/*
Copyright 2015 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 iscsi

import (
	"encoding/json"
	"fmt"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	"github.com/golang/glog"
	"k8s.io/kubernetes/pkg/util/mount"
	"k8s.io/kubernetes/pkg/volume"
)

var (
	chap_st = []string{
		"discovery.sendtargets.auth.username",
		"discovery.sendtargets.auth.password",
		"discovery.sendtargets.auth.username_in",
		"discovery.sendtargets.auth.password_in"}
	chap_sess = []string{
		"node.session.auth.username",
		"node.session.auth.password",
		"node.session.auth.username_in",
		"node.session.auth.password_in"}
)

func updateISCSIDiscoverydb(b iscsiDiskMounter, tp string) error {
	if b.chap_discovery {
		out, err := b.plugin.execCommand("iscsiadm", []string{"-m", "discoverydb", "-t", "sendtargets", "-p", tp, "-I", b.Iface, "-o", "update", "-n", "discovery.sendtargets.auth.authmethod", "-v", "CHAP"})
		if err != nil {
			return fmt.Errorf("iscsi: failed to update discoverydb with CHAP, output: %v", string(out))
		}

		for _, k := range chap_st {
			v := b.secret[k]
			if len(v) > 0 {
				out, err := b.plugin.execCommand("iscsiadm", []string{"-m", "discoverydb", "-t", "sendtargets", "-p", tp, "-I", b.Iface, "-o", "update", "-n", k, "-v", v})
				if err != nil {
					return fmt.Errorf("iscsi: failed to update discoverydb key %q with value %q error: %v", k, v, string(out))
				}
			}
		}
	}
	return nil
}

func updateISCSINode(b iscsiDiskMounter, tp string) error {
	if b.chap_session {
		out, err := b.plugin.execCommand("iscsiadm", []string{"-m", "node", "-p", tp, "-T", b.Iqn, "-I", b.Iface, "-o", "update", "-n", "node.session.auth.authmethod", "-v", "CHAP"})
		if err != nil {
			return fmt.Errorf("iscsi: failed to update node with CHAP, output: %v", string(out))
		}

		for _, k := range chap_sess {
			v := b.secret[k]
			if len(v) > 0 {
				out, err := b.plugin.execCommand("iscsiadm", []string{"-m", "node", "-p", tp, "-T", b.Iqn, "-I", b.Iface, "-o", "update", "-n", k, "-v", v})
				if err != nil {
					return fmt.Errorf("iscsi: failed to update node session key %q with value %q error: %v", k, v, string(out))
				}
			}
		}
	}
	return nil
}

// stat a path, if not exists, retry maxRetries times
// when iscsi transports other than default are used,  use glob instead as pci id of device is unknown
type StatFunc func(string) (os.FileInfo, error)
type GlobFunc func(string) ([]string, error)

func waitForPathToExist(devicePath *string, maxRetries int, deviceTransport string) bool {
	// This makes unit testing a lot easier
	return waitForPathToExistInternal(devicePath, maxRetries, deviceTransport, os.Stat, filepath.Glob)
}

func waitForPathToExistInternal(devicePath *string, maxRetries int, deviceTransport string, osStat StatFunc, filepathGlob GlobFunc) bool {
	if devicePath != nil {
		for i := 0; i < maxRetries; i++ {
			var err error
			if deviceTransport == "tcp" {
				_, err = osStat(*devicePath)
			} else {
				fpath, _ := filepathGlob(*devicePath)
				if fpath == nil {
					err = os.ErrNotExist
				} else {
					// There might be a case that fpath contains multiple device paths if
					// multiple PCI devices connect to same iscsi target. We handle this
					// case at subsequent logic. Pick up only first path here.
					*devicePath = fpath[0]
				}
			}
			if err == nil {
				return true
			}
			if err != nil && !os.IsNotExist(err) {
				return false
			}
			if i == maxRetries-1 {
				break
			}
			time.Sleep(time.Second)
		}
	}
	return false
}

// getDevicePrefixRefCount: given a prefix of device path, find its reference count from /proc/mounts
// returns the reference count to the device and error code
// for services like iscsi construct multiple device paths with the same prefix pattern.
// this function aggregates all references to a service based on the prefix pattern
// More specifically, this prefix semantics is to aggregate disk paths that belong to the same iSCSI target/iqn pair.
// an iSCSI target could expose multiple LUNs through the same IQN, and Linux iSCSI initiator creates disk paths that start the same prefix but end with different LUN number
// When we decide whether it is time to logout a target, we have to see if none of the LUNs are used any more.
// That's where the prefix based ref count kicks in. If we only count the disks using exact match, we could log other disks out.
func getDevicePrefixRefCount(mounter mount.Interface, deviceNamePrefix string) (int, error) {
	mps, err := mounter.List()
	if err != nil {
		return -1, err
	}

	// Find the number of references to the device.
	refCount := 0
	for i := range mps {
		if strings.HasPrefix(mps[i].Path, deviceNamePrefix) {
			refCount++
		}
	}
	return refCount, nil
}

// make a directory like /var/lib/kubelet/plugins/kubernetes.io/iscsi/iface_name/portal-some_iqn-lun-lun_id
func makePDNameInternal(host volume.VolumeHost, portal string, iqn string, lun string, iface string) string {
	return path.Join(host.GetPluginDir(iscsiPluginName), "iface-"+iface, portal+"-"+iqn+"-lun-"+lun)
}

type ISCSIUtil struct{}

func (util *ISCSIUtil) MakeGlobalPDName(iscsi iscsiDisk) string {
	return makePDNameInternal(iscsi.plugin.host, iscsi.Portals[0], iscsi.Iqn, iscsi.lun, iscsi.Iface)
}

func (util *ISCSIUtil) persistISCSI(conf iscsiDisk, mnt string) error {
	file := path.Join(mnt, "iscsi.json")
	fp, err := os.Create(file)
	if err != nil {
		return fmt.Errorf("iscsi: create %s err %s", file, err)
	}
	defer fp.Close()
	encoder := json.NewEncoder(fp)
	if err = encoder.Encode(conf); err != nil {
		return fmt.Errorf("iscsi: encode err: %v.", err)
	}
	return nil
}

func (util *ISCSIUtil) loadISCSI(conf *iscsiDisk, mnt string) error {
	// NOTE: The iscsi config json is not deleted after logging out from target portals.
	file := path.Join(mnt, "iscsi.json")
	fp, err := os.Open(file)
	if err != nil {
		return fmt.Errorf("iscsi: open %s err %s", file, err)
	}
	defer fp.Close()
	decoder := json.NewDecoder(fp)
	if err = decoder.Decode(conf); err != nil {
		return fmt.Errorf("iscsi: decode err: %v.", err)
	}
	return nil
}

func (util *ISCSIUtil) AttachDisk(b iscsiDiskMounter) error {
	var devicePath string
	var devicePaths []string
	var iscsiTransport string
	var lastErr error

	out, err := b.plugin.execCommand("iscsiadm", []string{"-m", "iface", "-I", b.Iface, "-o", "show"})
	if err != nil {
		glog.Errorf("iscsi: could not read iface %s error: %s", b.Iface, string(out))
		return err
	}

	iscsiTransport = extractTransportname(string(out))

	bkpPortal := b.Portals
	for _, tp := range bkpPortal {
		// Rescan sessions to discover newly mapped LUNs. Do not specify the interface when rescanning
		// to avoid establishing additional sessions to the same target.
		out, err := b.plugin.execCommand("iscsiadm", []string{"-m", "node", "-p", tp, "-T", b.Iqn, "-R"})
		if err != nil {
			glog.Errorf("iscsi: failed to rescan session with error: %s (%v)", string(out), err)
		}

		if iscsiTransport == "" {
			glog.Errorf("iscsi: could not find transport name in iface %s", b.Iface)
			return fmt.Errorf("Could not parse iface file for %s", b.Iface)
		} else if iscsiTransport == "tcp" {
			devicePath = strings.Join([]string{"/dev/disk/by-path/ip", tp, "iscsi", b.Iqn, "lun", b.lun}, "-")
		} else {
			devicePath = strings.Join([]string{"/dev/disk/by-path/pci", "*", "ip", tp, "iscsi", b.Iqn, "lun", b.lun}, "-")
		}
		exist := waitForPathToExist(&devicePath, 1, iscsiTransport)
		if exist == false {
			// build discoverydb and discover iscsi target
			b.plugin.execCommand("iscsiadm", []string{"-m", "discoverydb", "-t", "sendtargets", "-p", tp, "-I", b.Iface, "-o", "new"})
			// update discoverydb with CHAP secret
			err = updateISCSIDiscoverydb(b, tp)
			if err != nil {
				lastErr = fmt.Errorf("iscsi: failed to update discoverydb to portal %s error: %v", tp, err)
				continue
			}
			out, err := b.plugin.execCommand("iscsiadm", []string{"-m", "discoverydb", "-t", "sendtargets", "-p", tp, "-I", b.Iface, "--discover"})
			if err != nil {
				// delete discoverydb record
				b.plugin.execCommand("iscsiadm", []string{"-m", "discoverydb", "-t", "sendtargets", "-p", tp, "-I", b.Iface, "-o", "delete"})
				lastErr = fmt.Errorf("iscsi: failed to sendtargets to portal %s output: %s, err %v", tp, string(out), err)
				continue
			}
			err = updateISCSINode(b, tp)
			if err != nil {
				// failure to update node db is rare. But deleting record will likely impact those who already start using it.
				lastErr = fmt.Errorf("iscsi: failed to update iscsi node to portal %s error: %v", tp, err)
				continue
			}
			// login to iscsi target
			out, err = b.plugin.execCommand("iscsiadm", []string{"-m", "node", "-p", tp, "-T", b.Iqn, "-I", b.Iface, "--login"})
			if err != nil {
				// delete the node record from database
				b.plugin.execCommand("iscsiadm", []string{"-m", "node", "-p", tp, "-I", b.Iface, "-T", b.Iqn, "-o", "delete"})
				lastErr = fmt.Errorf("iscsi: failed to attach disk: Error: %s (%v)", string(out), err)
				continue
			}
			exist = waitForPathToExist(&devicePath, 10, iscsiTransport)
			if !exist {
				glog.Errorf("Could not attach disk: Timeout after 10s")
				// update last error
				lastErr = fmt.Errorf("Could not attach disk: Timeout after 10s")
				continue
			} else {
				devicePaths = append(devicePaths, devicePath)
			}
		} else {
			glog.V(4).Infof("iscsi: devicepath (%s) exists", devicePath)
			devicePaths = append(devicePaths, devicePath)
		}
	}

	if len(devicePaths) == 0 {
		glog.Errorf("iscsi: failed to get any path for iscsi disk, last err seen:\n%v", lastErr)
		return fmt.Errorf("failed to get any path for iscsi disk, last err seen:\n%v", lastErr)
	}

	//Make sure we use a valid devicepath to find mpio device.
	devicePath = devicePaths[0]

	// mount it
	globalPDPath := b.manager.MakeGlobalPDName(*b.iscsiDisk)
	notMnt, err := b.mounter.IsLikelyNotMountPoint(globalPDPath)
	if !notMnt {
		glog.Infof("iscsi: %s already mounted", globalPDPath)
		return nil
	}

	if err := os.MkdirAll(globalPDPath, 0750); err != nil {
		glog.Errorf("iscsi: failed to mkdir %s, error", globalPDPath)
		return err
	}

	// Persist iscsi disk config to json file for DetachDisk path
	util.persistISCSI(*(b.iscsiDisk), globalPDPath)

	for _, path := range devicePaths {
		// There shouldnt be any empty device paths. However adding this check
		// for safer side to avoid the possibility of an empty entry.
		if path == "" {
			continue
		}
		// check if the dev is using mpio and if so mount it via the dm-XX device
		if mappedDevicePath := b.deviceUtil.FindMultipathDeviceForDevice(path); mappedDevicePath != "" {
			devicePath = mappedDevicePath
			break
		}
	}
	err = b.mounter.FormatAndMount(devicePath, globalPDPath, b.fsType, nil)
	if err != nil {
		glog.Errorf("iscsi: failed to mount iscsi volume %s [%s] to %s, error %v", devicePath, b.fsType, globalPDPath, err)
	}

	return err
}

func (util *ISCSIUtil) DetachDisk(c iscsiDiskUnmounter, mntPath string) error {
	_, cnt, err := mount.GetDeviceNameFromMount(c.mounter, mntPath)
	if err != nil {
		glog.Errorf("iscsi detach disk: failed to get device from mnt: %s\nError: %v", mntPath, err)
		return err
	}
	if err = c.mounter.Unmount(mntPath); err != nil {
		glog.Errorf("iscsi detach disk: failed to unmount: %s\nError: %v", mntPath, err)
		return err
	}
	cnt--
	// if device is no longer used, see if need to logout the target
	if cnt == 0 {
		device, prefix, err := extractDeviceAndPrefix(mntPath)
		if err != nil {
			return err
		}
		refCount, err := getDevicePrefixRefCount(c.mounter, prefix)
		if err == nil && refCount == 0 {
			var bkpPortal []string
			var iqn, iface string
			found := true

			// load iscsi disk config from json file
			if err := util.loadISCSI(c.iscsiDisk, mntPath); err == nil {
				bkpPortal, iqn, iface = c.iscsiDisk.Portals, c.iscsiDisk.Iqn, c.iscsiDisk.Iface
			} else {
				// If the iscsi disk config is not found, fall back to the original behavior.
				// This portal/iqn/iface is no longer referenced, log out.
				// Extract the portal and iqn from device path.
				bkpPortal = make([]string, 1)
				bkpPortal[0], iqn, err = extractPortalAndIqn(device)
				if err != nil {
					return err
				}
				// Extract the iface from the mountPath and use it to log out. If the iface
				// is not found, maintain the previous behavior to facilitate kubelet upgrade.
				// Logout may fail as no session may exist for the portal/IQN on the specified interface.
				iface, found = extractIface(mntPath)
			}
			for _, portal := range removeDuplicate(bkpPortal) {
				logout := []string{"-m", "node", "-p", portal, "-T", iqn, "--logout"}
				delete := []string{"-m", "node", "-p", portal, "-T", iqn, "-o", "delete"}
				if found {
					logout = append(logout, []string{"-I", iface}...)
					delete = append(delete, []string{"-I", iface}...)
				}
				glog.Infof("iscsi: log out target %s iqn %s iface %s", portal, iqn, iface)
				out, err := c.plugin.execCommand("iscsiadm", logout)
				if err != nil {
					glog.Errorf("iscsi: failed to detach disk Error: %s", string(out))
				}
				// Delete the node record
				glog.Infof("iscsi: delete node record target %s iqn %s", portal, iqn)
				out, err = c.plugin.execCommand("iscsiadm", delete)
				if err != nil {
					glog.Errorf("iscsi: failed to delete node record Error: %s", string(out))
				}
			}
		}
	}
	return nil
}

func extractTransportname(ifaceOutput string) (iscsiTransport string) {
	re := regexp.MustCompile(`iface.transport_name = (.*)\n`)

	rex_output := re.FindStringSubmatch(ifaceOutput)
	if rex_output != nil {
		iscsiTransport = rex_output[1]
	} else {
		return ""
	}

	// While iface.transport_name is a required parameter, handle it being unspecified anyways
	if iscsiTransport == "<empty>" {
		iscsiTransport = "tcp"
	}
	return iscsiTransport
}

func extractDeviceAndPrefix(mntPath string) (string, string, error) {
	ind := strings.LastIndex(mntPath, "/")
	if ind < 0 {
		return "", "", fmt.Errorf("iscsi detach disk: malformatted mnt path: %s", mntPath)
	}
	device := mntPath[(ind + 1):]
	// strip -lun- from mount path
	ind = strings.LastIndex(mntPath, "-lun-")
	if ind < 0 {
		return "", "", fmt.Errorf("iscsi detach disk: malformatted mnt path: %s", mntPath)
	}
	prefix := mntPath[:ind]
	return device, prefix, nil
}

func extractIface(mntPath string) (string, bool) {
	re := regexp.MustCompile(`.+/iface-([^/]+)/.+`)

	re_output := re.FindStringSubmatch(mntPath)
	if re_output != nil {
		return re_output[1], true
	}

	return "", false
}

func extractPortalAndIqn(device string) (string, string, error) {
	ind1 := strings.Index(device, "-")
	if ind1 < 0 {
		return "", "", fmt.Errorf("iscsi detach disk: no portal in %s", device)
	}
	portal := device[0:ind1]
	ind2 := strings.Index(device, "iqn.")
	if ind2 < 0 {
		ind2 = strings.Index(device, "eui.")
	}
	if ind2 < 0 {
		return "", "", fmt.Errorf("iscsi detach disk: no iqn in %s", device)
	}
	ind := strings.LastIndex(device, "-lun-")
	iqn := device[ind2:ind]
	return portal, iqn, nil
}

// Remove duplicates or string
func removeDuplicate(s []string) []string {
	m := map[string]bool{}
	for _, v := range s {
		if v != "" && !m[v] {
			s[len(m)] = v
			m[v] = true
		}
	}
	s = s[:len(m)]
	return s
}