rpmmd: deduplicate RPM list based on NEVRA

Signed-off-by: Achilleas Koutsou <achilleas@koutsou.net>

internal/rpmmd/metadata.go

@@ -1,6 +1,8 @@
 package rpmmd
 
 import (
+	"fmt"
+
 	osbuild "github.com/osbuild/osbuild-composer/internal/osbuild2"
 )
 
@@ -15,6 +17,15 @@ type RPM struct {
 	Signature *string `json:"signature"`
 }
 
+// NEVRA string for the package
+func (r RPM) String() string {
+	epoch := ""
+	if r.Epoch != nil {
+		epoch = *r.Epoch + ":"
+	}
+	return fmt.Sprintf("%s-%s%s-%s.%s", r.Name, epoch, r.Version, r.Release, r.Arch)
+}
+
 func OSBuildMetadataToRPMs(stagesMetadata map[string]osbuild.StageMetadata) []RPM {
 	rpms := make([]RPM, 0)
 	for _, md := range stagesMetadata {
@@ -47,3 +58,17 @@ func PackageMetadataToSignature(pkg osbuild.RPMPackageMetadata) *string {
 	}
 	return nil
 }
+
+// Deduplicate a list of RPMs based on NEVRA string
+func DeduplicateRPMs(rpms []RPM) []RPM {
+	rpmMap := make(map[string]struct{}, len(rpms))
+	uniqueRPMs := make([]RPM, 0, len(rpms))
+
+	for _, rpm := range rpms {
+		if _, added := rpmMap[rpm.String()]; !added {
+			rpmMap[rpm.String()] = struct{}{}
+			uniqueRPMs = append(uniqueRPMs, rpm)
+		}
+	}
+	return uniqueRPMs
+}