Kivy: Support Lightning in Send tab

electrum/gui/kivy/main_window.py

@@ -162,11 +162,16 @@ class ElectrumWindow(App):
         self.switch_to('send')
         self.send_screen.set_URI(uri)
 
+    def set_ln_invoice(self, invoice):
+        self.switch_to('send')
+        self.send_screen.set_ln_invoice(invoice)
+
     def on_new_intent(self, intent):
-        if intent.getScheme() != 'bitcoin':
+        data = intent.getDataString()
-            return
+        if intent.getScheme() == 'bitcoin':
-        uri = intent.getDataString()
+            self.set_URI(data)
-        self.set_URI(uri)
+        elif intent.getScheme() == 'lightning':
+            self.set_ln_invoice(data)
 
     def on_language(self, instance, language):
         Logger.info('language: {}'.format(language))
@@ -355,6 +360,9 @@ class ElectrumWindow(App):
         if data.startswith('bitcoin:'):
             self.set_URI(data)
             return
+        if data.startswith('ln'):
+            self.set_ln_invoice(data)
+            return
         # try to decode transaction
         from electrum.transaction import Transaction
         from electrum.util import bh2u

electrum/gui/kivy/uix/screens.py

@@ -1,8 +1,10 @@
+import asyncio
 from weakref import ref
 from decimal import Decimal
 import re
 import datetime
 import traceback, sys
+from enum import Enum, auto
 
 from kivy.app import App
 from kivy.cache import Cache
@@ -19,19 +21,26 @@ from kivy.factory import Factory
 from kivy.utils import platform
 
 from electrum.util import profiler, parse_URI, format_time, InvalidPassword, NotEnoughFunds, Fiat
-from electrum import bitcoin
+from electrum import bitcoin, constants
 from electrum.transaction import TxOutput, Transaction, tx_from_str
 from electrum.util import send_exception_to_crash_reporter, parse_URI, InvalidBitcoinURI
 from electrum.paymentrequest import PR_UNPAID, PR_PAID, PR_UNKNOWN, PR_EXPIRED
 from electrum.plugin import run_hook
 from electrum.wallet import InternalAddressCorruption
 from electrum import simple_config
+from electrum.lnaddr import lndecode
+from electrum.lnutil import RECEIVED, SENT
 
 from .context_menu import ContextMenu
 
 
 from electrum.gui.kivy.i18n import _
 
+class Destination(Enum):
+    Address = auto()
+    PR = auto()
+    LN = auto()
+
 class HistoryRecycleView(RecycleView):
     pass
 
@@ -184,7 +193,19 @@ class SendScreen(CScreen):
         self.screen.message = uri.get('message', '')
         self.screen.amount = self.app.format_amount_and_units(amount) if amount else ''
         self.payment_request = None
-        self.screen.is_pr = False
+        self.screen.destinationtype = Destination.Address
+
+    def set_ln_invoice(self, invoice):
+        try:
+            lnaddr = lndecode(invoice, expected_hrp=constants.net.SEGWIT_HRP)
+        except Exception as e:
+            self.app.show_info(invoice + _(" is not a valid Lightning invoice: ") + repr(e)) # repr because str(Exception()) == ''
+            return
+        self.screen.address = invoice
+        self.screen.message = dict(lnaddr.tags).get('d', None)
+        self.screen.amount = self.app.format_amount_and_units(lnaddr.amount * bitcoin.COIN) if lnaddr.amount else ''
+        self.payment_request = None
+        self.screen.destinationtype = Destination.LN
 
     def update(self):
         if self.app.wallet and self.payment_request_queued:
@@ -196,7 +217,7 @@ class SendScreen(CScreen):
         self.screen.message = ''
         self.screen.address = ''
         self.payment_request = None
-        self.screen.is_pr = False
+        self.screen.destinationtype = Destination.Address
 
     def set_request(self, pr):
         self.screen.address = pr.get_requestor()
@@ -204,16 +225,16 @@ class SendScreen(CScreen):
         self.screen.amount = self.app.format_amount_and_units(amount) if amount else ''
         self.screen.message = pr.get_memo()
         if pr.is_pr():
-            self.screen.is_pr = True
+            self.screen.destinationtype = Destination.PR
             self.payment_request = pr
         else:
-            self.screen.is_pr = False
+            self.screen.destinationtype = Destination.Address
             self.payment_request = None
 
     def do_save(self):
         if not self.screen.address:
             return
-        if self.screen.is_pr:
+        if self.screen.destinationtype == Destination.PR:
             # it should be already saved
             return
         # save address as invoice
@@ -226,10 +247,10 @@ class SendScreen(CScreen):
         self.app.wallet.invoices.add(pr)
         self.app.show_info(_("Invoice saved"))
         if pr.is_pr():
-            self.screen.is_pr = True
+            self.screen.destinationtype = Destination.PR
             self.payment_request = pr
         else:
-            self.screen.is_pr = False
+            self.screen.destinationtype = Destination.Address
             self.payment_request = None
 
     def do_paste(self):
@@ -248,10 +269,42 @@ class SendScreen(CScreen):
             self.app.tx_dialog(tx)
             return
         # try to decode as URI/address
-        self.set_URI(data)
+        if data.startswith('ln'):
+            self.set_ln_invoice(data.rstrip())
+        else:
+            self.set_URI(data)
+
+    def _do_send_lightning(self):
+        if not self.screen.amount:
+            self.app.show_error(_('Since the invoice contained no amount, you must enter one'))
+            return
+        invoice = self.screen.address
+        amount_sat = self.app.get_amount(self.screen.amount)
+        try:
+            addr = self.app.wallet.lnworker._check_invoice(invoice, amount_sat)
+            route = self.app.wallet.lnworker._create_route_from_invoice(decoded_invoice=addr)
+        except Exception as e:
+            self.app.show_error(_('Could not find path for payment. Check if you have open channels. Error details:') + ':\n' + repr(e))
+        self.app.network.register_callback(self.payment_completed_async_thread, ['ln_payment_completed'])
+        _addr, _peer, coro = self.app.wallet.lnworker._pay(invoice, amount_sat)
+        fut = asyncio.run_coroutine_threadsafe(coro, self.app.network.asyncio_loop)
+        fut.add_done_callback(self.ln_payment_result)
+
+    def payment_completed_async_thread(self, event, direction, htlc, preimage):
+        Clock.schedule_once(lambda dt: self.payment_completed(direction, htlc, preimage))
+
+    def payment_completed(self, direction, htlc, preimage):
+        self.app.show_info(_('Payment received') if direction == RECEIVED else _('Payment sent'))
+
+    def ln_payment_result(self, fut):
+        if fut.exception():
+            self.app.show_error(_('Lightning payment failed:') + '\n' + repr(fut.exception()))
 
     def do_send(self):
-        if self.screen.is_pr:
+        if self.screen.destinationtype == Destination.LN:
+            self._do_send_lightning()
+            return
+        elif self.screen.destinationtype == Destination.PR:
             if self.payment_request.has_expired():
                 self.app.show_error(_('Payment request has expired'))
                 return

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

@@ -1,4 +1,5 @@
 #:import _ electrum.gui.kivy.i18n._
+#:import Destination electrum.gui.kivy.uix.screens.Destination
 #:import Decimal decimal.Decimal
 #:set btc_symbol chr(171)
 #:set mbtc_symbol chr(187)
@@ -11,7 +12,7 @@ SendScreen:
     address: ''
     amount: ''
     message: ''
-    is_pr: False
+    destinationtype: Destination.Address
     BoxLayout
         padding: '12dp', '12dp', '12dp', '12dp'
         spacing: '12dp'
@@ -36,7 +37,7 @@ SendScreen:
                     on_release: Clock.schedule_once(lambda dt: app.show_info(_('Copy and paste the recipient address using the Paste button, or use the camera to scan a QR code.')))
                     #on_release: Clock.schedule_once(lambda dt: app.popup_dialog('contacts'))
             CardSeparator:
-                opacity: int(not root.is_pr)
+                opacity: int(root.destinationtype == Destination.Address)
                 color: blue_bottom.foreground_color
             BoxLayout:
                 size_hint: 1, None
@@ -52,10 +53,10 @@ SendScreen:
                     id: amount_e
                     default_text: _('Amount')
                     text: s.amount if s.amount else _('Amount')
-                    disabled: root.is_pr
+                    disabled: root.destinationtype == Destination.PR or root.destinationtype == Destination.LN and not s.amount
                     on_release: Clock.schedule_once(lambda dt: app.amount_dialog(s, True))
             CardSeparator:
-                opacity: int(not root.is_pr)
+                opacity: int(root.destinationtype == Destination.Address)
                 color: blue_bottom.foreground_color
             BoxLayout:
                 id: message_selection
@@ -69,27 +70,27 @@ SendScreen:
                     pos_hint: {'center_y': .5}
                 BlueButton:
                     id: description
-                    text: s.message if s.message else (_('No Description') if root.is_pr else _('Description'))
+                    text: s.message if s.message else ({Destination.LN: _('Lightning invoice contains no description'), Destination.Address: _('Description'), Destination.PR: _('No Description')}[root.destinationtype])
-                    disabled: root.is_pr
+                    disabled: root.destinationtype != Destination.Address
                     on_release: Clock.schedule_once(lambda dt: app.description_dialog(s))
             CardSeparator:
-                opacity: int(not root.is_pr)
+                opacity: int(root.destinationtype == Destination.Address)
                 color: blue_bottom.foreground_color
             BoxLayout:
                 size_hint: 1, None
-                height: blue_bottom.item_height
+                height: blue_bottom.item_height if root.destinationtype != Destination.LN else 0
                 spacing: '5dp'
                 Image:
                     source: 'atlas://electrum/gui/kivy/theming/light/star_big_inactive'
-                    opacity: 0.7
+                    opacity: 0.7 if root.destinationtype != Destination.LN else 0
                     size_hint: None, None
                     size: '22dp', '22dp'
                     pos_hint: {'center_y': .5}
                 BlueButton:
                     id: fee_e
                     default_text: _('Fee')
-                    text: app.fee_status
+                    text: app.fee_status if root.destinationtype != Destination.LN else ''
-                    on_release: Clock.schedule_once(lambda dt: app.fee_dialog(s, True))
+                    on_release: Clock.schedule_once(lambda dt: app.fee_dialog(s, True)) if root.destinationtype != Destination.LN else None
         BoxLayout:
             size_hint: 1, None
             height: '48dp'

electrum/lnworker.py

@@ -97,6 +97,7 @@ class LNWorker(PrintError):
         l.append((time.time(), direction, json.loads(encoder.encode(htlc)), bh2u(preimage)))
         self.wallet.storage.put('lightning_payments_completed', l)
         self.wallet.storage.write()
+        self.network.trigger_callback('ln_payment_completed', direction, htlc, preimage)
 
     def list_invoices(self):
         report = self._list_invoices()