From e54d57bf734a7309347ef204cfea8179755de942 Mon Sep 17 00:00:00 2001
From: ThomasV <thomasv@electrum.org>
Date: Thu, 8 May 2025 19:28:05 +0200
Subject: [PATCH] Qt: improve closing warnings for submarine swaps

---
 electrum/gui/messages.py       | 10 ++++++++++
 electrum/gui/qt/main_window.py | 30 +++++++++++++++++++-----------
 2 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/electrum/gui/messages.py b/electrum/gui/messages.py
index 9d2fc376d..bdc7f600f 100644
--- a/electrum/gui/messages.py
+++ b/electrum/gui/messages.py
@@ -74,6 +74,16 @@ MSG_REVERSE_SWAP_FUNDING_MEMPOOL = (
       "you will not get back the already pre-paid mining fees.")
 )
 
+MSG_FORWARD_SWAP_WARNING = (
+    _('You will need to come back online after the funding transaction is confirmed, in order to settle the swap.') + ' ' +
+    _('If you remain offline for more than {} blocks, your channel will be force closed and you might lose the funds you sent in the swap.')
+)
+
+MSG_REVERSE_SWAP_WARNING = (
+    _('You will need to come back online after the funding transaction is confirmed, in order to settle the swap.') + ' ' +
+    _('If you remain offline for more than {} blocks, the swap will be cancelled and you will lose the prepaid mining fees.')
+)
+
 MSG_LN_UTXO_RESERVE = (
     _("You do not have enough on-chain funds to protect your Lightning channels.") + ' ' +
     _("You should have at least {} on-chain in order to be able to sweep channel outputs.")
diff --git a/electrum/gui/qt/main_window.py b/electrum/gui/qt/main_window.py
index 348330836..6aacc4bb7 100644
--- a/electrum/gui/qt/main_window.py
+++ b/electrum/gui/qt/main_window.py
@@ -2732,21 +2732,29 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
 
     def _check_ongoing_submarine_swaps_callback(self) -> Optional[str]:
         """Callback that will return a warning string if there are unconfirmed swap funding txs."""
+        from electrum.submarine_swaps import MIN_FINAL_CLTV_DELTA_FOR_CLIENT, LOCKTIME_DELTA_REFUND
         if not (self.wallet.has_lightning() and self.wallet.lnworker.swap_manager):
             return None
         if not self.network:
             return None
-        if ongoing_swaps := self.wallet.lnworker.swap_manager.get_pending_swaps():
-            return "".join((
-                f"{str(len(ongoing_swaps))} ",
-                _("pending submarine swap") if len(ongoing_swaps) == 1 else _("pending submarine swaps"),
-                ":\n",
-                _("Wait until the funding transaction of your swap confirms, otherwise you risk losing your"),
-                " ",
-                _("funds") if any(not swap.is_reverse for swap in ongoing_swaps) else _("mining fee prepayment"),
-                ".",
-            ))
-        return None
+        ongoing_swaps = self.wallet.lnworker.swap_manager.get_pending_swaps()
+        if not ongoing_swaps:
+            return None
+        is_forward = any(not swap.is_reverse for swap in ongoing_swaps)
+        if is_forward:
+            # fixme: this is inaccurate, we need local_height - cltv_of_htlc
+            delta = MIN_FINAL_CLTV_DELTA_FOR_CLIENT
+            warning = messages.MSG_FORWARD_SWAP_WARNING.format(delta)
+        else:
+            locktime = min(swap.locktime for swap in ongoing_swaps)
+            delta = locktime - self.wallet.adb.get_local_height()
+            warning = messages.MSG_REVERSE_SWAP_WARNING.format(delta)
+        return "".join((
+            f"{str(len(ongoing_swaps))} ",
+            _("pending submarine swap") if len(ongoing_swaps) == 1 else _("pending submarine swaps"),
+            "\n\n",
+            warning,
+        ))
 
     def closeEvent(self, event):
         # note that closeEvent is NOT called if the user quits with Ctrl-C