AddTransaction: add preliminary structure

pain/api.go

@@ -87,6 +87,10 @@ func (d *Document) Finalize(msgId string) error {
 	return d.Valid()
 }
 
-func (d *Document) AddTransaction() {
+func (d *Document) AddTransaction(tx *DrctDbtTxInf) error {
+	if len(d.Contents.PaymentInformation) == 0 {
+		return fmt.Errorf("payment information not yet initialized")
+	}
 
+	return nil
 }

pain/payment_information_transactions.go

@@ -15,6 +15,31 @@ type DrctDbtTxInf struct {
 	Info        RmtInf             `xml:"RmtInf"`
 }
 
+func NewDirectDebitTransaction(debtor Dbtr, account DbtrAcct, mandateInfo MndtRltdInf, amount float64, additionalInfo string) DrctDbtTxInf {
+	e2eid := fmt.Sprintf("%v%4d", time.Now().Format("20060102"), 4) // TODO: inform this function of current number of transactions
+	return DrctDbtTxInf{
+		Id: PaymentId{
+			InstrumentId: "asdfasdf",
+			EndToEndId:   e2eid,
+		},
+		Amount: CurrencyWithAmount{
+			Currency: "EUR",
+			Value:    fmt.Sprintf("%.2f", amount),
+		},
+		Transaction: DrctDbtTx{
+			MandateRelatedInfo: mandateInfo,
+		},
+		Agent: DbtrAgt{
+			InstitutionId: FinInstnId{
+				BIC: "KNABNL2H", // fixme
+			},
+		},
+		Debtor:  debtor,
+		Account: account,
+		Info:    additionalInfo,
+	}
+}
+
 func (d *DrctDbtTxInf) Valid() error {
 	var err []string
 	if e := d.Id.Valid(); e != nil {