hww: move trigger_pairings to DeviceMgr

electrum/plugin.py

@@ -43,7 +43,7 @@ from .logging import get_logger, Logger
 
 if TYPE_CHECKING:
     from .plugins.hw_wallet import HW_PluginBase, HardwareClientBase, HardwareHandlerBase
-    from .keystore import Hardware_KeyStore
+    from .keystore import Hardware_KeyStore, KeyStore
     from .wallet import Abstract_Wallet
 
 
@@ -776,3 +776,55 @@ class DeviceMgr(ThreadJob):
         except ImportError:
             ret["hidapi.version"] = None
         return ret
+
+    def trigger_pairings(
+            self,
+            keystores: Sequence['KeyStore'],
+            *,
+            allow_user_interaction: bool = True,
+            devices: Sequence['Device'] = None,
+    ) -> None:
+        """Given a list of keystores, try to pair each with a connected hardware device.
+
+        E.g. for a multisig-wallet, it is more user-friendly to use this method than to
+        try to pair each keystore individually. Consider the following scenario:
+        - three hw keystores in a 2-of-3 multisig wallet, devices d2 (for ks2) and d3 (for ks3) are connected
+        - assume none of the devices are paired yet
+        1. if we tried to individually pair keystores, we might try with ks1 first
+           - but ks1 cannot be paired automatically, as neither d2 nor d3 matches the stored fingerprint
+           - the user might then be prompted if they want to manually pair ks1 with either d2 or d3,
+             which is confusing and error-prone. It's especially problematic if the hw device does
+             not support labels (such as Ledger), as then the user cannot easily distinguish
+             same-type devices. (see #4199)
+        2. instead, if using this method, we would auto-pair ks2-d2 and ks3-d3 first,
+           and then tell the user ks1 could not be paired (and there are no devices left to try)
+        """
+        from .keystore import Hardware_KeyStore
+        keystores = [ks for ks in keystores if isinstance(ks, Hardware_KeyStore)]
+        if not keystores:
+            return
+        if devices is None:
+            devices = self.scan_devices()
+        # first pair with all devices that can be auto-selected
+        for ks in keystores:
+            try:
+                ks.plugin.get_client(
+                    keystore=ks,
+                    force_pair=True,
+                    allow_user_interaction=False,
+                    devices=devices,
+                )
+            except UserCancelled:
+                pass
+        if allow_user_interaction:
+            # now do manual selections
+            for ks in keystores:
+                try:
+                    ks.plugin.get_client(
+                        keystore=ks,
+                        force_pair=True,
+                        allow_user_interaction=True,
+                        devices=devices,
+                    )
+                except UserCancelled:
+                    pass

electrum/plugins/hw_wallet/qt.py

@@ -227,28 +227,8 @@ class QtPluginBase(object):
             keystore.thread = TaskThread(window, on_error=partial(self.on_task_thread_error, window, keystore))
             self.add_show_address_on_hw_device_button_for_receive_addr(wallet, keystore, window)
         # Trigger pairings
-        def trigger_pairings():
         devmgr = self.device_manager()
-            devices = devmgr.scan_devices()
-            # first pair with all devices that can be auto-selected
-            for keystore in relevant_keystores:
-                try:
-                    self.get_client(keystore=keystore,
-                                    force_pair=True,
-                                    allow_user_interaction=False,
-                                    devices=devices)
-                except UserCancelled:
-                    pass
-            # now do manual selections
-            for keystore in relevant_keystores:
-                try:
-                    self.get_client(keystore=keystore,
-                                    force_pair=True,
-                                    allow_user_interaction=True,
-                                    devices=devices)
-                except UserCancelled:
-                    pass
-
+        trigger_pairings = partial(devmgr.trigger_pairings, relevant_keystores, allow_user_interaction=True)
         some_keystore = relevant_keystores[0]
         some_keystore.thread.add(trigger_pairings)