all: implement API to get active payment method for merchant

The MerchantPaymentMethod method return list of payment methods enabled
by merchant (your project).

1 files changed, 64 insertions, 0 deletions

diff --git a/payment_method.go b/payment_method.go
new file mode 100644
index 0000000..b5e95fa
--- /dev/null
+++ b/payment_method.go
@@ -0,0 +1,64 @@
+// SPDX-FileCopyrightText: 2023 M. Shulhan <ms@kilabit.info>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package duitku
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"time"
+)
+
+const (
+	// PaymentMethodDatetimeLayout define the date and time format for
+	// PaymentMethod.DateTime.
+	PaymentMethodDatetimeLayout = time.DateTime
+)
+
+// PaymentMethod contains request for client MerchantPaymentMethod.
+type PaymentMethod struct {
+	// [REQ] Merchant code from Duitku.
+	// Set by calling sign from ClientOptions.
+	MerchantCode string `json:"merchantcode"`
+
+	// [REQ] Format: yyyy-MM-dd HH:mm:ss
+	// If empty, it will be set during sign using current date time.
+	DateTime string `json:"datetime"`
+
+	// [REQ] Formula: Sha256(merchantcode + paymentAmount + datetime +
+	// apiKey).
+	// The value of hash is stored as lowercase hexadecimal.
+	Signature string `json:"signature"`
+
+	// [REQ] Transaction amount. No decimal code (.) and no decimal digit.
+	Amount int64 `json:"amount"`
+}
+
+// SetDateTime set the field DateTime using t.
+func (req *PaymentMethod) SetDateTime(t time.Time) {
+	req.DateTime = t.Format(PaymentMethodDatetimeLayout)
+}
+
+// Sign the request.
+// Set the MerchantCode and DateTime if its empty, and then generate the
+// Signature.
+func (req *PaymentMethod) Sign(opts ClientOptions) {
+	var (
+		plain string
+		hash  [sha256.Size]byte
+	)
+
+	if len(req.MerchantCode) == 0 {
+		req.MerchantCode = opts.MerchantCode
+	}
+
+	if len(req.DateTime) == 0 {
+		req.SetDateTime(time.Now())
+	}
+
+	plain = fmt.Sprintf(`%s%d%s%s`, req.MerchantCode, req.Amount, req.DateTime, opts.MerchantApiKey)
+	hash = sha256.Sum256([]byte(plain))
+
+	req.Signature = hex.EncodeToString(hash[:])
+}