fix(drives): preserve filters and scroll position on navigation (#58)

Fixes issue where date/distance filters and scroll position were reset
when navigating back from drive details:

- Move date filter state from composable to ViewModel
- Add scroll position tracking in ViewModel
- Only apply default 7-day filter on first initialization
- Restore scroll position when returning to drives list

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -18,6 +18,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     - Over 150 km: shows weather every 35 km
   - Weather icons for: Clear, Partly Cloudy, Fog, Drizzle, Rain, Snow, Thunderstorm
 
+### Fixed
+- **Drives**: Date and distance filters now persist when navigating to drive details and back
+- **Drives**: Scroll position is now preserved when returning from drive details
+
 ## [0.9.4] - 2026-01-14
 
 ### Fixed

app/src/main/java/com/matedroid/ui/screens/drives/DrivesScreen.kt

@@ -17,6 +17,7 @@ import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.LazyRow
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.pager.HorizontalPager
 import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.foundation.shape.CircleShape
@@ -68,18 +69,9 @@ import com.matedroid.ui.components.BarChartData
 import com.matedroid.ui.components.InteractiveBarChart
 import com.matedroid.ui.theme.CarColorPalette
 import com.matedroid.ui.theme.CarColorPalettes
-import java.time.LocalDate
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 
-enum class DriveDateFilter(val label: String, val days: Long?) {
-    LAST_7_DAYS("Last 7 days", 7),
-    LAST_30_DAYS("Last 30 days", 30),
-    LAST_90_DAYS("Last 90 days", 90),
-    LAST_YEAR("Last year", 365),
-    ALL_TIME("All time", null)
-}
-
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun DrivesScreen(
@@ -91,16 +83,26 @@ fun DrivesScreen(
 ) {
     val uiState by viewModel.uiState.collectAsState()
     val snackbarHostState = remember { SnackbarHostState() }
-    var selectedFilter by remember { mutableStateOf(DriveDateFilter.LAST_7_DAYS) }
     val isDarkTheme = isSystemInDarkTheme()
     val palette = CarColorPalettes.forExteriorColor(exteriorColor, isDarkTheme)
 
+    // Remember scroll state and restore from ViewModel
+    val listState = rememberLazyListState(
+        initialFirstVisibleItemIndex = uiState.scrollPosition,
+        initialFirstVisibleItemScrollOffset = uiState.scrollOffset
+    )
+
+    // Initialize ViewModel with carId (only loads data on first call)
     LaunchedEffect(carId) {
         viewModel.setCarId(carId)
-        // Apply default 7-day filter on initial load
-        val endDate = LocalDate.now()
-        val startDate = endDate.minusDays(7)
-        viewModel.setDateFilter(startDate, endDate)
+    }
+
+    // Save scroll position when it changes
+    LaunchedEffect(listState.firstVisibleItemIndex, listState.firstVisibleItemScrollOffset) {
+        viewModel.saveScrollPosition(
+            listState.firstVisibleItemIndex,
+            listState.firstVisibleItemScrollOffset
+        )
     }
 
     LaunchedEffect(uiState.error) {
@@ -110,17 +112,6 @@ fun DrivesScreen(
         }
     }
 
-    fun applyDateFilter(filter: DriveDateFilter) {
-        selectedFilter = filter
-        if (filter.days != null) {
-            val endDate = LocalDate.now()
-            val startDate = endDate.minusDays(filter.days)
-            viewModel.setDateFilter(startDate, endDate)
-        } else {
-            viewModel.clearDateFilter()
-        }
-    }
-
     Scaffold(
         topBar = {
             TopAppBar(
@@ -160,11 +151,12 @@ fun DrivesScreen(
                     chartData = uiState.chartData,
                     chartGranularity = uiState.chartGranularity,
                     summary = uiState.summary,
-                    selectedDateFilter = selectedFilter,
+                    selectedDateFilter = uiState.dateFilter,
                     selectedDistanceFilter = uiState.distanceFilter,
                     units = uiState.units,
                     palette = palette,
-                    onDateFilterSelected = { applyDateFilter(it) },
+                    listState = listState,
+                    onDateFilterSelected = { viewModel.setDateFilter(it) },
                     onDistanceFilterSelected = { viewModel.setDistanceFilter(it) },
                     onDriveClick = onNavigateToDriveDetail
                 )
@@ -184,11 +176,13 @@ private fun DrivesContent(
     selectedDistanceFilter: DriveDistanceFilter,
     units: Units?,
     palette: CarColorPalette,
+    listState: androidx.compose.foundation.lazy.LazyListState,
     onDateFilterSelected: (DriveDateFilter) -> Unit,
     onDistanceFilterSelected: (DriveDistanceFilter) -> Unit,
     onDriveClick: (driveId: Int) -> Unit
 ) {
     LazyColumn(
+        state = listState,
         modifier = Modifier.fillMaxSize(),
         contentPadding = PaddingValues(16.dp),
         verticalArrangement = Arrangement.spacedBy(12.dp)

app/src/main/java/com/matedroid/ui/screens/drives/DrivesViewModel.kt

@@ -55,6 +55,14 @@ data class DriveChartData(
     val sortKey: Long
 )
 
+enum class DriveDateFilter(val label: String, val days: Long?) {
+    LAST_7_DAYS("Last 7 days", 7),
+    LAST_30_DAYS("Last 30 days", 30),
+    LAST_90_DAYS("Last 90 days", 90),
+    LAST_YEAR("Last year", 365),
+    ALL_TIME("All time", null)
+}
+
 data class DrivesUiState(
     val isLoading: Boolean = true,
     val isRefreshing: Boolean = false,
@@ -66,7 +74,10 @@ data class DrivesUiState(
     val endDate: LocalDate? = null,
     val summary: DrivesSummary = DrivesSummary(),
     val units: Units? = null,
-    val distanceFilter: DriveDistanceFilter = DriveDistanceFilter.ALL
+    val distanceFilter: DriveDistanceFilter = DriveDistanceFilter.ALL,
+    val dateFilter: DriveDateFilter = DriveDateFilter.LAST_7_DAYS,
+    val scrollPosition: Int = 0,
+    val scrollOffset: Int = 0
 )
 
 data class DrivesSummary(
@@ -90,6 +101,7 @@ class DrivesViewModel @Inject constructor(
     private var carId: Int? = null
     private var showShortDrivesCharges: Boolean = false
     private var allDrives: List<DriveData> = emptyList()
+    private var isInitialized: Boolean = false
 
     companion object {
         private const val MIN_DURATION_MINUTES = 1
@@ -97,18 +109,39 @@ class DrivesViewModel @Inject constructor(
     }
 
     fun setCarId(id: Int) {
+        if (carId == id && isInitialized) {
+            // Already initialized with this car, don't reload
+            return
+        }
         carId = id
         loadUnits(id)
+
+        // Only apply default filter on first initialization
+        if (!isInitialized) {
+            isInitialized = true
+            applyDateFilterEnum(_uiState.value.dateFilter)
+        }
     }
 
-    fun setDateFilter(startDate: LocalDate?, endDate: LocalDate?) {
-        _uiState.update { it.copy(startDate = startDate, endDate = endDate) }
-        loadDrives(startDate, endDate)
+    fun setDateFilter(filter: DriveDateFilter) {
+        _uiState.update { it.copy(dateFilter = filter) }
+        applyDateFilterEnum(filter)
     }
 
-    fun clearDateFilter() {
-        _uiState.update { it.copy(startDate = null, endDate = null) }
-        loadDrives(null, null)
+    private fun applyDateFilterEnum(filter: DriveDateFilter) {
+        if (filter.days != null) {
+            val endDate = LocalDate.now()
+            val startDate = endDate.minusDays(filter.days)
+            _uiState.update { it.copy(startDate = startDate, endDate = endDate) }
+            loadDrives(startDate, endDate)
+        } else {
+            _uiState.update { it.copy(startDate = null, endDate = null) }
+            loadDrives(null, null)
+        }
+    }
+
+    fun saveScrollPosition(index: Int, offset: Int) {
+        _uiState.update { it.copy(scrollPosition = index, scrollOffset = offset) }
     }
 
     fun setDistanceFilter(filter: DriveDistanceFilter) {