1 files changed, 53 insertions, 0 deletions
diff --git a/entities/bug/with_snapshot.go b/entities/bug/with_snapshot.go
new file mode 100644
index 00000000..0474cac7
--- /dev/null
+++ b/entities/bug/with_snapshot.go
@@ -0,0 +1,53 @@
+package bug
+
+import (
+	"github.com/MichaelMure/git-bug/repository"
+)
+
+var _ Interface = &WithSnapshot{}
+
+// WithSnapshot encapsulate a Bug and maintain the corresponding Snapshot efficiently
+type WithSnapshot struct {
+	*Bug
+	snap *Snapshot
+}
+
+func (b *WithSnapshot) Compile() *Snapshot {
+	if b.snap == nil {
+		snap := b.Bug.Compile()
+		b.snap = snap
+	}
+	return b.snap
+}
+
+// Append intercept Bug.Append() to update the snapshot efficiently
+func (b *WithSnapshot) Append(op Operation) {
+	b.Bug.Append(op)
+
+	if b.snap == nil {
+		return
+	}
+
+	op.Apply(b.snap)
+	b.snap.Operations = append(b.snap.Operations, op)
+}
+
+// Commit intercept Bug.Commit() to update the snapshot efficiently
+func (b *WithSnapshot) Commit(repo repository.ClockedRepo) error {
+	err := b.Bug.Commit(repo)
+
+	if err != nil {
+		b.snap = nil
+		return err
+	}
+
+	// Commit() shouldn't change anything of the bug state apart from the
+	// initial ID set
+
+	if b.snap == nil {
+		return nil
+	}
+
+	b.snap.id = b.Bug.Id()
+	return nil
+}