From 4b76aeabb9499c4a2d452ade0fe1e54ce0bf104d Mon Sep 17 00:00:00 2001
From: RunasSudo <runassudo@yingtongli.me>
Date: Mon, 21 Apr 2025 21:46:22 +1000
Subject: [PATCH] Implement write for Decimal (basic implementation)

---
 csla_binary/binary_writer.py | 17 +++++++++++++++--
 csla_binary/decimal.py       |  9 +++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/csla_binary/binary_writer.py b/csla_binary/binary_writer.py
index bcdea79..3eaf400 100644
--- a/csla_binary/binary_writer.py
+++ b/csla_binary/binary_writer.py
@@ -14,10 +14,12 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+from decimal import Decimal
 import io
 import struct
 from typing import List
 
+from .decimal import decimal_to_int32
 from .known_types import CslaKnownTypes
 from .serialization_info import SerializationInfo
 
@@ -95,12 +97,15 @@ class CslaBinaryWriter:
 		if isinstance(value, bool):
 			return self.write_object_bool(value)
 		
-		if isinstance(value, bytes):
-			return self.write_object_bytearray(value)
+		if isinstance(value, Decimal):
+			return self.write_object_decimal(value)
 		
 		if isinstance(value, str):
 			return self.write_object_string(value)
 		
+		if isinstance(value, bytes):
+			return self.write_object_bytearray(value)
+		
 		raise NotImplementedError('CslaBinaryWriter.Write not implemented for type {}'.format(type(value).__name__))
 	
 	def write_object_bool(self, value):
@@ -113,6 +118,14 @@ class CslaBinaryWriter:
 		self.write_int32(len(value))
 		self.stream.write(value)
 	
+	def write_object_decimal(self, value):
+		# CslaBinaryWriter.Write(Decimal)
+		self.stream.write(bytes([CslaKnownTypes.Decimal.value]))
+		int32_repr = decimal_to_int32(value)
+		self.write_int32(len(int32_repr))  # Should be 4 always
+		for part in int32_repr:
+			self.write_int32(part)
+	
 	def write_object_int32(self, value):
 		# CslaBinaryWriter.Write(int)
 		self.stream.write(bytes([CslaKnownTypes.Int32.value]))
diff --git a/csla_binary/decimal.py b/csla_binary/decimal.py
index db471e4..63eacfa 100644
--- a/csla_binary/decimal.py
+++ b/csla_binary/decimal.py
@@ -47,6 +47,15 @@ def int32_to_decimal(decimal_parts: List[int]) -> Decimal:
 	
 	return Decimal(mantissa * (-1 if sign == 1 else 1)) / (Decimal(10) ** exponent)
 
+def decimal_to_int32(decimal: Decimal) -> List[int]:
+	# FIXME: Only supports 32-bit integers
+	if decimal != decimal.to_integral_value():
+		raise NotImplementedError('decimal_to_int32 only supports 32-bit integers')
+	if decimal < Decimal('0') or decimal >= Decimal('2') ** 32:
+		raise NotImplementedError('decimal_to_int32 only supports 32-bit integers')
+	
+	return [int(decimal), 0, 0, 0]
+
 def test_int32_to_decimal():
 	# https://learn.microsoft.com/en-us/dotnet/api/system.decimal.-ctor?view=net-9.0#system-decimal-ctor(system-int32())
 	assert int32_to_decimal([0x0, 0x0, 0x0, 0x0]) == Decimal('0')