hww: smarter auto-selection of which device to pair with

scenario1:
- 2of2 multisig wallet with trezor1 and trezor2 keystores
- only trezor2 connected
- previously we would pair first keystore with connected device and then display error.
  now we will pair the device with the correct keystore on the first try

scenario2:
- standard wallet with trezor1 keystore
- trezor2 connected (different device)
- previously we would pair trezor2 with the keystore and then display error.
  now we will prompt the user to select which device to pair with (out of one)

related: #5789

electrum/plugins/coldcard/coldcard.py

@@ -4,7 +4,7 @@
 #
 import os, time, io
 import traceback
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 import struct
 
 from electrum import bip32
@@ -536,11 +536,12 @@ class ColdcardPlugin(HW_PluginBase):
         xpub = client.get_xpub(derivation, xtype)
         return xpub
 
-    def get_client(self, keystore, force_pair=True) -> 'CKCCClient':
+    def get_client(self, keystore, force_pair=True, *,
+                   devices=None, allow_user_interaction=True) -> Optional['CKCCClient']:
         # Acquire a connection to the hardware device (via USB)
-        devmgr = self.device_manager()
-        handler = keystore.handler
-        client = devmgr.client_for_keystore(self, handler, keystore, force_pair)
+        client = super().get_client(keystore, force_pair,
+                                    devices=devices,
+                                    allow_user_interaction=allow_user_interaction)
 
         if client is not None:
             client.ping_check()

electrum/plugins/digitalbitbox/digitalbitbox.py

@@ -741,10 +741,11 @@ class DigitalBitboxPlugin(HW_PluginBase):
         return xpub
 
 
-    def get_client(self, keystore, force_pair=True):
-        devmgr = self.device_manager()
-        handler = keystore.handler
-        client = devmgr.client_for_keystore(self, handler, keystore, force_pair)
+    def get_client(self, keystore, force_pair=True, *,
+                   devices=None, allow_user_interaction=True):
+        client = super().get_client(keystore, force_pair,
+                                    devices=devices,
+                                    allow_user_interaction=allow_user_interaction)
         if client is not None:
             client.check_device_dialog()
         return client

electrum/plugins/hw_wallet/plugin.py

@@ -83,8 +83,15 @@ class HW_PluginBase(BasePlugin):
         """
         raise NotImplementedError()
 
-    def get_client(self, keystore: 'Hardware_KeyStore', force_pair: bool = True) -> Optional['HardwareClientBase']:
-        raise NotImplementedError()
+    def get_client(self, keystore: 'Hardware_KeyStore', force_pair: bool = True, *,
+                   devices: Sequence['Device'] = None,
+                   allow_user_interaction: bool = True) -> Optional['HardwareClientBase']:
+        devmgr = self.device_manager()
+        handler = keystore.handler
+        client = devmgr.client_for_keystore(self, handler, keystore, force_pair,
+                                            devices=devices,
+                                            allow_user_interaction=allow_user_interaction)
+        return client
 
     def show_address(self, wallet: 'Abstract_Wallet', address, keystore: 'Hardware_KeyStore' = None):
         pass  # implemented in child classes

electrum/plugins/hw_wallet/qt.py

@@ -206,9 +206,11 @@ class QtPluginBase(object):
 
     @hook
     def load_wallet(self: Union['QtPluginBase', HW_PluginBase], wallet: 'Abstract_Wallet', window: ElectrumWindow):
-        for keystore in wallet.get_keystores():
-            if not isinstance(keystore, self.keystore_class):
-                continue
+        relevant_keystores = [keystore for keystore in wallet.get_keystores()
+                              if isinstance(keystore, self.keystore_class)]
+        if not relevant_keystores:
+            return
+        for keystore in relevant_keystores:
             if not self.libraries_available:
                 message = keystore.plugin.get_library_not_available_message()
                 window.show_error(message)
@@ -224,8 +226,31 @@ class QtPluginBase(object):
             keystore.handler = handler
             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 a pairing
-            keystore.thread.add(partial(self.get_client, keystore))
+        # 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
+
+        some_keystore = relevant_keystores[0]
+        some_keystore.thread.add(trigger_pairings)
 
     def _on_status_bar_button_click(self, *, window: ElectrumWindow, keystore: 'Hardware_KeyStore'):
         try:

electrum/plugins/keepkey/keepkey.py

@@ -179,10 +179,11 @@ class KeepKeyPlugin(HW_PluginBase):
 
         return client
 
-    def get_client(self, keystore, force_pair=True) -> Optional['KeepKeyClient']:
-        devmgr = self.device_manager()
-        handler = keystore.handler
-        client = devmgr.client_for_keystore(self, handler, keystore, force_pair)
+    def get_client(self, keystore, force_pair=True, *,
+                   devices=None, allow_user_interaction=True) -> Optional['KeepKeyClient']:
+        client = super().get_client(keystore, force_pair,
+                                    devices=devices,
+                                    allow_user_interaction=allow_user_interaction)
         # returns the client for a given keystore. can use xpub
         if client:
             client.used()

electrum/plugins/ledger/ledger.py

@@ -612,11 +612,12 @@ class LedgerPlugin(HW_PluginBase):
         xpub = client.get_xpub(derivation, xtype)
         return xpub
 
-    def get_client(self, keystore, force_pair=True):
+    def get_client(self, keystore, force_pair=True, *,
+                   devices=None, allow_user_interaction=True):
         # All client interaction should not be in the main GUI thread
-        devmgr = self.device_manager()
-        handler = keystore.handler
-        client = devmgr.client_for_keystore(self, handler, keystore, force_pair)
+        client = super().get_client(keystore, force_pair,
+                                    devices=devices,
+                                    allow_user_interaction=allow_user_interaction)
         # returns the client for a given keystore. can use xpub
         #if client:
         #    client.used()

electrum/plugins/safe_t/safe_t.py

@@ -141,10 +141,11 @@ class SafeTPlugin(HW_PluginBase):
 
         return client
 
-    def get_client(self, keystore, force_pair=True) -> Optional['SafeTClient']:
-        devmgr = self.device_manager()
-        handler = keystore.handler
-        client = devmgr.client_for_keystore(self, handler, keystore, force_pair)
+    def get_client(self, keystore, force_pair=True, *,
+                   devices=None, allow_user_interaction=True) -> Optional['SafeTClient']:
+        client = super().get_client(keystore, force_pair,
+                                    devices=devices,
+                                    allow_user_interaction=allow_user_interaction)
         # returns the client for a given keystore. can use xpub
         if client:
             client.used()

electrum/plugins/trezor/trezor.py

@@ -177,10 +177,11 @@ class TrezorPlugin(HW_PluginBase):
         # note that this call can still raise!
         return TrezorClientBase(transport, handler, self)
 
-    def get_client(self, keystore, force_pair=True) -> Optional['TrezorClientBase']:
-        devmgr = self.device_manager()
-        handler = keystore.handler
-        client = devmgr.client_for_keystore(self, handler, keystore, force_pair)
+    def get_client(self, keystore, force_pair=True, *,
+                   devices=None, allow_user_interaction=True) -> Optional['TrezorClientBase']:
+        client = super().get_client(keystore, force_pair,
+                                    devices=devices,
+                                    allow_user_interaction=allow_user_interaction)
         # returns the client for a given keystore. can use xpub
         if client:
             client.used()