From bb480f26d2c96526958e2a980ceb7cc5ac0aac12 Mon Sep 17 00:00:00 2001
From: Andreas Berthoud <andreasberthoud@gmail.com>
Date: Tue, 27 Jul 2021 19:16:50 +0200
Subject: [PATCH] backend: Add register function for Request and Response
 classes

---
 backend/monsun_backend/command_execution.py |  23 ++---
 backend/monsun_backend/commands.py          | 101 ++++++++++++++------
 2 files changed, 82 insertions(+), 42 deletions(-)

diff --git a/backend/monsun_backend/command_execution.py b/backend/monsun_backend/command_execution.py
index 95eb0e5..c0d796f 100644
--- a/backend/monsun_backend/command_execution.py
+++ b/backend/monsun_backend/command_execution.py
@@ -22,6 +22,7 @@ from .commands import CommandId
 from .commands import CommandTarget
 from .commands import Request
 from .commands import Response
+from .commands import get_response_class
 from .container import get_initialize_container
 
 _logger = logging.getLogger(__file__)
@@ -343,21 +344,17 @@ class SerialReceiver:
                     data=command_interpreter.payload,
                 )
                 commands_received.append(command)
-            elif command_id == CommandId.command_heartbeat_response:
-                responses_received.append(
-                    commands.HeartbeatResponse(command_interpreter.payload),
-                )
-            elif command_id == CommandId.command_led_response:
-                responses_received.append(
-                    commands.LEDResponse(command_interpreter.payload),
-                )
-            elif command_id == CommandId.command_gp_response:
-                responses_received.append(
-                    commands.GPResponse(command_interpreter.payload),
-                )
-            else:
+                continue
+
+            try:
+                response_class = get_response_class(command_id=command_id)
+            except KeyError:
                 raise RuntimeError
 
+            responses_received.append(
+                response_class(command_interpreter.payload),
+            )
+
         return commands_received, responses_received
 
 
diff --git a/backend/monsun_backend/commands.py b/backend/monsun_backend/commands.py
index 02e4648..146a2d2 100644
--- a/backend/monsun_backend/commands.py
+++ b/backend/monsun_backend/commands.py
@@ -5,6 +5,8 @@ from enum import Enum
 from random import randint
 from struct import pack
 from struct import unpack
+from typing import Dict
+from typing import Type
 from typing import Union
 
 from serial import Serial
@@ -31,35 +33,6 @@ class CommandTarget(Enum):
     server = 1
 
 
-def get_command_id_from_name(name: str) -> CommandId:
-    return {
-        "log": CommandId.command_log,
-        "led": CommandId.command_led_request,
-        "gp": CommandId.command_gp_request,
-    }[name]
-
-
-def get_request_class(
-    command_id: CommandId,
-):
-    return {
-        CommandId.command_log: LogCommand,
-        CommandId.command_heartbeat_request: HeartbeatRequest,
-        CommandId.command_led_request: LEDRequest,
-        CommandId.command_gp_request: GPRequest,
-    }[command_id]
-
-
-def get_response_class(
-    command_id: CommandId,
-):
-    return {
-        CommandId.command_heartbeat_response: HeartbeatResponse,
-        CommandId.command_led_response: LEDResponse,
-        CommandId.command_gp_response: GPResponse,
-    }[command_id]
-
-
 class Response(abc.ABC):
 
     identifier: int
@@ -148,6 +121,43 @@ class Request(Command):
         )
 
 
+__command_alias: Dict[str, CommandId] = dict()
+__request_by_id: Dict[CommandId, Type[Request]] = dict()
+__response_by_id: Dict[CommandId, Type[Response]] = dict()
+
+
+def get_command_id_from_name(name: str) -> CommandId:
+    return __command_alias[name]
+
+
+def get_request_class(
+    command_id: CommandId,
+):
+    return __request_by_id[command_id]
+
+
+def get_response_class(
+    command_id: CommandId,
+):
+    return __response_by_id[command_id]
+
+
+def register_request(
+    cls: Type[Request],
+    command_id: CommandId,
+    alias: str,
+):
+    __command_alias[alias] = command_id
+    __request_by_id[command_id] = cls
+
+
+def register_response(
+    cls: Type[Response],
+    command_id: CommandId,
+):
+    __response_by_id[command_id] = cls
+
+
 @dataclass
 class LogCommand(Command):
     """Command ID: command_log"""
@@ -216,6 +226,17 @@ class HeartbeatRequest(Request):
         )
 
 
+register_request(
+    cls=HeartbeatRequest,
+    command_id=CommandId.command_heartbeat_request,
+    alias="hp",
+)
+register_response(
+    cls=HeartbeatResponse,
+    command_id=CommandId.command_heartbeat_response,
+)
+
+
 class LEDResponse(Response):
     was_successful = True
 
@@ -293,6 +314,17 @@ class LEDRequest(Request):
         )
 
 
+register_request(
+    cls=LEDRequest,
+    command_id=CommandId.command_led_request,
+    alias="led",
+)
+register_response(
+    cls=LEDResponse,
+    command_id=CommandId.command_led_response,
+)
+
+
 class GPResponse(Response):
     was_successful = True
 
@@ -333,3 +365,14 @@ class GPRequest(Request):
             payload=payload,
             serial=serial,
         )
+
+
+register_request(
+    cls=GPRequest,
+    command_id=CommandId.command_gp_request,
+    alias="gp",
+)
+register_response(
+    cls=GPResponse,
+    command_id=CommandId.command_gp_response,
+)