1 files changed, 31 insertions, 0 deletions
diff --git a/entity/dag/operation.go b/entity/dag/operation.go
new file mode 100644
index 00000000..9fcc055b
--- /dev/null
+++ b/entity/dag/operation.go
@@ -0,0 +1,31 @@
+package dag
+
+import (
+	"github.com/MichaelMure/git-bug/entity"
+	"github.com/MichaelMure/git-bug/identity"
+)
+
+// Operation is a piece of data defining a change to reflect on the state of an Entity.
+// What this Operation or Entity's state looks like is not of the resort of this package as it only deals with the
+// data structure and storage.
+type Operation interface {
+	// Id return the Operation identifier
+	// Some care need to be taken to define a correct Id derivation and enough entropy in the data used to avoid
+	// collisions. Notably:
+	// - the Id of the first Operation will be used as the Id of the Entity. Collision need to be avoided across Entities.
+	// - collisions can also happen within the set of Operations of an Entity. Simple Operation might not have enough
+	//   entropy to yield unique Ids.
+	// A common way to derive an Id will be to use the DeriveId function on the serialized operation data.
+	Id() entity.Id
+	// Validate check if the Operation data is valid
+	Validate() error
+
+	Author() identity.Interface
+}
+
+type operationBase struct {
+	author identity.Interface
+
+	// Not serialized. Store the op's id in memory.
+	id entity.Id
+}