carrier ops; persistency; ui improvements; refactoring

userdata/persistency.py

@@ -0,0 +1,38 @@
+import pickle
+import os
+import shutil
+
+from game.game import Game
+
+
+def _save_file() -> str:
+    return "build/save"
+
+
+def _temporary_save_file() -> str:
+    return "build/save_tmp"
+
+
+def _save_file_exists() -> bool:
+    return os.path.exists(_save_file())
+
+
+def restore_game() -> Game:
+    if not _save_file_exists():
+        return None
+
+    try:
+        with open(_save_file(), "rb") as f:
+            return pickle.load(f)
+    except:
+        return None
+
+
+def save_game(game: Game) -> bool:
+    try:
+        with open(_temporary_save_file(), "wb") as f:
+            pickle.dump(game, f)
+            shutil.copy(_temporary_save_file(), _save_file())
+            return True
+    except:
+        return False