ADD: Breadcrumbs + navigation with "Zurücktaste"

.idea/deploymentTargetSelector.xml

@@ -4,7 +4,7 @@
     <selectionStates>
       <SelectionState runConfigName="app">
         <option name="selectionMode" value="DROPDOWN" />
-        <DropdownSelection timestamp="2025-05-03T08:34:29.354537334Z">
+        <DropdownSelection timestamp="2025-05-10T09:28:03.000292036Z">
           <Target type="DEFAULT_BOOT">
             <handle>
               <DeviceId pluginId="PhysicalDevice" identifier="serial=R52N50NLGRT" />

app/src/main/java/come/stormborntales/notevault/ui/screens/NotesBrowser.kt

@@ -1,11 +1,14 @@
 package come.stormborntales.notevault.ui.screens
 
 import android.util.Log
+import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.wrapContentWidth
@@ -37,6 +40,7 @@ import androidx.lifecycle.ViewModelStoreOwner
 import androidx.lifecycle.viewmodel.compose.LocalViewModelStoreOwner
 import androidx.lifecycle.viewmodel.compose.viewModel
 import come.stormborntales.notevault.data.local.AppDatabase
+import come.stormborntales.notevault.data.local.entity.NoteCollection
 import come.stormborntales.notevault.data.repository.CollectionRepository
 import come.stormborntales.notevault.data.repository.NoteRepository
 import come.stormborntales.notevault.ui.viewmodel.NoteBrowserViewModel
@@ -97,6 +101,39 @@ fun CreateCollectionDialog(
     )
 }
 
+@Composable
+fun CollectionBreadcrumbs(
+    path: List<NoteCollection>,
+    onNavigateTo: (index: Int) -> Unit
+) {
+    Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(8.dp),
+        verticalAlignment = Alignment.CenterVertically
+    ) {
+        Text(
+            text = "Start",
+            modifier = Modifier
+                .clickable { onNavigateTo(-1) }
+                .padding(horizontal = 4.dp),
+            style = MaterialTheme.typography.labelLarge
+        )
+
+        path.forEachIndexed { index, collection ->
+            Text(" / ", style = MaterialTheme.typography.labelLarge)
+            Text(
+                text = collection.name,
+                modifier = Modifier
+                    .clickable { onNavigateTo(index) }
+                    .padding(horizontal = 4.dp),
+                style = MaterialTheme.typography.labelLarge
+            )
+        }
+    }
+}
+
+
 @Composable
 fun NotesScreen(
     collectionRepository: CollectionRepository,
@@ -145,6 +182,19 @@ fun NotesScreen(
             }
         },
         content = { innerPadding ->
+
+            val path by viewModel.pathStack.collectAsState()
+            BackHandler(enabled = path.isNotEmpty()) {
+                viewModel.navigateUp()
+            }
+            CollectionBreadcrumbs(
+                path = path,
+                onNavigateTo = { index ->
+                    if (index == -1) viewModel.loadContentForParent(null)
+                    else viewModel.navigateToLevel(index)
+                }
+            )
+
             LazyColumn(
                 modifier = Modifier
                     .fillMaxSize()
@@ -162,7 +212,7 @@ fun NotesScreen(
                     ListItem(
                         headlineContent = { Text(collection.name) },
                         modifier = Modifier
-                            .clickable { viewModel.loadContentForParent(collection.id) }
+                            .clickable { viewModel.loadContentForParent(collection.id, collection) }
                             .padding(horizontal = 8.dp)
                     )
                 }

app/src/main/java/come/stormborntales/notevault/ui/viewmodel/NoteBrowserViewModel.kt

@@ -24,11 +24,14 @@ class NoteBrowserViewModel (
     private val _currentParentId = MutableStateFlow<Int?>(null)
     val currentParentId: StateFlow<Int?> = _currentParentId.asStateFlow()
 
+    private val _pathStack = MutableStateFlow<List<NoteCollection>>(emptyList())
+    val pathStack: StateFlow<List<NoteCollection>> = _pathStack.asStateFlow()
+
     init {
         loadContentForParent(null)
     }
 
-    fun loadContentForParent(parentId: Int?) {
+    fun loadContentForParent(parentId: Int?, selectedCollection: NoteCollection? = null) {
         _currentParentId.value = parentId
         viewModelScope.launch {
             launch {
@@ -41,6 +44,11 @@ class NoteBrowserViewModel (
                     _currentNotes.value = it
                 }
             }
+            if (selectedCollection != null) {
+                _pathStack.value = _pathStack.value + selectedCollection
+            } else if (parentId == null) {
+                _pathStack.value = emptyList()
+            }
         }
     }
 
@@ -51,4 +59,18 @@ class NoteBrowserViewModel (
             loadContentForParent(_currentParentId.value)
         }
     }
+
+    fun navigateToLevel(index: Int) {
+        val newStack = _pathStack.value.take(index + 1)
+        _pathStack.value = newStack
+        val newParent = newStack.lastOrNull()?.id
+        loadContentForParent(newParent)
+    }
+
+    fun navigateUp() {
+        val newStack = _pathStack.value.dropLast(1)
+        _pathStack.value = newStack
+        val newParentId = newStack.lastOrNull()?.id
+        loadContentForParent(newParentId)
+    }
 }