qml: Handle situation where no more addresses are available without

creating addresses beyond the gap limit.

- if lightning is enabled, propose to create a lightning-only invoice
- otherwise, propose to reuse an address
- never generate addresses beyond the gap limit

Implementation:
 - createDefaultRequest is removed
 - create_bitcoin_address is called whether the wallet has lightning
   or not

electrum/gui/qml/components/ReceiveDialog.qml

@@ -356,12 +356,7 @@ ElDialog {
     }
 
     Component.onCompleted: {
-        if (dialog.key) {
         request.key = dialog.key
-        } else {
-            // callLater to make sure any popups are on top of the dialog stacking order
-            Qt.callLater(createDefaultRequest)
-        }
     }
 
     // hack. delay qr rendering until dialog is shown

electrum/gui/qml/components/WalletMainView.qml

@@ -16,8 +16,9 @@ Item {
     property var _sendDialog
     property string _intentUri
 
-    property bool _ignore_gaplimit: false
-    property bool _reuse_address: false
+    property string _request_amount
+    property string _request_description
+    property string _request_expiry
 
     function openInvoice(key) {
         var dialog = invoiceDialog.createObject(app, { invoice: invoiceParser, invoice_key: key })
@@ -171,7 +172,7 @@ Item {
                 icon.source: '../../icons/tab_receive.png'
                 text: qsTr('Receive')
                 onClicked: {
-                    var dialog = receiveDetails.createObject(mainView)
+                    var dialog = receiveDetailsDialog.createObject(mainView)
                     dialog.open()
                 }
             }
@@ -247,17 +248,15 @@ Item {
             openRequest(key)
         }
         function onRequestCreateError(code, error) {
-            if (code == 'gaplimit') {
+            if (code == 'ln') {
                 var dialog = app.messageDialog.createObject(app, {text: error, yesno: true})
                 dialog.yesClicked.connect(function() {
-                    _ignore_gaplimit = true
-                    createDefaultRequest()
+		    createRequest(true, false)
                 })
-            } else if (code == 'non-deterministic') {
+            } else if (code == 'reuse_addr') {
                 var dialog = app.messageDialog.createObject(app, {text: error, yesno: true})
                 dialog.yesClicked.connect(function() {
-                    _reuse_address = true
-                    createDefaultRequest()
+                    createRequest(false, true)
                 })
             } else {
                 console.log(error)
@@ -354,24 +353,29 @@ Item {
         }
     }
 
-    function createRequest(receiveDetailsDialog) {
-        var qamt = Config.unitsToSats(receiveDetailsDialog.amount)
-	Daemon.currentWallet.createRequest(qamt, receiveDetailsDialog.description, receiveDetailsDialog.expiry, _ignore_gaplimit, _reuse_address)
+    function createRequest(lightning_only, reuse_address) {
+        var qamt = Config.unitsToSats(_request_amount)
+        Daemon.currentWallet.createRequest(qamt, _request_description, _request_expiry, lightning_only, reuse_address)
     }
 
     Component {
-        id: receiveDetails
-        ReceiveDetailsDialog {
         id: receiveDetailsDialog
+
+        ReceiveDetailsDialog {
+            id: _receiveDetailsDialog
             width: parent.width * 0.9
             anchors.centerIn: parent
             onAccepted: {
                 console.log('accepted')
-                createRequest(receiveDetailsDialog)
+                _request_amount = _receiveDetailsDialog.amount
+                _request_description = _receiveDetailsDialog.description
+                _request_expiry = _receiveDetailsDialog.expiry
+                createRequest(false, false)
             }
             onRejected: {
                 console.log('rejected')
             }
+            onClosed: destroy()
 	}
     }
 

electrum/gui/qml/qewallet.py

@@ -577,39 +577,26 @@ class QEWallet(AuthMixin, QObject, QtEventListener):
 
         threading.Thread(target=pay_thread, daemon=True).start()
 
-    def create_bitcoin_request(self, amount: int, message: str, expiration: int, *, ignore_gap: bool = False, reuse_address: bool = False) -> Optional[Tuple]:
+    def create_bitcoin_request(self, amount: int, message: str, expiration: int, *, lightning_only: bool = False, reuse_address: bool = False) -> Optional[Tuple]:
         addr = self.wallet.get_unused_address()
         if addr is None:
-            if not self.wallet.is_deterministic():  # imported wallet
-                if not reuse_address:
+            if reuse_address:
+                addr = self.wallet.get_receiving_address()
+            elif lightning_only:
+                addr = None
+            else:
+                has_lightning = self.wallet.has_lightning()
                 msg = [
-                        _('No more addresses in your wallet.'), ' ',
-                        _('You are using a non-deterministic wallet, which cannot create new addresses.'), ' ',
-                        _('If you want to create new addresses, use a deterministic wallet instead.'), '\n\n',
-                        _('Creating a new payment request will reuse one of your addresses and overwrite an existing request. Continue anyway?'),
+                    _('No more unused addresses in your wallet.'),
+                    _('All your addresses are used by unpaid requests.'),
                 ]
-                    self.requestCreateError.emit('non-deterministic',''.join(msg))
-                    return
-                addr = self.wallet.get_receiving_address()
-            else:  # deterministic wallet
-                if not ignore_gap:
-                    self.requestCreateError.emit('gaplimit',_("Warning: The next address will not be recovered automatically if you restore your wallet from seed; you may need to add it manually.\n\nThis occurs because you have too many unused addresses in your wallet. To avoid this situation, use the existing addresses first.\n\nCreate anyway?"))
+                msg.append(_('Do you wish to create a lightning-only request?') if has_lightning else _('Do you want to reuse an address?'))
                 return
-                addr = self.wallet.create_new_address(False)
 
         req_key = self.wallet.create_request(amount, message, expiration, addr)
-        self._logger.debug(f'created request with key {req_key}')
-        #try:
-            #self.wallet.add_payment_request(req)
-        #except Exception as e:
-            #self.logger.exception('Error adding payment request')
-            #self.requestCreateError.emit('fatal',_('Error adding payment request') + ':\n' + repr(e))
-        #else:
-            ## TODO: check this flow. Only if alias is defined in config. OpenAlias?
-            #pass
-            ##self.sign_payment_request(addr)
-
-        return req_key, addr
+        self._logger.debug(f'created request with key {req_key} addr {addr}')
+
+        return req_key
 
     def _delete_expired_requests(self):
         keys = self.wallet.delete_expired_requests()
@@ -620,17 +607,12 @@ class QEWallet(AuthMixin, QObject, QtEventListener):
     @pyqtSlot(QEAmount, str, int, bool)
     @pyqtSlot(QEAmount, str, int, bool, bool)
     @pyqtSlot(QEAmount, str, int, bool, bool, bool)
-    def createRequest(self, amount: QEAmount, message: str, expiration: int, ignore_gap: bool = False, reuse_address: bool = False):
+    def createRequest(self, amount: QEAmount, message: str, expiration: int, lightning_only: bool = False, reuse_address: bool = False):
         self._delete_expired_requests()
         try:
-            if self.wallet.lnworker and self.wallet.lnworker.channels:
-                # TODO maybe show a warning if amount exceeds lnworker.num_sats_can_receive (as in kivy)
-                # TODO fallback address robustness
-                addr = self.wallet.get_unused_address()
-                key = self.wallet.create_request(amount.satsInt, message, expiration, addr)
-            else:
-                key, addr = self.create_bitcoin_request(amount.satsInt, message, expiration, ignore_gap=ignore_gap, reuse_address=reuse_address)
+            key = self.create_bitcoin_request(amount.satsInt, message, expiration, lightning_only=lightning_only, reuse_address=reuse_address)
             if not key:
+                self.requestCreateError.emit('ln' if self.wallet.has_lightning() else 'reuse_addr', ' '.join(msg))
                 return
             self.addressModel.setDirty()
         except InvoiceError as e:
@@ -641,33 +623,6 @@ class QEWallet(AuthMixin, QObject, QtEventListener):
         self.requestModel.add_invoice(self.wallet.get_request(key))
         self.requestCreateSuccess.emit(key)
 
-    @pyqtSlot()
-    @pyqtSlot(bool)
-    @pyqtSlot(bool, bool)
-    def createDefaultRequest(self, ignore_gap: bool = False, reuse_address: bool = False):
-        self._delete_expired_requests()
-        try:
-            default_expiry = self.wallet.config.get('request_expiry', PR_DEFAULT_EXPIRATION_WHEN_CREATING)
-            if self.wallet.lnworker and self.wallet.lnworker.channels:
-                addr = self.wallet.get_unused_address()
-                # if addr is None, we ran out of addresses
-                if addr is None:
-                    # TODO: remove oldest unpaid request having a fallback address and try again
-                    pass
-                key = self.wallet.create_request(None, None, default_expiry, addr)
-            else:
-                req = self.create_bitcoin_request(None, None, default_expiry, ignore_gap=ignore_gap, reuse_address=reuse_address)
-                if not req:
-                    return
-                key, addr = req
-        except InvoiceError as e:
-            self.requestCreateError.emit('fatal',_('Error creating payment request') + ':\n' + str(e))
-            return
-
-        assert key is not None
-        self.requestModel.add_invoice(self.wallet.get_request(key))
-        self.requestCreateSuccess.emit(key)
-
     @pyqtSlot(str)
     def delete_request(self, key: str):
         self._logger.debug('delete req %s' % key)