refactor: Calculate amount received on close using channel only

Author: ovitrif

app/src/main/java/to/bitkit/ext/ChannelDetails.kt

@@ -4,6 +4,17 @@ import org.lightningdevkit.ldknode.ChannelConfig
 import org.lightningdevkit.ldknode.ChannelDetails
 import org.lightningdevkit.ldknode.MaxDustHtlcExposure
 
+/**
+ * Calculates the expected amount in sats that will be available upon channel closure.
+ */
+val ChannelDetails.amountOnClose: ULong
+    get() {
+        val outboundCapacitySat = this.outboundCapacityMsat / 1000u
+        val reserveSats = this.unspendablePunishmentReserve ?: 0u
+
+        return outboundCapacitySat + reserveSats
+    }
+
 fun mockChannelDetails(
     channelId: String,
     isChannelReady: Boolean = true,
@@ -13,7 +24,7 @@ fun mockChannelDetails(
         counterpartyNodeId = "counterpartyNodeId",
         fundingTxo = null,
         channelValueSats = 100_000uL,
-        unspendablePunishmentReserve = 0uL,
+        unspendablePunishmentReserve = 354uL,
         userChannelId = "userChannelId",
         feerateSatPer1000Weight = 5u,
         outboundCapacityMsat = 50_000uL,
@@ -25,7 +36,7 @@ fun mockChannelDetails(
         isUsable = true,
         isAnnounced = false,
         cltvExpiryDelta = null,
-        counterpartyUnspendablePunishmentReserve = 354uL,
+        counterpartyUnspendablePunishmentReserve = 0uL,
         counterpartyOutboundHtlcMinimumMsat = null,
         counterpartyOutboundHtlcMaximumMsat = null,
         counterpartyForwardingInfoFeeBaseMsat = null,

app/src/main/java/to/bitkit/services/LightningService.kt

@@ -271,21 +271,6 @@ class LightningService @Inject constructor(
             throw LdkError(e)
         }
     }
-
-    /** Calculates expected amount of funds received on channel close. */
-    fun getChannelAmountOnClose(channelId: String): ULong {
-        val channel = channels
-            ?.find { it.channelId == channelId }
-            ?.takeIf { it.isChannelReady } // only open channels
-            ?: return 0uL
-
-        val balance = balances?.lightningBalances
-            ?.filterIsInstance<LightningBalance.ClaimableOnChannelClose>()
-            ?.find { it.channelId == channel.channelId }
-            ?: return 0uL
-
-        return balance.amountSatoshis
-    }
     // endregion
 
     // region payments

app/src/main/java/to/bitkit/ui/screens/transfer/SavingsAdvancedScreen.kt

@@ -29,6 +29,7 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import to.bitkit.R
+import to.bitkit.ext.amountOnClose
 import to.bitkit.services.filterOpen
 import to.bitkit.ui.components.BodyM
 import to.bitkit.ui.components.Caption13Up
@@ -78,7 +79,7 @@ fun SavingsAdvancedScreen(
         openChannels.map {
             TransferChannelUiState(
                 channelId = it.channelId,
-                balance = transfer.getChannelAmountOnClose(it.channelId),
+                balance = it.amountOnClose,
                 isSelected = selectedChannelIds.contains(it.channelId),
             )
         }

app/src/main/java/to/bitkit/ui/screens/transfer/SavingsConfirmScreen.kt

@@ -30,6 +30,7 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import org.lightningdevkit.ldknode.ChannelDetails
 import to.bitkit.R
+import to.bitkit.ext.amountOnClose
 import to.bitkit.services.filterOpen
 import to.bitkit.ui.components.ButtonSize
 import to.bitkit.ui.components.Caption13Up
@@ -71,7 +72,7 @@ fun SavingsConfirmScreen(
 
     val channels = selectedChannels ?: openChannels
 
-    val amount = channels.sumOf { transfer.getChannelAmountOnClose(it.channelId) }
+    val amount = channels.sumOf { it.amountOnClose }
 
     SavingsConfirmContent(
         amount = amount,

app/src/main/java/to/bitkit/viewmodels/TransferViewModel.kt

@@ -144,10 +144,6 @@ class TransferViewModel @Inject constructor(
 
     // region Savings
 
-    fun getChannelAmountOnClose(channelId: String): ULong {
-        return lightningService.getChannelAmountOnClose(channelId)
-    }
-
     private var channelsToClose = emptyList<ChannelDetails>()
 
     fun setSelectedChannelIds(channelIds: Set<String>) {