feat: add Command classes

src/command.py

@@ -0,0 +1,66 @@
+from __future__ import annotations
+
+import abc
+from enum import IntEnum
+import struct
+from typing import Type
+
+
+class CommandType(IntEnum):
+    CAR_CONTROL = 0
+
+
+class CarControl(IntEnum):
+    FORWARD = 0
+    BACKWARD = 1
+    LEFT = 2
+    RIGHT = 3
+
+
+class Command(abc.ABC):
+    TYPE: CommandType
+    REGISTRY: dict[CommandType, Type[Command]] = {}
+
+    def __init_subclass__(cls) -> None:
+        super().__init_subclass__()
+        if cls.TYPE in Command.REGISTRY:
+            raise ValueError(
+                f"Command type {cls.TYPE} already registered by {Command.REGISTRY[cls.TYPE]}"
+            )
+        Command.REGISTRY[cls.TYPE] = cls
+
+    @abc.abstractmethod
+    def get_payload(self) -> bytes: ...
+
+    def pack(self) -> bytes:
+        payload: bytes = self.get_payload()
+        return struct.pack(">B", self.TYPE) + payload
+
+    @staticmethod
+    def unpack(data: bytes) -> Command:
+        type: CommandType = CommandType(data[0])
+        return Command.REGISTRY[type].from_payload(data[1:])
+
+    @classmethod
+    @abc.abstractmethod
+    def from_payload(cls, payload: bytes) -> Command: ...
+
+
+class ControlCommand(Command):
+    TYPE = CommandType.CAR_CONTROL
+    __match_args__ = ("control", "active")
+
+    def __init__(self, control: CarControl, active: bool) -> None:
+        super().__init__()
+        self.control: CarControl = control
+        self.active: bool = active
+
+    def get_payload(self) -> bytes:
+        return struct.pack(">B", (self.control << 1) | self.active)
+
+    @classmethod
+    def from_payload(cls, payload: bytes) -> Command:
+        value: int = payload[0]
+        active: bool = (value & 1) == 1
+        control: int = value >> 1
+        return ControlCommand(CarControl(control), active)