refactor: Move wallet methods out of chain.h and node.h

Add WalletClient interface so node interface is cleaner and don't need
wallet-specific methods.

The new NodeContext::wallet_client pointer will also be needed to eliminate
global wallet variables like ::vpwallets, because createWallet(), loadWallet(),
getWallets(), etc methods called by the GUI need a way to get a reference to
the list of open wallets if it is no longer a global variable.

Also tweaks splash screen registration for load wallet events to be delayed
until after wallet client is created.

src/qt/bitcoin.cpp

@@ -266,6 +266,7 @@ void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
     // We don't hold a direct pointer to the splash screen after creation, but the splash
     // screen will take care of deleting itself when finish() happens.
     m_splash->show();
+    connect(this, &BitcoinApplication::requestedInitialize, m_splash, &SplashScreen::handleLoadWallet);
     connect(this, &BitcoinApplication::splashFinished, m_splash, &SplashScreen::finish);
     connect(this, &BitcoinApplication::requestedShutdown, m_splash, &QWidget::close);
 }

src/qt/bitcoingui.cpp

@@ -1189,7 +1189,7 @@ void BitcoinGUI::incomingTransaction(const QString& date, int unit, const CAmoun
     // On new transaction, make an info balloon
     QString msg = tr("Date: %1\n").arg(date) +
                   tr("Amount: %1\n").arg(BitcoinUnits::formatWithUnit(unit, amount, true));
-    if (m_node.getWallets().size() > 1 && !walletName.isEmpty()) {
+    if (m_node.walletClient().getWallets().size() > 1 && !walletName.isEmpty()) {
         msg += tr("Wallet: %1\n").arg(walletName);
     }
     msg += tr("Type: %1\n").arg(type);

src/qt/splashscreen.cpp

@@ -198,8 +198,12 @@ void SplashScreen::subscribeToCoreSignals()
     // Connect signals to client
     m_handler_init_message = m_node->handleInitMessage(std::bind(InitMessage, this, std::placeholders::_1));
     m_handler_show_progress = m_node->handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
+}
+
+void SplashScreen::handleLoadWallet()
+{
 #ifdef ENABLE_WALLET
-    m_handler_load_wallet = m_node->handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) { ConnectWallet(std::move(wallet)); });
+    m_handler_load_wallet = m_node->walletClient().handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) { ConnectWallet(std::move(wallet)); });
 #endif
 }
 

src/qt/splashscreen.h

@@ -43,6 +43,9 @@ public Q_SLOTS:
     /** Show message and progress */
     void showMessage(const QString &message, int alignment, const QColor &color);
 
+    /** Handle wallet load notifications. */
+    void handleLoadWallet();
+
 protected:
     bool eventFilter(QObject * obj, QEvent * ev) override;
 

src/qt/walletcontroller.cpp

@@ -35,11 +35,11 @@ WalletController::WalletController(ClientModel& client_model, const PlatformStyl
     , m_platform_style(platform_style)
     , m_options_model(client_model.getOptionsModel())
 {
-    m_handler_load_wallet = m_node.handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) {
+    m_handler_load_wallet = m_node.walletClient().handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) {
         getOrCreateWallet(std::move(wallet));
     });
 
-    for (std::unique_ptr<interfaces::Wallet>& wallet : m_node.getWallets()) {
+    for (std::unique_ptr<interfaces::Wallet>& wallet : m_node.walletClient().getWallets()) {
         getOrCreateWallet(std::move(wallet));
     }
 
@@ -66,7 +66,7 @@ std::map<std::string, bool> WalletController::listWalletDir() const
 {
     QMutexLocker locker(&m_mutex);
     std::map<std::string, bool> wallets;
-    for (const std::string& name : m_node.listWalletDir()) {
+    for (const std::string& name : m_node.walletClient().listWalletDir()) {
         wallets[name] = false;
     }
     for (WalletModel* wallet_model : m_wallets) {
@@ -250,7 +250,7 @@ void CreateWalletActivity::createWallet()
 
     QTimer::singleShot(500, worker(), [this, name, flags] {
         WalletCreationStatus status;
-        std::unique_ptr<interfaces::Wallet> wallet = node().createWallet(m_passphrase, flags, name, m_error_message, m_warning_message, status);
+        std::unique_ptr<interfaces::Wallet> wallet = node().walletClient().createWallet(name, m_passphrase, flags, status, m_error_message, m_warning_message);
 
         if (status == WalletCreationStatus::SUCCESS) m_wallet_model = m_wallet_controller->getOrCreateWallet(std::move(wallet));
 
@@ -321,7 +321,7 @@ void OpenWalletActivity::open(const std::string& path)
     showProgressDialog(tr("Opening Wallet <b>%1</b>...").arg(name.toHtmlEscaped()));
 
     QTimer::singleShot(0, worker(), [this, path] {
-        std::unique_ptr<interfaces::Wallet> wallet = node().loadWallet(path, m_error_message, m_warning_message);
+        std::unique_ptr<interfaces::Wallet> wallet = node().walletClient().loadWallet(path, m_error_message, m_warning_message);
 
         if (wallet) m_wallet_model = m_wallet_controller->getOrCreateWallet(std::move(wallet));
 

src/qt/walletmodel.cpp

@@ -581,7 +581,7 @@ QString WalletModel::getDisplayName() const
 
 bool WalletModel::isMultiwallet()
 {
-    return m_node.getWallets().size() > 1;
+    return m_node.walletClient().getWallets().size() > 1;
 }
 
 void WalletModel::refresh(bool pk_hash_only)