store: refuse a card difference under 50 cents

apps/simplex-store-service/src/StoreService/Web/Names/Orders.hs

@@ -30,7 +30,7 @@ import Data.Word (Word32, Word64)
 import Network.HTTP.Types (status200, status409, status503)
 import Network.Wai (Request, Response, ResponseReceived)
 import Simplex.Chat.Badges.Code (NameCode (..), parseNameCode)
-import Simplex.Chat.PaymentService.Types (CurrencyAmount (..), InvoiceId (..), InvoiceStatus (..), ServicePaymentMethod)
+import Simplex.Chat.PaymentService.Types (CurrencyAmount (..), InvoiceId (..), InvoiceStatus (..), ServicePaymentMethod (..))
 import Simplex.Messaging.Agent.Store.Common (withTransaction)
 import qualified Simplex.Messaging.Agent.Store.DB as DB
 import Simplex.Messaging.Crypto.Secp256k1 (RecoverableSignature)
@@ -268,10 +268,16 @@ spendHandler env@OrdersEnv {oeStore, oeConfig, oeContracts, oeTurns, oeNow} cfg
         placeOrder env order (maybeToList holder) (coveredOrderInsert spend new) >>= \case
           Left refusal -> refuse refusal
           Right closed -> pure Answer {aResponse = registrationAnswer rid, aAfter = announceClosed env providers waiters closed}
+      Just (SPMCard _)
+        | spPrice - spBalance < minCardChargeCents -> refuse ORBadRequest
       Just method ->
         createAtProvider env cfg providers waiters what $
           InvoicedOrder {ivRequest = order, ivHolders = maybeToList holder, ivMethod = method, ivPrice = spPrice, ivAmount = fromIntegral (spPrice - spBalance), ivInsert = differenceOrderInsert spend}
 
+-- | Stripe refuses a USD charge under 50 cents, so the page offers only crypto for a smaller difference.
+minCardChargeCents :: Int
+minCardChargeCents = 50
+
 -- | Every format check, the method present exactly for a difference, then the length's range.
 parseSpend :: RegistrationId -> J.Object -> Either OrderRefusal ((OrderFields, Word64, RecoverableSignature), Spend)
 parseSpend spSource o = do

tests/Bots/StoreService/NamesSpendTests.hs

@@ -69,6 +69,7 @@ namesSpendTests = describe "StoreService names: spend" $ do
     it "refuses another signer and a stale timestamp, and answers an unknown order 404" testSignerAndId
     it "answers name_taken, catalog_changed, name_check_unavailable, provider_unavailable and order_exists, spending nothing" testOrderChecks
     it "runs its checks in the contract's order" testCheckOrder
+    it "refuses a card difference below the card minimum after the price check, accepting it by crypto and at the minimum" testCardMinimum
     it "refuses sealed missing or over 11095 characters and a body over 16384 bytes, accepting the longest" testSpendSizes
     it "counts spends against the create limit" testSpendLimit
   describe "holders" $ do
@@ -388,6 +389,19 @@ testCheckOrder = withSpend $ \ctx@Ctx {cNode = node, cStub} -> do
   spend ctx src (covered 31000) {sbOrder = aliceOrder {oCommitment = commitmentOf 3}} `shouldReturn` refusedWith 409 "order_exists"
   amountOf ctx src `shouldReturn` Just 20000
 
+testCardMinimum :: IO ()
+testCardMinimum = withSpend $ \ctx -> do
+  small <- sourceOf ctx "small" 9951
+  spend ctx small (difference 9951) {sbOrder = aliceOrder {oPrice = 9990}, sbMethod = Just "card"} `shouldReturn` (409, Just $ KM.fromList [("error", "catalog_changed"), ("price", J.Number 10000)])
+  spend ctx small (difference 9951) {sbMethod = Just "card"} `shouldReturn` refusedWith 400 "bad_request"
+  stubCalls (cStub ctx) `shouldReturn` []
+  amountOf ctx small `shouldReturn` Just 9951
+  fst <$> spend ctx small (difference 9951) `shouldReturn` 200
+  least <- sourceOf ctx "least" 19950
+  fst <$> spend ctx least (dynamis 19950 (Just "card")) `shouldReturn` 200
+  calls <- stubCalls (cStub ctx)
+  [odAmount d | StubCreate _ d <- calls] `shouldBe` [CurrencyAmount 49, CurrencyAmount 50]
+
 testSpendSizes :: IO ()
 testSpendSizes = withSpend $ \ctx -> do
   src <- sourceOf ctx "src" 15000