mqtt/payload: fix bitfields

2 files changed, 27 insertions, 31 deletions

diff --git a/src/home/mqtt/payload/base_payload.py b/src/home/mqtt/payload/base_payload.py
index c9ec907..108e0c0 100644
--- a/src/home/mqtt/payload/base_payload.py
+++ b/src/home/mqtt/payload/base_payload.py
@@ -1,7 +1,8 @@
 import abc
 import struct
+import re
 
-from typing import Generic, TypeVar
+from typing import Optional, Tuple
 
 
 class MQTTPayload(abc.ABC):
@@ -20,15 +21,9 @@ class MQTTPayload(abc.ABC):
         bf_progress = 0
 
         for field, field_type in self.__class__.__annotations__.items():
-            field_type_origin = None
-            if hasattr(field_type, '__extra__') or hasattr(field_type, '__origin__'):
-                try:
-                    field_type_origin = field_type.__extra__
-                except AttributeError:
-                    field_type_origin = field_type.__origin__
-
-            if field_type_origin is not None and issubclass(field_type_origin, MQTTPayloadBitField):
-                n, s, b = field_type.__args__
+            bfp = _bit_field_params(field_type)
+            if bfp:
+                n, s, b = bfp
                 if n != bf_number:
                     if bf_number != -1:
                         args.append(bf_arg)
@@ -61,15 +56,9 @@ class MQTTPayload(abc.ABC):
         bf_progress = 0
 
         for field, field_type in cls.__annotations__.items():
-            field_type_origin = None
-            if hasattr(field_type, '__extra__') or hasattr(field_type, '__origin__'):
-                try:
-                    field_type_origin = field_type.__extra__
-                except AttributeError:
-                    field_type_origin = field_type.__origin__
-
-            if field_type_origin is not None and issubclass(field_type_origin, MQTTPayloadBitField):
-                n, s, b = field_type.__args__
+            bfp = _bit_field_params(field_type)
+            if bfp:
+                n, s, b = bfp
                 if n != bf_number:
                     bf_number = n
                     bf_progress = 0
@@ -86,6 +75,7 @@ class MQTTPayload(abc.ABC):
             else:
                 kwargs[field] = cls._unpack_field(field, data[i])
             i += 1
+
         return cls(**kwargs)
 
     def _pack_field(self, name):
@@ -120,10 +110,16 @@ class MQTTPayloadCustomField(abc.ABC):
         pass
 
 
-NT = TypeVar('NT')  # number of bit field
-ST = TypeVar('ST')  # size in bytes
-BT = TypeVar('BT')  # size in bits of particular value
+def bit_field(seq_no: int, total_bits: int, bits: int):
+    return type(f'MQTTPayloadBitField_{seq_no}_{total_bits}_{bits}', (object,), {
+        'seq_no': seq_no,
+        'total_bits': total_bits,
+        'bits': bits
+    })
 
 
-class MQTTPayloadBitField(int, Generic[NT, ST, BT]):
-    pass
+def _bit_field_params(cl) -> Optional[Tuple[int, ...]]:
+    match = re.match(r'MQTTPayloadBitField_(\d+)_(\d+)_(\d)$', cl.__name__)
+    if match is not None:
+        return tuple([int(match.group(i)) for i in range(1, 4)])
+    return None
diff --git a/src/home/mqtt/payload/inverter.py b/src/home/mqtt/payload/inverter.py
index b3f4edd..1d4099c 100644
--- a/src/home/mqtt/payload/inverter.py
+++ b/src/home/mqtt/payload/inverter.py
@@ -1,6 +1,6 @@
 import struct
 
-from .base_payload import MQTTPayload, MQTTPayloadBitField
+from .base_payload import MQTTPayload, bit_field
 from typing import Tuple
 
 _mult_10 = lambda n: int(n*10)
@@ -57,12 +57,12 @@ class Status(MQTTPayload):
     pv2_input_voltage: float
 
     # H
-    mppt1_charger_status: MQTTPayloadBitField[0, 16, 2]
-    mppt2_charger_status: MQTTPayloadBitField[0, 16, 2]
-    battery_power_direction: MQTTPayloadBitField[0, 16, 2]
-    dc_ac_power_direction: MQTTPayloadBitField[0, 16, 2]
-    line_power_direction: MQTTPayloadBitField[0, 16, 2]
-    load_connected: MQTTPayloadBitField[0, 16, 1]
+    mppt1_charger_status: bit_field(0, 16, 2)
+    mppt2_charger_status: bit_field(0, 16, 2)
+    battery_power_direction: bit_field(0, 16, 2)
+    dc_ac_power_direction: bit_field(0, 16, 2)
+    line_power_direction: bit_field(0, 16, 2)
+    load_connected: bit_field(0, 16, 1)
 
 
 class Generation(MQTTPayload):