Updated on 2026-08-14

app/src/main/java/com/tangem/tap/network/exchangeServices/CurrencyExchangeManager.kt

@@ -1,8 +1,22 @@
 package com.tangem.tap.network.exchangeServices
 
+import com.tangem.Message
+import com.tangem.blockchain.blockchains.ethereum.EthereumWalletManager
+import com.tangem.blockchain.common.Amount
+import com.tangem.blockchain.common.AmountType
 import com.tangem.blockchain.common.Blockchain
+import com.tangem.blockchain.common.transaction.TransactionFee
+import com.tangem.blockchain.extensions.Result
+import com.tangem.domain.models.scan.CardDTO
+import com.tangem.tap.common.extensions.safeUpdate
 import com.tangem.tap.common.redux.global.CryptoCurrencyName
+import com.tangem.tap.common.redux.global.GlobalAction
+import com.tangem.tap.domain.TangemSigner
 import com.tangem.tap.domain.model.Currency
+import com.tangem.tap.features.demo.isDemoCard
+import com.tangem.tap.proxy.redux.DaggerGraphState
+import com.tangem.tap.store
+import java.math.BigDecimal
 
 /**
 [REDACTED_AUTHOR]
@@ -73,4 +87,42 @@ class CurrencyExchangeManager(
             primaryRules = ExchangeRules.dummy(),
         )
     }
+}
+
+suspend fun buyErc20TestnetTokens(card: CardDTO, walletManager: EthereumWalletManager, destinationAddress: String) {
+    walletManager.safeUpdate(card.isDemoCard())
+
+    val amountToSend = Amount(walletManager.wallet.blockchain)
+
+    val feeResult = walletManager.getFee(amountToSend, destinationAddress) as? Result.Success ?: return
+    val fee = when (val feeForTx = feeResult.data) {
+        is TransactionFee.Choosable -> feeForTx.minimum
+        is TransactionFee.Single -> feeForTx.normal
+    }
+
+    val coinValue = walletManager.wallet.amounts[AmountType.Coin]?.value ?: BigDecimal.ZERO
+    if (coinValue < fee.amount.value) return
+
+    val signer = TangemSigner(
+        card = card,
+        tangemSdk = store.state.daggerGraphState.get(DaggerGraphState::cardSdkConfigRepository).sdk,
+        initialMessage = Message(),
+    ) { signResponse ->
+        store.dispatch(
+            GlobalAction.UpdateWalletSignedHashes(
+                walletSignedHashes = signResponse.totalSignedHashes,
+                walletPublicKey = walletManager.wallet.publicKey.seedKey,
+                remainingSignatures = signResponse.remainingSignatures,
+            ),
+        )
+    }
+
+    walletManager.send(
+        transactionData = walletManager.createTransaction(
+            amount = amountToSend,
+            fee = fee,
+            destination = destinationAddress,
+        ),
+        signer = signer,
+    )
 }