Rework project's structure

internal/mojang/uuids_provider.go

@@ -0,0 +1,45 @@
+package mojang
+
+type MojangUuidsStorage interface {
+	// The second argument must be returned as a incoming username in case,
+	// when cached result indicates that there is no Mojang user with provided username
+	GetUuidForMojangUsername(username string) (foundUuid string, foundUsername string, err error)
+	// An empty uuid value can be passed if the corresponding account has not been found
+	StoreMojangUuid(username string, uuid string) error
+}
+
+type UuidsProviderWithCache struct {
+	Provider UuidsProvider
+	Storage  MojangUuidsStorage
+}
+
+func (p *UuidsProviderWithCache) GetUuid(username string) (*ProfileInfo, error) {
+	uuid, foundUsername, err := p.Storage.GetUuidForMojangUsername(username)
+	if err != nil {
+		return nil, err
+	}
+
+	if foundUsername != "" {
+		if uuid != "" {
+			return &ProfileInfo{Id: uuid, Name: foundUsername}, nil
+		}
+
+		return nil, nil
+	}
+
+	profile, err := p.Provider.GetUuid(username)
+	if err != nil {
+		return nil, err
+	}
+
+	freshUuid := ""
+	wellCasedUsername := username
+	if profile != nil {
+		freshUuid = profile.Id
+		wellCasedUsername = profile.Name
+	}
+
+	_ = p.Storage.StoreMojangUuid(wellCasedUsername, freshUuid)
+
+	return profile, nil
+}