Add update-credentials command (#620)

* Add change credentials command

* Rename command and add prompts for credential update

kasa/cli.py

@@ -997,5 +997,28 @@ async def turn_on_behavior(dev: SmartBulb, type, last, preset):
     return await dev.set_turn_on_behavior(settings)
 
 
+@cli.command()
+@pass_dev
+@click.option(
+    "--username", required=True, prompt=True, help="New username to set on the device"
+)
+@click.option(
+    "--password", required=True, prompt=True, help="New password to set on the device"
+)
+async def update_credentials(dev, username, password):
+    """Update device credentials for authenticated devices."""
+    # Importing here as this is not really a public interface for now
+    from kasa.tapo import TapoDevice
+
+    if not isinstance(dev, TapoDevice):
+        raise NotImplementedError(
+            "Credentials can only be updated on authenticated devices."
+        )
+
+    click.confirm("Do you really want to replace the existing credentials?", abort=True)
+
+    return await dev.update_credentials(username, password)
+
+
 if __name__ == "__main__":
     cli()

kasa/tapo/tapodevice.py

@@ -321,3 +321,18 @@ class TapoDevice(SmartDevice):
                 raise
 
             _LOGGER.debug("Received an expected for wifi join, but this is expected")
+
+    async def update_credentials(self, username: str, password: str):
+        """Update device credentials.
+
+        This will replace the existing authentication credentials on the device.
+        """
+        t = self.internal_state["time"]
+        payload = {
+            "account": {
+                "username": base64.b64encode(username.encode()).decode(),
+                "password": base64.b64encode(password.encode()).decode(),
+            },
+            "time": t,
+        }
+        return await self.protocol.query({"set_qs_info": payload})