refactor: use getVertexHeaderIdFromBuffer method where possible

Author: pedroferreira1

src/models/transaction.ts

@@ -38,6 +38,7 @@ import { OutputValueType } from '../types';
 import type Header from '../headers/base';
 import NanoContractHeader from '../nano_contracts/header';
 import HeaderParser from '../headers/parser';
+import { getVertexHeaderIdFromBuffer } from '../headers/types';
 
 enum txType {
   BLOCK = 'Block',
@@ -610,9 +611,8 @@ class Transaction {
     // so we must exhaust the buffer until it's empty
     // or we will throw an error
     while (buf.length > 0) {
-      const headerId = buf.subarray(0, 1);
-      const headerIdHex = headerId.toString('hex');
-      const headerClass = HeaderParser.getHeader(headerIdHex);
+      const headerId = getVertexHeaderIdFromBuffer(buf);
+      const headerClass = HeaderParser.getHeader(headerId);
       let header;
       // eslint-disable-next-line prefer-const -- To split this declaration would be confusing
       [header, buf] = headerClass.deserialize(buf);

src/nano_contracts/header.ts

@@ -151,18 +151,17 @@ class NanoContractHeader extends Header {
     // Copies buffer locally, not to change the original parameter
     let buf = Buffer.from(srcBuf);
 
-    /* eslint-disable prefer-const -- To split these declarations would be confusing.
-     * In all of them the first parameter should be a const and the second a let. */
-    let headerId;
-    [headerId, buf] = [buf.subarray(0, 1), buf.subarray(1)];
-
-    if (getVertexHeaderIdFromBuffer(headerId) !== VertexHeaderId.NANO_HEADER) {
+    if (getVertexHeaderIdFromBuffer(buf) !== VertexHeaderId.NANO_HEADER) {
       throw new Error('Invalid vertex header id for nano header.');
     }
 
+    buf = buf.subarray(1);
+
     // Create empty header to fill with the deserialization
     const header = new NanoContractHeader('', '', [], [], Buffer.from([]));
 
+    /* eslint-disable prefer-const -- To split these declarations would be confusing.
+     * In all of them the first parameter should be a const and the second a let. */
     // nc info version
     [header.nc_info_version, buf] = unpackToInt(1, false, buf);