Adds fiat currency support for expenses

Extends expense entry functionality to support fiat currencies.

Users can now specify a currency (e.g., EUR, USD) when creating expense entries. The specified amount is converted to satoshis using exchange rates. The converted amount and currency information are stored in the journal entry metadata. Also adds an API endpoint to retrieve allowed currencies and updates the UI to allow currency selection when creating expense entries.

migrations.py

@@ -61,7 +61,8 @@ async def m001_initial(db):
             account_id TEXT NOT NULL,
             debit INTEGER NOT NULL DEFAULT 0,
             credit INTEGER NOT NULL DEFAULT 0,
-            description TEXT
+            description TEXT,
+            metadata TEXT DEFAULT '{{}}'
         );
         """
     )

models.py

@@ -36,6 +36,7 @@ class EntryLine(BaseModel):
     debit: int = 0  # in satoshis
     credit: int = 0  # in satoshis
     description: Optional[str] = None
+    metadata: dict = {}  # Stores currency info: fiat_currency, fiat_amount, fiat_rate, etc.
 
 
 class CreateEntryLine(BaseModel):
@@ -43,6 +44,7 @@ class CreateEntryLine(BaseModel):
     debit: int = 0
     credit: int = 0
     description: Optional[str] = None
+    metadata: dict = {}  # Stores currency info
 
 
 class JournalEntry(BaseModel):
@@ -72,28 +74,31 @@ class ExpenseEntry(BaseModel):
     """Helper model for creating expense entries"""
 
     description: str
-    amount: int  # in satoshis
+    amount: float  # Amount in the specified currency (or satoshis if currency is None)
     expense_account: str  # account name or ID
     is_equity: bool = False  # True = equity contribution, False = liability (castle owes user)
     user_wallet: str
     reference: Optional[str] = None
+    currency: Optional[str] = None  # If None, amount is in satoshis. Otherwise, fiat currency code (EUR, USD, etc.)
 
 
 class ReceivableEntry(BaseModel):
     """Helper model for creating accounts receivable entries"""
 
     description: str
-    amount: int  # in satoshis
+    amount: float  # Amount in the specified currency (or satoshis if currency is None)
     revenue_account: str  # account name or ID
     user_wallet: str
     reference: Optional[str] = None
+    currency: Optional[str] = None  # If None, amount is in satoshis. Otherwise, fiat currency code
 
 
 class RevenueEntry(BaseModel):
     """Helper model for creating revenue entries"""
 
     description: str
-    amount: int  # in satoshis
+    amount: float  # Amount in the specified currency (or satoshis if currency is None)
     revenue_account: str
     payment_method_account: str  # e.g., "Cash", "Bank", "Lightning"
     reference: Optional[str] = None
+    currency: Optional[str] = None  # If None, amount is in satoshis. Otherwise, fiat currency code

static/js/index.js

@@ -10,6 +10,7 @@ window.app = Vue.createApp({
       balance: null,
       transactions: [],
       accounts: [],
+      currencies: [],
       expenseDialog: {
         show: false,
         description: '',
@@ -17,6 +18,7 @@ window.app = Vue.createApp({
         expenseAccount: '',
         isEquity: false,
         reference: '',
+        currency: null,
         loading: false
       },
       payDialog: {
@@ -29,6 +31,19 @@ window.app = Vue.createApp({
   computed: {
     expenseAccounts() {
       return this.accounts.filter(a => a.account_type === 'expense')
+    },
+    amountLabel() {
+      if (this.expenseDialog.currency) {
+        return `Amount (${this.expenseDialog.currency}) *`
+      }
+      return 'Amount (sats) *'
+    },
+    currencyOptions() {
+      const options = [{label: 'Satoshis (default)', value: null}]
+      this.currencies.forEach(curr => {
+        options.push({label: curr, value: curr})
+      })
+      return options
     }
   },
   methods: {
@@ -68,6 +83,18 @@ window.app = Vue.createApp({
         LNbits.utils.notifyApiError(error)
       }
     },
+    async loadCurrencies() {
+      try {
+        const response = await LNbits.api.request(
+          'GET',
+          '/castle/api/v1/currencies',
+          this.g.user.wallets[0].inkey
+        )
+        this.currencies = response.data
+      } catch (error) {
+        LNbits.utils.notifyApiError(error)
+      }
+    },
     async submitExpense() {
       this.expenseDialog.loading = true
       try {
@@ -81,7 +108,8 @@ window.app = Vue.createApp({
             expense_account: this.expenseDialog.expenseAccount,
             is_equity: this.expenseDialog.isEquity,
             user_wallet: this.g.user.wallets[0].id,
-            reference: this.expenseDialog.reference || null
+            reference: this.expenseDialog.reference || null,
+            currency: this.expenseDialog.currency || null
           }
         )
         this.$q.notify({
@@ -142,6 +170,7 @@ window.app = Vue.createApp({
       this.expenseDialog.expenseAccount = ''
       this.expenseDialog.isEquity = false
       this.expenseDialog.reference = ''
+      this.expenseDialog.currency = null
     },
     formatSats(amount) {
       return new Intl.NumberFormat().format(amount)
@@ -158,5 +187,6 @@ window.app = Vue.createApp({
     await this.loadBalance()
     await this.loadTransactions()
     await this.loadAccounts()
+    await this.loadCurrencies()
   }
 })

templates/castle/index.html

@@ -136,13 +136,26 @@
         placeholder="e.g., Groceries for the house"
       ></q-input>
 
+      <q-select
+        filled
+        dense
+        v-model="expenseDialog.currency"
+        :options="currencyOptions"
+        option-label="label"
+        option-value="value"
+        emit-value
+        map-options
+        label="Currency"
+      ></q-select>
+
       <q-input
         filled
         dense
         v-model.number="expenseDialog.amount"
         type="number"
-        label="Amount (sats) *"
+        :label="amountLabel"
-        min="1"
+        min="0.01"
+        step="0.01"
       ></q-input>
 
       <q-select

views_api.py

@@ -3,6 +3,7 @@ from http import HTTPStatus
 from fastapi import APIRouter, Depends, HTTPException
 from lnbits.core.models import WalletTypeInfo
 from lnbits.decorators import require_admin_key, require_invoice_key
+from lnbits.utils.exchange_rates import allowed_currencies, fiat_amount_as_satoshis
 
 from .crud import (
     create_account,
@@ -34,6 +35,15 @@ from .models import (
 castle_api_router = APIRouter(prefix="/api/v1", tags=["castle"])
 
 
+# ===== UTILITY ENDPOINTS =====
+
+
+@castle_api_router.get("/currencies")
+async def api_get_currencies() -> list[str]:
+    """Get list of allowed currencies for fiat conversion"""
+    return allowed_currencies()
+
+
 # ===== ACCOUNT ENDPOINTS =====
 
 
@@ -136,7 +146,32 @@ async def api_create_expense_entry(
     Create an expense entry for a user.
     If is_equity=True, records as equity contribution.
     If is_equity=False, records as liability (castle owes user).
+
+    If currency is provided, amount is converted from fiat to satoshis.
     """
+    # Handle currency conversion
+    amount_sats = int(data.amount)
+    metadata = {}
+
+    if data.currency:
+        # Validate currency
+        if data.currency.upper() not in allowed_currencies():
+            raise HTTPException(
+                status_code=HTTPStatus.BAD_REQUEST,
+                detail=f"Currency '{data.currency}' not allowed. Use one of: {', '.join(allowed_currencies())}",
+            )
+
+        # Convert fiat to satoshis
+        amount_sats = await fiat_amount_as_satoshis(data.amount, data.currency)
+
+        # Store currency metadata
+        metadata = {
+            "fiat_currency": data.currency.upper(),
+            "fiat_amount": round(data.amount, ndigits=3),
+            "fiat_rate": amount_sats / data.amount if data.amount > 0 else 0,
+            "btc_rate": (data.amount / amount_sats * 100_000_000) if amount_sats > 0 else 0,
+        }
+
     # Get or create expense account
     expense_account = await get_account_by_name(data.expense_account)
     if not expense_account:
@@ -162,21 +197,24 @@ async def api_create_expense_entry(
 
     # Create journal entry
     # DR Expense, CR User Account (Liability or Equity)
+    description_suffix = f" ({metadata['fiat_amount']} {metadata['fiat_currency']})" if metadata else ""
     entry_data = CreateJournalEntry(
-        description=data.description,
+        description=data.description + description_suffix,
         reference=data.reference,
         lines=[
             CreateEntryLine(
                 account_id=expense_account.id,
-                debit=data.amount,
+                debit=amount_sats,
                 credit=0,
                 description=f"Expense paid by user {data.user_wallet[:8]}",
+                metadata=metadata,
             ),
             CreateEntryLine(
                 account_id=user_account.id,
                 debit=0,
-                credit=data.amount,
+                credit=amount_sats,
                 description=f"{'Equity contribution' if data.is_equity else 'Amount owed to user'}",
+                metadata=metadata,
             ),
         ],
     )