all: implement API to check merchant transaction status

The MerchantTxStatus method check the payment status by its orderID and
payment method.

Reference: https://docs.duitku.com/api/en/#check-transaction

5 files changed, 133 insertions, 2 deletions

diff --git a/client.go b/client.go
index 4d4ceca..0933840 100644
--- a/client.go
+++ b/client.go
@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"net/url"
 	"sort"
 	"strings"
 
@@ -36,8 +37,9 @@ const (
 	PathTransferClearing        = `/webapi/api/disbursement/transferclearing`
 	PathTransferClearingSandbox = `/webapi/api/disbursement/transferclearingsandbox` // Used for testing.
 
-	PathMerchantPaymentMethod = `/webapi/api/merchant/paymentmethod/getpaymentmethod`
-	PathMerchantInquiry       = `/webapi/api/merchant/v2/inquiry`
+	PathMerchantInquiry           = `/webapi/api/merchant/v2/inquiry`
+	PathMerchantPaymentMethod     = `/webapi/api/merchant/paymentmethod/getpaymentmethod`
+	PathMerchantTransactionStatus = `/webapi/api/merchant/transactionStatus`
 )
 
 type Client struct {
@@ -323,6 +325,44 @@ func (cl *Client) MerchantPaymentMethod(req *PaymentMethod) (resp *PaymentMethod
 	return resp, nil
 }
 
+// [MerchantTxStatus] get the status of payment from customer.
+//
+// [MerchantTxStatus]: https://docs.duitku.com/api/en/#check-transaction
+func (cl *Client) MerchantTxStatus(orderID, paymentMethod string) (resp *TxStatusResponse, err error) {
+	var (
+		logp = `MerchantTxStatus`
+		req  = transactionStatus{
+			OrderID: orderID,
+		}
+
+		params  url.Values
+		httpRes *http.Response
+		resBody []byte
+	)
+
+	req.sign(cl.opts, paymentMethod)
+
+	params, err = libhttp.MarshalForm(req)
+	if err != nil {
+		return nil, fmt.Errorf(`%s: %w`, logp, err)
+	}
+
+	httpRes, resBody, err = cl.PostForm(PathMerchantTransactionStatus, nil, params)
+	if err != nil {
+		return nil, fmt.Errorf(`%s: %w`, logp, err)
+	}
+	if httpRes.StatusCode >= 400 {
+		return nil, fmt.Errorf(`%s: %s: %s`, logp, httpRes.Status, resBody)
+	}
+
+	err = json.Unmarshal(resBody, &resp)
+	if err != nil {
+		return nil, fmt.Errorf(`%s: %w`, logp, err)
+	}
+
+	return resp, nil
+}
+
 // Options return the current client configuration.
 func (cl *Client) Options() (opts ClientOptions) {
 	return cl.opts
diff --git a/client_test.go b/client_test.go
index 832bf3a..2c58db5 100644
--- a/client_test.go
+++ b/client_test.go
@@ -254,6 +254,28 @@ func TestClient_MerchantInquiry(t *testing.T) {
 	t.Logf(`MerchantInquiry: response: %s`, got)
 
 	test.Assert(t, `MerchantInquiry`, string(exp), string(got))
+
+	// Test checking the transaction status.
+
+	var (
+		txResp *TxStatusResponse
+	)
+
+	txResp, err = testClientMerchant.MerchantTxStatus(req.MerchantOrderId, req.PaymentMethod)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	got, err = json.MarshalIndent(txResp, ``, `  `)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tag = `tx_status_response.json`
+	exp = tdata.Output[tag]
+	exp = bytes.ReplaceAll(exp, []byte(`$ref`), []byte(resp.Reference))
+	t.Logf(`MerchantTxStatus: response: %s`, got)
+	test.Assert(t, `MerchantTxStatus`, string(exp), string(got))
 }
 
 func TestClient_MerchantPaymentMethod(t *testing.T) {
diff --git a/testdata/merchant/inquiry_test.txt b/testdata/merchant/inquiry_test.txt
index c597b22..05262d7 100644
--- a/testdata/merchant/inquiry_test.txt
+++ b/testdata/merchant/inquiry_test.txt
@@ -19,3 +19,12 @@
   "qrString": "",
   "amount": "10000"
 }
+
+<<< tx_status_response.json
+{
+  "merchantOrderId": "1",
+  "reference": "$ref",
+  "amount": "10000",
+  "statusCode": "01",
+  "statusMessage": "PROCESS"
+}
diff --git a/transaction_status.go b/transaction_status.go
new file mode 100644
index 0000000..7ddae30
--- /dev/null
+++ b/transaction_status.go
@@ -0,0 +1,32 @@
+// SPDX-FileCopyrightText: 2023 M. Shulhan <ms@kilabit.info>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package duitku
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"fmt"
+)
+
+type transactionStatus struct {
+	MerchantCode string `form:"merchantCode"`
+	OrderID      string `form:"merchantOrderId"`
+
+	// Transaction identification code.
+	// Formula: md5(merchantCode + merchantOrderId + apiKey).
+	Signature string `form:"signature"`
+}
+
+func (tx *transactionStatus) sign(opts ClientOptions, paymentMethod string) {
+	var merchant = opts.Merchant(paymentMethod)
+
+	tx.MerchantCode = merchant.Code
+
+	var (
+		plain    = fmt.Sprintf(`%s%s%s`, tx.MerchantCode, tx.OrderID, merchant.ApiKey)
+		md5Plain = md5.Sum([]byte(plain))
+	)
+
+	tx.Signature = hex.EncodeToString(md5Plain[:])
+}
diff --git a/transaction_status_response.go b/transaction_status_response.go
new file mode 100644
index 0000000..cba2fee
--- /dev/null
+++ b/transaction_status_response.go
@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2023 M. Shulhan <ms@kilabit.info>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package duitku
+
+// List of valid Code in TxStatusResponse.
+const (
+	MerchantTxStatusSuccess = `00`
+	MerchantTxStatusProcess = `01`
+	MerchantTxStatusFailed  = `02`
+)
+
+// TxStatusResponse contains response from checking merchant payment
+// status.
+type TxStatusResponse struct {
+	OrderID   string `json:"merchantOrderId"`
+	Reference string `json:"reference"`
+	Amount    string `json:"amount"`
+
+	// Status code transaction.
+	//   - 00 - Success
+	//   - 01 - Process
+	//   - 02 - Failed/Expired
+	Code string `json:"statusCode"`
+
+	// Description that explain the status Code.
+	Message string `json:"statusMessage"`
+}