Fix UPS functionality for multiple devices

bmspy/ups.py

@@ -9,6 +9,7 @@ import socket
 from collections import deque
 
 from bmspy import client
+from bmspy.classes import UPS, BMSScalarField
 
 DAEMON_UPDATE_PERIOD = 30
 
@@ -18,6 +19,46 @@ warning_sent = False
 alert_sent = False
 
 
+def _get_field_value(device: UPS, field_name: str) -> float | None:
+    """Return the raw_value of a named BMSScalarField from a UPS, or None if not found."""
+    for name, field in device.items():
+        if name == field_name and isinstance(field, BMSScalarField):
+            return field.raw_value
+    return None
+
+
+def _resolve_ups_device(data: dict[str, UPS], requested: str | None) -> str | None:
+    """Return the device name to monitor, or None and print an error if the selection is invalid.
+
+    Rules:
+    - No devices → error.
+    - requested is set and found → use it.
+    - requested is set but not found → error listing available devices.
+    - requested is None and exactly one device → use it.
+    - requested is None and multiple devices → error; user must specify one.
+    """
+    if not data:
+        print("Error: no UPS devices found")
+        return None
+    if requested is not None:
+        if requested not in data:
+            print(
+                "Error: UPS '{}' not found. Available: {}".format(
+                    requested, ", ".join(sorted(data))
+                )
+            )
+            return None
+        return requested
+    if len(data) > 1:
+        print(
+            "Error: multiple UPS devices found, specify one with --device: {}".format(
+                ", ".join(sorted(data))
+            )
+        )
+        return None
+    return next(iter(data))
+
+
 def handle_shutdown(action: str = "cancel", delay: int = 0, debug: int = 0) -> None:
     """Schedule or cancel a system shutdown; only schedules once per incident."""
     global scheduled_shutdown
@@ -157,6 +198,14 @@ def main() -> None:
         default="/run/bmspy/bms",
         help="Socket to communicate with daemon",
     )
+    parser.add_argument(
+        "--device",
+        dest="device",
+        action="store",
+        default=None,
+        metavar="NAME",
+        help="Name of the UPS device to monitor (required if multiple devices are available)",
+    )
     parser.add_argument(
         "--verbose",
         "-v",
@@ -173,10 +222,19 @@ def main() -> None:
     client.handle_registration(args.socket, "ups", debug)
     atexit.register(client.handle_registration, args.socket, "ups", debug)
 
+    initial_data = client.read_data(args.socket, "ups")
+    device_name = _resolve_ups_device(initial_data, args.device)
+    if device_name is None:
+        return
+
     history = deque()
     while True:
-        data = client.read_data(args.socket, "ups")
-        history.append(data)
+        data = client.read_data(args.socket, "ups", device=device_name)
+        device_obj = data.get(device_name)
+        if device_obj is None:
+            time.sleep(DAEMON_UPDATE_PERIOD)
+            continue
+        history.append(device_obj)
 
         # Remove the oldest data from the history
         while len(history) > 10:
@@ -192,19 +250,30 @@ def main() -> None:
             time.sleep(DAEMON_UPDATE_PERIOD)
             continue
 
-        current_amps = float(data["bms_current_amps"]["raw_value"])
-        charge_ratio = float(data["bms_capacity_charge_ratio"]["raw_value"]) * 100
-        comparison_1_current_amps = float(comparison_1["bms_current_amps"]["raw_value"])
+        current_amps = float(_get_field_value(device_obj, "bms_current_amps") or 0.0)
+        charge_ratio = (
+            float(_get_field_value(device_obj, "bms_capacity_charge_ratio") or 0.0) * 100
+        )
+        comparison_1_current_amps = float(
+            _get_field_value(comparison_1, "bms_current_amps") or 0.0
+        )
         comparison_1_charge_ratio = (
-            float(comparison_1["bms_capacity_charge_ratio"]["raw_value"]) * 100
+            float(_get_field_value(comparison_1, "bms_capacity_charge_ratio") or 0.0)
+            * 100
+        )
+        comparison_2_current_amps = float(
+            _get_field_value(comparison_2, "bms_current_amps") or 0.0
         )
-        comparison_2_current_amps = float(comparison_2["bms_current_amps"]["raw_value"])
         comparison_2_charge_ratio = (
-            float(comparison_2["bms_capacity_charge_ratio"]["raw_value"]) * 100
+            float(_get_field_value(comparison_2, "bms_capacity_charge_ratio") or 0.0)
+            * 100
+        )
+        comparison_3_current_amps = float(
+            _get_field_value(comparison_3, "bms_current_amps") or 0.0
         )
-        comparison_3_current_amps = float(comparison_3["bms_current_amps"]["raw_value"])
         comparison_3_charge_ratio = (
-            float(comparison_3["bms_capacity_charge_ratio"]["raw_value"]) * 100
+            float(_get_field_value(comparison_3, "bms_capacity_charge_ratio") or 0.0)
+            * 100
         )
 
         if debug > 1: