experiment: Multi-stack navigation tabs

common/src/commonMain/kotlin/com/artemchep/keyguard/feature/home/HomeScreen.kt

@@ -100,7 +100,6 @@ import com.artemchep.keyguard.feature.navigation.NavigationIntent
 import com.artemchep.keyguard.feature.navigation.NavigationNode
 import com.artemchep.keyguard.feature.navigation.NavigationRouter
 import com.artemchep.keyguard.feature.navigation.Route
-import com.artemchep.keyguard.feature.navigation.popById
 import com.artemchep.keyguard.feature.send.SendRoute
 import com.artemchep.keyguard.feature.sync.SyncRoute
 import com.artemchep.keyguard.platform.LocalLeContext
@@ -162,6 +161,16 @@ private val generatorRoute = GeneratorRoute(
 
 private val watchtowerRoute = WatchtowerRoute()
 
+private val settingsRoute = SettingsRoute
+
+val homeRoutes = listOf(
+    vaultRoute,
+    sendsRoute,
+    generatorRoute,
+    watchtowerRoute,
+    settingsRoute,
+)
+
 @Composable
 fun HomeScreen(
     navBarVisible: Boolean = true,
@@ -213,7 +222,7 @@ fun HomeScreen(
             ),
             Rail(
                 key = "settings",
-                route = SettingsRoute,
+                route = settingsRoute,
                 icon = Icons.Outlined.Settings,
                 iconSelected = Icons.Filled.Settings,
                 label = TextHolder.Res(Res.string.home_settings_label),
@@ -829,7 +838,10 @@ private fun isSelected(
     backStack: List<NavigationEntry>,
     route: Route,
 ) = run {
-    val entry = backStack.getOrNull(1) ?: backStack.firstOrNull()
+    val entry = backStack
+        .lastOrNull { entry ->
+            homeRoutes.any { it === entry.route }
+        }
     entry?.route === route
 }
 
@@ -864,18 +876,35 @@ private fun navigateOnClick(
     route: Route,
 ) {
     val intent = NavigationIntent.Manual { factory ->
-        // If the route exists in the stack, then simply
+        kotlin.run {
-        // navigate back to it.
+            val index = this.backStack.indexOfFirst { it.route === route }
-        val indexOfRoute = backStack.indexOfFirst { it.route === route }
+            if (index != -1) {
-        if (indexOfRoute != -1 && indexOfRoute <= 1) {
+                val end = this.backStack
-            return@Manual subList(0, indexOfRoute + 1)
+                    .drop(index + 1)
-                .toPersistentList()
+                    .indexOfFirst { entry ->
+                        homeRoutes.any { it === entry.route }
+                    }
+                    // Check if that's the end of list
+                    // or a middle part.
+                    .let {
+                        if (it != -1) {
+                            index + it + 1
+                        } else {
+                            this.backStack.size
+                        }
                     }
 
-        val stack = popById(ROUTE_NAME, exclusive = true)
+                val left = this.backStack.subList(0, index)
-            .orEmpty()
+                val center = this.backStack.subList(index, end)
-            .toPersistentList()
+                val right = this.backStack.subList(end, this.backStack.size)
-        stack.add(factory(route))
+                return@Manual left.toPersistentList()
+                    .addAll(right)
+                    .addAll(center)
+            }
+        }
+
+        val entry = factory(route)
+        this.backStack.add(entry)
     }
     controller.queue(intent)
 }

common/src/commonMain/kotlin/com/artemchep/keyguard/feature/navigation/NavigationEntry.kt

@@ -35,6 +35,8 @@ interface NavigationEntry : BackPressInterceptorHost {
 
     val activeBackPressInterceptorsStateFlow: StateFlow<ImmutableMap<String, BackPressInterceptorRegistration>>
 
+    fun getOrCreate(id: String, create: () -> NavigationEntry): NavigationStack
+
     fun destroy()
 }
 
@@ -96,6 +98,14 @@ data class NavigationEntryImpl(
         }
     }
 
+    private val subStacks = mutableMapOf<String, NavigationStack>()
+
+    override fun getOrCreate(id: String, create: () -> NavigationEntry): NavigationStack = subStacks
+        .getOrPut(id) {
+            val navEntry = create()
+            NavigationStack(navEntry)
+        }
+
     override fun destroy() {
         vm.destroy()
         job.cancel()

common/src/commonMain/kotlin/com/artemchep/keyguard/feature/navigation/NavigationIntent.kt

@@ -97,6 +97,6 @@ sealed interface NavigationIntent {
     // manual
 
     data class Manual(
-        val handle: PersistentList<NavigationEntry>.((Route) -> NavigationEntry) -> PersistentList<NavigationEntry>,
+        val handle: NavigationIntentScope.((Route) -> NavigationEntry) -> PersistentList<NavigationEntry>,
     ) : NavigationIntent
 }

common/src/commonMain/kotlin/com/artemchep/keyguard/feature/navigation/NavigationIntentScope.kt

@@ -0,0 +1,7 @@
+package com.artemchep.keyguard.feature.navigation
+
+import kotlinx.collections.immutable.PersistentList
+
+interface NavigationIntentScope {
+    val backStack: PersistentList<NavigationEntry>
+}

common/src/commonMain/kotlin/com/artemchep/keyguard/feature/navigation/NavigationRouter.kt

@@ -22,19 +22,18 @@ fun NavigationRouter(
     initial: Route,
     content: @Composable (PersistentList<NavigationEntry>) -> Unit,
 ) {
-    // Fid the top-level router and link the entry's lifecycle
+    // Find the top-level router and link the entry's lifecycle
     // to it, so if the top level gets destroyed we also get
     // destroyed.
     val f = LocalNavigationNodeLogicalStack.current.last()
     val parentScope = f.scope
-    val navStack = remember(id) {
+    val navStack = f.getOrCreate(id) {
-        val navEntry = NavigationEntryImpl(
+        NavigationEntryImpl(
             source = "router root",
             id = id,
             parent = parentScope,
             route = initial,
         )
-        NavigationStack(navEntry)
     }
     val canPop = remember(navStack) {
         snapshotFlow { navStack.value }
@@ -63,7 +62,8 @@ fun NavigationRouter(
                 val backPressInterceptorRegistration = backStack
                     .asReversed()
                     .firstNotNullOfOrNull { navEntry ->
-                        val backPressInterceptors = navEntry.activeBackPressInterceptorsStateFlow.value
+                        val backPressInterceptors =
+                            navEntry.activeBackPressInterceptorsStateFlow.value
                         backPressInterceptors.values.firstOrNull()
                     }
                 if (backPressInterceptorRegistration != null) {
@@ -72,7 +72,10 @@ fun NavigationRouter(
                 }
             }
 
-            val newBackStack = backStack
+            val scope = object : NavigationIntentScope {
+                override val backStack: PersistentList<NavigationEntry> = backStack
+            }
+            val newBackStack = scope
                 .exec(
                     intent = intent,
                     scope = parentScope,
@@ -146,29 +149,32 @@ class NavigationStack(
         }
 }
 
-private fun PersistentList<NavigationEntry>.exec(
+private fun NavigationIntentScope.exec(
     intent: NavigationIntent,
     scope: CoroutineScope,
 ): PersistentList<NavigationEntry>? = when (intent) {
     is NavigationIntent.Composite -> run compose@{
-        var backStack = this
+        var ns = this
         for (subIntent in intent.list) {
-            val new = backStack.exec(
+            val new = ns.exec(
                 intent = subIntent,
                 scope = scope,
-            )
+            ) ?: return@compose null
-            backStack = new
+            ns = object : NavigationIntentScope {
-                ?: return@compose null
+                override val backStack: PersistentList<NavigationEntry>
+                    get() = new
             }
-        backStack
+        }
+        ns.backStack
     }
 
     is NavigationIntent.NavigateToRoute -> kotlin.run {
         val backStack = when (intent.launchMode) {
-            NavigationIntent.NavigateToRoute.LaunchMode.DEFAULT -> this
+            NavigationIntent.NavigateToRoute.LaunchMode.DEFAULT -> backStack
             NavigationIntent.NavigateToRoute.LaunchMode.SINGLE -> {
-                val clearedBackStack = removeAll { it.route::class == intent.route::class }
+                val clearedBackStack =
-                val existingEntry = lastOrNull { it.route == intent.route }
+                    backStack.removeAll { it.route::class == intent.route::class }
+                val existingEntry = backStack.lastOrNull { it.route == intent.route }
                 if (existingEntry != null) {
                     // Fast path if existing route matches the new route.
                     return@run clearedBackStack.add(existingEntry)
@@ -201,14 +207,14 @@ private fun PersistentList<NavigationEntry>.exec(
 
     is NavigationIntent.NavigateToStack -> intent.stack.toPersistentList()
     is NavigationIntent.Pop -> {
-        if (size > 0) {
+        if (backStack.size > 0) {
-            removeAt(size - 1)
+            backStack.removeAt(backStack.size - 1)
         } else {
             null
         }
     }
 
-    is NavigationIntent.PopById -> popById(intent.id, intent.exclusive)
+    is NavigationIntent.PopById -> backStack.popById(intent.id, intent.exclusive)
     is NavigationIntent.Manual -> {
         val factory = fun(route: Route): NavigationEntry =
             NavigationEntryImpl(