package debian

import (
	"strings"
	"time"

	version "github.com/knqyf263/go-deb-version"
	"golang.org/x/xerrors"
	"k8s.io/utils/clock"

	ftypes "github.com/aquasecurity/fanal/types"
	dbTypes "github.com/aquasecurity/trivy-db/pkg/types"
	"github.com/aquasecurity/trivy-db/pkg/vulnsrc/debian"
	"github.com/aquasecurity/trivy-db/pkg/vulnsrc/vulnerability"
	"github.com/aquasecurity/trivy/pkg/log"
	"github.com/aquasecurity/trivy/pkg/scanner/utils"
	"github.com/aquasecurity/trivy/pkg/types"
)

var (
	eolDates = map[string]time.Time{
		"1.1": time.Date(1997, 6, 5, 23, 59, 59, 0, time.UTC),
		"1.2": time.Date(1998, 6, 5, 23, 59, 59, 0, time.UTC),
		"1.3": time.Date(1999, 3, 9, 23, 59, 59, 0, time.UTC),
		"2.0": time.Date(2000, 3, 9, 23, 59, 59, 0, time.UTC),
		"2.1": time.Date(2000, 10, 30, 23, 59, 59, 0, time.UTC),
		"2.2": time.Date(2003, 7, 30, 23, 59, 59, 0, time.UTC),
		"3.0": time.Date(2006, 6, 30, 23, 59, 59, 0, time.UTC),
		"3.1": time.Date(2008, 3, 30, 23, 59, 59, 0, time.UTC),
		"4.0": time.Date(2010, 2, 15, 23, 59, 59, 0, time.UTC),
		"5.0": time.Date(2012, 2, 6, 23, 59, 59, 0, time.UTC),
		// LTS
		"6.0": time.Date(2016, 2, 29, 23, 59, 59, 0, time.UTC),
		"7":   time.Date(2018, 5, 31, 23, 59, 59, 0, time.UTC),
		"8":   time.Date(2020, 6, 30, 23, 59, 59, 0, time.UTC),
		"9":   time.Date(2022, 6, 30, 23, 59, 59, 0, time.UTC),
		"10":  time.Date(2024, 6, 30, 23, 59, 59, 0, time.UTC),
		"11":  time.Date(2026, 8, 14, 23, 59, 59, 0, time.UTC),
		"12":  time.Date(3000, 1, 1, 23, 59, 59, 0, time.UTC),
	}
)

type options struct {
	clock clock.Clock
}

type option func(*options)

func WithClock(clock clock.Clock) option {
	return func(opts *options) {
		opts.clock = clock
	}
}

// Scanner implements the Debian scanner
type Scanner struct {
	vs debian.VulnSrc
	*options
}

// NewScanner is the factory method to return Scanner
func NewScanner(opts ...option) *Scanner {
	o := &options{
		clock: clock.RealClock{},
	}

	for _, opt := range opts {
		opt(o)
	}
	return &Scanner{
		vs:      debian.NewVulnSrc(),
		options: o,
	}
}

// Detect scans and return vulnerabilities using Debian scanner
func (s *Scanner) Detect(osVer string, _ *ftypes.Repository, pkgs []ftypes.Package) ([]types.DetectedVulnerability, error) {
	log.Logger.Info("Detecting Debian vulnerabilities...")

	if strings.Count(osVer, ".") > 0 {
		osVer = osVer[:strings.Index(osVer, ".")]
	}
	log.Logger.Debugf("debian: os version: %s", osVer)
	log.Logger.Debugf("debian: the number of packages: %d", len(pkgs))

	var vulns []types.DetectedVulnerability
	for _, pkg := range pkgs {
		installed := utils.FormatSrcVersion(pkg)
		installedVersion, err := version.NewVersion(installed)
		if err != nil {
			log.Logger.Debugf("Debian installed package version error: %s", err)
			continue
		}

		advisories, err := s.vs.Get(osVer, pkg.SrcName)
		if err != nil {
			return nil, xerrors.Errorf("failed to get debian advisories: %w", err)
		}

		for _, adv := range advisories {
			vuln := types.DetectedVulnerability{
				VulnerabilityID:  adv.VulnerabilityID,
				VendorIDs:        adv.VendorIDs,
				PkgName:          pkg.Name,
				InstalledVersion: installed,
				FixedVersion:     adv.FixedVersion,
				Layer:            pkg.Layer,
				Custom:           adv.Custom,
				DataSource:       adv.DataSource,
			}

			if adv.Severity != dbTypes.SeverityUnknown {
				// Package-specific severity
				vuln.SeveritySource = vulnerability.Debian
				vuln.Vulnerability = dbTypes.Vulnerability{
					Severity: adv.Severity.String(),
				}
			}

			// It means unfixed vulnerability. We don't have to compare versions.
			if adv.FixedVersion == "" {
				vulns = append(vulns, vuln)
				continue
			}

			var fixedVersion version.Version
			fixedVersion, err = version.NewVersion(adv.FixedVersion)
			if err != nil {
				log.Logger.Debugf("Debian advisory package version error: %s", err)
				continue
			}

			if installedVersion.LessThan(fixedVersion) {
				vulns = append(vulns, vuln)
			}
		}
	}
	return vulns, nil
}

// IsSupportedVersion checks is OSFamily can be scanned using Debian
func (s *Scanner) IsSupportedVersion(osFamily, osVer string) bool {
	if strings.Count(osVer, ".") > 0 {
		osVer = osVer[:strings.Index(osVer, ".")]
	}

	eol, ok := eolDates[osVer]
	if !ok {
		log.Logger.Warnf("This OS version is not on the EOL list: %s %s", osFamily, osVer)
		return false
	}
	return s.clock.Now().Before(eol)
}
