doorcontrol: Move HID card number decoding out of database query

Not really needed, and hard to make portable

doorcontrol/admin.py

@@ -44,9 +44,6 @@ class HIDEventAdmin(DjangoObjectActions, admin.ModelAdmin):
     readonly_fields = ["decoded_card_number"]
     changelist_actions = ("refresh_all_doors",)
 
-    def get_queryset(self, request):
-        return super().get_queryset(request).with_decoded_card_number()
-
     @admin.display(boolean=True)
     def _is_red(self, obj):
         return obj.is_red

doorcontrol/hid/Credential.py

@@ -1,41 +1,62 @@
+import dataclasses
+from typing import Literal
+
 import bitstring
 
 # Reference for H10301 card format:
 # https://www.hidglobal.com/sites/default/files/hid-understanding_card_data_formats-wp-en.pdf
 
 
+class InvalidHexCode(Exception):
+    pass
+
+
+class Not26Bit(InvalidHexCode):
+    def __init__(self) -> None:
+        super().__init__("Card number > 26 bits")
+
+
+class InvalidParity(InvalidHexCode):
+    def __init__(self, even_odd: Literal["even", "odd"]) -> None:
+        super().__init__(f"Bad {even_odd} parity")
+
+
+@dataclasses.dataclass
 class Credential:
-    def __init__(self, code=None, hex_code=None):
-        if code is None and hex_code is None:
-            raise TypeError("Must set either code or hex for a Credential")
-        elif code is not None and hex_code is not None:
-            raise TypeError("Cannot set both code and hex for a Credential")
-        elif code is not None:
-            self.bits = bitstring.pack(
-                "0b000000, 0b0, uint:8=facility, uint:16=number, 0b0",
-                facility=code[0],
-                number=code[1],
+    bits: bitstring.Bits
+
+    @classmethod
+    def from_code(cls, facility=int, card_number=int) -> "Credential":
+        bits = bitstring.pack(
+            "0b000000, 0b0, uint:8=facility, uint:16=card_number, 0b0",
+            facility=facility,
+            card_number=card_number,
         )
-            self.bits[6] = self.bits[7:19].count(1) % 2  # even parity
-            self.bits[31] = not (self.bits[19:31].count(1) % 2)  # odd parity
-        elif hex_code is not None:
-            self.bits = bitstring.Bits(hex=hex_code)
+        bits[6] = bits[7:19].count(1) % 2  # even parity
+        bits[31] = bits[19:31].count(0) % 2  # odd parity
+        return cls(bits)
 
-    def __repr__(self):
-        return f"Credential({self.code})"
+    @classmethod
+    def from_hex(cls, hex_code: str) -> "Credential":
+        bits = bitstring.Bits(hex=hex_code)
 
-    def __eq__(self, other):
-        return self.bits == other.bits
+        if bits[:6].any(1):
+            raise Not26Bit
+        if bits[6] != bits[7:19].count(1) % 2:
+            raise InvalidParity("even")
+        if bits[31] != (bits[19:31].count(0) % 2):
+            raise InvalidParity("odd")
 
-    def __hash__(self):
-        return self.bits.int
+        return cls(bits)
 
     @property
-    def code(self):
-        facility = self.bits[7:15].uint
-        code = self.bits[15:31].uint
-        return (facility, code)
+    def facility_code(self) -> int:
+        return self.bits[7:15].uint
 
     @property
-    def hex(self):
+    def card_number(self) -> int:
+        return self.bits[15:31].uint
+
+    @property
+    def hex(self) -> str:
         return self.bits.hex.upper()

doorcontrol/models.py

@@ -3,14 +3,14 @@ from typing import Self
 
 from django.conf import settings
 from django.db import models
-from django.db.models import F, Func, OuterRef, Q, Subquery
-from django.db.models.functions import Mod
+from django.db.models import OuterRef, Q, Subquery
 from django.utils import timezone
 from django.utils.functional import cached_property
 
 from membershipworks.models import Flag as MembershipWorksFlag
 from membershipworks.models import Member
 
+from .hid.Credential import Credential, InvalidHexCode
 from .hid.DoorController import DoorController
 
 
@@ -102,42 +102,6 @@ class AttributeScheduleRule(AbstractScheduleRule):
 
 
 class HIDEventQuerySet(models.QuerySet):
-    def with_decoded_card_number(self):
-        # TODO: CONV and BIT_COUNT are MySQL/MariaDB specific
-        class Conv(Func):
-            function = "CONV"
-            arity = 3
-            # This is technically not true, but fine for my purposes
-            output_field = models.IntegerField()
-
-        class BitCount(Func):
-            function = "BIT_COUNT"
-            arity = 1
-
-        return (
-            self.alias(card_number=Conv(F("raw_card_number"), 16, 10))
-            .alias(more_than_26_bits=F("card_number").bitrightshift(26))
-            .annotate(card_is_26_bit=Q(more_than_26_bits=0))
-            .alias(
-                parity_a=Mod(
-                    BitCount(F("card_number").bitrightshift(1).bitand(0xFFF)), 2
-                ),
-                parity_b=Mod(
-                    BitCount(F("card_number").bitrightshift(13).bitand(0xFFF)), 2
-                ),
-            )
-            .annotate(
-                card_is_valid_26_bit=~Q(parity_a=F("card_number").bitand(1))
-                & Q(parity_b=F("card_number").bitrightshift(25).bitand(1))
-            )
-            .annotate(
-                card_number_26_bit=F("card_number").bitrightshift(1).bitand(0xFFFF),
-                card_facility_code_26_bit=F("card_number")
-                .bitrightshift(17)
-                .bitand(0xFF),
-            )
-        )
-
     def with_member_id(self):
         return self.annotate(
             member_id=Subquery(
@@ -302,13 +266,10 @@ class HIDEvent(models.Model):
         return event_types.get(self.event_type, f"Unknown Event Type {self.event_type}")
 
     def decoded_card_number(self) -> str | None:
-        """Requires annotations from `with_decoded_card_number`"""
         if self.raw_card_number is None:
             return None
-        elif self.card_is_26_bit:
-            if self.card_is_valid_26_bit:
-                return f"{self.card_facility_code_26_bit} - {self.card_number_26_bit}"
-            else:
-                return "Invalid"
-        else:
-            return "Not 26 bit card"
+        try:
+            cred = Credential.from_hex(self.raw_card_number)
+            return f"{cred.facility_code} - {cred.card_number}"
+        except InvalidHexCode as e:
+            return f"Invalid: {e}"

doorcontrol/tables.py

@@ -20,6 +20,7 @@ class UnitTimeTable(tables.Table):
 
 
 class DeniedAccessTable(tables.Table):
+    decoded_card_number = tables.Column(orderable=False)
     name = tables.TemplateColumn(
         "{{ record.forename|default:'' }} {{ record.surname|default:'' }}"
     )

doorcontrol/tasks/update_doors.py

@@ -38,12 +38,10 @@ class DoorMember:
     def from_membershipworks_member(cls, member: Member, door: Door):
         if member.access_card_facility_code and member.access_card_number:
             credentials = {
-                Credential(
-                    code=(
+                Credential.from_code(
                     member.access_card_facility_code,
                     member.access_card_number,
                 )
-                )
             }
         else:
             credentials = set()
@@ -108,7 +106,7 @@ class DoorMember:
             },
             cardholderID=data.attrib["cardholderID"],
             credentials={
-                Credential(hex_code=(c.attrib["rawCardNumber"]))
+                Credential.from_hex(c.attrib["rawCardNumber"])
                 for c in data.findall("{*}Credential")
             },
             schedules={r.attrib["scheduleName"] for r in data.findall("{*}Role")},
@@ -172,9 +170,11 @@ class DoorMember:
                 xml_credentials = [
                     E.Credential(
                         {
-                            "formatName": str(credential.code[0]),
-                            "cardNumber": str(credential.code[1]),
-                            "formatID": self.door.card_formats[str(credential.code[0])],
+                            "formatName": str(credential.facility_code),
+                            "cardNumber": str(credential.card_number),
+                            "formatID": self.door.card_formats[
+                                str(credential.facility_code)
+                            ],
                             "isCard": "true",
                             "cardholderID": self.cardholderID,
                         }
@@ -222,7 +222,7 @@ def update_door(door: Door, dry_run: bool = False):
     }
 
     existing_door_credentials = {
-        Credential(hex_code=c.attrib["rawCardNumber"])
+        Credential.from_hex(c.attrib["rawCardNumber"])
         for c in door.controller.get_credentials()
     }
 

doorcontrol/views.py

@@ -206,12 +206,7 @@ class DeniedAccess(BaseAccessReport):
         denied_event_types = [
             t for t in HIDEvent.EventType if t.name.startswith("DENIED_ACCESS")
         ]
-        return (
-            super()
-            .get_table_data()
-            .filter(event_type__in=denied_event_types)
-            .with_decoded_card_number()
-        )
+        return super().get_table_data().filter(event_type__in=denied_event_types)
 
 
 @register_report