kivy: show channel backup before force-close

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

@@ -16,6 +16,8 @@ from electrum.transaction import PartialTxOutput, Transaction
 from electrum.util import NotEnoughFunds, NoDynamicFeeEstimates, format_fee_satoshis, quantize_feerate
 from electrum.lnutil import ln_dummy_address
 
+from .qr_dialog import QRDialog
+
 if TYPE_CHECKING:
     from ...main_window import ElectrumWindow
     from electrum import SimpleConfig
@@ -520,14 +522,38 @@ class ChannelDetailsPopup(Popup, Logger):
         self.app.qr_dialog(_("Channel Backup " + self.chan.short_id_for_GUI()), text, help_text=help_text)
 
     def force_close(self):
-        Question(_('Force-close channel?'), self._force_close).open()
-
-    def _force_close(self, b):
-        if not b:
-            return
         if self.chan.is_closed():
             self.app.show_error(_('Channel already closed'))
             return
+        to_self_delay = self.chan.config[REMOTE].to_self_delay
+        help_text = ' '.join([
+            _('If you force-close this channel, the funds you have in it will not be available for {} blocks.').format(to_self_delay),
+            _('During that time, funds will not be recoverabe from your seed, and may be lost if you lose your device.'),
+            _('To prevent that, please save this channel backup.'),
+            _('It may be imported in another wallet with the same seed.')
+        ])
+        title = _('Save backup and force-close')
+        data = self.app.wallet.lnworker.export_channel_backup(self.chan.channel_id)
+        popup = QRDialog(
+            title, data,
+            show_text=False,
+            text_for_clipboard=data,
+            help_text=help_text,
+            close_button_text=_('Next'),
+            on_close=self._confirm_force_close)
+        popup.open()
+
+    def _confirm_force_close(self):
+        Question(
+            _('Confirm force close?'),
+            self._do_force_close,
+            title=_('Force-close channel'),
+            no_str=_('Cancel'),
+            yes_str=_('Proceed')).open()
+
+    def _do_force_close(self, b):
+        if not b:
+            return
         loop = self.app.wallet.network.asyncio_loop
         coro = asyncio.run_coroutine_threadsafe(self.app.wallet.lnworker.force_close_channel(self.chan.channel_id), loop)
         try:

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

@@ -21,6 +21,7 @@ Builder.load_string('''
     data: ''
     shaded: False
     help_text: ''
+    close_button_text: ''
     AnchorLayout:
         anchor_x: 'center'
         BoxLayout:
@@ -56,14 +57,22 @@ Builder.load_string('''
                 Button:
                     size_hint: 1, None
                     height: '48dp'
-                    text: _('Close')
+                    text: root.close_button_text
                     on_release:
                         popup.dismiss()
+                        if root.on_close: root.on_close()
 ''')
 
 class QRDialog(Factory.Popup):
-    def __init__(self, title, data, show_text, *,
-                 failure_cb=None, text_for_clipboard=None, help_text=None):
+
+    def __init__(
+            self, title, data, show_text, *,
+            failure_cb=None,
+            text_for_clipboard=None,
+            help_text=None,
+            close_button_text=None,
+            on_close=None):
+
         Factory.Popup.__init__(self)
         self.app = App.get_running_app()  # type: ElectrumWindow
         self.title = title
@@ -71,6 +80,8 @@ class QRDialog(Factory.Popup):
         self.help_text = (data if show_text else help_text) or ''
         self.failure_cb = failure_cb
         self.text_for_clipboard = text_for_clipboard if text_for_clipboard else data
+        self.close_button_text = close_button_text or _('Close')
+        self.on_close = on_close
 
     def on_open(self):
         self.ids.qr.set_data(self.data, self.failure_cb)