impl and test src.ledger.Files.Amend(old, new Delta)

src/ledger/file.go

@@ -26,10 +26,15 @@ func NewFiles(p string, q ...string) (Files, error) {
 }
 
 func (files Files) Amend(old, now Delta) error {
+	if now.isSet {
+		return fmt.Errorf("cannot ammend: immutable isSet is set")
+	}
+
 	xactions, err := files.transactions()
 	if err != nil {
 		return err
 	}
+
 	var transaction transaction
 	for _, xaction := range xactions {
 		if xaction.name != old.transaction {
@@ -39,23 +44,13 @@ func (files Files) Amend(old, now Delta) error {
 		break
 	}
 
-	inverted := transaction.deltas()
-	for i := range inverted {
-		inverted[i].Value *= -1
-	}
-
-	if now.isSet {
-		return fmt.Errorf("cannot ammend: immutable isSet is set")
-	}
-	transaction.date = now.Date
-	transaction.description = now.Description
 	if transaction.payee == old.Name {
 		if len(transaction.recipients) != 1 {
 			return fmt.Errorf("cannot amend: modifying original payee, but many recipients cant share new value")
 		}
-		old.Value *= -1
-		old.Name = transaction.recipients[0].name
+		transaction.payee, transaction.recipients[0].name, transaction.recipients[0].value = transaction.recipients[0].name, transaction.payee, transaction.recipients[0].value*-1.0
 	}
+
 	idx := -1
 	for i, recipient := range transaction.recipients {
 		if recipient.name == old.Name && recipient.value == old.Value {
@@ -63,16 +58,11 @@ func (files Files) Amend(old, now Delta) error {
 		}
 	}
 	if idx == -1 {
-		return fmt.Errorf("cannot amend: no recipient with name %s found to set new value", old.Name)
+		return fmt.Errorf("cannot amend: no recipient with name %q value %.2f found in %+v to set new value", old.Name, old.Value, transaction)
 	}
-	transaction.recipients[idx].name = now.Name
-	transaction.recipients[idx].value = now.Value
-	transaction.recipients[idx].currency = string(now.Currency)
-	amendedDeltas := transaction.deltas().Like(func(d Delta) bool {
-		return d.Name != transaction.payee
-	})
 
-	return files.Add(transaction.payee, append(inverted, amendedDeltas...)...)
+	old.Value *= -1
+	return files.Add(transaction.payee, []Delta{old, now}...)
 }
 
 func (files Files) TempGetLastNLines(n int) ([]string, error) {