Add sweepAll to Electrum wallet RPC client.

Consolidate payto, deserialize, and broadcast into a single sweep helper for max-payment withdrawals.

backend/src/modules/bitcoinWallet/services/ElectrumWalletRpcClient.ts

@@ -88,6 +88,85 @@ export class ElectrumWalletRpcClient {
         };
     }
 
+    async sweepAll(
+        destinationAddress: string,
+        feeRateSatVbyte: number
+    ): Promise<{ txHash: string; amountAtomic: string }> {
+        const signedTransaction = await this.payToMax(destinationAddress, feeRateSatVbyte);
+        const transaction = await this.deserializeTransaction(signedTransaction);
+
+        const amountAtomic = this.sumOutputValueAtomic(transaction, destinationAddress);
+
+        if (amountAtomic === '0') {
+            throw new Error('Withdrawal transaction has no spendable output to the destination address');
+        }
+
+        const txHash = await this.broadcast(signedTransaction);
+
+        return { txHash, amountAtomic };
+    }
+
+    private async payToMax(destinationAddress: string, feeRateSatVbyte: number): Promise<string> {
+        const { walletPassword } = this.configService.get('electrumWallet') as Config['electrumWallet'];
+
+        const signedTransaction = await this.call<string>(
+            'payto',
+            {
+                destination: destinationAddress,
+                amount: '!',
+                feerate: String(feeRateSatVbyte),
+                password: walletPassword
+            },
+            { timeoutMs: 120_000 }
+        );
+
+        if (!signedTransaction) {
+            throw new Error('Electrum wallet RPC payto returned no transaction');
+        }
+
+        return signedTransaction;
+    }
+
+    private async broadcast(signedTransaction: string): Promise<string> {
+        const txHash = await this.call<string>('broadcast', { tx: signedTransaction });
+
+        if (!txHash) {
+            throw new Error('Electrum wallet RPC broadcast returned no transaction hash');
+        }
+
+        return txHash;
+    }
+
+    private async deserializeTransaction(signedTransaction: string): Promise<ElectrumWalletDeserializedTransaction> {
+        return this.call<ElectrumWalletDeserializedTransaction>('deserialize', { tx: signedTransaction });
+    }
+
+    private sumOutputValueAtomic(transaction: ElectrumWalletDeserializedTransaction, address: string): string {
+        if (!Array.isArray(transaction.outputs)) {
+            return '0';
+        }
+
+        return transaction.outputs.reduce((sum, output) => {
+            if (output.address !== address || !Number.isFinite(output.value_sats) || output.value_sats <= 0) {
+                return sum;
+            }
+
+            return addAtomic(sum, String(output.value_sats));
+        }, '0');
+    }
+
+    async getSeed(): Promise<string> {
+        const { walletPassword } = this.configService.get('electrumWallet') as Config['electrumWallet'];
+
+        const mnemonic = await this.call<string>('getseed', { password: walletPassword });
+
+        if (!mnemonic) {
+            throw new Error('Electrum wallet RPC getseed returned no mnemonic');
+        }
+
+        return mnemonic;
+    }
+
     async createAddress(label?: string): Promise<string> {
         const address = await this.call<string>('createnewaddress');
 
@@ -120,12 +199,8 @@ export class ElectrumWalletRpcClient {
                 }
 
                 const serializedTransaction = await this.call<string>('gettransaction', { txid: txHash });
-
-                const transaction = await this.call<ElectrumWalletDeserializedTransaction>('deserialize', {
-                    tx: serializedTransaction
-                });
-
-                const amountAtomic = this.sumIncomingOutputValueAtomic(transaction, address);
+                const transaction = await this.deserializeTransaction(serializedTransaction);
+                const amountAtomic = this.sumOutputValueAtomic(transaction, address);
 
                 return this.mapIncomingTransfer(entry, amountAtomic, blockHeight);
             })
@@ -134,20 +209,6 @@ export class ElectrumWalletRpcClient {
         return transfers.filter((transfer): transfer is ElectrumWalletIncomingTransfer => transfer !== null);
     }
 
-    private sumIncomingOutputValueAtomic(transaction: ElectrumWalletDeserializedTransaction, address: string): string {
-        if (!Array.isArray(transaction.outputs)) {
-            return '0';
-        }
-
-        return transaction.outputs.reduce((sum, output) => {
-            if (output.address !== address || !Number.isFinite(output.value_sats) || output.value_sats <= 0) {
-                return sum;
-            }
-
-            return addAtomic(sum, String(output.value_sats));
-        }, '0');
-    }
-
     private mapIncomingTransfer(
         entry: ElectrumWalletAddressHistoryEntry,
         amountAtomic: string,