Fix 5247: No rounding if users want to send/swap full token balance

BraveWallet/Crypto/BuySendSwap/SendTokenView.swift

@@ -15,14 +15,13 @@ struct SendTokenView: View {
 
   @Environment(\.presentationMode) @Binding private var presentationMode
 
-  @State private var amountInput = ""
   @State private var isShowingScanner = false
   @State private var isShowingError = false
 
   @ScaledMetric private var length: CGFloat = 16.0
 
   private var isSendDisabled: Bool {
-    guard let sendAmount = BDouble(amountInput),
+    guard let sendAmount = BDouble(sendTokenStore.sendAmount),
       let balance = sendTokenStore.selectedSendTokenBalance,
       let token = sendTokenStore.selectedSendToken,
       !sendTokenStore.isMakingTx
@@ -31,13 +30,13 @@ struct SendTokenView: View {
     }
 
     let weiFormatter = WeiFormatter(decimalFormatStyle: .decimals(precision: Int(token.decimals)))
-    if weiFormatter.weiString(from: amountInput, radix: .decimal, decimals: Int(token.decimals)) == nil {
+    if weiFormatter.weiString(from: sendTokenStore.sendAmount, radix: .decimal, decimals: Int(token.decimals)) == nil {
       return true
     }
 
     return sendAmount == 0
       || sendAmount > balance
-      || amountInput.isEmpty
+      || sendTokenStore.sendAmount.isEmpty
       || sendTokenStore.addressError != nil
   }
 
@@ -73,7 +72,7 @@ struct SendTokenView: View {
                 .font(.title3.weight(.semibold))
                 .foregroundColor(Color(.braveLabel))
               Spacer()
-              Text(String(format: "%.04f", sendTokenStore.selectedSendTokenBalance ?? 0))
+              Text(sendTokenStore.selectedSendTokenBalance?.decimalDescription ?? "0.0000")
                 .font(.title3.weight(.semibold))
                 .foregroundColor(Color(.braveLabel))
             }
@@ -91,7 +90,7 @@ struct SendTokenView: View {
               )
             ),
           footer: ShortcutAmountGrid(action: { amount in
-            amountInput = "\((sendTokenStore.selectedSendTokenBalance ?? 0) * amount.rawValue)"
+            sendTokenStore.suggestedAmountTapped(amount)
           })
           .listRowInsets(.zero)
           .padding(.bottom, 8)
@@ -100,7 +99,7 @@ struct SendTokenView: View {
             String.localizedStringWithFormat(
               Strings.Wallet.amountInCurrency,
               sendTokenStore.selectedSendToken?.symbol ?? ""),
-            text: $amountInput
+            text: $sendTokenStore.sendAmount
           )
           .keyboardType(.decimalPad)
         }
@@ -157,7 +156,7 @@ struct SendTokenView: View {
             WalletLoadingButton(
               isLoading: sendTokenStore.isMakingTx,
               action: {
-                sendTokenStore.sendToken(amount: amountInput) { success in
+                sendTokenStore.sendToken(amount: sendTokenStore.sendAmount) { success in
                   isShowingError = !success
                 }
               },

BraveWallet/Crypto/BuySendSwap/SwapCryptoView.swift

@@ -256,8 +256,7 @@ struct SwapCryptoView: View {
       ),
       footer: VStack(spacing: 20) {
         ShortcutAmountGrid(action: { amount in
-          swapTokensStore.sellAmount = ((swapTokensStore.selectedFromTokenBalance ?? 0) * amount.rawValue)
-            .decimalExpansion(precisionAfterDecimalPoint: Int(swapTokensStore.selectedFromToken?.decimals ?? 18))
+          swapTokensStore.suggestedAmountTapped(amount)
         })
         Button(action: {
           swapTokensStore.swapSelectedTokens()

BraveWallet/Crypto/Stores/SendTokenStore.swift

@@ -6,6 +6,7 @@
 import Foundation
 import BraveCore
 import Shared
+import BigNumber
 
 /// A store contains data for sending tokens
 public class SendTokenStore: ObservableObject {
@@ -18,7 +19,7 @@ public class SendTokenStore: ObservableObject {
     }
   }
   /// The current selected token balance. Default with nil value.
-  @Published var selectedSendTokenBalance: Double?
+  @Published var selectedSendTokenBalance: BDouble?
   /// A boolean indicates if this store is making an unapproved tx
   @Published var isMakingTx = false
   /// The destination account address
@@ -34,6 +35,8 @@ public class SendTokenStore: ObservableObject {
   }
   /// An error for input send address. Nil for no error.
   @Published var addressError: AddressError?
+  /// The amount the user inputs to send
+  @Published var sendAmount = ""
 
   enum AddressError: LocalizedError {
     case sameAsFromAddress
@@ -110,6 +113,16 @@ public class SendTokenStore: ObservableObject {
       }
     }
   }
+
+  func suggestedAmountTapped(_ amount: ShortcutAmountGrid.Amount) {
+    var decimalPoint = 6
+    var rounded = true
+    if amount == .all {
+      decimalPoint = Int(selectedSendToken?.decimals ?? 18)
+      rounded = false
+    }
+    sendAmount = ((selectedSendTokenBalance ?? 0) * amount.rawValue).decimalExpansion(precisionAfterDecimalPoint: decimalPoint, rounded: rounded)
+  }
 
   private func fetchAssetBalance() {
     guard let token = selectedSendToken else {
@@ -134,61 +147,13 @@ public class SendTokenStore: ObservableObject {
         self.selectedSendTokenBalance = nil
         return
       }
-
-      let balanceFormatter = WeiFormatter(decimalFormatStyle: .balance)
-      func updateBalance(_ status: BraveWallet.ProviderError, _ balance: String) {
-        guard status == .success,
-          let decimalString = balanceFormatter.decimalString(
-            for: balance.removingHexPrefix,
-            radix: .hex,
-            decimals: Int(token.decimals)
-          ), !decimalString.isEmpty, let decimal = Double(decimalString)
-        else {
-          return
-        }
-        selectedSendTokenBalance = decimal
-      }
-
-      self.rpcService.network { network in
-        // Get balance for ETH token
-        if token.symbol == network.symbol {
-          self.rpcService.balance(accountAddress, coin: .eth, chainId: network.chainId) { balance, status, _ in
-            guard status == .success else {
-              self.selectedSendTokenBalance = nil
-              return
-            }
-            updateBalance(status, balance)
-          }
-        }
-        // Get balance for erc20 token
-        else if token.isErc20 {
-          self.rpcService.erc20TokenBalance(
-            token.contractAddress,
-            address: accountAddress,
-            chainId: network.chainId
-          ) { balance, status, _ in
-            guard status == .success else {
-              self.selectedSendTokenBalance = nil
-              return
-            }
-            updateBalance(status, balance)
-          }
-        }
-        // Get balance for erc721 token
-        else if token.isErc721 {
-          self.rpcService.erc721TokenBalance(
-            token.contractAddress,
-            tokenId: token.id,
-            accountAddress: accountAddress,
-            chainId: network.chainId
-          ) { balance, status, _ in
-            guard status == .success else {
-              self.selectedSendTokenBalance = nil
-              return
-            }
-            updateBalance(status, balance)
-          }
-        }
+
+      rpcService.balance(
+        for: token,
+        in: accountAddress,
+        decimalFormatStyle: .decimals(precision: Int(token.decimals))
+      ) { [weak self] balance in
+        self?.selectedSendTokenBalance = balance
       }
     }
   }

BraveWallet/Crypto/Stores/SwapTokenStore.swift

@@ -176,9 +176,13 @@ public class SwapTokenStore: ObservableObject {
       completion(nil)
       return
     }
-
-    rpcService.balance(for: token, in: account) { balance in
-      completion(balance.map { BDouble($0) })
+
+    rpcService.balance(
+      for: token,
+      in: account.address,
+      decimalFormatStyle: .decimals(precision: Int(token.decimals))
+    ) { balance in
+      completion(balance)
     }
   }
 
@@ -356,13 +360,13 @@ public class SwapTokenStore: ObservableObject {
     checkBalanceShowError(swapResponse: response)
   }
 
-  private func createERC20SwapTransaction(_ spenderAddress: String) {
+  private func createERC20ApprovalTransaction(_ spenderAddress: String) {
     let weiFormatter = WeiFormatter(decimalFormatStyle: .decimals(precision: 18))
     guard
       let fromToken = selectedFromToken,
       let accountInfo = accountInfo,
       let balanceInWeiHex = weiFormatter.weiString(
-        from: selectedFromTokenBalance?.decimalDescription ?? "0",
+        from: selectedFromTokenBalance?.decimalExpansion(precisionAfterDecimalPoint: Int(fromToken.decimals), rounded: false) ?? "0",
         radix: .hex,
         decimals: Int(fromToken.decimals)
       )
@@ -517,7 +521,7 @@ public class SwapTokenStore: ObservableObject {
         ownerAddress: ownerAddress,
         spenderAddress: spenderAddress
       ) { allowance, status, _ in
-        let weiFormatter = WeiFormatter(decimalFormatStyle: .decimals(precision: 18))
+        let weiFormatter = WeiFormatter(decimalFormatStyle: .decimals(precision: Int(fromToken.decimals)))
         let allowanceValue = BDouble(weiFormatter.decimalString(for: allowance.removingHexPrefix, radix: .hex, decimals: Int(fromToken.decimals)) ?? "") ?? 0
         guard status == .success, amountToSend > allowanceValue else { return }  // no problem with its allowance
         self?.state = .lowAllowance(spenderAddress)
@@ -546,7 +550,7 @@ public class SwapTokenStore: ObservableObject {
       // will never come here
       break
     case .lowAllowance(let spenderAddress):
-      createERC20SwapTransaction(spenderAddress)
+      createERC20ApprovalTransaction(spenderAddress)
     case .swap:
       createETHSwapTransaction()
     }
@@ -592,17 +596,16 @@ public class SwapTokenStore: ObservableObject {
 
     func updateSelectedTokens(in network: BraveWallet.NetworkInfo) {
       if let fromToken = selectedFromToken {  // refresh balance
-        rpcService.balance(for: fromToken, in: accountInfo) { [weak self] balance in
-          self?.selectedFromTokenBalance = BDouble(balance ?? 0)
+        fetchTokenBalance(for: fromToken) { [weak self] balance in
+          self?.selectedFromTokenBalance = balance ?? 0
         }
       } else {
         selectedFromToken = allTokens.first(where: { $0.symbol == network.symbol })
       }
 
       if let toToken = selectedToToken {
-        rpcService.balance(for: toToken, in: accountInfo) { [weak self] balance in
-          self?.selectedToTokenBalance = BDouble(balance ?? 0)
-          completion?()
+        fetchTokenBalance(for: toToken) { [weak self] balance in
+          self?.selectedToTokenBalance = balance ?? 0
         }
       } else {
         if network.chainId == BraveWallet.MainnetChainId {
@@ -651,6 +654,17 @@ public class SwapTokenStore: ObservableObject {
       }
     }
   }
+
+  func suggestedAmountTapped(_ amount: ShortcutAmountGrid.Amount) {
+    var decimalPoint = 6
+    var rounded = true
+    if amount == .all {
+      decimalPoint = Int(selectedFromToken?.decimals ?? 18)
+      rounded = false
+    }
+    sellAmount = ((selectedFromTokenBalance ?? 0) * amount.rawValue)
+      .decimalExpansion(precisionAfterDecimalPoint: decimalPoint, rounded: rounded)
+  }
 
   #if DEBUG
   func setUpTest() {
@@ -660,6 +674,11 @@ public class SwapTokenStore: ObservableObject {
     sellAmount = "0.01"
     selectedFromTokenBalance = 0.02
   }
+
+  func setUpTestForRounding() {
+    accountInfo = .init()
+    selectedFromToken = .previewToken
+  }
   #endif
 }
 

BraveWallet/Extensions/RpcServiceExtensions.swift

@@ -5,6 +5,7 @@
 
 import Foundation
 import BraveCore
+import BigNumber
 
 extension BraveWalletJsonRpcService {
   /// Obtain the decimal balance of an `BlockchainToken` for a given account
@@ -54,4 +55,54 @@ extension BraveWalletJsonRpcService {
       }
     }
   }
+
+  /// Obtain the decimal balance in `BDouble` of an `BlockchainToken` for a given account
+  /// with certain decimal format style
+  ///
+  /// If the call fails for some reason or the resulting wei cannot be converted,
+  /// `completion` will be called with `nil`
+  func balance(
+    for token: BraveWallet.BlockchainToken,
+    in accountAddress: String,
+    decimalFormatStyle: WeiFormatter.DecimalFormatStyle,
+    completion: @escaping (BDouble?) -> Void
+  ) {
+    let convert: (String, BraveWallet.ProviderError, String) -> Void = { wei, status, _ in
+      guard status == .success && !wei.isEmpty else {
+        completion(nil)
+        return
+      }
+      let formatter = WeiFormatter(decimalFormatStyle: decimalFormatStyle)
+      if let valueString = formatter.decimalString(
+        for: wei.removingHexPrefix,
+        radix: .hex,
+        decimals: Int(token.decimals)
+      ) {
+        completion(BDouble(valueString))
+      } else {
+        completion(nil)
+      }
+    }
+    network { [self] network in
+      if token.symbol == network.symbol {
+        balance(accountAddress, coin: .eth, chainId: network.chainId, completion: convert)
+      } else if token.isErc20 {
+        erc20TokenBalance(
+          token.contractAddress(in: network),
+          address: accountAddress,
+          chainId: network.chainId,
+          completion: convert
+        )
+      } else if token.isErc721 {
+        erc721TokenBalance(
+          token.contractAddress,
+          tokenId: token.tokenId,
+          accountAddress: accountAddress,
+          chainId: network.chainId,
+          completion: convert)
+      } else {
+        completion(nil)
+      }
+    }
+  }
 }