implement undo function

views/control.py

@@ -51,3 +51,34 @@ async def start_next_trick(req, resp):
             pass
     api.redirect(resp, '/control/', status_code=303)
 
+
+@api.route("/control/undo_last/")
+async def undo_last(req, resp):
+    hand_finished = the_game.is_hand_finished()
+    if the_game.played_cards:
+        if not hand_finished:
+            p, c = the_game.played_cards.pop()
+            the_game.active_player -= 1
+            p.add_card(c)
+            for ws in the_game.websockets:
+                try:
+                    await ws.send_text("reload")
+                except Exception as e:
+                    pass
+    else:
+        if the_game.num_tricks_played > 0:
+            the_game.num_tricks_played -= 1;
+            the_game.played_cards = the_game.last_trick;
+            the_game.active_player = len(the_game.players) - 1
+            player, _ = the_game.get_trick_winner()
+            player.tricks_taken -= 1
+            the_game.players_ordered = [p for p, _ in the_game.played_cards]
+            p, c = the_game.played_cards.pop()
+            p.add_card(c)
+            for ws in the_game.websockets:
+                try:
+                    await ws.send_text("reload")
+                except Exception as e:
+                    pass
+
+    api.redirect(resp, '/control/', status_code=303)