refactor: use Decimal instead of float for monetary calculations

- calculations.py: Use Decimal for commission percentages, exchange rates,
  and client balances. Added to_decimal() helper for safe float conversion.
  Changed from banker's rounding to ROUND_HALF_UP.

- models.py: Changed all fiat amounts, percentages, and exchange rates to
  Decimal. Added json_encoders for API serialization.

- transaction_processor.py: Convert to Decimal at data ingestion boundary
  (CSV parsing). Updated all defaults and calculations to use Decimal.

- tests: Updated to work with Decimal return types.

This prevents floating-point precision issues in financial calculations.
All 23 tests pass.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
padreug 2026-01-11 14:47:56 +01:00
parent 397fd4b002
commit 6e86f53962
4 changed files with 180 additions and 101 deletions

View file

@ -3,6 +3,7 @@
import asyncio
import asyncpg
from datetime import datetime, timedelta, timezone
from decimal import Decimal
from typing import List, Optional, Dict, Any
from loguru import logger
import socket
@ -492,28 +493,38 @@ class LamassuTransactionProcessor:
results = []
for row in reader:
# Convert string values to appropriate types
# Use Decimal for monetary and percentage values
processed_row = {}
for key, value in row.items():
# Handle None/empty values consistently at data ingestion boundary
if value == '' or value is None:
if key in ['fiat_amount', 'crypto_amount']:
processed_row[key] = 0 # Default numeric fields to 0
if key == 'crypto_amount':
processed_row[key] = 0 # Sats are always int
elif key == 'fiat_amount':
processed_row[key] = Decimal("0") # Fiat as Decimal
elif key in ['commission_percentage', 'discount']:
processed_row[key] = 0.0 # Default percentage fields to 0.0
processed_row[key] = Decimal("0") # Percentages as Decimal
else:
processed_row[key] = None # Keep None for non-numeric fields
elif key in ['transaction_id', 'device_id', 'crypto_code', 'fiat_code']:
processed_row[key] = str(value)
elif key in ['fiat_amount', 'crypto_amount']:
elif key == 'crypto_amount':
try:
processed_row[key] = int(float(value))
processed_row[key] = int(float(value)) # Sats are always int
except (ValueError, TypeError):
processed_row[key] = 0 # Fallback to 0 for invalid values
processed_row[key] = 0
elif key == 'fiat_amount':
try:
# Convert via string to avoid float precision issues
processed_row[key] = Decimal(str(value))
except (ValueError, TypeError):
processed_row[key] = Decimal("0")
elif key in ['commission_percentage', 'discount']:
try:
processed_row[key] = float(value)
# Convert via string to avoid float precision issues
processed_row[key] = Decimal(str(value))
except (ValueError, TypeError):
processed_row[key] = 0.0 # Fallback to 0.0 for invalid values
processed_row[key] = Decimal("0")
elif key == 'transaction_time':
from datetime import datetime
# Parse PostgreSQL timestamp format and ensure it's in UTC for consistency
@ -679,13 +690,13 @@ class LamassuTransactionProcessor:
logger.info("No Flow Mode clients found - skipping distribution")
return {}
# Extract transaction details - guaranteed clean from data ingestion
# Extract transaction details - guaranteed clean from data ingestion (Decimal types)
crypto_atoms = transaction.get("crypto_amount", 0) # Total sats with commission baked in
fiat_amount = transaction.get("fiat_amount", 0) # Actual fiat dispensed (principal only)
commission_percentage = transaction.get("commission_percentage", 0.0) # Already stored as decimal (e.g., 0.045)
discount = transaction.get("discount", 0.0) # Discount percentage
fiat_amount = transaction.get("fiat_amount", Decimal("0")) # Actual fiat dispensed (principal only)
commission_percentage = transaction.get("commission_percentage", Decimal("0")) # Already stored as Decimal (e.g., 0.045)
discount = transaction.get("discount", Decimal("0")) # Discount percentage
transaction_time = transaction.get("transaction_time") # ATM transaction timestamp for temporal accuracy
# Normalize transaction_time to UTC if present
if transaction_time is not None:
if transaction_time.tzinfo is None:
@ -697,7 +708,7 @@ class LamassuTransactionProcessor:
original_tz = transaction_time.tzinfo
transaction_time = transaction_time.astimezone(timezone.utc)
logger.info(f"Converted transaction time from {original_tz} to UTC")
# Validate required fields
if crypto_atoms is None:
logger.error(f"Missing crypto_amount in transaction: {transaction}")
@ -707,10 +718,10 @@ class LamassuTransactionProcessor:
return {}
if commission_percentage is None:
logger.warning(f"Missing commission_percentage in transaction: {transaction}, defaulting to 0")
commission_percentage = 0.0
commission_percentage = Decimal("0")
if discount is None:
logger.info(f"Missing discount in transaction: {transaction}, defaulting to 0")
discount = 0.0
discount = Decimal("0")
if transaction_time is None:
logger.warning(f"Missing transaction_time in transaction: {transaction}")
# Could use current time as fallback, but this indicates a data issue
@ -733,15 +744,16 @@ class LamassuTransactionProcessor:
logger.warning("No transaction time available - using current balances (may be inaccurate)")
# Get balance summaries for all clients to calculate proportions
client_balances = {}
total_confirmed_deposits = 0
client_balances: Dict[str, Decimal] = {}
total_confirmed_deposits = Decimal("0")
min_balance = Decimal("0.01")
for client in flow_clients:
# Get balance as of the transaction time for temporal accuracy
balance = await get_client_balance_summary(client.id, as_of_time=transaction_time)
# Only include clients with positive remaining balance
# NOTE: This works for fiat amounts that use cents
if balance.remaining_balance >= 0.01:
if balance.remaining_balance >= min_balance:
client_balances[client.id] = balance.remaining_balance
total_confirmed_deposits += balance.remaining_balance
logger.debug(f"Client {client.id[:8]}... included with balance: {balance.remaining_balance:.2f} GTQ")
@ -766,7 +778,10 @@ class LamassuTransactionProcessor:
proportion = client_balances[client_id] / total_confirmed_deposits
# Calculate equivalent fiat value in GTQ for tracking purposes
client_fiat_amount = round(client_sats_amount / exchange_rate, 2) if exchange_rate > 0 else 0.0
if exchange_rate > 0:
client_fiat_amount = (Decimal(client_sats_amount) / exchange_rate).quantize(Decimal("0.01"))
else:
client_fiat_amount = Decimal("0")
distributions[client_id] = {
"fiat_amount": client_fiat_amount,
@ -1003,20 +1018,20 @@ class LamassuTransactionProcessor:
async def store_lamassu_transaction(self, transaction: Dict[str, Any]) -> Optional[str]:
"""Store the Lamassu transaction in our database for audit and UI"""
try:
# Extract transaction data - guaranteed clean from data ingestion boundary
# Extract transaction data - guaranteed clean from data ingestion boundary (Decimal types)
crypto_atoms = transaction.get("crypto_amount", 0)
fiat_amount = transaction.get("fiat_amount", 0)
commission_percentage = transaction.get("commission_percentage", 0.0)
discount = transaction.get("discount", 0.0)
fiat_amount = transaction.get("fiat_amount", Decimal("0"))
commission_percentage = transaction.get("commission_percentage", Decimal("0"))
discount = transaction.get("discount", Decimal("0"))
transaction_time = transaction.get("transaction_time")
# Normalize transaction_time to UTC if present
if transaction_time is not None:
if transaction_time.tzinfo is None:
transaction_time = transaction_time.replace(tzinfo=timezone.utc)
elif transaction_time.tzinfo != timezone.utc:
transaction_time = transaction_time.astimezone(timezone.utc)
# Calculate commission metrics using the extracted pure function
base_crypto_atoms, commission_amount_sats, effective_commission = calculate_commission(
crypto_atoms, commission_percentage, discount
@ -1024,11 +1039,13 @@ class LamassuTransactionProcessor:
# Calculate exchange rate
exchange_rate = calculate_exchange_rate(base_crypto_atoms, fiat_amount)
# Create transaction data with GTQ amounts
# Create transaction data with GTQ amounts (Decimal already, just ensure 2 decimal places)
fiat_amount_rounded = fiat_amount.quantize(Decimal("0.01")) if isinstance(fiat_amount, Decimal) else Decimal(str(fiat_amount)).quantize(Decimal("0.01"))
transaction_data = CreateLamassuTransactionData(
lamassu_transaction_id=transaction["transaction_id"],
fiat_amount=round(fiat_amount, 2), # Store GTQ with 2 decimal places
fiat_amount=fiat_amount_rounded,
crypto_amount=crypto_atoms,
commission_percentage=commission_percentage,
discount=discount,
@ -1148,9 +1165,9 @@ class LamassuTransactionProcessor:
# Calculate commission amount for sending to commission wallet
crypto_atoms = transaction.get("crypto_amount", 0)
commission_percentage = transaction.get("commission_percentage", 0.0)
discount = transaction.get("discount", 0.0)
commission_percentage = transaction.get("commission_percentage", Decimal("0"))
discount = transaction.get("discount", Decimal("0"))
# Calculate commission amount using the extracted pure function
_, commission_amount_sats, _ = calculate_commission(
crypto_atoms, commission_percentage, discount