Add NiaBackStack and BackStack providers

Bump agp versions and add navigation 3 dependency

Author: claraf3

app/build.gradle.kts

@@ -83,6 +83,7 @@ dependencies {
     implementation(projects.core.designsystem)
     implementation(projects.core.data)
     implementation(projects.core.model)
+    implementation(projects.core.navigation)
     implementation(projects.core.analytics)
     implementation(projects.sync.work)
 

app/src/main/kotlin/com/google/samples/apps/nowinandroid/di/BackStackProvider.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.di
+
+import androidx.compose.runtime.snapshots.SnapshotStateList
+import com.google.samples.apps.nowinandroid.core.navigation.BackStackFactory
+import com.google.samples.apps.nowinandroid.core.navigation.NiaBackStack
+import com.google.samples.apps.nowinandroid.feature.foryou.api.navigation.ForYouRoute
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import javax.inject.Singleton
+import dagger.hilt.components.SingletonComponent
+
+@Module
+@InstallIn(SingletonComponent::class)
+object NiaAppNavigation {
+    @Provides
+    @Singleton
+    fun provideBackStack(backStackFactory: BackStackFactory) : SnapshotStateList<Any> =
+        backStackFactory.create()
+
+    @Provides
+    @Singleton
+    fun provideNiaBackStack(backStack: SnapshotStateList<Any>): NiaBackStack =
+        NiaBackStack(backStack, startKey = ForYouRoute)
+}

build-logic/convention/src/main/kotlin/AndroidApplicationConventionPlugin.kt

@@ -37,7 +37,7 @@ class AndroidApplicationConventionPlugin : Plugin<Project> {
 
             extensions.configure<ApplicationExtension> {
                 configureKotlinAndroid(this)
-                defaultConfig.targetSdk = 35
+                defaultConfig.targetSdk = 36
                 @Suppress("UnstableApiUsage")
                 testOptions.animationsDisabled = true
                 configureGradleManagedDevices(this)

build-logic/convention/src/main/kotlin/AndroidLibraryConventionPlugin.kt

@@ -37,7 +37,7 @@ class AndroidLibraryConventionPlugin : Plugin<Project> {
 
             extensions.configure<LibraryExtension> {
                 configureKotlinAndroid(this)
-                defaultConfig.targetSdk = 35
+                defaultConfig.targetSdk = 36
                 defaultConfig.testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
                 testOptions.animationsDisabled = true
                 configureFlavors(this)

build-logic/convention/src/main/kotlin/AndroidTestConventionPlugin.kt

@@ -30,7 +30,7 @@ class AndroidTestConventionPlugin : Plugin<Project> {
 
             extensions.configure<TestExtension> {
                 configureKotlinAndroid(this)
-                defaultConfig.targetSdk = 35
+                defaultConfig.targetSdk = 36
                 configureGradleManagedDevices(this)
             }
         }

build-logic/convention/src/main/kotlin/com/google/samples/apps/nowinandroid/KotlinAndroid.kt

@@ -35,7 +35,7 @@ internal fun Project.configureKotlinAndroid(
     commonExtension: CommonExtension<*, *, *, *, *, *>,
 ) {
     commonExtension.apply {
-        compileSdk = 35
+        compileSdk = 36
 
         defaultConfig {
             minSdk = 21

core/navigation/.gitignore

@@ -0,0 +1 @@
+/build

core/navigation/build.gradle.kts

@@ -0,0 +1,8 @@
+plugins {
+    alias(libs.plugins.nowinandroid.jvm.library)
+    alias(libs.plugins.nowinandroid.hilt)
+}
+
+dependencies {
+    implementation(libs.androidx.navigation3.runtime)
+}

core/navigation/src/main/kotlin/com/google/samples/apps/nowinandroid/core/navigation/BackStackFactoryProvider.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.navigation
+
+import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.snapshots.SnapshotStateList
+import javax.inject.Inject
+
+class BackStackFactory @Inject constructor() {
+    fun create() : SnapshotStateList<Any> = mutableStateListOf()
+}

core/navigation/src/main/kotlin/com/google/samples/apps/nowinandroid/core/navigation/NiaBackStack.kt

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.navigation
+
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.SnapshotStateList
+import javax.inject.Inject
+import kotlin.collections.remove
+
+class NiaBackStack @Inject constructor(
+    val backStack: SnapshotStateList<Any>,
+    startKey: Any,
+) {
+    init {
+        backStack.add(startKey)
+    }
+
+    // Maintain a stack for each top level route
+    private var topLevelStacks : LinkedHashMap<Any, SnapshotStateList<Any>> = linkedMapOf(
+        startKey to mutableStateListOf(startKey)
+    )
+
+    // Expose the current top level route for consumers
+    var topLevelKey by mutableStateOf(startKey)
+        private set
+
+    private fun updateBackStack() =
+        backStack.apply {
+            clear()
+            addAll(topLevelStacks.flatMap { it.value })
+        }
+            .also { println("cfok currBackStack:$backStack") }
+
+    fun navigateToTopLevelDestination(key: Any){
+        // If the top level doesn't exist, add it
+        if (topLevelStacks[key] == null){
+            topLevelStacks.put(key, mutableStateListOf(key))
+        } else {
+            // Otherwise just move it to the end of the stacks
+            topLevelStacks.apply {
+                remove(key)?.let {
+                    put(key, it)
+                }
+            }
+        }
+        topLevelKey = key
+        updateBackStack()
+    }
+
+    fun navigate(key: Any){
+        println("cfok navigate $key")
+        topLevelStacks[topLevelKey]?.add(key)
+        updateBackStack()
+    }
+
+    fun removeLast(){
+        val removedKey = topLevelStacks[topLevelKey]?.removeLastOrNull()
+        // If the removed key was a top level key, remove the associated top level stack
+        topLevelStacks.remove(removedKey)
+        topLevelKey = topLevelStacks.keys.last()
+        updateBackStack()
+    }
+
+}