feat: add utility to deserialize signable payload hex

TICKET: COIN-5797

Author: bhavidhingra

modules/sdk-coin-apt/src/lib/utils.ts

@@ -4,6 +4,7 @@ import {
   Deserializer,
   Ed25519PublicKey,
   EntryFunctionArgument,
+  FeePayerRawTransaction,
   Hex,
   SignedTransaction,
   TransactionPayload,
@@ -19,18 +20,18 @@ import {
   TransactionType,
 } from '@bitgo/sdk-core';
 import {
+  ADDRESS_BYTES_LENGTH,
+  AMOUNT_BYTES_LENGTH,
   APT_ADDRESS_LENGTH,
   APT_BLOCK_ID_LENGTH,
   APT_SIGNATURE_LENGTH,
   APT_TRANSACTION_ID_LENGTH,
   COIN_BATCH_TRANSFER_FUNCTION,
   COIN_TRANSFER_FUNCTION,
   DIGITAL_ASSET_TRANSFER_FUNCTION,
+  FUNGIBLE_ASSET_BATCH_TRANSFER_FUNCTION,
   FUNGIBLE_ASSET_TRANSFER_FUNCTION,
   SECONDS_PER_WEEK,
-  ADDRESS_BYTES_LENGTH,
-  AMOUNT_BYTES_LENGTH,
-  FUNGIBLE_ASSET_BATCH_TRANSFER_FUNCTION,
 } from './constants';
 import BigNumber from 'bignumber.js';
 import { RecipientsValidationResult } from './iface';
@@ -148,6 +149,12 @@ export class Utils implements BaseUtils {
     return deserializer.deserialize(SignedTransaction);
   }
 
+  deserializeFeePayerRawTransaction(rawTransaction: string): FeePayerRawTransaction {
+    const txnBytes = Hex.fromHexString(rawTransaction).toUint8Array();
+    const deserializer = new Deserializer(txnBytes);
+    return FeePayerRawTransaction.load(deserializer);
+  }
+
   deserializeAccountAddressVector(serializedBytes: Uint8Array): string[] {
     const deserializer = new Deserializer(serializedBytes);
     const deserializedAddresses = deserializer.deserializeVector(AccountAddress);

modules/sdk-coin-apt/test/unit/utils.ts

@@ -1,7 +1,11 @@
 import * as testData from '../resources/apt';
 import should from 'should';
 import utils from '../../src/lib/utils';
-import { SignedTransaction, TransactionAuthenticatorFeePayer } from '@aptos-labs/ts-sdk';
+import {
+  SignedTransaction,
+  TransactionAuthenticatorFeePayer,
+  TransactionPayloadEntryFunction,
+} from '@aptos-labs/ts-sdk';
 
 describe('Aptos util library', function () {
   describe('isValidAddress', function () {
@@ -48,4 +52,36 @@ describe('Aptos util library', function () {
     // without 0x prefix
     should.equal(true, utils.isValidPublicKey('9b4e96086d111500259f9b38680b0509a405c1904da18976455a20c691d3bb07'));
   });
+
+  it('deserializeFeePayerRawTransaction', function () {
+    const signablePayloadHex =
+      '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';
+    const feePayerRawTransactionHex = signablePayloadHex.slice(66); // remove the first 33 bytes (66 hex characters)
+    const feePayerRawTransaction = utils.deserializeFeePayerRawTransaction(feePayerRawTransactionHex);
+    const rawTxn = feePayerRawTransaction.raw_txn;
+
+    const sender = rawTxn.sender.toString();
+    const sequenceNumber = utils.castToNumber(rawTxn.sequence_number);
+    const maxGasAmount = utils.castToNumber(rawTxn.max_gas_amount);
+    const gasUnitPrice = utils.castToNumber(rawTxn.gas_unit_price);
+    const expirationTime = utils.castToNumber(rawTxn.expiration_timestamp_secs);
+    should.equal(sender, '0xf22fa009b6473cdc539ecbd570d00d0585682f5939ffe256a90ddee0d616292f');
+    should.equal(sequenceNumber, 0);
+    should.equal(maxGasAmount, 25000);
+    should.equal(gasUnitPrice, 100);
+    should.equal(expirationTime, 1759321232);
+
+    const entryFunction = (rawTxn.payload as TransactionPayloadEntryFunction).entryFunction;
+    const functionName = `${entryFunction.module_name.address.toString()}::${entryFunction.module_name.name.identifier.toString()}::${entryFunction.function_name.identifier.toString()}`;
+    should.equal(functionName, '0x1::coin::transfer');
+    const assetId = entryFunction.type_args[0].toString();
+    should.equal(assetId, '0x1::aptos_coin::AptosCoin');
+
+    const addressArg = entryFunction.args[0];
+    const amountArg = entryFunction.args[1];
+    const recipients = utils.parseRecipients(addressArg, amountArg);
+    should.equal(recipients.length, 1);
+    should.equal(recipients[0].address, '0xda22bdc19f873fd6ce48c32912965c8a9dde578b2a3cf4fae3dd85dfaac784c9');
+    should.equal(recipients[0].amount, '1000');
+  });
 });