On Android, if channels are not recoverable, display channel backup when a new channel is created.

Remove the 'android_backups' setting, which was unpractical.

electrum/gui/kivy/main_window.py

@@ -193,10 +193,6 @@ class ElectrumWindow(App, Logger):
             self.network.run_from_another_thread(
                 self.network.stop_gossip())
 
-    android_backups = BooleanProperty(False)
-    def on_android_backups(self, instance, x):
-        self.electrum_config.set_key('android_backups', self.android_backups, True)
-
     use_change = BooleanProperty(False)
     def on_use_change(self, instance, x):
         if self.wallet:
@@ -407,7 +403,6 @@ class ElectrumWindow(App, Logger):
         self.daemon = self.gui_object.daemon
         self.fx = self.daemon.fx
         self.use_rbf = config.get('use_rbf', True)
-        self.android_backups = config.get('android_backups', False)
         self.use_gossip = config.get('use_gossip', False)
         self.use_unconfirmed = not config.get('confirmed_only', False)
 
@@ -1300,9 +1295,14 @@ class ElectrumWindow(App, Logger):
 
     def save_backup(self):
         if platform != 'android':
-            self._save_backup()
+            backup_dir = util.get_backup_dir(self.electrum_config)
+            if backup_dir:
+                self._save_backup(backup_dir)
+            else:
+                self.show_error(_("Backup NOT saved. Backup directory not configured."))
             return
 
+        backup_dir = util.android_backup_dir()
         from android.permissions import request_permissions, Permission
         def cb(permissions, grant_results: Sequence[bool]):
             if not grant_results or not grant_results[0]:
@@ -1313,17 +1313,14 @@ class ElectrumWindow(App, Logger):
             Clock.schedule_once(lambda dt: self._save_backup())
         request_permissions([Permission.WRITE_EXTERNAL_STORAGE], cb)
 
-    def _save_backup(self):
+    def _save_backup(self, backup_dir):
         try:
-            new_path = self.wallet.save_backup()
+            new_path = self.wallet.save_backup(backup_dir)
         except Exception as e:
             self.logger.exception("Failed to save wallet backup")
             self.show_error("Failed to save wallet backup" + '\n' + str(e))
             return
-        if new_path:
         self.show_info(_("Backup saved:") + f"\n{new_path}")
-        else:
-            self.show_error(_("Backup NOT saved. Backup directory not configured."))
 
     def export_private_keys(self, pk_label, addr):
         if self.wallet.is_watching_only():

electrum/gui/kivy/uix/dialogs/lightning_open_channel.py

@@ -13,6 +13,7 @@ from electrum.lnutil import ln_dummy_address, extract_nodeid
 
 from .label_dialog import LabelDialog
 from .confirm_tx_dialog import ConfirmTxDialog
+from .qr_dialog import QRDialog
 
 if TYPE_CHECKING:
     from ...main_window import ElectrumWindow
@@ -208,6 +209,27 @@ class LightningOpenChannelDialog(Factory.Popup, Logger):
             self.app.logger.exception("Problem opening channel")
             self.app.show_error(_('Problem opening channel: ') + '\n' + repr(e))
             return
+        # TODO: it would be nice to show this before broadcasting
+        if lnworker.has_recoverable_channels():
+            self.maybe_show_funding_tx(chan, funding_tx)
+        else:
+            title = _('Save backup')
+            help_text = ' '.join([
+                _('Your wallet does not have recoverable channels.'),
+                _('Please save this channel backup on another device.'),
+                _('It may be imported in another Electrum wallet with the same seed.')
+            ])
+            data = lnworker.export_channel_backup(chan.channel_id)
+            popup = QRDialog(
+                title, data,
+                show_text=False,
+                text_for_clipboard=data,
+                help_text=help_text,
+                close_button_text=_('OK'),
+                on_close=lambda: self.maybe_show_funding_tx(chan, funding_tx))
+            popup.open()
+
+    def maybe_show_funding_tx(self, chan, funding_tx):
         n = chan.constraints.funding_txn_minimum_depth
         message = '\n'.join([
             _('Channel established.'),
@@ -217,5 +239,6 @@ class LightningOpenChannelDialog(Factory.Popup, Logger):
         if not funding_tx.is_complete():
             message += '\n\n' + _('Please sign and broadcast the funding transaction')
         self.app.show_info(message)
+
         if not funding_tx.is_complete():
             self.app.tx_dialog(funding_tx)

electrum/gui/kivy/uix/dialogs/settings.py

@@ -93,13 +93,6 @@ Builder.load_string('''
                     title: _('Lightning Routing') + ': ' + self.status
                     description: _("Use trampoline routing or gossip.")
                     action: partial(root.routing_dialog, self)
-                CardSeparator
-                SettingsItem:
-                    status: _('Yes') if app.android_backups else _('No')
-                    title: _('Backups') + ': ' + self.status
-                    description: _("Backup wallet to external storage.")
-                    message: _("If this option is checked, a backup of your wallet will be written to external storage everytime you create a new channel. Make sure your wallet is protected with a strong password before you enable this option.")
-                    action: partial(root.boolean_dialog, 'android_backups', _('Backups'), self.message)
 
                 # disabled: there is currently only one coin selection policy
                 #CardSeparator

electrum/gui/kivy/uix/ui_screens/status.kv

@@ -81,7 +81,6 @@ Popup:
                 size_hint: 0.5, None
                 height: '48dp'
                 text: _('Export Backup')
-                disabled: not app.android_backups
                 on_release:
                     root.dismiss()
                     app.save_backup()

electrum/gui/qt/main_window.py

@@ -627,18 +627,18 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         vbox.addLayout(Buttons(CancelButton(d), OkButton(d)))
         if not d.exec_():
             return False
+        backup_dir = get_backup_dir(self.config)
+        if backup_dir is not None:
+            self.show_message(_("You need to configure a backup directory in your preferences"), title=_("Backup not configured"))
+            return
         try:
-            new_path = self.wallet.save_backup()
+            new_path = self.wallet.save_backup(backup_dir)
         except BaseException as reason:
             self.show_critical(_("Electrum was unable to copy your wallet file to the specified location.") + "\n" + str(reason), title=_("Unable to create backup"))
             return
-        if new_path:
         msg = _("A copy of your wallet file was created in")+" '%s'" % str(new_path)
         self.show_message(msg, title=_("Wallet backup created"))
         return True
-        else:
-            self.show_message(_("You need to configure a backup directory in your preferences"), title=_("Backup not created"))
-            return False
 
     def update_recently_visited(self, filename):
         recent = self.config.get('recently_open', [])

electrum/lnworker.py

@@ -26,7 +26,7 @@ from aiorpcx import run_in_thread, TaskGroup, NetAddress, ignore_after
 
 from . import constants, util
 from . import keystore
-from .util import profiler, chunks
+from .util import profiler, chunks, get_backup_dir
 from .invoices import PR_TYPE_LN, PR_UNPAID, PR_EXPIRED, PR_PAID, PR_INFLIGHT, PR_FAILED, PR_ROUTING, LNInvoice, LN_EXPIRY_NEVER
 from .util import NetworkRetryManager, JsonRPCClient
 from .lnutil import LN_MAX_FUNDING_SAT
@@ -1003,7 +1003,9 @@ class LNWallet(LNWorker):
             self.wallet.set_reserved_state_of_address(addr, reserved=True)
         try:
             self.save_channel(chan)
-            self.wallet.save_backup()
+            backup_dir = get_backup_dir(self.config)
+            if backup_dir is not None:
+                self.wallet.save_backup(backup_dir)
         except:
             chan.set_state(ChannelState.REDEEMED)
             self.remove_channel(chan.channel_id)

electrum/util.py

@@ -428,8 +428,10 @@ def android_data_dir():
     return PythonActivity.mActivity.getFilesDir().getPath() + '/data'
 
 def get_backup_dir(config):
+    # this is used to save a backup everytime a channel is created
+    # on Android, the export backup button uses android_backup_dir()
     if 'ANDROID_DATA' in os.environ:
-        return android_backup_dir() if config.get('android_backups') else None
+        return None
     else:
         return config.get('backup_dir')
 

electrum/wallet.py

@@ -57,7 +57,6 @@ from .util import (NotEnoughFunds, UserCancelled, profiler,
                    WalletFileException, BitcoinException, MultipleSpendMaxTxOutputs,
                    InvalidPassword, format_time, timestamp_to_datetime, Satoshis,
                    Fiat, bfh, bh2u, TxMinedInfo, quantize_feerate, create_bip21_uri, OrderedDictWithIndex)
-from .util import get_backup_dir
 from .simple_config import SimpleConfig, FEE_RATIO_HIGH_WARNING, FEERATE_WARNING_HIGH_FEE
 from .bitcoin import COIN, TYPE_ADDRESS
 from .bitcoin import is_address, address_to_script, is_minikey, relayfee, dust_threshold
@@ -315,10 +314,7 @@ class Abstract_Wallet(AddressSynchronizer, ABC):
         if self.storage:
             self.db.write(self.storage)
 
-    def save_backup(self):
-        backup_dir = get_backup_dir(self.config)
-        if backup_dir is None:
-            return
+    def save_backup(self, backup_dir):
         new_db = WalletDB(self.db.dump(), manual_upgrades=False)
 
         if self.lnworker: