From 842677fab4f2faa84bd290bb35145e2fe1b13983 Mon Sep 17 00:00:00 2001
From: Alexander Capehart <alex@oxycblt.org>
Date: Tue, 25 Jul 2023 19:51:08 -0600
Subject: [PATCH] ui: fix broken back navigation

Caused by a change in a dependency update that suddenly causes
FragmentManager's back callback to to jump ahead of ours for no
reason.
---
 .../java/org/oxycblt/auxio/MainFragment.kt    | 53 ++++++-------------
 1 file changed, 15 insertions(+), 38 deletions(-)

diff --git a/app/src/main/java/org/oxycblt/auxio/MainFragment.kt b/app/src/main/java/org/oxycblt/auxio/MainFragment.kt
index b1183b194..2d510ea36 100644
--- a/app/src/main/java/org/oxycblt/auxio/MainFragment.kt
+++ b/app/src/main/java/org/oxycblt/auxio/MainFragment.kt
@@ -26,7 +26,6 @@ import androidx.activity.OnBackPressedCallback
 import androidx.core.view.ViewCompat
 import androidx.core.view.isInvisible
 import androidx.core.view.updatePadding
-import androidx.fragment.app.FragmentContainerView
 import androidx.fragment.app.activityViewModels
 import androidx.navigation.NavController
 import androidx.navigation.NavDestination
@@ -78,7 +77,6 @@ class MainFragment :
     private var sheetBackCallback: SheetBackPressedCallback? = null
     private var detailBackCallback: DetailBackPressedCallback? = null
     private var selectionBackCallback: SelectionBackPressedCallback? = null
-    private var exploreBackCallback: ExploreBackPressedCallback? = null
     private var lastInsets: WindowInsets? = null
     private var elevationNormal = 0f
     private var initialNavDestinationChange = true
@@ -104,28 +102,17 @@ class MainFragment :
         // Currently all back press callbacks are handled in MainFragment, as it's not guaranteed
         // that instantiating these callbacks in their respective fragments would result in the
         // correct order.
-        val sheetBackCallback =
+        sheetBackCallback =
             SheetBackPressedCallback(
-                    playbackSheetBehavior = playbackSheetBehavior,
-                    queueSheetBehavior = queueSheetBehavior)
-                .also { sheetBackCallback = it }
+                playbackSheetBehavior = playbackSheetBehavior,
+                queueSheetBehavior = queueSheetBehavior)
         val detailBackCallback =
             DetailBackPressedCallback(detailModel).also { detailBackCallback = it }
         val selectionBackCallback =
             SelectionBackPressedCallback(listModel).also { selectionBackCallback = it }
-        val exploreBackCallback =
-            ExploreBackPressedCallback(binding.exploreNavHost).also { exploreBackCallback = it }
 
         // --- UI SETUP ---
         val context = requireActivity()
-        // Override the back pressed listener so we can map back navigation to collapsing
-        // navigation, navigation out of detail views, etc.
-        context.onBackPressedDispatcher.apply {
-            addCallback(viewLifecycleOwner, exploreBackCallback)
-            addCallback(viewLifecycleOwner, selectionBackCallback)
-            addCallback(viewLifecycleOwner, detailBackCallback)
-            addCallback(viewLifecycleOwner, sheetBackCallback)
-        }
 
         binding.root.setOnApplyWindowInsetsListener { _, insets ->
             lastInsets = insets
@@ -182,6 +169,18 @@ class MainFragment :
         binding.playbackSheet.viewTreeObserver.addOnPreDrawListener(this@MainFragment)
     }
 
+    override fun onResume() {
+        super.onResume()
+        // Override the back pressed listener so we can map back navigation to collapsing
+        // navigation, navigation out of detail views, etc. We have to do this here in
+        // onResume or otherwise the FragmentManager will have precedence.
+        requireActivity().onBackPressedDispatcher.apply {
+            addCallback(viewLifecycleOwner, requireNotNull(selectionBackCallback))
+            addCallback(viewLifecycleOwner, requireNotNull(detailBackCallback))
+            addCallback(viewLifecycleOwner, requireNotNull(sheetBackCallback))
+        }
+    }
+
     override fun onStop() {
         super.onStop()
         val binding = requireBinding()
@@ -194,7 +193,6 @@ class MainFragment :
         sheetBackCallback = null
         detailBackCallback = null
         selectionBackCallback = null
-        exploreBackCallback = null
     }
 
     override fun onPreDraw(): Boolean {
@@ -296,8 +294,6 @@ class MainFragment :
         // Drop the initial call by NavController that simply provides us with the current
         // destination. This would cause the selection state to be lost every time the device
         // rotates.
-        requireNotNull(exploreBackCallback) { "ExploreBackPressedCallback was not available" }
-            .invalidateEnabled()
         if (!initialNavDestinationChange) {
             initialNavDestinationChange = true
             return
@@ -486,23 +482,4 @@ class MainFragment :
             isEnabled = selection.isNotEmpty()
         }
     }
-
-    private inner class ExploreBackPressedCallback(
-        private val exploreNavHost: FragmentContainerView
-    ) : OnBackPressedCallback(false) {
-        // Note: We cannot cache the NavController in a variable since it's current destination
-        // value goes stale for some reason.
-
-        override fun handleOnBackPressed() {
-            exploreNavHost.findNavController().navigateUp()
-            logD("Forwarded back navigation to explore nav host")
-        }
-
-        fun invalidateEnabled() {
-            val exploreNavController = exploreNavHost.findNavController()
-            isEnabled =
-                exploreNavController.currentDestination?.id !=
-                    exploreNavController.graph.startDestinationId
-        }
-    }
 }