feat(sitemap): add last updated for packages (#1070)

server/server/sitemap.go

@@ -3,13 +3,15 @@ package server
 import (
 	"fmt"
 	"net/http"
+	"time"
 
 	"pacstall.dev/webserver/types/pac/pacstore"
 )
 
 type SitemapEntry struct {
 	Location        string
 	ChangeFrequency string
+	LastUpdated     *string
 }
 
 func registerSiteMap() {
@@ -42,9 +44,11 @@ func generateDynamicSiteMap() []SitemapEntry {
 	entries := make([]SitemapEntry, len(packages))
 
 	for idx, pkg := range packages {
+        lastUpdated := pkg.LastUpdatedAt.Format(time.RFC3339)
 		entries[idx] = SitemapEntry{
 			Location:        fmt.Sprintf("https://pacstall.dev/packages/%s/", pkg.PackageName),
 			ChangeFrequency: "monthly",
+			LastUpdated:     &lastUpdated,
 		}
 	}
 
@@ -55,7 +59,13 @@ func (entry SitemapEntry) generateSiteMapUrls() string {
 	return fmt.Sprintf(`<url>
 	<loc>%s</loc>
 	<changefreq>%s</changefreq>
-</url>`, entry.Location, entry.ChangeFrequency)
+    %s
+</url>`, entry.Location, entry.ChangeFrequency, func() string {
+		if entry.LastUpdated != nil {
+			return fmt.Sprintf("<lastmod>%s</lastmod>", *entry.LastUpdated)
+		}
+		return ""
+	}())
 }
 
 func generateSiteMapXML() string {