fees fix

.env.example

@@ -13,7 +13,10 @@ MINT_SERVER_HOST=127.0.0.1
 MINT_SERVER_PORT=3338
 
 LIGHTNING=TRUE
-LIGHTNING_FEE=1.01
+# fee to reserve in percent of the amount
+LIGHTNING_FEE_PERCENT=1.0 
+# minimum fee to reserve
+LIGHTNING_RESERVE_FEE_MIN=4000 
 
 LNBITS_ENDPOINT=https://legend.lnbits.com
 LNBITS_KEY=yourkeyasdasdasd

core/helpers.py

@@ -1,5 +1,6 @@
 import asyncio
 from functools import partial, wraps
+from core.settings import LIGHTNING_FEE_PERCENT, LIGHTNING_RESERVE_FEE_MIN
 
 
 def async_wrap(func):
@@ -24,3 +25,10 @@ def async_unwrap(to_await):
     coroutine = run_and_capture_result()
     loop.run_until_complete(coroutine)
     return async_response[0]
+
+
+def fee_reserve(amount_msat: int) -> int:
+    """Function for calculating the Lightning fee reserve"""
+    return max(
+        int(LIGHTNING_RESERVE_FEE_MIN), int(amount_msat * LIGHTNING_FEE_PERCENT / 100.0)
+    )

core/settings.py

@@ -5,8 +5,9 @@ env.read_env()
 
 DEBUG = env.bool("DEBUG", default=False)
 LIGHTNING = env.bool("LIGHTNING", default=True)
-LIGHTNING_FEE = env.float("LIGHTNING_FEE", default=1.01)
+LIGHTNING_FEE_PERCENT = env.float("LIGHTNING_FEE_PERCENT", default=1.0)
-assert LIGHTNING_FEE >= 1.0, "LIGHTNING_FEE must be at least 1.0"
+assert LIGHTNING_FEE_PERCENT >= 0, "LIGHTNING_FEE_PERCENT must be at least 0"
+LIGHTNING_RESERVE_FEE_MIN = env.float("LIGHTNING_RESERVE_FEE_MIN", default=4000)
 
 MINT_PRIVATE_KEY = env.str("MINT_PRIVATE_KEY")
 

mint/ledger.py

@@ -13,7 +13,9 @@ from core.base import Proof, BlindedMessage, BlindedSignature, BasePoint
 import core.b_dhke as b_dhke
 from core.base import Invoice
 from core.db import Database
-from core.settings import MAX_ORDER, LIGHTNING, LIGHTNING_FEE
+from core.settings import MAX_ORDER, LIGHTNING
+from core.helpers import fee_reserve
+
 from core.split import amount_split
 from lightning import WALLET
 from mint.crud import (
@@ -161,7 +163,7 @@ class Ledger:
         if error:
             raise Exception(f"Lightning wallet not responding: {error}")
         ok, checking_id, fee_msat, preimage, error_message = await WALLET.pay_invoice(
-            invoice, fee_limit_msat=amount * (1 - LIGHTNING_FEE)
+            invoice, fee_limit_msat=fee_reserve(amount * 1000)
         )
         return ok, preimage
 
@@ -213,7 +215,7 @@ class Ledger:
         # if not LIGHTNING:
         total = sum([p["amount"] for p in proofs])
         # check that lightning fees are included
-        assert math.ceil(total * LIGHTNING_FEE) >= amount, Exception(
+        assert total + fee_reserve(amount * 1000) >= amount, Exception(
             "provided proofs not enough for Lightning payment."
         )
 

wallet/cashu.py

@@ -9,9 +9,10 @@ from functools import wraps
 import click
 from bech32 import bech32_decode, bech32_encode, convertbits
 
-from core.settings import MINT_URL, LIGHTNING, LIGHTNING_FEE
+from core.settings import MINT_URL, LIGHTNING
 from core.migrations import migrate_databases
 from core.base import Proof
+from core.helpers import fee_reserve
 import core.bolt11 as bolt11
 from core.bolt11 import Invoice
 from wallet.wallet import Wallet as Wallet
@@ -142,7 +143,7 @@ async def pay(ctx, invoice: str):
     wallet.status()
     decoded_invoice: Invoice = bolt11.decode(invoice)
     amount = math.ceil(
-        decoded_invoice.amount_msat / 1000 * LIGHTNING_FEE
+        (decoded_invoice.amount_msat + fee_reserve(decoded_invoice.amount_msat)) / 1000
     )  # 1% fee for Lightning
     print(
         f"Paying Lightning invoice of {decoded_invoice.amount_msat // 1000} sat ({amount} sat incl. fees)"