package scanner

import (
	"bufio"
	"crypto/rand"
	"encoding/binary"
	"fmt"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/future-architect/vuls/cache"
	"github.com/future-architect/vuls/config"
	"github.com/future-architect/vuls/constant"
	"github.com/future-architect/vuls/logging"
	"github.com/future-architect/vuls/models"
	"github.com/future-architect/vuls/util"
	version "github.com/knqyf263/go-deb-version"
	"golang.org/x/xerrors"
)

// inherit OsTypeInterface
type debian struct {
	base
}

// NewDebian is constructor
func newDebian(c config.ServerInfo) *debian {
	d := &debian{
		base: base{
			osPackages: osPackages{
				Packages:  models.Packages{},
				VulnInfos: models.VulnInfos{},
			},
		},
	}
	d.log = logging.NewNormalLogger()
	d.setServerInfo(c)
	return d
}

// Ubuntu, Debian, Raspbian
// https://github.com/serverspec/specinfra/blob/master/lib/specinfra/helper/detect_os/debian.rb
func detectDebian(c config.ServerInfo) (bool, osTypeInterface) {
	if r := exec(c, "ls /etc/debian_version", noSudo); !r.isSuccess() {
		logging.Log.Debugf("Not Debian like Linux. %s", r)
		return false, nil
	}

	// Raspbian
	// lsb_release in Raspbian Jessie returns 'Distributor ID: Raspbian'.
	// However, lsb_release in Raspbian Wheezy returns 'Distributor ID: Debian'.
	if r := exec(c, "cat /etc/issue", noSudo); r.isSuccess() {
		//  e.g.
		//  Raspbian GNU/Linux 7 \n \l
		result := strings.Fields(r.Stdout)
		if len(result) > 2 && result[0] == constant.Raspbian {
			deb := newDebian(c)
			deb.setDistro(strings.ToLower(trim(result[0])), trim(result[2]))
			return true, deb
		}
	}

	if r := exec(c, "lsb_release -ir", noSudo); r.isSuccess() {
		//  e.g.
		//  root@fa3ec524be43:/# lsb_release -ir
		//  Distributor ID:	Ubuntu
		//  Release:	14.04
		re := regexp.MustCompile(`(?s)^Distributor ID:\s*(.+?)\n*Release:\s*(.+?)$`)
		result := re.FindStringSubmatch(trim(r.Stdout))

		deb := newDebian(c)
		if len(result) == 0 {
			deb.setDistro("debian/ubuntu", "unknown")
			logging.Log.Warnf("Unknown Debian/Ubuntu version. lsb_release -ir: %s", r)
		} else {
			distro := strings.ToLower(trim(result[1]))
			deb.setDistro(distro, trim(result[2]))
		}
		return true, deb
	}

	if r := exec(c, "cat /etc/lsb-release", noSudo); r.isSuccess() {
		//  e.g.
		//  DISTRIB_ID=Ubuntu
		//  DISTRIB_RELEASE=14.04
		//  DISTRIB_CODENAME=trusty
		//  DISTRIB_DESCRIPTION="Ubuntu 14.04.2 LTS"
		re := regexp.MustCompile(`(?s)^DISTRIB_ID=(.+?)\n*DISTRIB_RELEASE=(.+?)\n.*$`)
		result := re.FindStringSubmatch(trim(r.Stdout))
		deb := newDebian(c)
		if len(result) == 0 {
			logging.Log.Warnf(
				"Unknown Debian/Ubuntu. cat /etc/lsb-release: %s", r)
			deb.setDistro("debian/ubuntu", "unknown")
		} else {
			distro := strings.ToLower(trim(result[1]))
			deb.setDistro(distro, trim(result[2]))
		}
		return true, deb
	}

	// Debian
	cmd := "cat /etc/debian_version"
	if r := exec(c, cmd, noSudo); r.isSuccess() {
		deb := newDebian(c)
		deb.setDistro(constant.Debian, trim(r.Stdout))
		return true, deb
	}

	logging.Log.Debugf("Not Debian like Linux: %s", c.ServerName)
	return false, nil
}

func trim(str string) string {
	return strings.TrimSpace(str)
}

func (o *debian) checkScanMode() error {
	return nil
}

func (o *debian) checkIfSudoNoPasswd() error {
	if o.getServerInfo().Mode.IsFast() {
		o.log.Infof("sudo ... No need")
		return nil
	}

	cmds := []string{
		"checkrestart",
		"stat /proc/1/exe",
		"ls -l /proc/1/exe",
		"cat /proc/1/maps",
		"lsof -i -P -n -V",
	}

	if !o.getServerInfo().Mode.IsOffline() {
		cmds = append(cmds, "apt-get update")
	}

	for _, cmd := range cmds {
		cmd = util.PrependProxyEnv(cmd)
		o.log.Infof("Checking... sudo %s", cmd)
		r := o.exec(cmd, sudo)
		if !r.isSuccess() {
			o.log.Errorf("sudo error on %s", r)
			return xerrors.Errorf("Failed to sudo: %s", r)
		}
	}

	initName, err := o.detectInitSystem()
	if initName == upstart && err == nil {
		cmd := util.PrependProxyEnv("initctl status --help")
		o.log.Infof("Checking... sudo %s", cmd)
		r := o.exec(cmd, sudo)
		if !r.isSuccess() {
			o.log.Errorf("sudo error on %s", r)
			return xerrors.Errorf("Failed to sudo: %s", r)
		}
	}

	o.log.Infof("Sudo... Pass")
	return nil
}

type dep struct {
	packName      string
	required      bool
	logFunc       func(string, ...interface{})
	additionalMsg string
}

func (o *debian) checkDeps() error {
	deps := []dep{}
	if o.getServerInfo().Mode.IsDeep() || o.getServerInfo().Mode.IsFastRoot() {
		// checkrestart
		deps = append(deps, dep{
			packName: "debian-goodies",
			required: true,
			logFunc:  o.log.Errorf,
		})
	}

	if o.Distro.Family == constant.Debian {
		// https://askubuntu.com/a/742844
		if !o.ServerInfo.IsContainer() {
			deps = append(deps, dep{
				packName:      "reboot-notifier",
				required:      false,
				logFunc:       o.log.Warnf,
				additionalMsg: ". Install it if you want to detect whether not rebooted after kernel update. To install `reboot-notifier` on Debian, see https://feeding.cloud.geek.nz/posts/introducing-reboot-notifier/",
			})
		}

		// Changelogs will be fetched only in deep scan mode
		if o.getServerInfo().Mode.IsDeep() {
			// Debian needs aptitude to get changelogs.
			// Because unable to get changelogs via `apt-get changelog` on Debian.
			deps = append(deps, dep{
				packName: "aptitude",
				required: true,
				logFunc:  o.log.Errorf,
			})
		}
	}

	for _, dep := range deps {
		cmd := fmt.Sprintf("%s %s", dpkgQuery, dep.packName)
		msg := fmt.Sprintf("%s is not installed", dep.packName)
		r := o.exec(cmd, noSudo)
		if !r.isSuccess() {
			if dep.additionalMsg != "" {
				msg += dep.additionalMsg
			}
			dep.logFunc(msg)
			if dep.required {
				return xerrors.New(msg)
			}
			continue
		}

		_, status, _, _, _, _ := o.parseScannedPackagesLine(r.Stdout)
		if status != "ii" {
			if dep.additionalMsg != "" {
				msg += dep.additionalMsg
			}
			dep.logFunc(msg)
			if dep.required {
				return xerrors.New(msg)
			}
		}

	}
	o.log.Infof("Dependencies... Pass")
	return nil
}

func (o *debian) preCure() error {
	if err := o.detectIPAddr(); err != nil {
		o.log.Warnf("Failed to detect IP addresses: %s", err)
		o.warns = append(o.warns, err)
	}
	// Ignore this error as it just failed to detect the IP addresses
	return nil
}

func (o *debian) postScan() error {
	if o.getServerInfo().Mode.IsDeep() || o.getServerInfo().Mode.IsFastRoot() {
		if err := o.pkgPs(o.getOwnerPkgs); err != nil {
			err = xerrors.Errorf("Failed to dpkg-ps: %w", err)
			o.log.Warnf("err: %+v", err)
			o.warns = append(o.warns, err)
			// Only warning this error
		}

		if err := o.checkrestart(); err != nil {
			err = xerrors.Errorf("Failed to scan need-restarting processes: %w", err)
			o.log.Warnf("err: %+v", err)
			o.warns = append(o.warns, err)
			// Only warning this error
		}
	}
	return nil
}

func (o *debian) detectIPAddr() (err error) {
	o.ServerInfo.IPv4Addrs, o.ServerInfo.IPv6Addrs, err = o.ip()
	return err
}

func (o *debian) scanPackages() error {
	o.log.Infof("Scanning OS pkg in %s", o.getServerInfo().Mode)
	// collect the running kernel information
	release, version, err := o.runningKernel()
	if err != nil {
		o.log.Errorf("Failed to scan the running kernel version: %s", err)
		return err
	}
	rebootRequired, err := o.rebootRequired()
	if err != nil {
		o.log.Warnf("Failed to detect the kernel reboot required: %s", err)
		o.warns = append(o.warns, err)
		// Only warning this error
	}
	o.Kernel = models.Kernel{
		Version:        version,
		Release:        release,
		RebootRequired: rebootRequired,
	}

	installed, updatable, srcPacks, err := o.scanInstalledPackages()
	if err != nil {
		o.log.Errorf("Failed to scan installed packages: %s", err)
		return err
	}
	o.Packages = installed
	o.SrcPackages = srcPacks

	if o.getServerInfo().Mode.IsOffline() {
		return nil
	}

	if !o.getServerInfo().Mode.IsDeep() && o.Distro.Family == constant.Raspbian {
		raspbianPacks := o.grepRaspbianPackages(updatable)
		unsecures, err := o.scanUnsecurePackages(raspbianPacks)
		if err != nil {
			o.log.Errorf("Failed to scan vulnerable packages: %s", err)
			return err
		}
		o.VulnInfos = unsecures
		return nil
	}

	if o.getServerInfo().Mode.IsDeep() {
		unsecures, err := o.scanUnsecurePackages(updatable)
		if err != nil {
			o.log.Errorf("Failed to scan vulnerable packages: %s", err)
			return err
		}
		o.VulnInfos = unsecures
		return nil
	}

	return nil
}

// https://askubuntu.com/a/742844
func (o *debian) rebootRequired() (bool, error) {
	r := o.exec("test -f /var/run/reboot-required", noSudo)
	switch r.ExitStatus {
	case 0:
		return true, nil
	case 1:
		return false, nil
	default:
		return false, xerrors.Errorf("Failed to check reboot required: %s", r)
	}
}

const dpkgQuery = `dpkg-query -W -f="\${binary:Package},\${db:Status-Abbrev},\${Version},\${source:Package},\${source:Version}\n"`

func (o *debian) scanInstalledPackages() (models.Packages, models.Packages, models.SrcPackages, error) {
	updatable := models.Packages{}
	r := o.exec(dpkgQuery, noSudo)
	if !r.isSuccess() {
		return nil, nil, nil, xerrors.Errorf("Failed to SSH: %s", r)
	}

	installed, srcPacks, err := o.parseInstalledPackages(r.Stdout)
	if err != nil {
		return nil, nil, nil, err
	}

	if o.getServerInfo().Mode.IsOffline() || o.getServerInfo().Mode.IsFast() {
		return installed, updatable, srcPacks, nil
	}

	if err := o.aptGetUpdate(); err != nil {
		return nil, nil, nil, err
	}
	updatableNames, err := o.getUpdatablePackNames()
	if err != nil {
		return nil, nil, nil, err
	}
	for _, name := range updatableNames {
		for _, pack := range installed {
			if pack.Name == name {
				updatable[name] = pack
				break
			}
		}
	}

	// Fill the candidate versions of upgradable packages
	err = o.fillCandidateVersion(updatable)
	if err != nil {
		return nil, nil, nil, xerrors.Errorf("Failed to fill candidate versions. err: %w", err)
	}
	installed.MergeNewVersion(updatable)

	return installed, updatable, srcPacks, nil
}

func (o *debian) parseInstalledPackages(stdout string) (models.Packages, models.SrcPackages, error) {
	installed, srcPacks := models.Packages{}, models.SrcPackages{}

	// e.g.
	// curl,ii ,7.38.0-4+deb8u2,,7.38.0-4+deb8u2
	// openssh-server,ii ,1:6.7p1-5+deb8u3,openssh,1:6.7p1-5+deb8u3
	// tar,ii ,1.27.1-2+b1,tar (1.27.1-2),1.27.1-2
	lines := strings.Split(stdout, "\n")
	for _, line := range lines {
		if trimmed := strings.TrimSpace(line); len(trimmed) != 0 {
			name, status, version, srcName, srcVersion, err := o.parseScannedPackagesLine(trimmed)
			if err != nil || len(status) < 2 {
				return nil, nil, xerrors.Errorf(
					"Debian: Failed to parse package line: %s", line)
			}

			packageStatus := status[1]
			// Package status:
			//     n = Not-installed
			//     c = Config-files
			//     H = Half-installed
			//     U = Unpacked
			//     F = Half-configured
			//     W = Triggers-awaiting
			//     t = Triggers-pending
			//     i = Installed
			if packageStatus != 'i' {
				o.log.Debugf("%s package status is '%c', ignoring", name, packageStatus)
				continue
			}
			installed[name] = models.Package{
				Name:    name,
				Version: version,
			}

			if pack, ok := srcPacks[srcName]; ok {
				pack.AddBinaryName(name)
				srcPacks[srcName] = pack
			} else {
				srcPacks[srcName] = models.SrcPackage{
					Name:        srcName,
					Version:     srcVersion,
					BinaryNames: []string{name},
				}
			}
		}
	}

	return installed, srcPacks, nil
}

func (o *debian) parseScannedPackagesLine(line string) (name, status, version, srcName, srcVersion string, err error) {
	ss := strings.Split(line, ",")
	if len(ss) == 5 {
		// remove :amd64, i386...
		name = ss[0]
		if i := strings.IndexRune(name, ':'); i >= 0 {
			name = name[:i]
		}
		status = strings.TrimSpace(ss[1])
		version = ss[2]
		// remove version. ex: tar (1.27.1-2)

		// Source name and version are computed from binary package name and version in dpkg.
		// Source package name:
		// https://git.dpkg.org/cgit/dpkg/dpkg.git/tree/lib/dpkg/pkg-format.c#n338
		srcName = strings.Split(ss[3], " ")[0]
		if srcName == "" {
			srcName = name
		}
		// Source package version:
		// https://git.dpkg.org/cgit/dpkg/dpkg.git/tree/lib/dpkg/pkg-show.c#n428
		srcVersion = ss[4]
		if srcVersion == "" {
			srcVersion = version
		}
		return
	}

	return "", "", "", "", "", xerrors.Errorf("Unknown format: %s", line)
}

func (o *debian) aptGetUpdate() error {
	o.log.Infof("apt-get update...")
	cmd := util.PrependProxyEnv("apt-get update")
	if r := o.exec(cmd, sudo); !r.isSuccess() {
		return xerrors.Errorf("Failed to apt-get update: %s", r)
	}
	return nil
}

func (o *debian) grepRaspbianPackages(updatables models.Packages) models.Packages {
	raspbianPacks := models.Packages{}

	for _, pack := range updatables {
		if models.IsRaspbianPackage(pack.Name, pack.Version) {
			raspbianPacks[pack.Name] = pack
		}
	}
	return raspbianPacks
}

func (o *debian) scanUnsecurePackages(updatable models.Packages) (models.VulnInfos, error) {
	// Setup changelog cache
	current := cache.Meta{
		Name:   o.getServerInfo().GetServerName(),
		Distro: o.getServerInfo().Distro,
		Packs:  updatable,
	}

	o.log.Debugf("Ensure changelog cache: %s", current.Name)
	meta, err := o.ensureChangelogCache(current)
	if err != nil {
		return nil, err
	}

	// Make a directory for saving changelog to get changelog in Raspbian
	tmpClogPath := ""
	if o.Distro.Family == constant.Raspbian {
		tmpClogPath, err = o.makeTempChangelogDir()
		if err != nil {
			return nil, err
		}
	}

	// Collect CVE information of upgradable packages
	vulnInfos, err := o.scanChangelogs(updatable, meta, tmpClogPath)
	if err != nil {
		return nil, xerrors.Errorf("Failed to scan unsecure packages. err: %w", err)
	}

	// Delete a directory for saving changelog to get changelog in Raspbian
	if o.Distro.Family == constant.Raspbian {
		err := o.deleteTempChangelogDir(tmpClogPath)
		if err != nil {
			return nil, xerrors.Errorf("Failed to delete directory to save changelog for Raspbian. err: %w", err)
		}
	}

	return vulnInfos, nil
}

func (o *debian) ensureChangelogCache(current cache.Meta) (*cache.Meta, error) {
	// Search from cache
	cached, found, err := cache.DB.GetMeta(current.Name)
	if err != nil {
		return nil, xerrors.Errorf(
			"Failed to get meta. Please remove cache.db and then try again. err: %w", err)
	}

	if !found {
		o.log.Debugf("Not found in meta: %s", current.Name)
		err = cache.DB.EnsureBuckets(current)
		if err != nil {
			return nil, xerrors.Errorf("Failed to ensure buckets. err: %w", err)
		}
		return &current, nil
	}

	if current.Distro.Family != cached.Distro.Family ||
		current.Distro.Release != cached.Distro.Release {
		o.log.Debugf("Need to refresh meta: %s", current.Name)
		err = cache.DB.EnsureBuckets(current)
		if err != nil {
			return nil, xerrors.Errorf("Failed to ensure buckets. err: %w", err)
		}
		return &current, nil

	}

	o.log.Debugf("Reuse meta: %s", current.Name)
	if config.Conf.Debug {
		cache.DB.PrettyPrint(current)
	}
	return &cached, nil
}

func (o *debian) fillCandidateVersion(updatables models.Packages) (err error) {
	names := []string{}
	for name := range updatables {
		names = append(names, name)
	}
	cmd := fmt.Sprintf("LANGUAGE=en_US.UTF-8 apt-cache policy %s", strings.Join(names, " "))
	r := o.exec(cmd, noSudo)
	if !r.isSuccess() {
		return xerrors.Errorf("Failed to SSH: %s", r)
	}
	packAptPolicy := o.splitAptCachePolicy(r.Stdout)
	for k, v := range packAptPolicy {
		ver, err := o.parseAptCachePolicy(v, k)
		if err != nil {
			return xerrors.Errorf("Failed to parse %w", err)
		}
		pack, ok := updatables[k]
		if !ok {
			return xerrors.Errorf("Not found: %s", k)
		}
		pack.NewVersion = ver.Candidate
		pack.Repository = ver.Repo
		updatables[k] = pack
	}
	return
}

func (o *debian) getUpdatablePackNames() (packNames []string, err error) {
	cmd := util.PrependProxyEnv("LANGUAGE=en_US.UTF-8 apt-get dist-upgrade --dry-run")
	r := o.exec(cmd, noSudo)
	if r.isSuccess(0, 1) {
		return o.parseAptGetUpgrade(r.Stdout)
	}
	return packNames, xerrors.Errorf(
		"Failed to %s. status: %d, stdout: %s, stderr: %s",
		cmd, r.ExitStatus, r.Stdout, r.Stderr)
}

func (o *debian) parseAptGetUpgrade(stdout string) (updatableNames []string, err error) {
	startRe := regexp.MustCompile(`The following packages will be upgraded:`)
	stopRe := regexp.MustCompile(`^(\d+) upgraded.*`)
	startLineFound, stopLineFound := false, false

	lines := strings.Split(stdout, "\n")
	for _, line := range lines {
		if !startLineFound {
			if matche := startRe.MatchString(line); matche {
				startLineFound = true
			}
			continue
		}
		result := stopRe.FindStringSubmatch(line)
		if len(result) == 2 {
			nUpdatable, err := strconv.Atoi(result[1])
			if err != nil {
				return nil, xerrors.Errorf(
					"Failed to scan upgradable packages number. line: %s", line)
			}
			if nUpdatable != len(updatableNames) {
				return nil, xerrors.Errorf(
					"Failed to scan upgradable packages, expected: %s, detected: %d",
					result[1], len(updatableNames))
			}
			stopLineFound = true
			break
		}
		updatableNames = append(updatableNames, strings.Fields(line)...)
	}
	if !startLineFound {
		// no upgrades
		return
	}
	if !stopLineFound {
		// There are upgrades, but not found the stop line.
		return nil, xerrors.New("Failed to scan upgradable packages")
	}
	return
}

func (o *debian) makeTempChangelogDir() (string, error) {
	suffix, err := generateSuffix()
	if err != nil {
		return "", err
	}
	path := "/tmp/vuls-" + suffix
	cmd := fmt.Sprintf(`mkdir -p %s`, path)
	cmd = util.PrependProxyEnv(cmd)
	r := o.exec(cmd, noSudo)
	if !r.isSuccess() {
		return "", xerrors.Errorf("Failed to create directory to save changelog for Raspbian. cmd: %s, status: %d, stdout: %s, stderr: %s", cmd, r.ExitStatus, r.Stdout, r.Stderr)
	}
	return path, nil
}

func generateSuffix() (string, error) {
	var n uint64
	if err := binary.Read(rand.Reader, binary.LittleEndian, &n); err != nil {
		return "", xerrors.Errorf("Failed to generate Suffix. err: %w", err)
	}
	return strconv.FormatUint(n, 36), nil
}

func (o *debian) deleteTempChangelogDir(tmpClogPath string) error {
	cmd := fmt.Sprintf(`rm -rf %s`, tmpClogPath)
	cmd = util.PrependProxyEnv(cmd)
	r := o.exec(cmd, noSudo)
	if !r.isSuccess() {
		return xerrors.Errorf("Failed to delete directory to save changelog for Raspbian. cmd: %s, status: %d, stdout: %s, stderr: %s", cmd, r.ExitStatus, r.Stdout, r.Stderr)
	}
	return nil
}

// DetectedCveID has CveID, Confidence and DetectionMethod fields
// LenientMatching will be true if this vulnerability is not detected by accurate version matching.
// see https://github.com/future-architect/vuls/pull/328
type DetectedCveID struct {
	CveID      string
	Confidence models.Confidence
}

func (o *debian) scanChangelogs(updatablePacks models.Packages, meta *cache.Meta, tmpClogPath string) (models.VulnInfos, error) {
	type response struct {
		pack           *models.Package
		DetectedCveIDs []DetectedCveID
	}
	resChan := make(chan response, len(updatablePacks))
	errChan := make(chan error, len(updatablePacks))
	reqChan := make(chan models.Package, len(updatablePacks))
	defer close(resChan)
	defer close(errChan)
	defer close(reqChan)

	go func() {
		for _, pack := range updatablePacks {
			reqChan <- pack
		}
	}()

	timeout := time.After(30 * 60 * time.Second)
	concurrency := 10
	tasks := util.GenWorkers(concurrency)
	for range updatablePacks {
		tasks <- func() {
			select {
			case pack := <-reqChan:
				func(p models.Package) {
					changelog := o.getChangelogCache(meta, p)
					if 0 < len(changelog) {
						cveIDs, pack := o.getCveIDsFromChangelog(changelog, p.Name, p.Version)
						resChan <- response{pack, cveIDs}
						return
					}

					// if the changelog is not in cache or failed to get from local cache,
					// get the changelog of the package via internet.
					// After that, store it in the cache.
					if cveIDs, pack, err := o.fetchParseChangelog(p, tmpClogPath); err != nil {
						errChan <- err
					} else {
						resChan <- response{pack, cveIDs}
					}
				}(pack)
			}
		}
	}

	// { DetectedCveID{} : [package] }
	cvePackages := make(map[DetectedCveID][]string)
	errs := []error{}
	for i := 0; i < len(updatablePacks); i++ {
		select {
		case response := <-resChan:
			if response.pack == nil {
				continue
			}
			o.Packages[response.pack.Name] = *response.pack
			cves := response.DetectedCveIDs
			for _, cve := range cves {
				packNames, ok := cvePackages[cve]
				if ok {
					packNames = append(packNames, response.pack.Name)
				} else {
					packNames = []string{response.pack.Name}
				}
				cvePackages[cve] = packNames
			}
			o.log.Infof("(%d/%d) Scanned %s: %s",
				i+1, len(updatablePacks), response.pack.Name, cves)
		case err := <-errChan:
			errs = append(errs, err)
		case <-timeout:
			errs = append(errs, xerrors.New("Timeout scanPackageCveIDs"))
		}
	}
	if 0 < len(errs) {
		return nil, xerrors.Errorf("errs: %w", errs)
	}

	cveIDs := []DetectedCveID{}
	for k := range cvePackages {
		cveIDs = append(cveIDs, k)
	}
	o.log.Debugf("%d Cves are found. cves: %v", len(cveIDs), cveIDs)
	vinfos := models.VulnInfos{}
	for cveID, names := range cvePackages {
		affected := models.PackageFixStatuses{}
		for _, n := range names {
			affected = append(affected, models.PackageFixStatus{Name: n})
		}

		vinfos[cveID.CveID] = models.VulnInfo{
			CveID:            cveID.CveID,
			Confidences:      models.Confidences{cveID.Confidence},
			AffectedPackages: affected,
		}
	}

	// Update meta package information of changelog cache to the latest one.
	meta.Packs = updatablePacks
	if err := cache.DB.RefreshMeta(*meta); err != nil {
		return nil, err
	}

	return vinfos, nil
}

func (o *debian) getChangelogCache(meta *cache.Meta, pack models.Package) string {
	cachedPack, found := meta.Packs[pack.Name]
	if !found {
		o.log.Debugf("Not found in cache: %s", pack.Name)
		return ""
	}

	if cachedPack.NewVersion != pack.NewVersion {
		o.log.Debugf("Expired: %s, cache: %s, new: %s",
			pack.Name, cachedPack.NewVersion, pack.NewVersion)
		return ""
	}
	changelog, err := cache.DB.GetChangelog(meta.Name, pack.Name)
	if err != nil {
		o.log.Warnf("Failed to get changelog. bucket: %s, key:%s, err: %+v",
			meta.Name, pack.Name, err)
		return ""
	}
	if len(changelog) == 0 {
		o.log.Debugf("Empty string: %s", pack.Name)
		return ""
	}

	o.log.Debugf("Hit: %s, %s, cache: %s, new: %s len: %d, %s...",
		meta.Name, pack.Name, cachedPack.NewVersion, pack.NewVersion, len(changelog), util.Truncate(changelog, 30))
	return changelog
}

func (o *debian) fetchParseChangelog(pack models.Package, tmpClogPath string) ([]DetectedCveID, *models.Package, error) {
	cmd := ""

	switch o.Distro.Family {
	case constant.Ubuntu:
		cmd = fmt.Sprintf(`PAGER=cat apt-get -q=2 changelog %s`, pack.Name)
	case constant.Debian:
		cmd = fmt.Sprintf(`PAGER=cat aptitude -q=2 changelog %s`, pack.Name)
	case constant.Raspbian:
		changelogPath, err := o.getChangelogPath(pack.Name, tmpClogPath)
		if err != nil {
			// Ignore this Error.
			o.log.Warnf("Failed to get Path to Changelog for Package: %s, err: %+v", pack.Name, err)
			return nil, nil, nil
		}
		cmd = fmt.Sprintf(`gzip -cd %s | cat`, changelogPath)
	}
	cmd = util.PrependProxyEnv(cmd)

	r := o.exec(cmd, noSudo)
	if !r.isSuccess() {
		o.log.Warnf("Failed to SSH: %s", r)
		// Ignore this Error.
		return nil, nil, nil
	}

	stdout := strings.Replace(r.Stdout, "\r", "", -1)
	cveIDs, clogFilledPack := o.getCveIDsFromChangelog(stdout, pack.Name, pack.Version)

	if clogFilledPack.Changelog.Method != models.FailedToGetChangelog {
		err := cache.DB.PutChangelog(
			o.getServerInfo().GetServerName(), pack.Name, stdout)
		if err != nil {
			return nil, nil, xerrors.New("Failed to put changelog into cache")
		}
	}

	// No error will be returned. Only logging.
	return cveIDs, clogFilledPack, nil
}

func (o *debian) getChangelogPath(packName, tmpClogPath string) (string, error) {
	// `apt download` downloads deb package to current directory
	cmd := fmt.Sprintf(`cd %s && apt download %s`, tmpClogPath, packName)
	cmd = util.PrependProxyEnv(cmd)
	r := o.exec(cmd, noSudo)
	if !r.isSuccess() {
		return "", xerrors.Errorf("Failed to Fetch deb package. cmd: %s, status: %d, stdout: %s, stderr: %s", cmd, r.ExitStatus, r.Stdout, r.Stderr)
	}

	cmd = fmt.Sprintf(`find %s -name "%s_*.deb"`, tmpClogPath, packName)
	cmd = util.PrependProxyEnv(cmd)
	r = o.exec(cmd, noSudo)
	if !r.isSuccess() || r.Stdout == "" {
		return "", xerrors.Errorf("Failed to find deb package. cmd: %s, status: %d, stdout: %s, stderr: %s", cmd, r.ExitStatus, r.Stdout, r.Stderr)
	}

	// e.g. <tmpPath>/ffmpeg_7%3a4.1.6-1~deb10u1+rpt1_armhf.deb\n => <tmpPath>/ffmpeg_7%3a4.1.6-1~deb10u1+rpt1_armhf
	packChangelogDir := strings.Split(r.Stdout, ".deb")[0]
	cmd = fmt.Sprintf(`dpkg-deb -x %s.deb %s`, packChangelogDir, packChangelogDir)
	cmd = util.PrependProxyEnv(cmd)
	r = o.exec(cmd, noSudo)
	if !r.isSuccess() {
		return "", xerrors.Errorf("Failed to dpkg-deb. cmd: %s, status: %d, stdout: %s, stderr: %s", cmd, r.ExitStatus, r.Stdout, r.Stderr)
	}

	// recurse if doc/packName is symbolic link
	changelogDocDir := fmt.Sprintf("%s/usr/share/doc/%s", packChangelogDir, packName)
	cmd = fmt.Sprintf(`test -L %s && readlink --no-newline %s`, changelogDocDir, changelogDocDir)
	cmd = util.PrependProxyEnv(cmd)
	r = o.exec(cmd, noSudo)
	if r.isSuccess() {
		return o.getChangelogPath(r.Stdout, tmpClogPath)
	}

	var results = make(map[string]execResult, 2)
	packChangelogPath := fmt.Sprintf("%s/changelog.Debian.gz", changelogDocDir)
	cmd = fmt.Sprintf(`test -e %s`, packChangelogPath)
	cmd = util.PrependProxyEnv(cmd)
	r = o.exec(cmd, noSudo)
	if r.isSuccess() {
		return packChangelogPath, nil
	}
	results["changelog.Debian.gz"] = r

	packChangelogPath = fmt.Sprintf("%s/changelog.gz", changelogDocDir)
	cmd = fmt.Sprintf(`test -e %s`, packChangelogPath)
	cmd = util.PrependProxyEnv(cmd)
	r = o.exec(cmd, noSudo)
	if r.isSuccess() {
		return packChangelogPath, nil
	}
	results["changelog.gz"] = r

	return "", xerrors.Errorf(
		"Failed to get changelog.\nresult(changelog.Debian.gz):%v\nresult(changelog.Debian.gz):%v",
		results["changelog.Debian.gz"], results["changelog.gz"])
}

func (o *debian) getCveIDsFromChangelog(
	changelog, name, ver string) ([]DetectedCveID, *models.Package) {

	if cveIDs, pack, err := o.parseChangelog(
		changelog, name, ver, models.ChangelogExactMatch); err == nil {
		return cveIDs, pack
	}

	var verAfterColon string

	splittedByColon := strings.Split(ver, ":")
	if 1 < len(splittedByColon) {
		verAfterColon = splittedByColon[1]
		if cveIDs, pack, err := o.parseChangelog(
			changelog, name, verAfterColon, models.ChangelogRoughMatch); err == nil {
			return cveIDs, pack
		}
	}

	delim := []string{"+", "~", "build"}
	switch o.Distro.Family {
	case constant.Ubuntu:
		delim = append(delim, constant.Ubuntu)
	case constant.Debian:
	case constant.Raspbian:
	}

	for _, d := range delim {
		ss := strings.Split(ver, d)
		if 1 < len(ss) {
			if cveIDs, pack, err := o.parseChangelog(
				changelog, name, ss[0], models.ChangelogRoughMatch); err == nil {
				return cveIDs, pack
			}
		}

		ss = strings.Split(verAfterColon, d)
		if 1 < len(ss) {
			if cveIDs, pack, err := o.parseChangelog(
				changelog, name, ss[0], models.ChangelogRoughMatch); err == nil {
				return cveIDs, pack
			}
		}
	}

	// Only logging the error.
	o.log.Warnf("Failed to find the version in changelog: %s-%s", name, ver)
	o.log.Debugf("Changelog of %s-%s: %s", name, ver, changelog)

	// If the version is not in changelog, return entire changelog to put into cache
	pack := o.Packages[name]
	pack.Changelog = &models.Changelog{
		Contents: changelog,
		Method:   models.FailedToFindVersionInChangelog,
	}

	return []DetectedCveID{}, &pack
}

var cveRe = regexp.MustCompile(`(CVE-\d{4}-\d{4,})`)

// Collect CVE-IDs included in the changelog.
// The version specified in argument(versionOrLater) is used to compare.
func (o *debian) parseChangelog(changelog, name, ver string, confidence models.Confidence) ([]DetectedCveID, *models.Package, error) {
	installedVer, err := version.NewVersion(ver)
	if err != nil {
		return nil, nil, xerrors.Errorf("Failed to parse installed version: %s, err: %w", ver, err)
	}
	buf, cveIDs := []string{}, []string{}
	scanner := bufio.NewScanner(strings.NewReader(changelog))
	found := false
	for scanner.Scan() {
		line := scanner.Text()
		buf = append(buf, line)
		if matches := cveRe.FindAllString(line, -1); 0 < len(matches) {
			for _, m := range matches {
				cveIDs = util.AppendIfMissing(cveIDs, m)
			}
		}

		ss := strings.Fields(line)
		if len(ss) < 2 {
			continue
		}

		if !strings.HasPrefix(ss[1], "(") || !strings.HasSuffix(ss[1], ")") {
			continue
		}
		clogVer, err := version.NewVersion(ss[1][1 : len(ss[1])-1])
		if err != nil {
			continue
		}
		if installedVer.Equal(clogVer) || installedVer.GreaterThan(clogVer) {
			found = true
			break
		}
	}

	if !found {
		if o.Distro.Family == constant.Raspbian {
			pack := o.Packages[name]
			pack.Changelog = &models.Changelog{
				Contents: strings.Join(buf, "\n"),
				Method:   models.ChangelogRoughMatchStr,
			}

			cves := []DetectedCveID{}
			for _, id := range cveIDs {
				cves = append(cves, DetectedCveID{id, confidence})
			}

			return cves, &pack, nil
		}

		pack := o.Packages[name]
		pack.Changelog = &models.Changelog{
			Contents: "",
			Method:   models.FailedToFindVersionInChangelog,
		}
		return nil, &pack, xerrors.Errorf(
			"Failed to scan CVE IDs. The version is not in changelog. name: %s, version: %s",
			name, ver)
	}

	clog := models.Changelog{
		Contents: strings.Join(buf[0:len(buf)-1], "\n"),
		Method:   confidence.DetectionMethod,
	}
	pack := o.Packages[name]
	pack.Changelog = &clog

	cves := []DetectedCveID{}
	for _, id := range cveIDs {
		cves = append(cves, DetectedCveID{id, confidence})
	}

	return cves, &pack, nil
}

func (o *debian) splitAptCachePolicy(stdout string) map[string]string {
	re := regexp.MustCompile(`(?m:^[^ \t]+:\r?\n)`)
	ii := re.FindAllStringIndex(stdout, -1)
	ri := []int{}
	for i := len(ii) - 1; 0 <= i; i-- {
		ri = append(ri, ii[i][0])
	}
	splitted := []string{}
	lasti := len(stdout)
	for _, i := range ri {
		splitted = append(splitted, stdout[i:lasti])
		lasti = i
	}

	packAptPolicy := map[string]string{}
	for _, r := range splitted {
		packName := r[:strings.Index(r, ":")]
		packAptPolicy[packName] = r
	}
	return packAptPolicy
}

type packCandidateVer struct {
	Name      string
	Installed string
	Candidate string
	Repo      string
}

// parseAptCachePolicy the stdout of parse pat-get cache policy
func (o *debian) parseAptCachePolicy(stdout, name string) (packCandidateVer, error) {
	ver := packCandidateVer{Name: name}
	lines := strings.Split(stdout, "\n")
	isRepoline := false
	for _, line := range lines {
		fields := strings.Fields(line)
		if len(fields) < 2 {
			continue
		}
		switch fields[0] {
		case "Installed:":
			ver.Installed = fields[1]
		case "Candidate:":
			ver.Candidate = fields[1]
			goto nextline
		default:
			// nop
		}
		if ver.Candidate != "" && strings.Contains(line, ver.Candidate) {
			isRepoline = true
			goto nextline
		}

		if isRepoline {
			ss := strings.Split(strings.TrimSpace(line), " ")
			if len(ss) == 5 {
				ver.Repo = ss[2]
				return ver, nil
			}
		}
	nextline:
	}
	return ver, xerrors.Errorf("Unknown Format: %s", stdout)
}

func (o *debian) checkrestart() error {
	initName, err := o.detectInitSystem()
	if err != nil {
		o.log.Warn(err)
		// continue scanning
	}

	cmd := "LANGUAGE=en_US.UTF-8 checkrestart"
	r := o.exec(cmd, sudo)
	if !r.isSuccess() {
		return xerrors.Errorf(
			"Failed to %s. status: %d, stdout: %s, stderr: %s",
			cmd, r.ExitStatus, r.Stdout, r.Stderr)
	}
	packs, unknownServices := o.parseCheckRestart(r.Stdout)
	pidService := map[string]string{}
	if initName == upstart {
		for _, s := range unknownServices {
			cmd := "LANGUAGE=en_US.UTF-8 initctl status " + s
			r := o.exec(cmd, sudo)
			if !r.isSuccess() {
				continue
			}
			if ss := strings.Fields(r.Stdout); len(ss) == 4 && ss[2] == "process" {
				pidService[ss[3]] = s
			}
		}
	}

	for i, p := range packs {
		pack := o.Packages[p.Name]
		pack.NeedRestartProcs = p.NeedRestartProcs
		o.Packages[p.Name] = pack

		for j, proc := range p.NeedRestartProcs {
			if !proc.HasInit {
				continue
			}
			packs[i].NeedRestartProcs[j].InitSystem = initName
			if initName == systemd {
				name, err := o.detectServiceName(proc.PID)
				if err != nil {
					o.log.Warn(err)
					// continue scanning
				}
				packs[i].NeedRestartProcs[j].ServiceName = name
			} else {
				if proc.ServiceName == "" {
					if ss := strings.Fields(r.Stdout); len(ss) == 4 && ss[2] == "process" {
						if name, ok := pidService[ss[3]]; ok {
							packs[i].NeedRestartProcs[j].ServiceName = name
						}
					}
				}
			}
		}
		o.Packages[p.Name] = p
	}
	return nil
}

func (o *debian) parseCheckRestart(stdout string) (models.Packages, []string) {
	services := []string{}
	scanner := bufio.NewScanner(strings.NewReader(stdout))
	for scanner.Scan() {
		line := scanner.Text()
		if strings.HasPrefix(line, "service") && strings.HasSuffix(line, "restart") {
			ss := strings.Fields(line)
			if len(ss) != 3 {
				continue
			}
			services = append(services, ss[1])
		}
	}

	packs := models.Packages{}
	packName := ""
	hasInit := true
	scanner = bufio.NewScanner(strings.NewReader(stdout))
	for scanner.Scan() {
		line := scanner.Text()
		if strings.HasSuffix(line, "do not seem to have an associated init script to restart them:") {
			hasInit = false
			continue
		}
		if strings.HasSuffix(line, ":") && len(strings.Fields(line)) == 1 {
			packName = strings.TrimSuffix(line, ":")
			continue
		}
		if strings.HasPrefix(line, "\t") {
			ss := strings.Fields(line)
			if len(ss) != 2 {
				continue
			}

			serviceName := ""
			for _, s := range services {
				if packName == s {
					serviceName = s
				}
			}
			if p, ok := packs[packName]; ok {
				p.NeedRestartProcs = append(p.NeedRestartProcs, models.NeedRestartProcess{
					PID:         ss[0],
					Path:        ss[1],
					ServiceName: serviceName,
					HasInit:     hasInit,
				})
				packs[packName] = p
			} else {
				packs[packName] = models.Package{
					Name: packName,
					NeedRestartProcs: []models.NeedRestartProcess{
						{
							PID:         ss[0],
							Path:        ss[1],
							ServiceName: serviceName,
							HasInit:     hasInit,
						},
					},
				}
			}
		}
	}

	unknownServices := []string{}
	for _, s := range services {
		found := false
		for _, p := range packs {
			for _, proc := range p.NeedRestartProcs {
				if proc.ServiceName == s {
					found = true
				}
			}
		}
		if !found {
			unknownServices = append(unknownServices, s)
		}
	}
	return packs, unknownServices
}

func (o *debian) getOwnerPkgs(paths []string) (pkgNames []string, err error) {
	cmd := "dpkg -S " + strings.Join(paths, " ")
	r := o.exec(util.PrependProxyEnv(cmd), noSudo)
	if !r.isSuccess(0, 1) {
		return nil, xerrors.Errorf("Failed to SSH: %s", r)
	}
	return o.parseGetPkgName(r.Stdout), nil
}

func (o *debian) parseGetPkgName(stdout string) (pkgNames []string) {
	uniq := map[string]struct{}{}
	scanner := bufio.NewScanner(strings.NewReader(stdout))
	for scanner.Scan() {
		line := scanner.Text()
		ss := strings.Fields(line)
		if len(ss) < 2 || ss[1] == "no" {
			continue
		}
		s := strings.Split(ss[0], ":")[0]
		uniq[s] = struct{}{}
	}
	for n := range uniq {
		pkgNames = append(pkgNames, n)
	}
	return pkgNames
}