Handle traversal state changes and errors

Traversal connections show in the joining info UI.
Non fatal errors show the retry button.
Fatal errors end the netplay session.

6 files changed, 134 insertions, 9 deletions

diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/NetplaySession.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/NetplaySession.kt
index 8af9cf9806..d8f2ce8860 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/NetplaySession.kt
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/NetplaySession.kt
@@ -25,11 +25,12 @@ import kotlinx.coroutines.flow.runningFold
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.withContext
 import org.dolphinemu.dolphinemu.features.netplay.model.GameDigestProgress
-import org.dolphinemu.dolphinemu.model.GameFile
 import org.dolphinemu.dolphinemu.features.netplay.model.NetplayMessage
 import org.dolphinemu.dolphinemu.features.netplay.model.Player
 import org.dolphinemu.dolphinemu.features.netplay.model.SaveTransferProgress
+import org.dolphinemu.dolphinemu.features.netplay.model.TraversalState
 import org.dolphinemu.dolphinemu.features.settings.model.StringSetting
+import org.dolphinemu.dolphinemu.model.GameFile
 
 class NetplaySession(
     private val onClosed: (NetplaySession) -> Unit,
@@ -117,6 +118,15 @@ class NetplaySession(
     private val _gameDigestProgress = MutableStateFlow<GameDigestProgress?>(null)
     val gameDigestProgress = _gameDigestProgress.asStateFlow()
 
+    private val _traversalState = MutableSharedFlow<TraversalState>(
+        replay = 1,
+        onBufferOverflow = BufferOverflow.DROP_OLDEST
+    )
+    val traversalState = _traversalState.asSharedFlow()
+
+    private val _fatalTraversalError = Channel<TraversalState.Failure>(Channel.CONFLATED)
+    val fatalTraversalError = _fatalTraversalError.receiveAsFlow()
+
     suspend fun join(): Boolean = withContext(Dispatchers.IO) {
         if (isClosed) throw IllegalStateException("Cannot join a closed session")
 
@@ -148,7 +158,7 @@ class NetplaySession(
     }
 
     fun sendMessage(message: String) {
-        _chatMessages.tryEmit( "$nickName: $message")
+        _chatMessages.tryEmit("$nickName: $message")
         nativeSendMessage(message)
     }
 
@@ -162,6 +172,8 @@ class NetplaySession(
 
     fun getExternalIpAddress(): String? = nativeGetExternalIpAddress()
 
+    fun reconnectTraversal() = nativeReconnectTraversal()
+
     fun consumeBootSessionData(): Long {
         return bootSessionDataPointer.also {
             bootSessionDataPointer = 0
@@ -247,6 +259,8 @@ class NetplaySession(
 
     private external fun nativeGetExternalIpAddress(): String?
 
+    private external fun nativeReconnectTraversal()
+
     // NetPlayUI callbacks
 
     @Keep
@@ -390,6 +404,26 @@ class NetplaySession(
     fun onAbortGameDigest() {
         _gameDigestProgress.value = null
     }
+
+    @Keep
+    fun onTraversalStateChanged(
+        state: Int,
+        hostCode: String?,
+        externalAddress: String?,
+        failureReason: String?,
+    ) {
+        val traversalState = when (state) {
+            0 -> TraversalState.Connecting
+            1 -> TraversalState.Connected(hostCode!!, externalAddress!!)
+            2 -> TraversalState.Failure(failureReason!!)
+            else -> return
+        }
+        _traversalState.tryEmit(traversalState)
+
+        if (failureReason == "BadHost" || failureReason == "VersionTooOld") {
+            _fatalTraversalError.trySend(TraversalState.Failure(failureReason))
+        }
+    }
 }
 
 private fun <T> Channel<T>.flush() {
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/JoinInfo.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/JoinInfo.kt
index ba350a3caf..7403f06f32 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/JoinInfo.kt
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/JoinInfo.kt
@@ -6,6 +6,7 @@ import androidx.annotation.StringRes
 import org.dolphinemu.dolphinemu.R
 
 enum class JoinInfoType(@StringRes val labelId: Int) {
+    ROOM_ID(R.string.netplay_address_type_room_id),
     EXTERNAL(R.string.netplay_address_type_external),
     LOCAL(R.string.netplay_address_type_local),
 }
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/NetplayViewModel.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/NetplayViewModel.kt
index 923cfc314d..4ebea7e283 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/NetplayViewModel.kt
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/NetplayViewModel.kt
@@ -12,7 +12,9 @@ import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import org.dolphinemu.dolphinemu.features.netplay.NetplaySession
@@ -28,20 +30,29 @@ class NetplayViewModel(
     private val networkHelper: NetworkHelper,
 ) : ViewModel() {
 
+    private val isTraversal = StringSetting.NETPLAY_TRAVERSAL_CHOICE.string == "traversal"
+
     val launchGame = netplaySession.launchGame
 
     val isHosting = netplaySession.isHosting
 
     private val _joinAddresses = MutableStateFlow(
-        mapOf(
-            JoinInfoType.EXTERNAL to JoinAddress.Loading,
-            JoinInfoType.LOCAL to getLocalIp(),
-        )
+        buildMap {
+            if (isHosting) {
+                if (isTraversal) {
+                    put(JoinInfoType.ROOM_ID, JoinAddress.Loading)
+                }
+                put(JoinInfoType.EXTERNAL, JoinAddress.Loading)
+                put(JoinInfoType.LOCAL, getLocalIp())
+            }
+        }
     )
     val joinAddresses = _joinAddresses.asStateFlow()
 
     val connectionLost = netplaySession.connectionLost
 
+    val fatalTraversalError = netplaySession.fatalTraversalError
+
     val players = netplaySession.players
         .stateIn(viewModelScope, SharingStarted.WhileSubscribed(), emptyList())
 
@@ -72,7 +83,11 @@ class NetplayViewModel(
     init {
         if (netplaySession.isHosting) {
             setInitialGame()
-            fetchExternalIp()
+            if (isTraversal) {
+                collectTraversalState()
+            } else {
+                fetchExternalIp()
+            }
         }
     }
 
@@ -118,6 +133,32 @@ class NetplayViewModel(
         }
     }
 
+    private fun collectTraversalState() {
+        val retry = { netplaySession.reconnectTraversal() }
+        netplaySession.traversalState.onEach { state ->
+            when (state) {
+                is TraversalState.Connecting -> {
+                    _joinAddresses.value += mapOf(
+                        JoinInfoType.ROOM_ID to JoinAddress.Loading,
+                        JoinInfoType.EXTERNAL to JoinAddress.Loading,
+                    )
+                }
+                is TraversalState.Connected -> {
+                    _joinAddresses.value += mapOf(
+                        JoinInfoType.ROOM_ID to JoinAddress.Loaded(state.hostCode),
+                        JoinInfoType.EXTERNAL to JoinAddress.Loaded(state.externalAddress),
+                    )
+                }
+                is TraversalState.Failure -> {
+                    _joinAddresses.value += mapOf(
+                        JoinInfoType.ROOM_ID to JoinAddress.Unknown(retry),
+                        JoinInfoType.EXTERNAL to JoinAddress.Unknown(retry),
+                    )
+                }
+            }
+        }.launchIn(viewModelScope)
+    }
+
     private fun setInitialGame() {
         val game = gameFiles.value
             .find { it.getGameId() == StringSetting.NETPLAY_GAME.string }
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/TraversalState.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/TraversalState.kt
new file mode 100644
index 0000000000..9b574e4f63
--- /dev/null
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/TraversalState.kt
@@ -0,0 +1,18 @@
+package org.dolphinemu.dolphinemu.features.netplay.model
+
+import android.content.Context
+import org.dolphinemu.dolphinemu.R
+
+sealed class TraversalState {
+    data object Connecting : TraversalState()
+
+    data class Connected(val hostCode: String, val externalAddress: String) : TraversalState()
+
+    data class Failure(val reason: String) : TraversalState() {
+        fun message(context: Context) = when (reason) {
+            "BadHost" -> context.getString(R.string.netplay_traversal_error_bad_host)
+            "VersionTooOld" -> context.getString(R.string.netplay_traversal_error_version_too_old)
+            else -> reason
+        }
+    }
+}
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayActivity.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayActivity.kt
index a9bf0309a5..e45ba7e7c1 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayActivity.kt
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayActivity.kt
@@ -50,6 +50,7 @@ class NetplayActivity : AppCompatActivity(), ThemeProvider {
                 NetplayScreen(
                     onBackClicked = { finish() },
                     connectionLost = viewModel.connectionLost,
+                    fatalTraversalError = viewModel.fatalTraversalError,
                     messages = viewModel.messages.collectAsState().value,
                     onSendMessage = viewModel::sendMessage,
                     game = viewModel.game.collectAsState().value,
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayScreen.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayScreen.kt
index eeba0f1541..71b427a8c8 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayScreen.kt
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayScreen.kt
@@ -97,6 +97,7 @@ import org.dolphinemu.dolphinemu.features.netplay.model.JoinInfoType
 import org.dolphinemu.dolphinemu.features.netplay.model.NetplayMessage
 import org.dolphinemu.dolphinemu.features.netplay.model.Player
 import org.dolphinemu.dolphinemu.features.netplay.model.SaveTransferProgress
+import org.dolphinemu.dolphinemu.features.netplay.model.TraversalState
 import org.dolphinemu.dolphinemu.model.GameFile
 import org.dolphinemu.dolphinemu.ui.theme.DolphinTheme
 import org.dolphinemu.dolphinemu.ui.theme.MenuSpacer
@@ -112,6 +113,7 @@ fun NetplayScreen(
     onBackClicked: () -> Unit,
     isHosting: Boolean,
     connectionLost: Flow<Unit>,
+    fatalTraversalError: Flow<TraversalState.Failure>,
     messages: List<NetplayMessage>,
     onSendMessage: (String) -> Unit,
     game: String,
@@ -156,7 +158,9 @@ fun NetplayScreen(
         // State which must live above the landscape/portrait split.
         var showChat by rememberSaveable { mutableStateOf(false) }
         var showGamePicker by rememberSaveable { mutableStateOf(false) }
-        var selectedJoinInfoType by rememberSaveable { mutableStateOf(JoinInfoType.EXTERNAL) }
+        var selectedJoinInfoType by rememberSaveable {
+            mutableStateOf(joinAddresses.keys.firstOrNull() ?: JoinInfoType.EXTERNAL)
+        }
 
         if (LocalConfiguration.current.orientation == Configuration.ORIENTATION_LANDSCAPE) {
             LandscapeContent(
@@ -207,6 +211,11 @@ fun NetplayScreen(
             connectionLost.collect { showConnectionLostDialog = true }
         }
 
+        var traversalError by rememberSaveable { mutableStateOf<TraversalState.Failure?>(null) }
+        LaunchedEffect(Unit) {
+            fatalTraversalError.collect { traversalError = it }
+        }
+
         var dismissSaveTransferProgressDialog by rememberSaveable { mutableStateOf(false) }
         if (saveTransferProgress == null) {
             dismissSaveTransferProgressDialog = false
@@ -217,6 +226,8 @@ fun NetplayScreen(
             dismissGameDigestDialog = false
         }
 
+        val currentTraversalError = traversalError
+
         when {
             showConnectionLostDialog -> {
                 AlertDialog(
@@ -230,6 +241,18 @@ fun NetplayScreen(
                 )
             }
 
+            currentTraversalError != null -> {
+                AlertDialog(
+                    text = { Text(currentTraversalError.message(LocalContext.current)) },
+                    confirmButton = {
+                        TextButton(onClick = onBackClicked) {
+                            Text(stringResource(R.string.ok))
+                        }
+                    },
+                    onDismissRequest = onBackClicked,
+                )
+            }
+
             saveTransferProgress != null && !dismissSaveTransferProgressDialog -> {
                 SaveTransferProgressDialog(
                     saveTransferProgress = saveTransferProgress,
@@ -669,6 +692,7 @@ private fun JoinAddressSection(
                     modifier = Modifier.weight(0.39f),
                 )
                 AddressRow(
+                    joinInfoType = selectedType,
                     address = address,
                     modifier = Modifier.weight(0.61f),
                 )
@@ -683,6 +707,7 @@ private fun JoinAddressSection(
                 )
                 MenuSpacer()
                 AddressRow(
+                    joinInfoType = selectedType,
                     address = address,
                     modifier = Modifier.fillMaxWidth(),
                 )
@@ -737,6 +762,7 @@ private fun JoinInfoDropdown(
 
 @Composable
 private fun AddressRow(
+    joinInfoType: JoinInfoType,
     address: JoinAddress,
     modifier: Modifier = Modifier,
 ) {
@@ -748,7 +774,10 @@ private fun AddressRow(
             is JoinAddress.Loaded -> address.address
             is JoinAddress.Unknown -> stringResource(R.string.netplay_address_unknown)
         },
-        label = stringResource(R.string.netplay_address_label),
+        label = stringResource(
+            if (joinInfoType == JoinInfoType.ROOM_ID) R.string.netplay_code_label
+            else R.string.netplay_address_label
+        ),
         onClick = when (address) {
             is JoinAddress.Loaded -> {
                 {
@@ -1128,6 +1157,7 @@ private fun PreviewNetplayScreen() {
     NetplayScreen(
         onBackClicked = {},
         connectionLost = emptyFlow(),
+        fatalTraversalError = emptyFlow(),
         players = listOf(
             Player(
                 pid = 1,