support mixing to multisig wallets

build.gradle

@@ -91,7 +91,7 @@ dependencies {
     implementation('org.slf4j:jul-to-slf4j:1.7.30') {
         exclude group: 'org.slf4j'
     }
-    implementation('com.sparrowwallet.nightjar:nightjar:0.2.12-SNAPSHOT')
+    implementation('com.sparrowwallet.nightjar:nightjar:0.2.13-SNAPSHOT')
     testImplementation('junit:junit:4.12')
 }
 
@@ -387,7 +387,7 @@ extraJavaModuleInfo {
     module('cbor-0.9.jar', 'co.nstant.in.cbor', '0.9') {
         exports('co.nstant.in.cbor')
     }
-    module('nightjar-0.2.12-SNAPSHOT.jar', 'com.sparrowwallet.nightjar', '0.2.12-SNAPSHOT') {
+    module('nightjar-0.2.13-SNAPSHOT.jar', 'com.sparrowwallet.nightjar', '0.2.13-SNAPSHOT') {
         requires('com.google.common')
         requires('net.sourceforge.streamsupport')
         requires('org.slf4j')
@@ -401,6 +401,7 @@ extraJavaModuleInfo {
         exports('com.samourai.wallet.api.backend.beans')
         exports('com.samourai.wallet.client.indexHandler')
         exports('com.samourai.wallet.hd')
+        exports('com.samourai.wallet.util')
         exports('com.samourai.whirlpool.client.event')
         exports('com.samourai.whirlpool.client.wallet')
         exports('com.samourai.whirlpool.client.wallet.beans')

src/main/java/com/sparrowwallet/sparrow/wallet/MixToController.java

@@ -44,7 +44,6 @@ public class MixToController implements Initializable {
 
         List<Wallet> destinationWallets = AppServices.get().getOpenWallets().keySet().stream().filter(openWallet -> openWallet.isValid()
                 && openWallet != wallet && openWallet != wallet.getMasterWallet()
-                && openWallet.getPolicyType().equals(PolicyType.SINGLE)
                 && !StandardAccount.WHIRLPOOL_ACCOUNTS.contains(openWallet.getStandardAccountType())).collect(Collectors.toList());
         allWallets.addAll(destinationWallets);
 

src/main/java/com/sparrowwallet/sparrow/whirlpool/Whirlpool.java

@@ -7,6 +7,7 @@ import com.samourai.wallet.api.backend.beans.UnspentOutput;
 import com.samourai.wallet.hd.HD_Wallet;
 import com.samourai.wallet.hd.HD_WalletFactoryGeneric;
 import com.samourai.whirlpool.client.event.*;
+import com.samourai.whirlpool.client.mix.handler.IPostmixHandler;
 import com.samourai.whirlpool.client.tx0.*;
 import com.samourai.whirlpool.client.wallet.WhirlpoolEventService;
 import com.samourai.whirlpool.client.wallet.WhirlpoolWallet;
@@ -41,6 +42,7 @@ import com.sparrowwallet.sparrow.wallet.UtxoEntry;
 import com.sparrowwallet.sparrow.whirlpool.dataPersister.SparrowDataPersister;
 import com.sparrowwallet.sparrow.whirlpool.dataSource.SparrowDataSource;
 import com.sparrowwallet.sparrow.whirlpool.dataSource.SparrowMinerFeeSupplier;
+import com.sparrowwallet.sparrow.whirlpool.dataSource.SparrowPostmixHandler;
 import javafx.application.Platform;
 import javafx.beans.property.BooleanProperty;
 import javafx.beans.property.SimpleBooleanProperty;
@@ -365,18 +367,12 @@ public class Whirlpool {
                 throw new IllegalStateException("Cannot find mix to wallet with id " + mixToWalletId);
             }
 
-            if(mixToWallet.getPolicyType() != PolicyType.SINGLE) {
-                throw new IllegalStateException("Only single signature mix to wallets are currently supported");
-            }
-
-            List<ExtendedKey.Header> headers = ExtendedKey.Header.getHeaders(Network.get());
-            ExtendedKey.Header header = headers.stream().filter(head -> head.getDefaultScriptType().equals(mixToWallet.getScriptType()) && !head.isPrivateKey()).findFirst().orElse(ExtendedKey.Header.xpub);
-            ExtendedKey extPubKey = mixToWallet.getKeystores().get(0).getExtendedPublicKey();
-            String xpub = extPubKey.toString(header);
             Integer highestUsedIndex = mixToWallet.getNode(KeyPurpose.RECEIVE).getHighestUsedIndex();
+            int startIndex = highestUsedIndex == null ? 0 : highestUsedIndex + 1;
             int mixes = minMixes == null ? DEFAULT_MIXTO_MIN_MIXES : minMixes;
 
-            ExternalDestination externalDestination = new ExternalDestination(xpub, 0, highestUsedIndex == null ? 0 : highestUsedIndex + 1, mixes, DEFAULT_MIXTO_RANDOM_FACTOR);
+            IPostmixHandler postmixHandler = new SparrowPostmixHandler(whirlpoolWalletService, mixToWallet, KeyPurpose.RECEIVE, startIndex);
+            ExternalDestination externalDestination = new ExternalDestination(postmixHandler, 0, startIndex, mixes, DEFAULT_MIXTO_RANDOM_FACTOR);
             config.setExternalDestination(externalDestination);
         }
 

src/main/java/com/sparrowwallet/sparrow/whirlpool/dataSource/SparrowPostmixHandler.java

@@ -0,0 +1,75 @@
+package com.sparrowwallet.sparrow.whirlpool.dataSource;
+
+import com.samourai.wallet.client.indexHandler.IIndexHandler;
+import com.samourai.wallet.util.XPubUtil;
+import com.samourai.whirlpool.client.mix.handler.DestinationType;
+import com.samourai.whirlpool.client.mix.handler.IPostmixHandler;
+import com.samourai.whirlpool.client.mix.handler.MixDestination;
+import com.samourai.whirlpool.client.wallet.WhirlpoolWalletService;
+import com.sparrowwallet.drongo.KeyPurpose;
+import com.sparrowwallet.drongo.address.Address;
+import com.sparrowwallet.drongo.wallet.Wallet;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class SparrowPostmixHandler implements IPostmixHandler {
+    private static final Logger log = LoggerFactory.getLogger(SparrowPostmixHandler.class);
+
+    private final WhirlpoolWalletService whirlpoolWalletService;
+    private final Wallet wallet;
+    private final KeyPurpose keyPurpose;
+    private final int startIndex;
+
+    protected MixDestination destination;
+
+    public SparrowPostmixHandler(WhirlpoolWalletService whirlpoolWalletService, Wallet wallet, KeyPurpose keyPurpose, int startIndex) {
+        this.whirlpoolWalletService = whirlpoolWalletService;
+        this.wallet = wallet;
+        this.keyPurpose = keyPurpose;
+        this.startIndex = startIndex;
+    }
+
+    public Wallet getWallet() {
+        return wallet;
+    }
+
+    protected MixDestination computeNextDestination() throws Exception {
+        // index
+        int index = Math.max(getIndexHandler().getAndIncrementUnconfirmed(), startIndex);
+
+        // address
+        Address address = wallet.getAddress(keyPurpose, index);
+        String path = XPubUtil.getInstance().getPath(index, keyPurpose.getPathIndex().num());
+
+        log.info("Mixing to external xPub -> receiveAddress=" + address + ", path=" + path);
+        return new MixDestination(DestinationType.XPUB, index, address.toString(), path);
+    }
+
+    @Override
+    public MixDestination getDestination() {
+        return destination; // may be NULL
+    }
+
+    public final MixDestination computeDestination() throws Exception {
+        // use "unconfirmed" index to avoid huge index gaps on multiple mix failures
+        this.destination = computeNextDestination();
+        return destination;
+    }
+
+    @Override
+    public void onMixFail() {
+        if(destination != null) {
+            getIndexHandler().cancelUnconfirmed(destination.getIndex());
+        }
+    }
+
+    @Override
+    public void onRegisterOutput() {
+        // confirm receive address even when REGISTER_OUTPUT fails, to avoid 'ouput already registered'
+        getIndexHandler().confirmUnconfirmed(destination.getIndex());
+    }
+
+    private IIndexHandler getIndexHandler() {
+        return whirlpoolWalletService.whirlpoolWallet().getWalletStateSupplier().getIndexHandlerExternal();
+    }
+}

src/main/java/com/sparrowwallet/sparrow/whirlpool/dataSource/SparrowWalletStateSupplier.java

@@ -58,9 +58,15 @@ public class SparrowWalletStateSupplier implements WalletStateSupplier {
         }
 
         if(externalIndexHandler == null) {
-            Wallet externalWallet = SparrowDataSource.getWallet(externalDestination.getXpub());
+            Wallet externalWallet = null;
+            if(externalDestination.getPostmixHandler() instanceof SparrowPostmixHandler sparrowPostmixHandler) {
+                externalWallet = sparrowPostmixHandler.getWallet();
+            } else if(externalDestination.getXpub() != null) {
+                externalWallet = SparrowDataSource.getWallet(externalDestination.getXpub());
+            }
+
             if(externalWallet == null) {
-                throw new IllegalStateException("Cannot find wallet for external destination xpub " + externalDestination.getXpub());
+                throw new IllegalStateException("Cannot find wallet for external destination " + externalDestination);
             }
 
             KeyPurpose keyPurpose = KeyPurpose.fromChildNumber(new ChildNumber(externalDestination.getChain()));