From 9c76617700d901b9fceaa80ae38bb8aeab99ffa9 Mon Sep 17 00:00:00 2001
From: Harsh Shandilya <me@msfjarvis.dev>
Date: Sun, 25 May 2025 17:52:37 +0530
Subject: [PATCH] refactor: properly use TopLevelRoute

---
 .../android/ui/navigation/ClawBackStack.kt    | 23 +++++++++++++++++--
 .../claw/android/ui/screens/Nav3Screen.kt     |  2 --
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/navigation/ClawBackStack.kt b/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/navigation/ClawBackStack.kt
index d7b7db59..7f2870f0 100644
--- a/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/navigation/ClawBackStack.kt
+++ b/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/navigation/ClawBackStack.kt
@@ -22,14 +22,33 @@ import io.github.aakira.napier.Napier
  * to the front while lists add behind. To counter these expectations with the actual backing data
  * structure, many APIs in this class inverse of identically named functions on [List].
  */
-class ClawBackStack<T : NavKey>(startRoute: T) {
+class ClawBackStack<T : NavKey>(private val startRoute: T) {
+  /**
+   * Marker interface for routes that occupy the "top" level of the back stack.
+   *
+   * This is used by [dev.msfjarvis.claw.android.ui.navigation.ClawBackStack.add] to ensure that
+   * duplicate instances of these routes do not end up in the back stack.
+   */
   interface TopLevelRoute
 
   val backStack = mutableStateListOf(startRoute)
 
-  /** Pushes a new destination onto the stack. */
+  /**
+   * Pushes a new destination onto the stack.
+   *
+   * Top level routes are specially handled to ensure that the distance between the incoming [route]
+   * and the [startRoute] cannot have anything in between. This prevents users from getting stuck in
+   * a frustratingly long stack of top level destinations that are so easily accessible that they
+   * have no reason to be on the stack.
+   */
   fun add(route: T) {
     logCurrentState("add")
+    if (route is TopLevelRoute) {
+      backStack.clear()
+      if (route != startRoute) {
+        backStack.add(startRoute)
+      }
+    }
     backStack.add(route)
   }
 
diff --git a/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/screens/Nav3Screen.kt b/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/screens/Nav3Screen.kt
index f4d5c418..12e35984 100644
--- a/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/screens/Nav3Screen.kt
+++ b/android/src/main/kotlin/dev/msfjarvis/claw/android/ui/screens/Nav3Screen.kt
@@ -78,7 +78,6 @@ import dev.msfjarvis.claw.common.urllauncher.UrlLauncher
 import dev.msfjarvis.claw.common.user.UserProfile
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.persistentMapOf
-import kotlinx.collections.immutable.toPersistentList
 import kotlinx.coroutines.launch
 
 @OptIn(ExperimentalMaterial3Api::class)
@@ -131,7 +130,6 @@ fun Nav3Screen(
         coroutineScope.launch { if (savedPosts.isNotEmpty()) savedListState.scrollToItem(0) }
       },
     )
-  val navDestinations = navItems.map(NavigationItem::destination).toPersistentList()
   // endregion
 
   val postActions = remember {