VNPay Payment URL

vnpay_payment_url.go

package payment

import (
	"crypto/sha256"
	"encoding/hex"
	"net/http"
	"sort"
	"strings"
	"time"
)

type Payment struct {
	OrderInfo string `json:"order_info"`
	Amount    string `json:"amount"`
	BankCode  string `json:"bank_code"`
	OrderType string `json:"order_type"`
	VnpUrl    string
	ReturnUrl string
	IpAddr    string
	SecretKey string
	TmnCode   string
}

func (pay Payment) GeneratePaymentUrl() string {
	currentDate := time.Now()

	m := map[string]string{}

	m["vnp_Version"] = "2"
	m["vnp_Command"] = "pay"
	m["vnp_TmnCode"] = pay.TmnCode
	m["vnp_Amount"] = pay.Amount + "00"
	m["vnp_CreateDate"] = currentDate.Format("20060102150405")
	m["vnp_CurrCode"] = "VND"
	m["vnp_IpAddr"] = pay.IpAddr
	m["vnp_Locale"] = "vn"
	m["vnp_OrderInfo"] = pay.OrderInfo
	m["vnp_OrderType"] = pay.OrderType
	m["vnp_ReturnUrl"] = pay.ReturnUrl
	m["vnp_TxnRef"] = currentDate.Format("150405")
	m["vnp_BankCode"] = pay.BankCode
	m["vnp_ExpireDate"] = currentDate.Format("20060102150405")

	req, _ := http.NewRequest("GET", pay.VnpUrl, nil)
	q := req.URL.Query()

	for key := range m {
		q.Add(key, m[key])
	}
	keys := []string{}
	for k := range q {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	qData := ""
	for _, key := range keys {
		qData += key + "=" + strings.Join(q[key], "") + "&"
	}

	signData := pay.SecretKey + qData

	lengSignData := len(signData)
	signData = signData[:lengSignData-1]

	hash := sha256.New()
	hash.Write([]byte(signData))
	hashed := hex.EncodeToString(hash.Sum(nil))

	q.Add("vnp_SecureHashType", "SHA256")
	q.Add("vnp_SecureHash", hashed)

	req.URL.RawQuery = q.Encode()

	return req.URL.String()
}