Merge pull request #51 from dreipol/feature/abstract-navigation-state

[abstract-navigation-state] Abstract navigation state

src/commonMain/kotlin/ch/dreipol/dreimultiplatform/reduxkotlin/navigation/AbstractNavigationState.kt

@@ -0,0 +1,24 @@
+package ch.dreipol.dreimultiplatform.reduxkotlin.navigation
+
+abstract class AbstractNavigationState<Screen> {
+    abstract val homeScreen: Screen
+    abstract val pushedScreens: List<Screen>
+    val screens: List<Screen>
+        get() = listOf(homeScreen) + pushedScreens
+
+    val currentScreen: Screen
+        get() = screens.last()
+}
+
+// used in Android for showing correct animation when
+// navigating back from deep link jump
+enum class NavigationDirection {
+    PUSH,
+    POP
+}
+
+data class DirectionalNavigationState<Screen>(
+    override val homeScreen: Screen,
+    override val pushedScreens: List<Screen> = emptyList(),
+    val navigationDirection: NavigationDirection = NavigationDirection.POP,
+) : AbstractNavigationState<Screen>()

src/commonMain/kotlin/ch/dreipol/dreimultiplatform/reduxkotlin/navigation/NavigationReducer.kt

@@ -1,13 +1,4 @@
 package ch.dreipol.dreimultiplatform.reduxkotlin.navigation
 
-fun navigateBack(state: NavigationState): NavigationState {
-    if (state.sheet != null) {
-        return state.copy(sheet = null)
-    }
-    val screens = state.screens.toMutableList()
-    if (screens.size == 1) {
-        return state
-    }
-    screens.removeAt(screens.lastIndex)
-    return state.copy(screens = screens, navigationDirection = NavigationDirection.POP)
-}
+fun <Screen> navigateBack(state: DirectionalNavigationState<Screen>): DirectionalNavigationState<Screen> =
+    state.copy(pushedScreens = state.pushedScreens.dropLast(1), navigationDirection = NavigationDirection.POP)

src/commonMain/kotlin/ch/dreipol/dreimultiplatform/reduxkotlin/navigation/Navigator.kt

@@ -4,13 +4,16 @@ import ch.dreipol.dreimultiplatform.reduxkotlin.subscribeChanges
 import org.reduxkotlin.Store
 import org.reduxkotlin.StoreSubscriber
 
-interface Navigator<RootState : Any> {
+interface Navigator<RootState : Any, NavigationState : AbstractNavigationState<*>> {
     val store: Store<RootState>
     fun updateNavigationState(navigationState: NavigationState)
     fun getNavigationState(): NavigationState
 }
 
-fun <RootState : Any> Navigator<RootState>.subscribeNavigationState(): StoreSubscriber {
+fun <
+    RootState : Any,
+    NavigationState : AbstractNavigationState<*>
+    > Navigator<RootState, NavigationState>.subscribeNavigationState(): StoreSubscriber {
     return store.subscribeChanges({ getNavigationState() }) {
         updateNavigationState(getNavigationState())
     }