chore(ada): ada sponsor txn example script

ada sponsor transaction example script using ada SDK
Ticket: WIN-8061

Author: krupanand-bitgo

examples/ts/ada/adaSponsorshipTransaction.ts

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+/**
+ * ADA Sponsorship Transaction Script
+ *
+ * Builds and broadcasts a sponsored ADA transaction where:
+ * - Sender sends funds to recipient
+ * - Sponsor pays the transaction fee
+ * - Both sender and sponsor sign the transaction
+ * Example sponsor transaction: https://preprod.cardanoscan.io/transaction/2197f936e53414a21e4967b9530f8d40b644ed31d07364cca8ce4f424a3fb061?tab=utxo
+ */
+
+import { coins } from '@bitgo/statics';
+import { TransactionBuilderFactory, Transaction } from '@bitgo/sdk-coin-ada';
+import * as CardanoWasm from '@emurgo/cardano-serialization-lib-nodejs';
+import axios from 'axios';
+
+const DEFAULT_CONFIG = {
+  senderPrivateKey:
+    'ed25519e_sk15qjyp5gkcfdz79awg4dfg2krscpcp5m5rsqmd53qnqtgnxn0jfpuln32hw6kudcvvedkpwepm2dm95pp9u25shju3n7872fkmly7k8sgpqj4h',
+  senderAddress:
+    'addr_test1qr3nwg8cpm9w3ga2v0peens94zey7js9zdu4h738gthck5ulny0aw0lpkn0nh6j7fzy0ddhfhe2968hvgcxflzr6a2fsg442nk',
+  sponsorPrivateKey:
+    'ed25519e_sk1ez29dxmsn8cwlxpk6ztef604ms2mzvmyjtsw85erxylesehk64g4dn73wqepnh7qzjzu0qqr9qppvgj3swv8hx808dn2dfrayzwj2uch5zac7',
+  sponsorAddress:
+    'addr_test1qp9jnqmkkkgwen0cqm4d7cstesw9um0wuduxwdfj3g7jtdsywn92ak44jje4h7q2gl3zkkhwks05z482ck86fmr4seas5ev9mc',
+  recipientAddress:
+    'addr_test1qzmdme7mn38nck3335zl6xavtmqxxr0x67jdffq38ms2tn4kmhnah8z083drrrg9l5d6chkqvvx7d4ay6jjpz0hq5h8qf4j042',
+  amountToSend: '1000000',
+  fee: '200000',
+  minUtxoValue: '1000000',
+};
+
+const KOIOS_API = 'https://preprod.koios.rest/api/v1';
+
+// ============================================================================
+// Main: Build Sponsorship Transaction
+// ============================================================================
+
+/**
+ * Build and sign a sponsorship transaction
+ *
+ * Transaction structure:
+ * - Inputs: [sender UTXOs] + [sponsor UTXOs]
+ * - Outputs: [recipient] + [sponsor change] + [sender change]
+ */
+async function buildSponsorshipTransaction() {
+  // Step 1: Select unspents
+  const unspents = await selectUnspents();
+
+  // Step 2: Generate transaction with outputs
+  const unsignedTx = await generateTransaction(unspents);
+
+  // Step 3: Sign transaction
+  const signedTx = signTransaction(unsignedTx);
+
+  const txData = signedTx.toJson();
+  const signedTxHex = signedTx.toBroadcastFormat();
+
+  console.log(`Transaction ID: ${txData.id}`);
+  console.log(`Fee: ${signedTx.getFee} lovelace`);
+
+  // Step 4: Submit transaction
+  try {
+    const submittedTxHash = await submitTransaction(signedTxHex);
+    console.log(`Submitted: https://preprod.cardanoscan.io/transaction/${submittedTxHash}`);
+  } catch (error: unknown) {
+    const axiosError = error as { response?: { data?: unknown }; message?: string };
+    const errMsg = axiosError.response?.data ? JSON.stringify(axiosError.response.data) : axiosError.message;
+    console.error(`Submission failed: ${errMsg}`);
+    console.log(`Signed tx hex: ${signedTxHex}`);
+  }
+
+  return { txId: txData.id, signedTxHex, fee: signedTx.getFee };
+}
+
+// ============================================================================
+// Entry Point
+// ============================================================================
+
+buildSponsorshipTransaction()
+  .then(() => process.exit(0))
+  .catch((error: Error) => {
+    console.error('Error:', error.message);
+    process.exit(1);
+  });
+
+// ============================================================================
+// Step 1: Select Unspents
+// ============================================================================
+
+/**
+ * Select UTXOs from sender and sponsor addresses
+ * - Sender UTXOs cover the transfer amount
+ * - Sponsor UTXOs cover the fee
+ */
+async function selectUnspents(): Promise<SelectedUnspents> {
+  const [senderInfo, sponsorInfo] = await Promise.all([
+    getAddressInfo(DEFAULT_CONFIG.senderAddress),
+    getAddressInfo(DEFAULT_CONFIG.sponsorAddress),
+  ]);
+
+  if (senderInfo.utxo_set.length === 0) throw new Error('Sender has no UTXOs');
+  if (sponsorInfo.utxo_set.length === 0) throw new Error('Sponsor has no UTXOs');
+
+  const amountToSend = BigInt(DEFAULT_CONFIG.amountToSend);
+  const fee = BigInt(DEFAULT_CONFIG.fee);
+  const minUtxoValue = BigInt(DEFAULT_CONFIG.minUtxoValue);
+
+  // Select sender UTXOs to cover amount + change
+  let senderInputTotal = BigInt(0);
+  const senderInputs: UTXO[] = [];
+  for (const utxo of senderInfo.utxo_set) {
+    senderInputs.push(utxo);
+    senderInputTotal += BigInt(utxo.value);
+    if (senderInputTotal >= amountToSend + minUtxoValue) break;
+  }
+  if (senderInputTotal < amountToSend) {
+    throw new Error(`Insufficient sender funds. Have: ${senderInputTotal}, Need: ${amountToSend}`);
+  }
+
+  // Select sponsor UTXOs to cover fee + change
+  let sponsorInputTotal = BigInt(0);
+  const sponsorInputs: UTXO[] = [];
+  for (const utxo of sponsorInfo.utxo_set) {
+    sponsorInputs.push(utxo);
+    sponsorInputTotal += BigInt(utxo.value);
+    if (sponsorInputTotal >= fee + minUtxoValue) break;
+  }
+  if (sponsorInputTotal < fee) {
+    throw new Error(`Insufficient sponsor funds. Have: ${sponsorInputTotal}, Need: ${fee}`);
+  }
+
+  return { senderInputs, senderInputTotal, sponsorInputs, sponsorInputTotal };
+}
+
+// ============================================================================
+// Step 2: Generate and Set Outputs
+// ============================================================================
+
+/**
+ * Build unsigned transaction with inputs and outputs
+ * Outputs: [recipient] + [sponsor change] + [sender change]
+ */
+async function generateTransaction(unspents: SelectedUnspents): Promise<Transaction> {
+  const factory = new TransactionBuilderFactory(coins.get('tada'));
+  const txBuilder = factory.getTransferBuilder();
+
+  const currentSlot = await getTip();
+  const ttl = currentSlot + 7200;
+
+  const amountToSend = BigInt(DEFAULT_CONFIG.amountToSend);
+  const fee = BigInt(DEFAULT_CONFIG.fee);
+  const minUtxoValue = BigInt(DEFAULT_CONFIG.minUtxoValue);
+
+  // Add sender inputs
+  for (const utxo of unspents.senderInputs) {
+    txBuilder.input({ transaction_id: utxo.tx_hash, transaction_index: utxo.tx_index });
+  }
+
+  // Add sponsor inputs
+  for (const utxo of unspents.sponsorInputs) {
+    txBuilder.input({ transaction_id: utxo.tx_hash, transaction_index: utxo.tx_index });
+  }
+
+  // Output 1: Recipient receives the transfer amount
+  txBuilder.output({ address: DEFAULT_CONFIG.recipientAddress, amount: amountToSend.toString() });
+
+  // Output 2: Sponsor change (sponsor input - fee)
+  const sponsorChange = unspents.sponsorInputTotal - fee;
+  if (sponsorChange >= minUtxoValue) {
+    txBuilder.output({ address: DEFAULT_CONFIG.sponsorAddress, amount: sponsorChange.toString() });
+  }
+
+  // Output 3: Sender change (handled by changeAddress)
+  const totalInputBalance = unspents.senderInputTotal + unspents.sponsorInputTotal;
+  txBuilder.changeAddress(DEFAULT_CONFIG.senderAddress, totalInputBalance.toString());
+
+  // Set TTL and fee
+  txBuilder.ttl(ttl);
+  txBuilder.fee(fee.toString());
+
+  return (await txBuilder.build()) as Transaction;
+}
+
+// ============================================================================
+// Step 3: Sign Transaction
+// ============================================================================
+
+/**
+ * Sign transaction with both sender and sponsor keys
+ */
+function signTransaction(unsignedTx: Transaction): Transaction {
+  const senderPrivKey = CardanoWasm.PrivateKey.from_bech32(DEFAULT_CONFIG.senderPrivateKey);
+  const sponsorPrivKey = CardanoWasm.PrivateKey.from_bech32(DEFAULT_CONFIG.sponsorPrivateKey);
+
+  const txHash = CardanoWasm.hash_transaction(unsignedTx.transaction.body());
+
+  // Create witnesses for both parties
+  const senderWitness = CardanoWasm.make_vkey_witness(txHash, senderPrivKey);
+  const sponsorWitness = CardanoWasm.make_vkey_witness(txHash, sponsorPrivKey);
+
+  // Build witness set
+  const witnessSet = CardanoWasm.TransactionWitnessSet.new();
+  const vkeyWitnesses = CardanoWasm.Vkeywitnesses.new();
+  vkeyWitnesses.add(senderWitness);
+  vkeyWitnesses.add(sponsorWitness);
+  witnessSet.set_vkeys(vkeyWitnesses);
+
+  // Create signed transaction
+  const signedCardanoTx = CardanoWasm.Transaction.new(
+    unsignedTx.transaction.body(),
+    witnessSet,
+    unsignedTx.transaction.auxiliary_data()
+  );
+
+  unsignedTx.transaction = signedCardanoTx;
+  return unsignedTx;
+}
+
+// ============================================================================
+// Step 4: Submit Transaction
+// ============================================================================
+
+/**
+ * Submit signed transaction to the blockchain
+ */
+async function submitTransaction(signedTxHex: string): Promise<string> {
+  const bytes = Uint8Array.from(Buffer.from(signedTxHex, 'hex'));
+  const response = await axios.post(`${KOIOS_API}/submittx`, bytes, {
+    headers: { 'Content-Type': 'application/cbor' },
+    timeout: 30000,
+  });
+  return response.data;
+}
+
+// ============================================================================
+// Helper Functions
+// ============================================================================
+
+/**
+ * Fetch UTXOs for an address from Koios API
+ */
+async function getAddressInfo(address: string): Promise<AddressInfo> {
+  try {
+    const response = await axios.post(
+      `${KOIOS_API}/address_info`,
+      { _addresses: [address] },
+      { headers: { 'Content-Type': 'application/json' }, timeout: 30000 }
+    );
+
+    if (!response.data || response.data.length === 0) {
+      return { balance: '0', utxo_set: [] };
+    }
+
+    const data = response.data[0];
+    return {
+      balance: data.balance || '0',
+      utxo_set: (data.utxo_set || []).map((utxo: { tx_hash: string; tx_index: number; value: string }) => ({
+        tx_hash: utxo.tx_hash,
+        tx_index: utxo.tx_index,
+        value: utxo.value,
+      })),
+    };
+  } catch (error: unknown) {
+    const axiosError = error as { response?: { status?: number }; message?: string };
+    if (axiosError.response?.status === 400) {
+      return { balance: '0', utxo_set: [] };
+    }
+    throw new Error(`Failed to fetch address info: ${axiosError.message}`);
+  }
+}
+
+/**
+ * Get current blockchain tip for TTL calculation
+ */
+async function getTip(): Promise<number> {
+  const response = await axios.get(`${KOIOS_API}/tip`, {
+    headers: { 'Content-Type': 'application/json' },
+    timeout: 30000,
+  });
+  if (!response.data || response.data.length === 0) {
+    throw new Error('Failed to get blockchain tip');
+  }
+  return response.data[0].abs_slot;
+}
+
+// ============================================================================
+// Types
+// ============================================================================
+
+interface UTXO {
+  tx_hash: string;
+  tx_index: number;
+  value: string;
+}
+
+interface AddressInfo {
+  balance: string;
+  utxo_set: UTXO[];
+}
+
+interface SelectedUnspents {
+  senderInputs: UTXO[];
+  senderInputTotal: bigint;
+  sponsorInputs: UTXO[];
+  sponsorInputTotal: bigint;
+}
+