1 files changed, 68 insertions, 0 deletions
diff --git a/entity/merge.go b/entity/merge.go
new file mode 100644
index 00000000..544f2168
--- /dev/null
+++ b/entity/merge.go
@@ -0,0 +1,68 @@
+package entity
+
+import "fmt"
+
+// MergeStatus represent the result of a merge operation of an entity
+type MergeStatus int
+
+const (
+	_ MergeStatus = iota
+	MergeStatusNew
+	MergeStatusInvalid
+	MergeStatusUpdated
+	MergeStatusNothing
+)
+
+type MergeResult struct {
+	// Err is set when a terminal error occur in the process
+	Err error
+
+	Id     string
+	Status MergeStatus
+
+	// Only set for invalid status
+	Reason string
+
+	// Not set for invalid status
+	Entity Interface
+}
+
+func (mr MergeResult) String() string {
+	switch mr.Status {
+	case MergeStatusNew:
+		return "new"
+	case MergeStatusInvalid:
+		return fmt.Sprintf("invalid data: %s", mr.Reason)
+	case MergeStatusUpdated:
+		return "updated"
+	case MergeStatusNothing:
+		return "nothing to do"
+	default:
+		panic("unknown merge status")
+	}
+}
+
+func NewMergeError(err error, id string) MergeResult {
+	return MergeResult{
+		Err: err,
+		Id:  id,
+	}
+}
+
+func NewMergeStatus(status MergeStatus, id string, entity Interface) MergeResult {
+	return MergeResult{
+		Id:     id,
+		Status: status,
+
+		// Entity is not set for an invalid merge result
+		Entity: entity,
+	}
+}
+
+func NewMergeInvalidStatus(id string, reason string) MergeResult {
+	return MergeResult{
+		Id:     id,
+		Status: MergeStatusInvalid,
+		Reason: reason,
+	}
+}