From 1c29cb5fff526f4fcb44fd33b100352817a782b7 Mon Sep 17 00:00:00 2001
From: Doston Kamalov <dkamalov@tangem.com>
Date: Wed, 6 Sep 2023 11:49:13 +0500
Subject: [PATCH] AND-4457 Added Chia unspents sort and limit to inputs

---
 .../blockchains/chia/ChiaAddressService.kt    |  2 +-
 .../chia/ChiaTransactionBuilder.kt            | 29 ++++++++++++++++---
 .../tangem/blockchain/common/Exceptions.kt    | 18 ++++++++++++
 3 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaAddressService.kt b/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaAddressService.kt
index 5bd19a452..9cedb5636 100644
--- a/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaAddressService.kt
+++ b/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaAddressService.kt
@@ -47,4 +47,4 @@ class ChiaAddressService(blockchain: Blockchain) : AddressService() {
             return Crypto.convertBits(dataBytes, 0, dataBytes.size, 5, 8, false)
         }
     }
-}
\ No newline at end of file
+}
diff --git a/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaTransactionBuilder.kt b/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaTransactionBuilder.kt
index 657a9b730..7d4aca3fc 100644
--- a/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaTransactionBuilder.kt
+++ b/blockchain/src/main/java/com/tangem/blockchain/blockchains/chia/ChiaTransactionBuilder.kt
@@ -16,7 +16,9 @@ import com.tangem.blockchain.common.TransactionData
 import com.tangem.blockchain.extensions.Result
 import com.tangem.blstlib.generated.P2
 import com.tangem.blstlib.generated.P2_Affine
-import com.tangem.common.extensions.*
+import com.tangem.common.extensions.calculateSha256
+import com.tangem.common.extensions.hexToBytes
+import com.tangem.common.extensions.toHexString
 import java.math.BigDecimal
 
 class ChiaTransactionBuilder(private val walletPublicKey: ByteArray, val blockchain: Blockchain) {
@@ -35,9 +37,20 @@ class ChiaTransactionBuilder(private val walletPublicKey: ByteArray, val blockch
             BlockchainSdkError.CustomError("Unspent coins are missing")
         )
 
-        val change = calculateChange(transactionData, unspentCoins)
+        val unspentsToSpend = getUnspentsToSpend()
 
-        coinSpends = transactionData.toChiaCoinSpends(unspentCoins, change)
+        val change = calculateChange(transactionData, unspentsToSpend)
+        if (change < 0) { // unspentsToSpend not enough to cover transaction amount
+            val maxAmount = transactionData.amount.value!! + change.toBigDecimal().movePointLeft(blockchain.decimals())
+            return Result.Failure(
+                BlockchainSdkError.Chia.UtxoAmountError(
+                    maxOutputs = MAX_INPUT_COUNT,
+                    maxAmount = maxAmount
+                )
+            )
+        }
+
+        coinSpends = transactionData.toChiaCoinSpends(unspentsToSpend, change)
 
         val hashesForSign = coinSpends.map { it ->
             // our solutions are always Cons
@@ -61,6 +74,12 @@ class ChiaTransactionBuilder(private val walletPublicKey: ByteArray, val blockch
         return (coinSpends.size * COIN_SPEND_COST) + (numberOfCoinsCreated * CREATE_COIN_COST)
     }
 
+    private fun getUnspentsToSpend() = unspentCoins
+        .sortedByDescending { it.amount }
+        .take(getUnspentsToSpendCount())
+
+    private fun getUnspentsToSpendCount(): Int = unspentCoins.size.coerceAtMost(MAX_INPUT_COUNT)
+
     private fun calculateChange(
         transactionData: TransactionData,
         unspentCoins: List<ChiaCoin>,
@@ -143,6 +162,8 @@ class ChiaTransactionBuilder(private val walletPublicKey: ByteArray, val blockch
         private const val COIN_SPEND_COST = 4500000L
         private const val CREATE_COIN_COST = 2400000L
 
+        private const val MAX_INPUT_COUNT = 50 // Aligned inside Tangem. In iOS max input count is 15.
+
         private const val AUG_SCHEME_DST = "BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_AUG_"
     }
-}
\ No newline at end of file
+}
diff --git a/blockchain/src/main/java/com/tangem/blockchain/common/Exceptions.kt b/blockchain/src/main/java/com/tangem/blockchain/common/Exceptions.kt
index 2c740dcd1..57e158e05 100644
--- a/blockchain/src/main/java/com/tangem/blockchain/common/Exceptions.kt
+++ b/blockchain/src/main/java/com/tangem/blockchain/common/Exceptions.kt
@@ -119,6 +119,23 @@ sealed class BlockchainSdkError(
         cause = throwable,
     )
 
+    sealed class Chia(
+        subCode: Int,
+        customMessage: String? = null,
+        throwable: Throwable? = null,
+    ) : BlockchainSdkError(
+        code = ERROR_CODE_CHIA + subCode,
+        customMessage = customMessage ?: (ERROR_CODE_CHIA + subCode).toString(),
+        messageResId = null,
+        cause = throwable,
+    ) {
+        class UtxoAmountError(val maxOutputs: Int, val maxAmount: BigDecimal) : Chia(
+            1,
+            "Due to Chia limitations only $maxOutputs UTXOs can fit in a single transaction. This means you can only" +
+                " send ${maxAmount.toPlainString()}."
+        )
+    }
+
     companion object {
         const val ERROR_CODE_SOLANA = 1000
         const val ERROR_CODE_POLKADOT = 2000
@@ -126,6 +143,7 @@ sealed class BlockchainSdkError(
         const val ERROR_CODE_TON = 4000
         const val ERROR_CODE_COSMOS = 5000
         const val ERROR_CODE_WALLET_CORE = 6000
+        const val ERROR_CODE_CHIA = 7000
     }
 }