Prompt to start Tor only if user has enabled autofuse for wallet

This fixes issue #1970.  It turns out we shouldn't be prompting users if
they want to enable Tor unconditionally, even if autofuse is disabled.
Many users have no idea what CashFusion is and may find this prompt
annoying.  We only kick off the task to maybe prompt the user if no Tor
port is found only after the user has actually enabled autofuse (or if
autofuse is on due to wallet settings).

The net result is:

- On startup, if wallet is set to autofuse in config, the prompt appears
as before

- On manual enable of wallet from the "no autofuse" state, the prompt
appears (this behavior is new).

- If wallet has autofuse disabled, no prompt appears for that wallet
if Tor is missing (this behavior fixes #1970).

Closes #1970.

plugins/fusion/qt.py

@@ -198,9 +198,6 @@ def callback(password):
             d.show()
             self.widgets.add(d)
 
-        # this runs at most once and only if absolutely no Tor ports are found
-        self._maybe_prompt_user_if_they_want_integrated_tor_if_no_tor_found()
-
     @hook
     def on_close_window(self, window):
         # Invoked when closing wallet or entire application
@@ -344,23 +341,34 @@ def cache_pw(cls, wallet, password):
         if window:
             window.gui_object.cache_password(wallet, password)
 
-    _integrated_tor_asked = [False, None]
-    def _maybe_prompt_user_if_they_want_integrated_tor_if_no_tor_found(self):
-        if any(self._integrated_tor_asked):
+    def enable_autofusing(self, wallet, password):
+        """ Overrides super, if super successfully turns on autofusing, kicks
+        off the timer to check that Tor is working. """
+        super().enable_autofusing(wallet, password)
+        if self.is_autofusing(wallet):
+            # ok, autofuse enable success -- kick of the timer task to check if
+            # Tor is good
+            do_in_main_thread(self._maybe_prompt_user_if_they_want_integrated_tor_if_no_tor_found, wallet)
+
+    _integrated_tor_timer = None
+    def _maybe_prompt_user_if_they_want_integrated_tor_if_no_tor_found(self, wallet):
+        if self._integrated_tor_timer:
             # timer already active or already prompted user
             return
         weak_self = weakref.ref(self)
+        weak_window = wallet.weak_window
+        if not weak_window or not weak_window():
+            # Something's wrong -- no window for wallet
+            return;
         def chk_tor_ok():
             self = weak_self()
             if not self:
                 return
-            self._integrated_tor_asked[1] = None  # kill QTimer reference
-            if self.active and self.gui and self.gui.windows and self.tor_port_good is None and not self._integrated_tor_asked[0]:
-                # prompt user to enable automatic Tor if not enabled and no auto-detected Tor ports were found
-                window = self.gui.windows[-1]
+            self._integrated_tor_timer = None  # kill QTimer reference
+            window = weak_window()
+            if window and self.active and self.gui and self.gui.windows and self.tor_port_good is None:
                 network = self.gui.daemon.network
                 if network and network.tor_controller.is_available() and not network.tor_controller.is_enabled():
-                    self._integrated_tor_asked[0] = True
                     icon_pm = icon_fusion_logo.pixmap(32)
                     answer = window.question(
                         _('CashFusion requires Tor to operate anonymously. Would'
@@ -399,11 +407,11 @@ def on_status(controller):
                                 window.show_error(_('There was an error starting the Tor client'))
                         network.tor_controller.status_changed.append(on_status)
                         network.tor_controller.set_enabled(True)
-        self._integrated_tor_asked[1] = t = QTimer()
+        self._integrated_tor_timer = t = QTimer()
         # if in 5 seconds no tor port, ask user if they want to enable the Tor
         t.timeout.connect(chk_tor_ok)
         t.setSingleShot(True)
-        t.start(5000)
+        t.start(2500)
 
     @hook
     def history_list_filter(self, history_list, h_item, label):