Calculates user balance from journal entries

Refactors user balance calculation to directly parse journal
entries, enhancing accuracy and efficiency. This change
eliminates reliance on direct database queries and provides a
more reliable mechanism for determining user balances.

Adds logging for debugging purposes.

Also extracts and uses fiat metadata from invoice/payment extras.

views_api.py

@@ -3,6 +3,7 @@ from decimal import Decimal
 from http import HTTPStatus
 
 from fastapi import APIRouter, Depends, HTTPException
+from loguru import logger
 from lnbits.core.models import User, WalletTypeInfo
 from lnbits.decorators import (
     check_super_user,
@@ -1234,6 +1235,8 @@ async def api_generate_payment_invoice(
     # Calculate proportional fiat amount for this invoice
     invoice_extra = {"tag": "castle", "user_id": target_user_id}
 
+    logger.info(f"User balance for invoice generation - sats: {user_balance.balance}, fiat_balances: {user_balance.fiat_balances}")
+
     if user_balance.fiat_balances:
         # Simple single-currency solution: use the first (and should be only) currency
         currencies = list(user_balance.fiat_balances.keys())
@@ -1267,6 +1270,8 @@ async def api_generate_payment_invoice(
                     "btc_rate": btc_rate,
                 })
 
+    logger.info(f"Invoice extra metadata: {invoice_extra}")
+
     # Create invoice on castle wallet
     invoice_data = CreateInvoice(
         out=False,
@@ -1366,12 +1371,15 @@ async def api_record_payment(
     fiat_currency = None
     fiat_amount = None
     if payment.extra and isinstance(payment.extra, dict):
+        logger.info(f"Payment.extra contents: {payment.extra}")
         fiat_currency = payment.extra.get("fiat_currency")
         fiat_amount_str = payment.extra.get("fiat_amount")
         if fiat_amount_str:
             from decimal import Decimal
             fiat_amount = Decimal(str(fiat_amount_str))
 
+    logger.info(f"Extracted fiat metadata - currency: {fiat_currency}, amount: {fiat_amount}")
+
     # Get user's receivable account (what user owes)
     user_receivable = await get_or_create_user_account(
         target_user_id, AccountType.ASSET, "Accounts Receivable"
@@ -1399,6 +1407,8 @@ async def api_record_payment(
         reference=data.payment_hash
     )
 
+    logger.info(f"Formatted payment entry: {entry}")
+
     # Submit to Fava
     result = await fava.add_entry(entry)
     logger.info(f"Payment entry submitted to Fava: {result.get('data', 'Unknown')}")