IOS-7809 Show provider slippage

Tangem/Common/UI/ReceiveCurrencyView/ReceiveCurrencyViewModel.swift

@@ -14,6 +14,9 @@ class ReceiveCurrencyViewModel: ObservableObject, Identifiable {
     @Published private(set) var expressCurrencyViewModel: ExpressCurrencyViewModel
     @Published private(set) var cryptoAmountState: LoadableTextView.State
 
+    private(set) var expectAmount: Decimal = 0
+    private(set) var expectAmountDecimals: Int = 0
+
     init(
         expressCurrencyViewModel: ExpressCurrencyViewModel,
         cryptoAmountState: LoadableTextView.State = .initialized
@@ -31,10 +34,15 @@ class ReceiveCurrencyViewModel: ObservableObject, Identifiable {
 
         guard let expectAmount else {
             update(cryptoAmountState: .loaded(text: "0"))
+            self.expectAmount = 0
+            expectAmountDecimals = 0
             return
         }
 
+        self.expectAmount = expectAmount
+
         let decimals = tokenItem?.decimalCount ?? 8
+        expectAmountDecimals = decimals
         let formatter = DecimalNumberFormatter(maximumFractionDigits: decimals)
         let formatted: String = formatter.format(value: expectAmount)
         update(cryptoAmountState: .loaded(text: formatted))

Tangem/Modules/ExpressView/ExpressViewModel.swift

@@ -108,22 +108,37 @@ final class ExpressViewModel: ObservableObject {
     }
 
     func userDidTapPriceChangeInfoButton(isBigLoss: Bool) {
-        runTask(in: self) { viewModel in
-            guard let providerType = await viewModel.interactor.getSelectedProvider()?.provider.type else {
+        runTask(in: self) { [weak self] viewModel in
+            guard
+                let selectedProvider = await viewModel.interactor.getSelectedProvider()?.provider,
+                let tokenItemSymbol = viewModel.interactor.getDestination()?.tokenItem.currencySymbol
+            else {
                 return
             }
 
-            let message: String = {
-                switch providerType {
+            let message: String = { [weak self] in
+
+                guard let self else { return "" }
+
+                let slippage = Provider(rawValue: selectedProvider.name).maxSlippage
+                let formattedAmountAfterSlippage = formattedAmountAfterSlippage(for: selectedProvider.name)
+
+                switch selectedProvider.type {
                 case .cex:
-                    let tokenItemSymbol = viewModel.interactor.getDestination()?.tokenItem.currencySymbol ?? ""
-                    return Localization.swappingAlertCexDescription(tokenItemSymbol)
+                    return formSlippageMessage(
+                        tokenItemSymbol: tokenItemSymbol,
+                        slippage: slippage,
+                        providerName: selectedProvider.name,
+                        formattedAmountAfterSlippage
+                    )
                 case .dex, .dexBridge:
-                    if isBigLoss {
-                        return "\(Localization.swappingHighPriceImpactDescription)\n\n\(Localization.swappingAlertDexDescription)"
-                    }
-
-                    return Localization.swappingAlertDexDescription
+                    return formSlippageMessage(
+                        tokenItemSymbol: tokenItemSymbol,
+                        slippage: slippage,
+                        isBigLoss: isBigLoss,
+                        providerName: selectedProvider.name,
+                        formattedAmountAfterSlippage
+                    )
                 }
             }()
 
@@ -166,6 +181,100 @@ final class ExpressViewModel: ObservableObject {
     }
 }
 
+// MARK: - Provider slippage message
+
+extension ExpressViewModel {
+    // TODO: Should be removed into IOS-8137
+    enum Provider {
+        case changenow
+        case changelly
+        case simpleswap
+        case changehero
+        case oneInch
+        case okxOnchain
+        case okxCrossChain
+        case unknown
+
+        init(rawValue: String) {
+            switch rawValue.lowercased() {
+            case "changenow": self = .changenow
+            case "changelly": self = .changelly
+            case "simpleswap": self = .simpleswap
+            case "changehero": self = .changehero
+            case "1inch": self = .oneInch
+            case "okx onchain": self = .okxOnchain
+            case "okx crosschain": self = .okxCrossChain
+            default: self = .unknown
+            }
+        }
+
+        var maxSlippage: Decimal {
+            switch self {
+            case .changenow: 3
+            case .changelly, .simpleswap, .changehero: 5
+            case .oneInch, .okxOnchain: 2
+            case .okxCrossChain: 3.5
+            default: 0
+            }
+        }
+    }
+}
+
+private extension ExpressViewModel {
+    func fetchAmountAfterSlippage(for providerName: String, expectAmount: Decimal) -> Decimal {
+        let providerSlippage = Provider(rawValue: providerName).maxSlippage
+        let slippagePercent = (100 - providerSlippage) / 100
+
+        return expectAmount * slippagePercent
+    }
+
+    func formattedAmountAfterSlippage(for providerName: String) -> String {
+        let formatter = DecimalNumberFormatter(
+            maximumFractionDigits: receiveCurrencyViewModel?.expectAmountDecimals ?? 8
+        )
+        let expectAmount = receiveCurrencyViewModel?.expectAmount ?? 0
+
+        return formatter.format(
+            value: fetchAmountAfterSlippage(for: providerName, expectAmount: expectAmount)
+        )
+    }
+
+    func formSlippageMessage(
+        tokenItemSymbol: String,
+        slippage: Decimal,
+        providerName: String,
+        _ formattedAmountAfterSlippage: String
+    ) -> String {
+        if case .unknown = Provider(rawValue: providerName) {
+            return Localization.swappingAlertCexDescriptionWithoutSlippage(tokenItemSymbol)
+        } else {
+            return Localization.swappingAlertCexDescription(tokenItemSymbol, "\(slippage)%", formattedAmountAfterSlippage)
+        }
+    }
+
+    func formSlippageMessage(
+        tokenItemSymbol: String,
+        slippage: Decimal,
+        isBigLoss: Bool,
+        providerName: String,
+        _ formattedAmountAfterSlippage: String
+    ) -> String {
+        let swappingAlertDexDescription: String = {
+            if case .unknown = Provider(rawValue: providerName) {
+                Localization.swappingAlertDexDescriptionWithoutSlippage
+            } else {
+                Localization.swappingAlertDexDescription("\(slippage)%", formattedAmountAfterSlippage)
+            }
+        }()
+
+        if isBigLoss {
+            return "\(Localization.swappingHighPriceImpactDescription)\n\n\(swappingAlertDexDescription)"
+        }
+
+        return swappingAlertDexDescription
+    }
+}
+
 // MARK: - Navigation
 
 private extension ExpressViewModel {

Tangem/Resources/Localizations/de.lproj/Localizable.strings

@@ -744,8 +744,10 @@
 "story_web3_title" = "Web 3.0-kompatibel";
 "swap_promo_text" = "Tausche mehr Token zu besseren Kursen direkt in deiner Brieftasche.";
 "swap_promo_title" = "Neuer Swap-Anbieter verfügbar!";
-"swapping_alert_cex_description" = "Der Betrag umfasst:\n- Gebühr des Dienstanbieters\n- Netzgebühr für die Rücksendung von %@ von der Vermittlungsstelle an die Adresse des Nutzers.";
-"swapping_alert_dex_description" = "Der Betrag enthält die Gebühren des Dienstleisters.";
+"swapping_alert_cex_description" = "Der Betrag beinhaltet:\n• Honorar des Dienstleisters\n• Netzwerkgebühr für das Senden %@ von der Börse zurück an die Adresse des Benutzers. \n\n Provider-Slippage kann bis zu %@ \n Bei maximaler Abweichung beträgt der zu erhaltende Betrag %@";
+"swapping_alert_cex_description_without_slippage" = "Der Betrag beinhaltet:\n• Honorar des Dienstleisters\n• Netzwerkgebühr für das Senden %@ von der Börse zurück an die Adresse des Benutzers. \n\n Provider-Slippage kann bis zu %@ \n Bei maximaler Abweichung beträgt der zu erhaltende Betrag %@";
+"swapping_alert_dex_description" = "The amount includes the service provider's fee. \n\nProvider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_dex_description_without_slippage" = "Der Betrag enthält die Gebühren des Dienstleisters.";
 "swapping_alert_title" = "Gebühren";
 "swapping_approve_information_text" = "Alle dezentralen Börsen benötigen Genehmigungen, um zu verhindern, dass intelligente Verträge ohne Ihre Erlaubnis auf Ihre Geldbörse zugreifen. Smart Contracts können nicht auf Ihre Token zugreifen, wenn Sie nicht zustimmen. Indem Sie Ihre Token \"freischalten\", ermächtigen Sie den 1-Zoll-Smart-Contract, sie auszugeben. Die Miner des Netzwerks erhalten eine (von Ihnen bezahlte) Gasgebühr, um diese Aktion in der Blockchain aufzuzeichnen. Sie können Ihre Token tauschen, nachdem Sie Ihre Zustimmung gegeben haben.";
 "swapping_approve_information_title" = "Genehmigen";

Tangem/Resources/Localizations/en.lproj/Localizable.strings

@@ -744,8 +744,10 @@
 "story_web3_title" = "Web 3.0 Compatible";
 "swap_promo_text" = "Exchange more tokens at better rates directly in your wallet.";
 "swap_promo_title" = "New Swap Provider Available!";
-"swapping_alert_cex_description" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address.";
-"swapping_alert_dex_description" = "The amount includes the service provider's fee.";
+"swapping_alert_cex_description" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address. \n\n Provider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_cex_description_without_slippage" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address.";
+"swapping_alert_dex_description" = "The amount includes the service provider's fee. \n\nProvider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_dex_description_without_slippage" = "The amount includes the service provider's fee.";
 "swapping_alert_title" = "Fees";
 "swapping_approve_information_text" = "All decentralized exchanges require approvals to prevent smart contracts from accessing your wallet without your permission. By design, smart contracts can't access your tokens unless you approve. By \"unlocking\" your tokens, you authorize the 1-inch smart contract to spend them. The network's miners receive a gas fee (paid by you) to record this action on the blockchain. You can swap your token after giving approval.";
 "swapping_approve_information_title" = "Approve";

Tangem/Resources/Localizations/es.lproj/Localizable.strings

@@ -744,8 +744,10 @@
 "story_web3_title" = "Compatible con Web 3.0";
 "swap_promo_text" = "Intercambie más tokens a mejores tasas directamente en su billetera.";
 "swap_promo_title" = "¡Nuevo proveedor de intercambio disponible!";
-"swapping_alert_cex_description" = "El monto incluye:\n• Tarifas del proveedor de servicios\n• Tarifas de red por enviar %@ desde el intercambio a la dirección del usuario.";
-"swapping_alert_dex_description" = "El importe incluye los honorarios del proveedor de servicios.";
+"swapping_alert_cex_description" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address. \n\n Provider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_cex_description_without_slippage" = "El monto incluye:\n• Tarifas del proveedor de servicios\n• Tarifas de red por enviar %@ desde el intercambio a la dirección del usuario.";
+"swapping_alert_dex_description" = "The amount includes the service provider's fee. \n\nProvider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_dex_description_without_slippage" = "El importe incluye los honorarios del proveedor de servicios.";
 "swapping_alert_title" = "Tarifa";
 "swapping_approve_information_text" = "Todos los exchanges descentralizados requieren aprobaciones para evitar que los smart contracts accedan a su billetera sin su permiso. Por diseño, los smart contracts no pueden acceder a tus tokens a menos que lo apruebes. Al \"desbloquear\" sus tokens, autoriza al smart contract de 1-inch a gastarlos. Los mineros de la red reciben una tarifa de gas (pagada por voz) para registrar esta acción en la blockchain. Puede intercambiar su token después de dar la aprobación.";
 "swapping_approve_information_title" = "Aprobar";

Tangem/Resources/Localizations/fr.lproj/Localizable.strings

@@ -744,8 +744,10 @@
 "story_web3_title" = "Compatible avec Web 3.0";
 "swap_promo_text" = "Échangez plus de jetons à de meilleurs taux directement dans votre portefeuille.";
 "swap_promo_title" = "Nouveau fournisseur d'échange disponible !";
-"swapping_alert_cex_description" = "Le montant comprend :\n• les frais du fournisseur de services\n• les frais de réseau pour l'envoi de %@ depuis l'échange vers l'adresse de l'utilisateur.";
-"swapping_alert_dex_description" = "Le montant comprend les frais du fournisseur de services.";
+"swapping_alert_cex_description" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address. \n\n Provider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_cex_description_without_slippage" = "Le montant comprend :\n• les frais du fournisseur de services\n• les frais de réseau pour l'envoi de %@ depuis l'échange vers l'adresse de l'utilisateur.";
+"swapping_alert_dex_description" = "The amount includes the service provider's fee. \n\nProvider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_dex_description_without_slippage" = "Le montant comprend les frais du fournisseur de services.";
 "swapping_alert_title" = "Frais";
 "swapping_approve_information_text" = "Tous les échanges décentralisés nécessitent des approbations pour empêcher les smart contracts d'accéder à votre portefeuille sans votre permission. Par conception, les smart contracts ne peuvent pas accéder à vos jetons sans votre approbation. En « déverrouillant » vos jetons, vous autorisez le smart contract 1-inch à les dépenser. Les mineurs du réseau reçoivent des frais de gaz (payés par vous) pour enregistrer cette action sur la blockchain. Vous pouvez échanger votre jeton après avoir donné votre approbation.";
 "swapping_approve_information_title" = "Approuver";

Tangem/Resources/Localizations/it.lproj/Localizable.strings

@@ -744,8 +744,10 @@
 "story_web3_title" = "Web 3.0 Compatible";
 "swap_promo_text" = "Exchange more tokens at better rates directly in your wallet.";
 "swap_promo_title" = "New Swap Provider Available!";
-"swapping_alert_cex_description" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address.";
-"swapping_alert_dex_description" = "The amount includes the service provider's fee.";
+"swapping_alert_cex_description" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address. \n\n Provider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_cex_description_without_slippage" = "The amount includes:\n• service provider's fee\n• network fee for sending %@ from the exchange back to the user's address.";
+"swapping_alert_dex_description" = "The amount includes the service provider's fee. \n\nProvider slippage is up to %@ \n At maximum slippage, the amount to be received will be %@";
+"swapping_alert_dex_description_without_slippage" = "The amount includes the service provider's fee.";
 "swapping_alert_title" = "Fees";
 "swapping_approve_information_text" = "All decentralized exchanges require approvals to prevent smart contracts from accessing your wallet without your permission. By design, smart contracts can't access your tokens unless you approve. By \"unlocking\" your tokens, you authorize the 1-inch smart contract to spend them. The network's miners receive a gas fee (paid by you) to record this action on the blockchain. You can swap your token after giving approval.";
 "swapping_approve_information_title" = "Approve";

Tangem/Resources/Localizations/ja.lproj/Localizable.strings

@@ -744,8 +744,10 @@
 "story_web3_title" = "Web3.0対応";
 "swap_promo_text" = "より多くのトークンをより良いレートで、ウォレット内にて直接交換します。";
 "swap_promo_title" = "新しいスワッププロバイダーが利用可能になりました！";
-"swapping_alert_cex_description" = "この金額には以下が含まれます：\n- サービスプロバイダーの手数料\n- 取引所からユーザーのアドレスに%@ を送り返すためのネットワーク手数料。";
-"swapping_alert_dex_description" = "この金額には、サービスプロバイダーの手数料が含まれています。";
+"swapping_alert_cex_description" = "金額には以下が含まれます: \n • サービス プロバイダーの手数料\n • 取引所からユーザーのアドレスに%@を送金するためのネットワーク手数料。 \n\nプロバイダーのスリッページは最大%@です\n最大スリッページの場合、受け取る金額は%@になります。";
+"swapping_alert_cex_description_without_slippage" = "この金額には以下が含まれます：\n- サービスプロバイダーの手数料\n- 取引所からユーザーのアドレスに%@ を送り返すためのネットワーク手数料。";
+"swapping_alert_dex_description" = "金額にはサービスプロバイダーの手数料が含まれます。 \n\nプロバイダーのスリッページは最大%@です\n。最大スリッページの場合、受け取る金額は%@になります。";
+"swapping_alert_dex_description_without_slippage" = "この金額には、サービスプロバイダーの手数料が含まれています。";
 "swapping_alert_title" = "手数料";
 "swapping_approve_information_text" = "すべての分散型取引所は、スマートコントラクトがあなたの許可なくウォレットにアクセスするのを防ぐために承認を必要とします。設計上、スマートコントラクトは承認なしでトークンにアクセスできません。トークンを「ロック解除」することで、あなたは1-inchのスマートコントラクトがトークンを使うことを承認します。ネットワークのマイナーは、このアクションをブロックチェーンに記録するためのガス料金（あなたが支払う）を受け取ります。承認後、トークンを交換することができます。";
 "swapping_approve_information_title" = "承認";