st3m/utils: add save_file_if_changed function

python_payload/apps/w1f1/__init__.py

@@ -3,6 +3,7 @@ from st3m.input import InputState
 from st3m.goose import Optional
 from st3m.ui.view import ViewManager
 from st3m.settings import SETTINGS_JSON_FILE
+from st3m.utils import save_file_if_changed
 from ctx import Context
 import network
 import leds
@@ -210,23 +211,19 @@ class WifiApp(Application):
         settings_json["system"]["wifi"]["ssid"] = ssid
         settings_json["system"]["wifi"]["psk"] = psk
 
-        with open(SETTINGS_JSON_FILE, "w") as f:
-            json.dump(settings_json, f)
+        save_file_if_changed(SETTINGS_JSON_FILE, json.dumps(settings_json))
 
     def add_wlan_to_config_json(self, ssid: str, psk: str) -> None:
         self._wifi_config["networks"][ssid] = {"psk": psk}
         self.save_config_json()
 
     def save_config_json(self) -> None:
-        with open(self.WIFI_CONFIG_FILE, "w") as f:
-            json.dump(self._wifi_config, f)
+        config_str = json.dumps(self._wifi_config)
+        save_file_if_changed(self.WIFI_CONFIG_FILE, config_str)
 
         if sd_card_plugged():
             try:
-                if os.path.exists(self.WIFI_CONFIG_FILE_SD):
-                    os.remove(self.WIFI_CONFIG_FILE_SD)
-
-                copy_across_devices(self.WIFI_CONFIG_FILE, self.WIFI_CONFIG_FILE_SD)
+                save_file_if_changed(self.WIFI_CONFIG_FILE_SD, config_str)
             except OSError as e:
                 print("SD issue:", str(e), ":(")
 

python_payload/st3m/settings.py

@@ -20,7 +20,7 @@ from st3m.goose import (
     Optional,
     Callable,
 )
-from st3m.utils import reduce
+from st3m.utils import reduce, save_file_if_changed
 
 log = logging.Log(__name__, level=logging.INFO)
 
@@ -319,16 +319,20 @@ def save_all() -> None:
     Save all settings to flash.
     """
     res: Dict[str, Any] = {}
+    saved_settings = False
     for setting in load_save_settings:
         res = _update(res, setting.save())
     try:
-        with open(SETTINGS_JSON_FILE, "w") as f:
-            json.dump(res, f)
+        saved_settings = save_file_if_changed(SETTINGS_JSON_FILE, json.dumps(res))
     except Exception as e:
         log.warning("Could not save settings: " + str(e))
         return
 
-    log.info("Saved settings to flash")
+    log.info(
+        "Saved settings to flash"
+        if saved_settings
+        else "Skipped saving settings to flash as nothing changed"
+    )
 
 
 load_all()

python_payload/st3m/utils.py

 import math
+import os
 
 try:
     import inspect
@@ -121,4 +122,19 @@ def get_function_args(fun: Any) -> list[str]:
         raise NotImplementedError("No implementation of getfullargspec found")
 
 
+def save_file_if_changed(filename: str, desired_contents: str) -> bool:
+    save = False
+    if not os.path.exists(filename):
+        save = True
+    else:
+        with open(filename, "r") as f:
+            save = f.read() != desired_contents
+
+    if save:
+        with open(filename, "w") as f:
+            f.write(desired_contents)
+
+    return save
+
+
 tau = math.pi * 2