qt paytoedit: evaluate text on textChanged(), but no network requests

- add param to _check_text to toggle if network requests are allowed ("full check")
- every 0.5 sec, if the textedit has no focus, do full check
- on textChanged()
  - detect if user copy-pasted by comparing current text against clipboard contents,
    if so, do full check
  - otherwise, do partial check
- on clicking ButtonsWidget btns (scan qr, paste, read file), do full check

electrum/gui/qt/main_window.py

@@ -916,7 +916,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
             self.update_status()
         # resolve aliases
         # FIXME this might do blocking network calls that has a timeout of several seconds
-        self.payto_e.check_text()
+        self.payto_e.on_timer_check_text()
         self.notify_transactions()
 
     def format_amount(self, amount_sat, is_diff=False, whitespaces=False) -> str:
@@ -1527,7 +1527,6 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         from .paytoedit import PayToEdit
         self.amount_e = BTCAmountEdit(self.get_decimal_point)
         self.payto_e = PayToEdit(self)
-        self.payto_e.addPasteButton()
         msg = (_("Recipient of the funds.") + "\n\n"
                + _("You may enter a Bitcoin address, a label from your list of contacts "
                    "(a list of completions will be proposed), "
@@ -2252,17 +2251,17 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         else:
             self.payment_request_error_signal.emit()
 
-    def set_lnurl6_bech32(self, lnurl: str):
+    def set_lnurl6_bech32(self, lnurl: str, *, can_use_network: bool = True):
         try:
             url = decode_lnurl(lnurl)
         except LnInvoiceException as e:
             self.show_error(_("Error parsing Lightning invoice") + f":\n{e}")
             return
-        self.set_lnurl6_url(url)
+        self.set_lnurl6_url(url, can_use_network=can_use_network)
 
-    def set_lnurl6_url(self, url: str, *, lnurl_data: LNURL6Data = None):
+    def set_lnurl6_url(self, url: str, *, lnurl_data: LNURL6Data = None, can_use_network: bool = True):
         domain = urlparse(url).netloc
-        if lnurl_data is None:
+        if lnurl_data is None and can_use_network:
             lnurl_data = request_lnurl(url, self.network.send_http_on_proxy)
         if not lnurl_data:
             return
@@ -2303,9 +2302,10 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         self._is_onchain = b
         self.max_button.setEnabled(b)
 
-    def set_bip21(self, text: str):
+    def set_bip21(self, text: str, *, can_use_network: bool = True):
+        on_bip70_pr = self.on_pr if can_use_network else None
         try:
-            out = util.parse_URI(text, self.on_pr)
+            out = util.parse_URI(text, on_bip70_pr)
         except InvalidBitcoinURI as e:
             self.show_error(_("Error parsing URI") + f":\n{e}")
             return
@@ -2313,7 +2313,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         r = out.get('r')
         sig = out.get('sig')
         name = out.get('name')
-        if r or (name and sig):
+        if (r or (name and sig)) and can_use_network:
             self.prepare_for_payment_request()
             return
         address = out.get('address')
@@ -2322,7 +2322,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         message = out.get('message')
         lightning = out.get('lightning')
         if lightning:
-            self.handle_payment_identifier(lightning)
+            self.handle_payment_identifier(lightning, can_use_network=can_use_network)
             return
         # use label as description (not BIP21 compliant)
         if label and not message:
@@ -2334,7 +2334,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         if amount:
             self.amount_e.setAmount(amount)
 
-    def handle_payment_identifier(self, text: str):
+    def handle_payment_identifier(self, text: str, *, can_use_network: bool = True):
         """Takes
         Lightning identifiers:
         * lightning-URI (containing bolt11 or lnurl)
@@ -2350,7 +2350,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         invoice_or_lnurl = maybe_extract_lightning_payment_identifier(text)
         if invoice_or_lnurl:
             if invoice_or_lnurl.startswith('lnurl'):
-                self.set_lnurl6_bech32(invoice_or_lnurl)
+                self.set_lnurl6_bech32(invoice_or_lnurl, can_use_network=can_use_network)
             else:
                 self.set_bolt11(invoice_or_lnurl)
         elif text.lower().startswith(util.BITCOIN_BIP21_URI_SCHEME + ':'):

electrum/gui/qt/paytoedit.py

@@ -63,9 +63,10 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
 
     def __init__(self, win: 'ElectrumWindow'):
         CompletionTextEdit.__init__(self)
-        ScanQRTextEdit.__init__(self, config=win.config)
+        ScanQRTextEdit.__init__(self, config=win.config, setText=self._on_input_btn)
         Logger.__init__(self)
         self.win = win
+        self.app = win.app
         self.amount_edit = win.amount_e
         self.setFont(QFont(MONOSPACE_FONT))
         document = self.document()
@@ -84,6 +85,8 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         self.heightMax = (self.fontSpacing * 10) + self.verticalMargins
 
         self.c = None
+        self.addPasteButton(setText=self._on_input_btn)
+        self.textChanged.connect(self._on_text_changed)
         self.outputs = []  # type: List[PartialTxOutput]
         self.errors = []  # type: List[PayToLineError]
         self.is_pr = False
@@ -100,8 +103,8 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
 
     def setTextNoCheck(self, text: str):
         """Sets the text, while also ensuring the new value will not be resolved/checked."""
-        self.setText(text)
         self.previous_payto = text
+        self.setText(text)
 
     def do_clear(self):
         self.is_pr = False
@@ -168,19 +171,27 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         assert bitcoin.is_address(address)
         return address
 
-    def check_text(self):
+    def _on_input_btn(self, text: str):
+        self.setText(text)
+        self._check_text(full_check=True)
+
+    def _on_text_changed(self):
+        if self.app.clipboard().text() == self.toPlainText():
+            # user likely pasted from clipboard
+            self._check_text(full_check=True)
+        else:
+            self._check_text(full_check=False)
+
+    def on_timer_check_text(self):
         if self.hasFocus():
             return
-        if self.is_pr:
-            return
-        text = str(self.toPlainText())
-        text = text.strip()  # strip whitespaces
-        if text == self.previous_payto:
-            return
-        self.previous_payto = text
-        self._check_text()
+        self._check_text(full_check=True)
 
-    def _check_text(self):
+    def _check_text(self, *, full_check: bool):
+        if self.previous_payto == str(self.toPlainText()).strip():
+            return
+        if full_check:
+            self.previous_payto = str(self.toPlainText()).strip()
         self.errors = []
         if self.is_pr:
             return
@@ -194,10 +205,10 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         if len(lines) == 1:
             data = lines[0]
             try:
-                self.win.handle_payment_identifier(data)
+                self.win.handle_payment_identifier(data, can_use_network=full_check)
             except LNURLError as e:
                 self.logger.exception("")
-                self.show_error(e)
+                self.win.show_error(e)
             except ValueError:
                 pass
             else:
@@ -218,17 +229,18 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
                 self.win.set_onchain(True)
                 self.win.lock_amount(False)
                 return
-            # try lightning address lnurl-16 (note: names can collide with openalias, so order matters)
-            lnurl_data = self._resolve_lightning_address_lnurl16(data)
-            if lnurl_data:
-                url = lightning_address_to_url(data)
-                self.win.set_lnurl6_url(url, lnurl_data=lnurl_data)
-                return
-            # try openalias
-            oa_data = self._resolve_openalias(data)
-            if oa_data:
-                self._set_openalias(key=data, data=oa_data)
-                return
+            if full_check:  # network requests
+                # try lightning address lnurl-16 (note: names can collide with openalias, so order matters)
+                lnurl_data = self._resolve_lightning_address_lnurl16(data)
+                if lnurl_data:
+                    url = lightning_address_to_url(data)
+                    self.win.set_lnurl6_url(url, lnurl_data=lnurl_data)
+                    return
+                # try openalias
+                oa_data = self._resolve_openalias(data)
+                if oa_data:
+                    self._set_openalias(key=data, data=oa_data)
+                    return
         else:
             # there are multiple lines
             self._parse_as_multiline(lines, raise_errors=False)

electrum/gui/qt/qrtextedit.py

@@ -1,3 +1,5 @@
+from typing import Callable
+
 from electrum.i18n import _
 from electrum.plugin import run_hook
 from electrum.simple_config import SimpleConfig
@@ -21,11 +23,16 @@ class ShowQRTextEdit(ButtonsTextEdit):
 
 class ScanQRTextEdit(ButtonsTextEdit, MessageBoxMixin):
 
-    def __init__(self, text="", allow_multi: bool = False, *, config: SimpleConfig):
+    def __init__(
+            self, text="", allow_multi: bool = False,
+            *,
+            config: SimpleConfig,
+            setText: Callable[[str], None] = None,
+    ):
         ButtonsTextEdit.__init__(self, text)
         self.setReadOnly(False)
-        self.add_file_input_button(config=config, show_error=self.show_error)
-        self.add_qr_input_button(config=config, show_error=self.show_error, allow_multi=allow_multi)
+        self.add_file_input_button(config=config, show_error=self.show_error, setText=setText)
+        self.add_qr_input_button(config=config, show_error=self.show_error, allow_multi=allow_multi, setText=setText)
         run_hook('scan_text_edit', self)
 
     def contextMenuEvent(self, e):