✨ Prevent same link got expanded at the same (will wait cache now)

pkg/internal/server/api/link_expander.go

@@ -4,11 +4,25 @@ import (
 	"encoding/base64"
 	"git.solsynth.dev/hydrogen/dealer/pkg/internal/services"
 	"github.com/gofiber/fiber/v2"
+	"sync"
 )
 
+var inProgress sync.Map
+
 func getLinkMeta(c *fiber.Ctx) error {
 	targetEncoded := c.Params("target")
-	targetRaw, _ := base64.StdEncoding.DecodeString(targetEncoded)
+	targetRaw, _ := base64.URLEncoding.DecodeString(targetEncoded)
+
+	if ch, loaded := inProgress.LoadOrStore(targetEncoded, make(chan struct{})); loaded {
+		// If the request is already in progress, wait for it to complete
+		<-ch.(chan struct{})
+	} else {
+		// If this is the first request, process it and signal others
+		defer func() {
+			close(ch.(chan struct{}))
+			inProgress.Delete(targetEncoded)
+		}()
+	}
 
 	if meta, err := services.LinkExpand(string(targetRaw)); err != nil {
 		return fiber.NewError(fiber.StatusBadRequest, err.Error())