feat(utxo-staking): add createDelegationMessageFromPsbt utils

Added utility functions to create delegation message from PSBT,
including staker info and transaction conversion helpers.

Issue: BTC-1933

Author: OttoAllmendinger

modules/utxo-staking/src/babylon/delegationMessage.ts

@@ -8,11 +8,13 @@ import * as babylonProtobuf from '@babylonlabs-io/babylon-proto-ts';
 import * as bitcoinjslib from 'bitcoinjs-lib';
 import * as utxolib from '@bitgo/utxo-lib';
 import { Descriptor } from '@bitgo/wasm-miniscript';
+import { toXOnlyPublicKey } from '@bitgo/utxo-core';
 import { toWrappedPsbt } from '@bitgo/utxo-core/descriptor';
 
 import { BabylonDescriptorBuilder } from './descriptor';
 import { createStakingManager } from './stakingManager';
 import { getStakingParams } from './stakingParams';
+import { BabylonNetworkLike, toBitcoinJsNetwork } from './network';
 
 export type ValueWithTypeUrl<T> = { typeUrl: string; value: T };
 
@@ -86,6 +88,77 @@ type Result = {
   stakingTx: bitcoinjslib.Transaction;
 };
 
+/**
+ * @param stakingKey - this is the single-sig key that is used for co-signing the staking output
+ * @param changeAddress - this is unrelated to the staking key and is used for the change output
+ */
+export function toStakerInfo(
+  stakingKey: utxolib.ECPairInterface | Buffer | string,
+  changeAddress: string
+): vendor.StakerInfo {
+  if (typeof stakingKey === 'object' && 'publicKey' in stakingKey) {
+    stakingKey = stakingKey.publicKey;
+  }
+  if (typeof stakingKey === 'string') {
+    stakingKey = Buffer.from(stakingKey, 'hex');
+  }
+  return {
+    publicKeyNoCoordHex: toXOnlyPublicKey(stakingKey).toString('hex'),
+    address: changeAddress,
+  };
+}
+
+export function createStaking(
+  network: BabylonNetworkLike,
+  blockHeight: number,
+  stakerBtcInfo: vendor.StakerInfo,
+  stakingInput: vendor.StakingInputs,
+  versionedParams: vendor.VersionedStakingParams[] = getStakingParams(network)
+): vendor.Staking {
+  if (blockHeight === 0) {
+    throw new Error('Babylon BTC tip height cannot be 0');
+  }
+
+  // Get the Babylon params based on the BTC tip height from Babylon chain
+  const params = vendor.getBabylonParamByBtcHeight(blockHeight, versionedParams);
+
+  return new vendor.Staking(
+    toBitcoinJsNetwork(network),
+    stakerBtcInfo,
+    params,
+    stakingInput.finalityProviderPkNoCoordHex,
+    stakingInput.stakingTimelock
+  );
+}
+
+type TransactionLike =
+  | bitcoinjslib.Psbt
+  | bitcoinjslib.Transaction
+  | utxolib.Transaction
+  | utxolib.bitgo.UtxoTransaction<bigint | number>
+  | utxolib.Psbt
+  | utxolib.bitgo.UtxoPsbt;
+
+function toStakingTransactionFromPsbt(
+  psbt: bitcoinjslib.Psbt | utxolib.Psbt | utxolib.bitgo.UtxoPsbt
+): bitcoinjslib.Transaction {
+  if (!(psbt instanceof utxolib.bitgo.UtxoPsbt)) {
+    psbt = utxolib.bitgo.createPsbtFromBuffer(psbt.toBuffer(), utxolib.networks.bitcoin);
+  }
+  if (psbt instanceof utxolib.bitgo.UtxoPsbt) {
+    // only utxolib.bitgo.UtxoPsbt has the getUnsignedTx method
+    return bitcoinjslib.Transaction.fromHex(psbt.getUnsignedTx().toHex());
+  }
+  throw new Error('illegal state');
+}
+
+export function toStakingTransaction(tx: TransactionLike): bitcoinjslib.Transaction {
+  if (tx instanceof bitcoinjslib.Psbt || tx instanceof utxolib.Psbt) {
+    return toStakingTransactionFromPsbt(tx);
+  }
+  return bitcoinjslib.Transaction.fromHex(tx.toHex());
+}
+
 /*
  * This is mostly lifted from
  * https://github.com/babylonlabs-io/btc-staking-ts/blob/v0.4.0-rc.2/src/staking/manager.ts#L100-L172