Dev

composeApp/src/androidMain/kotlin/SystemNavigation.android.kt

@@ -0,0 +1,8 @@
+import ui.navigation.Screen
+
+class AndroidSystemNavigation : SystemNavigation {
+    override fun navigateTo(screen: Screen) {}
+    override fun navigateBack() {}
+}
+
+actual fun systemNavigation(): SystemNavigation = AndroidSystemNavigation()

composeApp/src/commonMain/kotlin/SystemNavigation.kt

@@ -0,0 +1,8 @@
+import ui.navigation.Screen
+
+interface SystemNavigation {
+    fun navigateTo(screen: Screen)
+    fun navigateBack()
+}
+
+expect fun systemNavigation(): SystemNavigation

composeApp/src/commonMain/kotlin/di/AppModule.kt

@@ -4,6 +4,7 @@ import ivy.di.Di
 import ivy.di.Di.register
 import ivy.di.Di.singleton
 import ivy.di.DiModule
+import systemNavigation
 import ui.navigation.Navigation
 import util.DispatchersProvider
 import util.DispatchersProviderImpl
@@ -12,7 +13,8 @@ object AppModule : DiModule {
 
     override fun init() {
         Di.appScope {
-            singleton { Navigation() }
+            register { systemNavigation() }
+            singleton { Navigation(Di.get()) }
             register<DispatchersProvider> { DispatchersProviderImpl() }
         }
     }

composeApp/src/commonMain/kotlin/ui/navigation/Navigation.kt

@@ -1,11 +1,12 @@
 package ui.navigation
 
+import SystemNavigation
 import androidx.compose.runtime.*
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.plus
 import kotlinx.collections.immutable.toPersistentList
 
-class Navigation {
+class Navigation(private val systemNavigation: SystemNavigation) {
     private var backstack by mutableStateOf(persistentListOf<Screen>())
 
     @Composable
@@ -18,6 +19,7 @@ class Navigation {
 
     fun navigate(screen: Screen) {
         backstack = backstack.plus(screen.also(Screen::initialize))
+        systemNavigation.navigateTo(screen)
     }
 
     fun backUntil(predicate: (Screen) -> Boolean) {
@@ -30,6 +32,9 @@ class Navigation {
     fun back(): Screen? {
         val lastScreen = backstack.lastOrNull()
         backstack = backstack.dropLast(1).toPersistentList()
-        return lastScreen?.also(Screen::destroy)
+        return lastScreen?.also {
+            it.destroy()
+            systemNavigation.navigateBack()
+        }
     }
 }

composeApp/src/commonMain/kotlin/ui/navigation/Screen.kt

@@ -9,6 +9,8 @@ import kotlinx.coroutines.SupervisorJob
 
 abstract class Screen {
 
+    abstract val path: String
+
     private lateinit var job: CompletableJob
     protected lateinit var screenScope: CoroutineScope
 

composeApp/src/commonMain/kotlin/ui/screen/debug/ColorDemoScreen.kt

@@ -1,11 +1,7 @@
 package ui.screen.debug
 
 import androidx.compose.foundation.background
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.LazyListScope
 import androidx.compose.material.Text
@@ -18,15 +14,11 @@ import component.LearnScaffold
 import ivy.di.Di
 import ui.navigation.Navigation
 import ui.navigation.Screen
-import ui.theme.Blue
-import ui.theme.BlueVariant
-import ui.theme.Gray
-import ui.theme.Green
-import ui.theme.Orange
-import ui.theme.OrangeVariant
-import ui.theme.Red
+import ui.theme.*
 
 class ColorDemoScreen : Screen() {
+    override val path: String = "colorDemo"
+
     private val navigation: Navigation = Di.get()
 
     override fun onDi(): Di.ScreenScope.() -> Unit = {}

composeApp/src/commonMain/kotlin/ui/screen/home/HomeScreen.kt

@@ -7,6 +7,8 @@ import ui.navigation.Screen
 import ui.screen.home.composable.HomeContent
 
 class HomeScreen : Screen() {
+    override val path: String = "home"
+
     override fun onDi(): Di.ScreenScope.() -> Unit = {
         register { HomeViewModel(Di.get()) }
     }

composeApp/src/commonMain/kotlin/ui/screen/intro/IntroScreen.kt

@@ -7,6 +7,8 @@ import ui.navigation.Screen
 import ui.screen.intro.composable.IntroContent
 
 class IntroScreen : Screen() {
+    override val path: String = "intro"
+
     override fun onDi(): Di.ScreenScope.() -> Unit = {
         register { IntroViewModel(Di.get()) }
     }

composeApp/src/desktopMain/kotlin/SystemNavigation.desktop.kt

@@ -0,0 +1,8 @@
+import ui.navigation.Screen
+
+class DesktopSystemNavigation : SystemNavigation {
+    override fun navigateTo(screen: Screen) {}
+    override fun navigateBack() {}
+}
+
+actual fun systemNavigation(): SystemNavigation = DesktopSystemNavigation()

composeApp/src/iosMain/kotlin/SystemNavigation.ios.kt

@@ -0,0 +1,9 @@
+import ui.navigation.Screen
+
+class IOSSystemNavigation : SystemNavigation {
+    override fun navigateTo(screen: Screen) {}
+
+    override fun navigateBack() {}
+}
+
+actual fun systemNavigation(): SystemNavigation = IOSSystemNavigation()

composeApp/src/jsMain/kotlin/SystemNavigation.js.kt

@@ -0,0 +1,20 @@
+import kotlinx.browser.window
+import ui.navigation.Screen
+
+class WebSystemNavigation : SystemNavigation {
+    override fun navigateTo(screen: Screen) {
+        // TODO: Temporary workaround until we support deep links
+        val path = "" // "/${screen.path}"
+
+        val stateObject = js("({})")
+        // TODO: Temporary workaround until we support deep links
+        stateObject.screen = "" //screen.path
+        window.history.pushState(stateObject, "", path)
+    }
+
+    override fun navigateBack() {
+        window.history.back()
+    }
+}
+
+actual fun systemNavigation(): SystemNavigation = WebSystemNavigation()

composeApp/src/jsMain/kotlin/main.js.kt

@@ -1,6 +1,9 @@
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.window.CanvasBasedWindow
+import ivy.di.Di
+import kotlinx.browser.window
 import org.jetbrains.skiko.wasm.onWasmReady
+import ui.navigation.Navigation
 
 @OptIn(ExperimentalComposeUiApi::class)
 fun main() {
@@ -9,4 +12,14 @@ fun main() {
             App()
         }
     }
+    setupBackNavigationHandler()
+}
+
+fun setupBackNavigationHandler() {
+    window.addEventListener("popstate", {
+        val navigation = Di.get<Navigation>()
+        if (navigation.backstack().size > 1) {
+            navigation.back()
+        }
+    })
 }

server/src/main/kotlin/ivy/learn/api/LessonsApi.kt

@@ -2,6 +2,7 @@ package ivy.learn.api
 
 import arrow.core.raise.ensureNotNull
 import io.ktor.server.routing.*
+import io.ktor.util.*
 import ivy.learn.api.common.Api
 import ivy.learn.api.common.endpoint
 import ivy.learn.api.common.model.ServerError
@@ -13,7 +14,11 @@ class LessonsApi(
     private val repository: LessonsRepository
 ) : Api {
     override fun Routing.endpoints() {
-        // Endpoint that gets a lesson by ID
+        lessonById()
+    }
+
+    @KtorDsl
+    private fun Routing.lessonById() {
         get("/lessons/{id}", endpoint<Lesson> { params ->
             val lessonId = params["id"]?.let(::LessonId)
             ensureNotNull(lessonId) { ServerError.BadRequest("Lesson id is missing!") }

shared/src/androidMain/kotlin/Platform.android.kt

@@ -6,7 +6,6 @@ import io.ktor.client.engine.android.*
 
 class AndroidPlatform : Platform {
     override val name: String = "Android ${Build.VERSION.SDK_INT}"
-    override val debug: Boolean = false
 
     override fun log(level: LogLevel, msg: String) {
         val tag = ""

shared/src/commonMain/kotlin/Platform.kt

@@ -2,7 +2,6 @@ import io.ktor.client.*
 
 interface Platform {
     val name: String
-    val debug: Boolean
     fun log(level: LogLevel, msg: String)
     fun httpClient(config: HttpClientConfig<*>.() -> Unit = {}): HttpClient
 }

shared/src/iosMain/kotlin/Platform.ios.kt

@@ -4,7 +4,6 @@ import platform.UIKit.UIDevice
 
 class IOSPlatform : Platform {
     override val name: String = UIDevice.currentDevice.systemName() + " " + UIDevice.currentDevice.systemVersion
-    override val debug: Boolean = false
 
     override fun log(level: LogLevel, msg: String) {
         println("${level.name}: $msg")

shared/src/jsMain/kotlin/Platform.js.kt

@@ -3,7 +3,6 @@ import io.ktor.client.engine.js.*
 
 class JsPlatform : Platform {
     override val name: String = "Web with Kotlin/JS"
-    override val debug: Boolean = false
 
     override fun log(level: LogLevel, msg: String) {
         console.log("${level.name}: $msg")

shared/src/jvmMain/kotlin/Platform.jvm.kt

@@ -3,7 +3,6 @@ import io.ktor.client.engine.java.*
 
 class JVMPlatform: Platform {
     override val name: String = "Java ${System.getProperty("java.version")}"
-    override val debug: Boolean = false
 
     override fun log(level: LogLevel, msg: String) {
         println("${level.name}: $msg")