Allow arbitrary denominations in wallet minting (#684)

- Update `mint` method to use allowed amounts from the mint
- Add `get_allowed_amounts` method to fetch supported denominations
- Modify `test_mint_amounts_wrong_order` to expect new error message

Co-authored-by: callebtc <93376500+callebtc@users.noreply.github.com>

cashu/wallet/transactions.py

@@ -111,6 +111,21 @@ class WalletTransactions(SupportsDb, SupportsKeysets):
         proofs_send = self.coinselect(proofs, amount, include_fees=True)
         return self.get_fees_for_proofs(proofs_send)
 
+    def get_allowed_amounts(self):
+        """
+        Infer the allowed amounts from the current keyset's public keys.
+
+        Returns:
+            List[int]: A sorted list of allowed token amounts for the current keyset.
+
+        Raises:
+            Exception: If no active keyset is set.
+        """
+
+        if not self.keyset_id or self.keyset_id not in self.keysets:
+            raise Exception("No active keyset")
+        return sorted(list(self.keysets[self.keyset_id].public_keys.keys()))
+
     def split_wallet_state(self, amount: int) -> List[int]:
         """This function produces an amount split for outputs based on the current state of the wallet.
         Its objective is to fill up the wallet so that it reaches `n_target` coins of each amount.
@@ -125,8 +140,9 @@ class WalletTransactions(SupportsDb, SupportsKeysets):
         n_target = settings.wallet_target_amount_count
         amounts_we_have = [p.amount for p in self.proofs if p.reserved is not True]
         amounts_we_have.sort()
-        # NOTE: Do not assume 2^n here
+
-        all_possible_amounts: list[int] = [2**i for i in range(settings.max_order)]
+        all_possible_amounts = self.get_allowed_amounts()
+
         amounts_we_want_ll = [
             [a] * max(0, n_target - amounts_we_have.count(a))
             for a in all_possible_amounts

cashu/wallet/wallet.py

@@ -519,6 +519,8 @@ class Wallet(
         await store_bolt11_mint_quote(db=self.db, quote=quote)
         return quote
 
+
+
     async def mint(
         self,
         amount: int,
@@ -529,7 +531,7 @@ class Wallet(
 
         Args:
             amount (int): Total amount of tokens to be minted
-            id (str): Id for looking up the paid Lightning invoice.
+            quote_id (str): Id for looking up the paid Lightning invoice.
             split (Optional[List[str]], optional): List of desired amount splits to be minted. Total must sum to `amount`.
 
         Raises:
@@ -543,11 +545,11 @@ class Wallet(
         if split:
             logger.trace(f"Mint with split: {split}")
             assert sum(split) == amount, "split must sum to amount"
-            allowed_amounts = [2**i for i in range(settings.max_order)]
+            allowed_amounts = self.get_allowed_amounts()  # Get allowed amounts from the mint
             for a in split:
                 if a not in allowed_amounts:
                     raise Exception(
-                        f"Can only mint amounts with 2^n up to {2**settings.max_order}."
+                        f"Can only mint amounts supported by the mint: {allowed_amounts}"
                     )
 
         # split based on our wallet state

tests/test_wallet.py

@@ -221,9 +221,10 @@ async def test_mint_amounts_wrong_order(wallet1: Wallet):
     """Mint amount that is not part in 2^n"""
     amts = [1, 2, 3]
     mint_quote = await wallet1.request_mint(sum(amts))
+    allowed_amounts = wallet1.get_allowed_amounts()
     await assert_err(
         wallet1.mint(amount=sum(amts), split=[1, 2, 3], quote_id=mint_quote.quote),
-        f"Can only mint amounts with 2^n up to {2**settings.max_order}.",
+        f"Can only mint amounts supported by the mint: {allowed_amounts}",
     )