Minor API improvements for sending/receiving payments (#619)

Define a `NodeEvent.PaymentReceived` that aims to replace the eponym class in the `Peer` (which is marked as deprecated, but otherwise left untouched). The previous impl wasn't emitted for pay-to-open parts.

Also define a "synchronous' `sendLightning` method similar to other peer methods.

src/commonMain/kotlin/fr/acinq/lightning/NodeEvents.kt

@@ -7,6 +7,9 @@ import fr.acinq.lightning.channel.SharedFundingInput
 import fr.acinq.lightning.channel.states.ChannelStateWithCommitments
 import fr.acinq.lightning.channel.states.Normal
 import fr.acinq.lightning.channel.states.WaitForFundingCreated
+import fr.acinq.lightning.db.IncomingPayment
+import fr.acinq.lightning.utils.sum
+import fr.acinq.lightning.wire.Node
 import fr.acinq.lightning.wire.PleaseOpenChannel
 import kotlinx.coroutines.CompletableDeferred
 
@@ -58,3 +61,10 @@ sealed interface SensitiveTaskEvents : NodeEvents {
 
 /** This will be emitted in a corner case where the user restores a wallet on an older version of the app, which is unable to read the channel data. */
 data object UpgradeRequired : NodeEvents
+
+sealed interface PaymentEvents : NodeEvents {
+    data class PaymentReceived(val paymentHash: ByteVector32, val receivedWith: List<IncomingPayment.ReceivedWith>) : PaymentEvents {
+        val amount: MilliSatoshi = receivedWith.map { it.amount }.sum()
+        val fees: MilliSatoshi = receivedWith.map { it.fees }.sum()
+    }
+}

src/commonMain/kotlin/fr/acinq/lightning/io/Peer.kt

@@ -18,6 +18,7 @@ import fr.acinq.lightning.serialization.Encryption.from
 import fr.acinq.lightning.serialization.Serialization.DeserializationResult
 import fr.acinq.lightning.transactions.Transactions
 import fr.acinq.lightning.utils.*
+import fr.acinq.lightning.utils.UUID.Companion.randomUUID
 import fr.acinq.lightning.wire.*
 import fr.acinq.lightning.wire.Ping
 import kotlinx.coroutines.*
@@ -77,10 +78,14 @@ data class SendPayment(val paymentId: UUID, val amount: MilliSatoshi, val recipi
 data class PurgeExpiredPayments(val fromCreatedAt: Long, val toCreatedAt: Long) : PaymentCommand()
 
 sealed class PeerEvent
+@Deprecated("Replaced by NodeEvents", replaceWith = ReplaceWith("PaymentEvents.PaymentReceived", "fr.acinq.lightning.PaymentEvents"))
 data class PaymentReceived(val incomingPayment: IncomingPayment, val received: IncomingPayment.Received) : PeerEvent()
 data class PaymentProgress(val request: SendPayment, val fees: MilliSatoshi) : PeerEvent()
-data class PaymentNotSent(val request: SendPayment, val reason: OutgoingPaymentFailure) : PeerEvent()
-data class PaymentSent(val request: SendPayment, val payment: LightningOutgoingPayment) : PeerEvent()
+sealed class SendPaymentResult : PeerEvent() {
+    abstract val request: SendPayment
+}
+data class PaymentNotSent(override val request: SendPayment, val reason: OutgoingPaymentFailure) : SendPaymentResult()
+data class PaymentSent(override val request: SendPayment, val payment: LightningOutgoingPayment) : SendPaymentResult()
 data class ChannelClosing(val channelId: ByteVector32) : PeerEvent()
 
 /**
@@ -603,6 +608,20 @@ class Peer(
             }
     }
 
+    suspend fun sendLightning(amount: MilliSatoshi, paymentRequest: Bolt11Invoice): SendPaymentResult {
+        val res = CompletableDeferred<SendPaymentResult>()
+        val paymentId = randomUUID()
+        this.launch {
+            res.complete(eventsFlow
+                .filterIsInstance<SendPaymentResult>()
+                .filter { it.request.paymentId == paymentId }
+                .first()
+            )
+        }
+        send(SendPayment(paymentId, amount, paymentRequest.nodeId, paymentRequest))
+        return res.await()
+    }
+
     suspend fun createInvoice(paymentPreimage: ByteVector32, amount: MilliSatoshi?, description: Either<String, ByteVector32>, expirySeconds: Long? = null): Bolt11Invoice {
         // we add one extra hop which uses a virtual channel with a "peer id", using the highest remote fees and expiry across all
         // channels to maximize the likelihood of success on the first payment attempt
@@ -795,6 +814,7 @@ class Peer(
                     // this was a multi-part payment, we signal that the task is finished
                     nodeParams._nodeEvents.tryEmit(SensitiveTaskEvents.TaskEnded(SensitiveTaskEvents.TaskIdentifier.IncomingMultiPartPayment(result.incomingPayment.paymentHash)))
                 }
+                @Suppress("DEPRECATION")
                 _eventsFlow.emit(PaymentReceived(result.incomingPayment, result.received))
             }
             is IncomingPaymentHandler.ProcessAddResult.Pending -> if (result.pendingPayment.parts.size == 1) {

src/commonMain/kotlin/fr/acinq/lightning/payment/IncomingPaymentHandler.kt

@@ -5,11 +5,8 @@ import fr.acinq.bitcoin.ByteVector32
 import fr.acinq.bitcoin.Crypto
 import fr.acinq.bitcoin.PrivateKey
 import fr.acinq.bitcoin.utils.Either
-import fr.acinq.lightning.CltvExpiry
+import fr.acinq.lightning.*
 import fr.acinq.lightning.Lightning.randomBytes32
-import fr.acinq.lightning.LiquidityEvents
-import fr.acinq.lightning.MilliSatoshi
-import fr.acinq.lightning.NodeParams
 import fr.acinq.lightning.channel.ChannelAction
 import fr.acinq.lightning.channel.ChannelCommand
 import fr.acinq.lightning.channel.Origin
@@ -136,12 +133,14 @@ class IncomingPaymentHandler(val nodeParams: NodeParams, val db: IncomingPayment
                 )
         }
         when (val origin = action.origin) {
-            is Origin.PayToOpenOrigin ->
+            is Origin.PayToOpenOrigin -> {
                 // there already is a corresponding Lightning invoice in the db
                 db.receivePayment(
                     paymentHash = origin.paymentHash,
                     receivedWith = listOf(receivedWith)
                 )
+                nodeParams._nodeEvents.emit(PaymentEvents.PaymentReceived(origin.paymentHash, listOf(receivedWith)))
+            }
             else -> {
                 // this is a swap, there was no pre-existing invoice, we need to create a fake one
                 val incomingPayment = db.addIncomingPayment(
@@ -152,6 +151,7 @@ class IncomingPaymentHandler(val nodeParams: NodeParams, val db: IncomingPayment
                     paymentHash = incomingPayment.paymentHash,
                     receivedWith = listOf(receivedWith)
                 )
+                nodeParams._nodeEvents.emit(PaymentEvents.PaymentReceived(incomingPayment.paymentHash, listOf(receivedWith)))
             }
         }
     }
@@ -299,7 +299,7 @@ class IncomingPaymentHandler(val nodeParams: NodeParams, val db: IncomingPayment
                             pending.remove(paymentPart.paymentHash)
                             val received = IncomingPayment.Received(receivedWith = receivedWith)
                             db.receivePayment(paymentPart.paymentHash, received.receivedWith)
-
+                            nodeParams._nodeEvents.emit(PaymentEvents.PaymentReceived(paymentPart.paymentHash, received.receivedWith))
                             return ProcessAddResult.Accepted(actions, incomingPayment.copy(received = received), received)
                         }
                     }