From 41f22df26b09c7a5c03baaeb3aa7a09e742ac998 Mon Sep 17 00:00:00 2001
From: ThomasV <thomasv@electrum.org>
Date: Fri, 26 Mar 2021 16:27:32 +0100
Subject: [PATCH] submarine swaps: use num_sats_can_receive_no_mpp, to prevent
 funds being locked

---
 electrum/gui/kivy/uix/dialogs/lightning_channels.py | 2 +-
 electrum/gui/qt/swap_dialog.py                      | 6 +++---
 electrum/lnworker.py                                | 9 +++++++++
 electrum/submarine_swaps.py                         | 5 +++++
 4 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/electrum/gui/kivy/uix/dialogs/lightning_channels.py b/electrum/gui/kivy/uix/dialogs/lightning_channels.py
index 082542a0d..aa28c95bc 100644
--- a/electrum/gui/kivy/uix/dialogs/lightning_channels.py
+++ b/electrum/gui/kivy/uix/dialogs/lightning_channels.py
@@ -726,7 +726,7 @@ class SwapDialog(Factory.Popup):
             max_onchain_spend = 0
         reverse = int(min(self.lnworker.num_sats_can_send(),
                           self.swap_manager.get_max_amount()))
-        forward = int(min(self.lnworker.num_sats_can_receive(),
+        forward = int(min(self.swap_manager.num_sats_can_receive(),
                           # maximally supported swap amount by provider
                           self.swap_manager.get_max_amount(),
                           max_onchain_spend))
diff --git a/electrum/gui/qt/swap_dialog.py b/electrum/gui/qt/swap_dialog.py
index e08419d64..c5fa16e71 100644
--- a/electrum/gui/qt/swap_dialog.py
+++ b/electrum/gui/qt/swap_dialog.py
@@ -126,7 +126,7 @@ class SwapDialog(WindowModalDialog):
         if self.tx:
             amount = self.tx.output_value_for_address(ln_dummy_address())
             max_swap_amt = self.swap_manager.get_max_amount()
-            max_recv_amt = int(self.lnworker.num_sats_can_receive())
+            max_recv_amt = int(self.swap_manager.num_sats_can_receive())
             max_amt = min(max_swap_amt, max_recv_amt)
             if amount > max_amt:
                 amount = max_amt
@@ -149,7 +149,7 @@ class SwapDialog(WindowModalDialog):
         if self.is_reverse and send_amount and send_amount > self.lnworker.num_sats_can_send():
             # cannot send this much on lightning
             recv_amount = None
-        if (not self.is_reverse) and recv_amount and recv_amount > self.lnworker.num_sats_can_receive():
+        if (not self.is_reverse) and recv_amount and recv_amount > self.swap_manager.num_sats_can_receive():
             # cannot receive this much on lightning
             recv_amount = None
         self.recv_amount_e.follows = True
@@ -228,7 +228,7 @@ class SwapDialog(WindowModalDialog):
             onchain_amount = self.send_amount_e.get_amount()
             if lightning_amount is None or onchain_amount is None:
                 return
-            if lightning_amount > self.lnworker.num_sats_can_receive():
+            if lightning_amount > self.swap_manager.num_sats_can_receive():
                 if not self.window.question(CANNOT_RECEIVE_WARNING):
                     return
             self.window.protect(self.do_normal_swap, (lightning_amount, onchain_amount))
diff --git a/electrum/lnworker.py b/electrum/lnworker.py
index e5b8fc1cd..a36f31213 100644
--- a/electrum/lnworker.py
+++ b/electrum/lnworker.py
@@ -1951,6 +1951,15 @@ class LNWallet(LNWorker):
                         can_receive += c.available_to_spend(REMOTE)
         return Decimal(can_receive) / 1000
 
+    def num_sats_can_receive_no_mpp(self) -> Decimal:
+        with self.lock:
+            if self.channels:
+                can_receive = max([
+                    c.available_to_spend(REMOTE) for c in self.channels.values()
+                    if c.is_active() and not c.is_frozen_for_receiving()
+                ])
+        return Decimal(can_receive) / 1000
+
     def can_pay_invoice(self, invoice: LNInvoice) -> bool:
         return invoice.get_amount_sat() <= self.num_sats_can_send()
 
diff --git a/electrum/submarine_swaps.py b/electrum/submarine_swaps.py
index 24fb4e248..5b469ab2a 100644
--- a/electrum/submarine_swaps.py
+++ b/electrum/submarine_swaps.py
@@ -225,6 +225,11 @@ class SwapManager(Logger):
         callback = lambda: self._claim_swap(swap)
         self.lnwatcher.add_callback(swap.lockup_address, callback)
 
+    def num_sats_can_receive(self):
+        # finding how to do MPP is too hard for sender,
+        # might result in our coins being locked
+        return self.lnworker.num_sats_can_receive_no_mpp()
+
     async def normal_swap(
             self,
             *,