Webhooks

      package main

      import (
          "crypto/hmac"
          "crypto/sha256"
          "encoding/base64"
          "encoding/json"
          "fmt"
          "log"
          "strings"
      )

      // --- Struct Definitions for JSON Mapping ---

      type Payload struct {
          EventType string `json:"event_type"`
          RequestID string `json:"requestId"`
          Data      Data   `json:"data"`
      }

      type Data struct {
          Merchant    Merchant    `json:"merchant"`
          Terminal    map[string]interface{} `json:"terminal"`
          Transaction Transaction `json:"transaction"`
          Customer    Customer    `json:"customer"`
      }

      type Merchant struct {
          WalletID       string  `json:"walletId"`
          WalletBalance  float64 `json:"walletBalance"`
          UserID         string  `json:"userId"`
      }

      type Transaction struct {
          AliasAccountNumber   string  `json:"aliasAccountNumber"`
          Fee                  float64 `json:"fee"`
          SessionID            string  `json:"sessionId"`
          Type                 string  `json:"type"`
          TransactionID        string  `json:"transactionId"`
          AliasAccountName     string  `json:"aliasAccountName"`
          ResponseCode         string  `json:"responseCode"`
          OriginatingFrom      string  `json:"originatingFrom"`
          TransactionAmount    float64 `json:"transactionAmount"`
          Narration            string  `json:"narration"`
          Time                 string  `json:"time"`
          AliasAccountReference string `json:"aliasAccountReference"`
          AliasAccountType     string  `json:"aliasAccountType"`
      }

      type Customer struct {
          BankCode     string `json:"bankCode"`
          SenderName   string `json:"senderName"`
          BankName     string `json:"bankName"`
          AccountNumber string `json:"accountNumber"`
      }

      // --- Core Logic ---

      func main() {
          hooksCron2()
      }

      func hooksCron2() {
          payloadJSON := `
          {
          "event_type": "payment_success",
          "requestId": "45f2dc2d-d559-4773-bba3-2d5ec17b2e20",
          "data": {
              "merchant": {
              "walletId": "6756ff80aafe04a795f18b38",
              "walletBalance": 6052,
              "userId": "b7b10e81-e57d-41d0-8fdc-f4e23a132bbf"
              },
              "terminal": {},
              "transaction": {
              "aliasAccountNumber": "5343270516",
              "fee": 5,
              "sessionId": "IFAP-TRANSFER-46501-e0339485-1a2f-4b43-9bd5-fec9649e5928",
              "type": "vact_transfer",
              "transactionId": "API-VACT_TRA-B7B10-0435b274-807a-4bc7-8abe-9dbb4548fd7a",
              "aliasAccountName": "ZAXBOX/EZENNA NWACHUKWU",
              "responseCode": "",
              "originatingFrom": "api",
              "transactionAmount": 10,
              "narration": "Habiblahi Hamzat Transfer 10.00 To ZAXBOX/EZENNA NWACHUKWU - Nomba",
              "time": "2025-09-29T10:51:44Z",
              "aliasAccountReference": "654f7c80bd4a510c90fb7f92",
              "aliasAccountType": "VIRTUAL"
              },
              "customer": {
              "bankCode": "090645",
              "senderName": "Habiblahi Hamzat",
              "bankName": "Nombank",
              "accountNumber": "9617811496"
              }
          }
          }`

          signatureValue := "Kt9095hQxfgmVbx6iz7G2tPhHdbdXgLlyY/mf35sptw="
          nombaTimeStamp := "2025-09-29T10:51:44Z"
          secret := "HkatexKDZg7CLWy96q5sfrVHSvtoz92B"

          mySig, err := generateSignature(payloadJSON, secret, nombaTimeStamp)
          if err != nil {
              log.Fatalf("Error generating signature: %v", err)
          }

          log.Printf("Generated signature [%s]", mySig)
          log.Printf("Expected signature [%s]", signatureValue)

          if strings.EqualFold(signatureValue, mySig) {
              log.Println(">>>>>>> Signatures match <<<<<<<<<")
          } else {
              log.Println("<<<<<<<<< Signatures did not match >>>>>>>>>")
          }
      }

      func generateSignature(payloadJSON, secret, timeStamp string) (string, error) {
          var payload Payload
          if err := json.Unmarshal([]byte(payloadJSON), &payload); err != nil {
              return "", fmt.Errorf("error parsing JSON payload: %w", err)
          }

          transaction := payload.Data.Transaction
          merchant := payload.Data.Merchant

          transactionResponseCode := transaction.ResponseCode
          if transactionResponseCode == "null" {
              transactionResponseCode = ""
          }

          // Construct the exact signature payload as in Java
          hashingPayload := fmt.Sprintf(
              "%s:%s:%s:%s:%s:%s:%s:%s:%s",
              payload.EventType,
              payload.RequestID,
              merchant.UserID,
              merchant.WalletID,
              transaction.TransactionID,
              transaction.Type,
              transaction.Time,
              transactionResponseCode,
              timeStamp,
          )

          log.Printf("::: payload to hash --> [%s] :::", hashingPayload)

          // Generate HMAC SHA256 and encode Base64
          h := hmac.New(sha256.New, []byte(secret))
          h.Write([]byte(hashingPayload))
          hash := h.Sum(nil)

          return base64.StdEncoding.EncodeToString(hash), nil
      }