From c7a0428b96678fb32b4b6de3bd59b243b1d26c20 Mon Sep 17 00:00:00 2001
From: Ryan Moelter <hello@ryanmoelter.com>
Date: Sun, 15 Oct 2023 11:30:20 -0700
Subject: [PATCH] [WIP] Start to proactively handle back

---
 .../compose/ActivityLifecycleComposeAdapter.kt        | 11 +++++++++++
 .../magellanx/compose/navigation/ComposeNavigator.kt  |  5 +++++
 .../magellanx/core/lifecycle/LifecycleAware.kt        |  1 +
 3 files changed, 17 insertions(+)

diff --git a/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/ActivityLifecycleComposeAdapter.kt b/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/ActivityLifecycleComposeAdapter.kt
index f1931816..c3b13044 100644
--- a/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/ActivityLifecycleComposeAdapter.kt
+++ b/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/ActivityLifecycleComposeAdapter.kt
@@ -2,6 +2,7 @@ package com.ryanmoelter.magellanx.compose
 
 import android.app.Activity
 import androidx.activity.ComponentActivity
+import androidx.activity.OnBackPressedCallback
 import androidx.activity.compose.setContent
 import androidx.compose.runtime.Composable
 import androidx.lifecycle.DefaultLifecycleObserver
@@ -55,6 +56,16 @@ public fun ComponentActivity.setContentNavigable(navigable: Navigable<@Composabl
   val lifecycleAdapter = ActivityLifecycleComposeAdapter(navigable, this)
   navigable.attachAndAddToStaticMap(lifecycleAdapter, lifecycle)
   setContent { navigable.Content() }
+
+  onBackPressedDispatcher.addCallback(object : OnBackPressedCallback(false) {
+    init {
+      isEnabled = navigable.willHandleBack { willHandleBack -> isEnabled = willHandleBack }
+    }
+
+    override fun handleOnBackPressed() {
+      navigable.backPressed()
+    }
+  })
 }
 
 private fun Navigable<@Composable () -> Unit>.attachAndAddToStaticMap(
diff --git a/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/navigation/ComposeNavigator.kt b/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/navigation/ComposeNavigator.kt
index 14db5c49..d92bcad1 100644
--- a/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/navigation/ComposeNavigator.kt
+++ b/magellanx-compose/src/main/java/com/ryanmoelter/magellanx/compose/navigation/ComposeNavigator.kt
@@ -68,6 +68,7 @@ public open class ComposeNavigator :
 
     AnimatedContent(
       targetState = currentNavigable,
+      label = "ComposeNavigator container",
       transitionSpec = currentTransitionSpec.getTransitionForDirection(currentDirection),
     ) { navigable ->
       DisposableEffect(
@@ -203,6 +204,10 @@ public open class ComposeNavigator :
 
   override fun onBackPressed(): Boolean = currentNavigable?.backPressed() ?: false || goBack()
 
+  override fun willHandleBack(changeWillHandleBack: (Boolean) -> Unit): Boolean {
+    return super.willHandleBack(changeWillHandleBack)
+  }
+
   public open fun atRoot(): Boolean = backStack.size <= 1
 }
 
diff --git a/magellanx-core/src/main/java/com/ryanmoelter/magellanx/core/lifecycle/LifecycleAware.kt b/magellanx-core/src/main/java/com/ryanmoelter/magellanx/core/lifecycle/LifecycleAware.kt
index a88db89f..d9fd4ed7 100644
--- a/magellanx-core/src/main/java/com/ryanmoelter/magellanx/core/lifecycle/LifecycleAware.kt
+++ b/magellanx-core/src/main/java/com/ryanmoelter/magellanx/core/lifecycle/LifecycleAware.kt
@@ -8,4 +8,5 @@ public interface LifecycleAware {
   public fun hide() {}
   public fun destroy() {}
   public fun backPressed(): Boolean = false
+  public fun willHandleBack(changeWillHandleBack: (Boolean) -> Unit): Boolean = false
 }