all: implement API to do online transfer

The RtolTransfer do the actual transfer to customer's bank account using
the request and response from RtolInquiry.

1 files changed, 92 insertions, 0 deletions

diff --git a/rtol_transfer.go b/rtol_transfer.go
new file mode 100644
index 0000000..db6eabc
--- /dev/null
+++ b/rtol_transfer.go
@@ -0,0 +1,92 @@
+package duitku
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"strconv"
+	"time"
+)
+
+// rtolTransfer containts request to transfer amount from merchant to
+// customer's bank account, using the previous data obtained from the inquiry
+// process.
+//
+// The formula to generate Signature is SHA256(email + timestamp + bankCode +
+// bankAccount + accountName + custRefNumber + amountTransfer + purpose +
+// disburseId + secretKey).
+//
+// Ref: https://docs.duitku.com/disbursement/en/#online-transfer-transfer-request
+type rtolTransfer struct {
+	// Bank Account owner, obtained after getting a response from the
+	// inquiry process.
+	AccountName string `json:"accountName"`
+
+	// Destination Bank Code sent when inquiry process.
+	BankCode string `json:"bankCode"`
+
+	// Destination account number sent when inquiry procces.
+	BankAccount string `json:"bankAccount"`
+
+	// Customer reference number, obtained after getting a response from
+	// the inquiry process.
+	CustRefNumber string `json:"custRefNumber"`
+
+	// Description of transfer purpose.
+	Purpose string `json:"purpose"`
+
+	request
+
+	// Disbursement transfer amount.
+	Amount int64 `json:"amountTransfer"`
+
+	// Disbursement Id provided by Duitku, obtained after getting a
+	// response from the inquiry process.
+	DisburseID int64 `json:"disburseId"`
+}
+
+// newRtolTransfer create new rtolTransfer request from request and response
+// of RtolInquiry.
+func newRtolTransfer(inquiryReq *RtolInquiry, inquiryRes *RtolInquiryResponse) (req *rtolTransfer) {
+	req = &rtolTransfer{
+		Amount:  inquiryReq.Amount,
+		Purpose: inquiryReq.Purpose,
+
+		AccountName:   inquiryRes.AccountName,
+		BankCode:      inquiryRes.BankCode,
+		BankAccount:   inquiryRes.BankAccount,
+		CustRefNumber: inquiryRes.CustRefNumber,
+		DisburseID:    inquiryRes.DisburseID,
+	}
+	return req
+}
+
+func (req *rtolTransfer) sign(opts ClientOptions) (err error) {
+	var (
+		logp = `sign`
+		now  = time.Now()
+
+		bb        bytes.Buffer
+		plainHash [sha256.Size]byte
+	)
+
+	req.UserID, err = strconv.ParseInt(opts.UserID, 10, 64)
+	if err != nil {
+		return fmt.Errorf(`%s: %s`, logp, err)
+	}
+
+	req.Email = opts.Email
+	req.Timestamp = now.UnixMilli()
+
+	fmt.Fprintf(&bb, `%s%d%s%s%s%s%d%s%d%s`, req.Email, req.Timestamp,
+		req.BankCode, req.BankAccount, req.AccountName,
+		req.CustRefNumber, req.Amount, req.Purpose,
+		req.DisburseID, opts.ApiKey)
+
+	plainHash = sha256.Sum256(bb.Bytes())
+
+	req.Signature = hex.EncodeToString(plainHash[:])
+
+	return nil
+}