feat(abstract-utxo): make TransactionExplanation more flexible

Adjust TransactionExplanation interface to allow for undefined locktime and
parameterized fee type to support both string and undefined return types.
This change helps with different use cases across the codebase.

Issue: BTC-2732

Co-authored-by: llm-git <[email protected]>

Author: OttoAllmendinger

modules/abstract-utxo/src/abstractUtxoCoin.ts

@@ -200,8 +200,8 @@ export function isWalletOutput(output: Output): output is FixedScriptWalletOutpu
   );
 }
 
-export interface TransactionExplanation extends BaseTransactionExplanation<string, string> {
-  locktime: number;
+export interface TransactionExplanation<TFee = string> extends BaseTransactionExplanation<TFee, string> {
+  locktime?: number;
   /** NOTE: this actually only captures external outputs */
   outputs: Output[];
   changeOutputs: Output[];
@@ -872,7 +872,7 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
    */
   async explainTransaction<TNumber extends number | bigint = number>(
     params: ExplainTransactionOptions<TNumber>
-  ): Promise<TransactionExplanation> {
+  ): Promise<TransactionExplanation<string | undefined>> {
     return explainTx(this.decodeTransactionFromPrebuild(params), params, this.network);
   }
 

modules/abstract-utxo/src/impl/doge/doge.ts

@@ -114,7 +114,7 @@ export class Doge extends AbstractUtxoCoin {
 
   async explainTransaction<TNumber extends number | bigint = bigint>(
     params: ExplainTransactionOptions<TNumber> | (ExplainTransactionOptions<TNumber> & { txInfo: TransactionInfoJSON })
-  ): Promise<TransactionExplanation> {
+  ): Promise<TransactionExplanation<string | undefined>> {
     return super.explainTransaction({
       ...params,
       txInfo: params.txInfo ? parseTransactionInfo(params.txInfo as TransactionInfoJSON) : undefined,

modules/abstract-utxo/src/offlineVault/TransactionExplanation.ts

@@ -8,18 +8,18 @@ export interface ExplanationOutput {
   amount: string | number;
 }
 
-export interface TransactionExplanation {
+export interface TransactionExplanation<TFee> {
   outputs: ExplanationOutput[];
   changeOutputs: ExplanationOutput[];
   fee: {
     /* network fee */
-    fee: string | number;
+    fee: TFee;
     payGoFeeString: string | number | undefined;
     payGoFeeAddress: string | undefined;
   };
 }
 
-export function getTransactionExplanation(coin: string, tx: unknown): TransactionExplanation {
+export function getTransactionExplanation(coin: string, tx: unknown): TransactionExplanation<string> {
   if (!OfflineVaultSignable.is(tx)) {
     throw new Error('not a signable transaction');
   }

modules/abstract-utxo/src/offlineVault/descriptor/transaction.ts

@@ -45,7 +45,7 @@ export function getHalfSignedPsbt(
 export function getTransactionExplanationFromPsbt(
   tx: DescriptorTransaction,
   network: utxolib.Network
-): TransactionExplanation {
+): TransactionExplanation<string> {
   const psbt = utxolib.bitgo.createPsbtDecode(tx.coinSpecific.txHex, network);
   const descriptorMap = getDescriptorsFromDescriptorTransaction(tx);
   const { outputs, changeOutputs, fee } = explainPsbt(psbt, descriptorMap);

modules/abstract-utxo/src/transaction/descriptor/explainPsbt.ts

@@ -34,7 +34,7 @@ function getInputSignatures(psbt: utxolib.bitgo.UtxoPsbt): number[] {
 export function explainPsbt(
   psbt: utxolib.bitgo.UtxoPsbt,
   descriptors: coreDescriptors.DescriptorMap
-): TransactionExplanation {
+): TransactionExplanation<string> {
   const parsedTransaction = coreDescriptors.parse(psbt, descriptors, psbt.network);
   const { inputs, outputs } = parsedTransaction;
   const externalOutputs = outputs.filter((o) => o.scriptId === undefined);

modules/abstract-utxo/src/transaction/explainTransaction.ts

@@ -22,7 +22,7 @@ export function explainTx<TNumber extends number | bigint>(
     changeInfo?: fixedScript.ChangeAddressInfo[];
   },
   network: utxolib.Network
-): TransactionExplanation {
+): TransactionExplanation<string | undefined> {
   if (params.wallet && isDescriptorWallet(params.wallet)) {
     if (tx instanceof utxolib.bitgo.UtxoPsbt) {
       if (!params.pubs || !isTriple(params.pubs)) {

modules/abstract-utxo/src/transaction/fixedScript/explainTransaction.ts

@@ -345,7 +345,7 @@ export function explainPsbt(
     inputSignatures: inputSignaturesCount,
     signatures: inputSignaturesCount.reduce((prev, curr) => (curr > prev ? curr : prev), 0),
     messages,
-  } as TransactionExplanation;
+  };
 }
 
 export function explainLegacyTx<TNumber extends number | bigint>(
@@ -356,12 +356,12 @@ export function explainLegacyTx<TNumber extends number | bigint>(
     changeInfo?: { address: string; chain: number; index: number }[];
   },
   network: utxolib.Network
-): TransactionExplanation {
+): TransactionExplanation<string | undefined> {
   const common = explainCommon(tx, params, network);
   const inputSignaturesCount = getTxInputSignaturesCount(tx, params, network);
   return {
     ...common,
     inputSignatures: inputSignaturesCount,
     signatures: inputSignaturesCount.reduce((prev, curr) => (curr > prev ? curr : prev), 0),
-  } as TransactionExplanation;
+  };
 }

modules/abstract-utxo/src/transaction/fixedScript/parseTransaction.ts

@@ -53,7 +53,7 @@ export async function parseTransaction<TNumber extends bigint | number>(
   }
 
   // obtain all outputs
-  const explanation: TransactionExplanation = await coin.explainTransaction<TNumber>({
+  const explanation: TransactionExplanation<string | undefined> = await coin.explainTransaction<TNumber>({
     txHex: txPrebuild.txHex,
     txInfo: txPrebuild.txInfo,
     pubs: keychainArray.map((k) => k.pub) as Triple<string>,