package vex

import (
	csaf "github.com/csaf-poc/csaf_distribution/v3/csaf"
	"github.com/package-url/packageurl-go"
	"github.com/samber/lo"
	"go.uber.org/zap"

	"github.com/aquasecurity/trivy/pkg/log"
	"github.com/aquasecurity/trivy/pkg/purl"
	"github.com/aquasecurity/trivy/pkg/types"
)

type CSAF struct {
	advisory csaf.Advisory
	logger   *zap.SugaredLogger
}

func newCSAF(advisory csaf.Advisory) VEX {
	return &CSAF{
		advisory: advisory,
		logger:   log.Logger.With(zap.String("VEX format", "CSAF")),
	}
}

func (v *CSAF) Filter(result *types.Result) {
	result.Vulnerabilities = lo.Filter(result.Vulnerabilities, func(vuln types.DetectedVulnerability, _ int) bool {
		found, ok := lo.Find(v.advisory.Vulnerabilities, func(item *csaf.Vulnerability) bool {
			return string(*item.CVE) == vuln.VulnerabilityID
		})
		if !ok {
			return true
		}

		if status := v.match(found, vuln.PkgIdentifier.PURL); status != "" {
			result.ModifiedFindings = append(result.ModifiedFindings,
				types.NewModifiedFinding(vuln, status, statement(found), "CSAF VEX"))
			return false
		}
		return true
	})
}

func (v *CSAF) match(vuln *csaf.Vulnerability, pkgURL *packageurl.PackageURL) types.FindingStatus {
	if pkgURL == nil || vuln.ProductStatus == nil {
		return ""
	}

	var status types.FindingStatus
	switch {
	case v.matchPURL(vuln.ProductStatus.KnownNotAffected, pkgURL):
		status = types.FindingStatusNotAffected
	case v.matchPURL(vuln.ProductStatus.Fixed, pkgURL):
		status = types.FindingStatusFixed
	}

	return status
}

// matchPURL returns true if the given PackageURL is found in the ProductTree.
func (v *CSAF) matchPURL(products *csaf.Products, pkgURL *packageurl.PackageURL) bool {
	for _, product := range lo.FromPtr(products) {
		helpers := v.advisory.ProductTree.CollectProductIdentificationHelpers(lo.FromPtr(product))
		purls := lo.FilterMap(helpers, func(helper *csaf.ProductIdentificationHelper, _ int) (*purl.PackageURL, bool) {
			if helper == nil || helper.PURL == nil {
				return nil, false
			}
			p, err := purl.FromString(string(*helper.PURL))
			if err != nil {
				v.logger.Errorw("Invalid PURL", zap.String("purl", string(*helper.PURL)), zap.Error(err))
				return nil, false
			}
			return p, true
		})
		for _, p := range purls {
			if p.Match(pkgURL) {
				return true
			}
		}
	}

	return false
}

func statement(vuln *csaf.Vulnerability) string {
	threat, ok := lo.Find(vuln.Threats, func(threat *csaf.Threat) bool {
		return lo.FromPtr(threat.Category) == csaf.CSAFThreatCategoryImpact
	})
	if !ok {
		return ""
	}
	return lo.FromPtr(threat.Details)
}