: map[string]string{
					k8sutil.AppAttr: AppName,
					NodeAttr:        nodeName,
				},
			},
			Data: data,
		}

		// Get the discover daemon pod details to attach the owner reference to the config map
		discoverPod, err := k8sutil.GetRunningPod(ctx, clusterdContext.Clientset)
		if err != nil {
			logger.Warningf("failed to get discover pod to set ownerref. %+v", err)
		} else {
			k8sutil.SetOwnerRefsWithoutBlockOwner(&cm.ObjectMeta, discoverPod.OwnerReferences)
		}

		cm, err = clusterdContext.Clientset.CoreV1().ConfigMaps(namespace).Create(ctx, cm, metav1.CreateOptions{})
		if err != nil {
			logger.Infof("failed to create configmap: %v", err)
			return fmt.Errorf("failed to create local device map %s: %+v", cmName, err)
		}
		lastDevice = deviceStr
	}
	devicesEqual, err := DeviceListsEqual(lastDevice, deviceStr)
	if err != nil {
		return fmt.Errorf("failed to compare device lists: %v", err)
	}
	if !devicesEqual {
		data := make(map[string]string, 1)
		data[LocalDiskCMData] = deviceStr
		cm.Data = data
		cm, err = clusterdContext.Clientset.CoreV1().ConfigMaps(namespace).Update(ctx, cm, metav1.UpdateOptions{})
		if err != nil {
			logger.Infof("failed to update configmap %s: %v", cmName, err)
			return err
		}
	}
	return nil
}

func logDevices(devices []*sys.LocalDisk) {
	var devicesList []string
	for _, device := range devices {
		logger.Debugf("localdevice %q: %+v", device.Name, device)
		devicesList = append(devicesList, device.Name)
	}
	logger.Infof("localdevices: %q", strings.Join(devicesList, ", "))
}

func probeDevices(context *clusterd.Context) ([]sys.LocalDisk, error) {
	devices := make([]sys.LocalDisk, 0)
	localDevices, err := clusterd.DiscoverDevices(context.Executor)
	if err != nil {
		return devices, fmt.Errorf("failed initial hardware discovery. %+v", err)
	}

	logDevices(localDevices)

	// ceph-volume inventory command takes a little time to complete.
	// Get this data only if it is needed and once by function execution
	var cvInventory *map[string]string = nil
	if useCVInventory {
		logger.Infof("Getting ceph-volume inventory information")
		cvInventory, err = getCephVolumeInventory(context)
		if err != nil {
			logger.Errorf("error getting ceph-volume inventory: %v", err)
		}
	}

	for _, device := range localDevices {
		if device == nil {
			continue
		}

		partitions, _, err := sys.GetDevicePartitions(device.Name, context.Executor)
		if err != nil {
			logger.Infof("failed to check device partitions %s: %v", device.Name, err)
			continue
		}

		// check if there is a file system on the device
		fs, err := sys.GetDeviceFilesystems(device.Name, context.Executor)
		if err != nil {
			logger.Infof("failed to check device filesystem %s: %v", device.Name, err)
			continue
		}
		device.Partitions = partitions
		device.Filesystem = fs
		device.Empty = clusterd.GetDeviceEmpty(device)

		// Add the information provided by ceph-volume inventory
		if cvInventory != nil {
			CVData, deviceExists := (*cvInventory)[path.Join("/dev/", device.Name)]
			if deviceExists {
				device.CephVolumeData = CVData
			} else {
				logger.Errorf("ceph-volume information for device %q not found", device.Name)
			}
		} else {
			device.CephVolumeData = ""
		}

		devices = append(devices, *device)
	}

	logger.Infof("available devices: %+v", devices)
	return devices, nil
}

// getCephVolumeInventory: Return a map of strings indexed by device with the
// information about the device returned by the command <ceph-volume inventory>
func getCephVolumeInventory(context *clusterd.Context) (*map[string]string, error) {
	inventory, err := context.Executor.ExecuteCommandWithOutput("ceph-volume", "inventory", "--format", "json")
	if err != nil {
		return nil, fmt.Errorf("failed to execute ceph-volume inventory. %+v", err)
	}

	// Return a map with the information of each device indexed by path
	CVDevices := make(map[string]string)

	// No data retrieved from ceph-volume
	if inventory == "" {
		return &CVDevices, nil
	}

	// Get a slice to store the json data
	bInventory := []byte(inventory)
	var CVInventory []CephVolumeInventory
	err = json.Unmarshal(bInventory, &CVInventory)
	if err != nil {
		return &CVDevices, fmt.Errorf("error unmarshalling json data coming from ceph-volume inventory. %v", err)
	}

	for _, device := range CVInventory {
		jsonData, err := json.Marshal(device)
		if err != nil {
			logger.Errorf("error marshaling json data for device: %v", device.Path)
		} else {
			CVDevices[device.Path] = string(jsonData)
		}
	}

	return &CVDevices, nil
}