feat(profiles): Add drag-to-reorder for profile list

Wire up the missing drag-to-reorder UI that the priority hint already advertises. Long-press a profile row to reorder. Extracts a reusable ReorderableState component into common/compose.

Backend (repo + ViewModel) was already in place; this adds the gesture handling, auto-scroll, visual feedback, and ID-based reorder validation.

app/src/main/java/eu/darken/capod/common/compose/Reorderable.kt

@@ -0,0 +1,191 @@
+package eu.darken.capod.common.compose
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.gestures.detectDragGesturesAfterLongPress
+import androidx.compose.foundation.gestures.scrollBy
+import androidx.compose.foundation.lazy.LazyListState
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.ui.hapticfeedback.HapticFeedback
+import androidx.compose.ui.hapticfeedback.HapticFeedbackType
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.platform.LocalHapticFeedback
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.zIndex
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
+
+class ReorderableState<T>(
+    val lazyListState: LazyListState,
+    private val hapticFeedback: HapticFeedback,
+    private val key: (T) -> Any,
+) {
+    private val _items = mutableStateListOf<T>()
+    val items: List<T> get() = _items
+
+    private var originalItems: List<T> = emptyList()
+
+    var draggedIndex: Int? by mutableStateOf(null)
+        private set
+
+    var dragOffsetY: Float by mutableFloatStateOf(0f)
+        private set
+
+    val isDragging: Boolean get() = draggedIndex != null
+
+    fun syncItems(newItems: List<T>) {
+        if (isDragging) return
+        _items.clear()
+        _items.addAll(newItems)
+    }
+
+    fun onDragStart(item: T) {
+        val itemKey = key(item)
+        val index = _items.indexOfFirst { key(it) == itemKey }
+        if (index == -1) return
+        originalItems = _items.toList()
+        draggedIndex = index
+        dragOffsetY = 0f
+        hapticFeedback.performHapticFeedback(HapticFeedbackType.LongPress)
+    }
+
+    fun onDrag(delta: Float) {
+        val currentIndex = draggedIndex ?: return
+        dragOffsetY += delta
+
+        val layoutInfo = lazyListState.layoutInfo
+        val draggedItemInfo = layoutInfo.visibleItemsInfo
+            .firstOrNull { it.index == currentIndex } ?: return
+        val draggedCenter = draggedItemInfo.offset + draggedItemInfo.size / 2 + dragOffsetY.toInt()
+
+        val targetInfo = layoutInfo.visibleItemsInfo.firstOrNull { itemInfo ->
+            itemInfo.index != currentIndex &&
+                itemInfo.index < _items.size &&
+                draggedCenter in itemInfo.offset..(itemInfo.offset + itemInfo.size)
+        } ?: return
+
+        val targetIndex = targetInfo.index
+        dragOffsetY += (draggedItemInfo.offset - targetInfo.offset).toFloat()
+        _items.swap(currentIndex, targetIndex)
+        draggedIndex = targetIndex
+    }
+
+    fun onDragEnd(onReorder: (List<T>) -> Unit) {
+        val reordered = _items.toList()
+        draggedIndex = null
+        dragOffsetY = 0f
+        originalItems = emptyList()
+        onReorder(reordered)
+    }
+
+    fun onDragCancel() {
+        if (originalItems.isNotEmpty()) {
+            _items.clear()
+            _items.addAll(originalItems)
+        }
+        draggedIndex = null
+        dragOffsetY = 0f
+        originalItems = emptyList()
+    }
+}
+
+private fun <T> MutableList<T>.swap(from: Int, to: Int) {
+    val temp = this[from]
+    this[from] = this[to]
+    this[to] = temp
+}
+
+@Composable
+fun <T> rememberReorderableState(
+    lazyListState: LazyListState,
+    items: List<T>,
+    key: (T) -> Any,
+): ReorderableState<T> {
+    val hapticFeedback = LocalHapticFeedback.current
+    return remember(lazyListState) {
+        ReorderableState(lazyListState, hapticFeedback, key).also {
+            it.syncItems(items)
+        }
+    }
+}
+
+@Composable
+fun <T> ReorderableAutoScroll(state: ReorderableState<T>) {
+    val scrollThresholdPx = with(LocalDensity.current) { 80.dp.toPx() }
+    LaunchedEffect(state.isDragging) {
+        if (!state.isDragging) return@LaunchedEffect
+        while (isActive) {
+            val layoutInfo = state.lazyListState.layoutInfo
+            val viewportStart = layoutInfo.viewportStartOffset
+            val viewportEnd = layoutInfo.viewportEndOffset
+            val draggedIdx = state.draggedIndex ?: break
+            val draggedItem = layoutInfo.visibleItemsInfo.firstOrNull { it.index == draggedIdx }
+            if (draggedItem != null) {
+                val itemCenter = draggedItem.offset + draggedItem.size / 2 + state.dragOffsetY
+                val scrollSpeed = 8f
+                val delta = when {
+                    itemCenter < viewportStart + scrollThresholdPx -> -scrollSpeed
+                    itemCenter > viewportEnd - scrollThresholdPx -> scrollSpeed
+                    else -> 0f
+                }
+                if (delta != 0f) state.lazyListState.scrollBy(delta)
+            }
+            delay(16)
+        }
+    }
+}
+
+@Composable
+fun <T> reorderableItemModifier(
+    state: ReorderableState<T>,
+    index: Int,
+    item: T,
+    enabled: Boolean = true,
+    onReorder: (List<T>) -> Unit = {},
+): Modifier {
+    val isDragging = state.draggedIndex == index
+    val dragOffsetY = if (isDragging) state.dragOffsetY else 0f
+
+    val currentItem by rememberUpdatedState(item)
+    val currentOnReorder by rememberUpdatedState(onReorder)
+
+    val surfaceColor = MaterialTheme.colorScheme.surface
+
+    return Modifier
+        .zIndex(if (isDragging) 1f else 0f)
+        .background(surfaceColor)
+        .then(
+            if (enabled) {
+                Modifier.pointerInput(Unit) {
+                    detectDragGesturesAfterLongPress(
+                        onDragStart = { state.onDragStart(currentItem) },
+                        onDrag = { change, dragAmount ->
+                            change.consume()
+                            state.onDrag(dragAmount.y)
+                        },
+                        onDragEnd = { state.onDragEnd(currentOnReorder) },
+                        onDragCancel = { state.onDragCancel() },
+                    )
+                }
+            } else {
+                Modifier
+            }
+        )
+        .graphicsLayer {
+            if (isDragging) {
+                translationY = dragOffsetY
+                shadowElevation = 8.dp.toPx()
+            }
+        }
+}

app/src/main/java/eu/darken/capod/profiles/core/DeviceProfilesRepo.kt

@@ -88,12 +88,18 @@ class DeviceProfilesRepo @Inject constructor(
         deviceStateCache.delete(profileId)
     }
 
-    suspend fun reorderProfiles(profiles: List<DeviceProfile>) = mutex.withLock {
+    suspend fun reorderProfilesById(orderedIds: List<ProfileId>) = mutex.withLock {
-        settings.profiles.valueBlocking = DeviceProfilesContainer(profiles.toList())
+        val current = settings.profiles.valueBlocking.profiles
-        log(VERBOSE) { "Reordered ${profiles.size} device profiles" }
+        require(orderedIds.size == current.size && orderedIds.toSet() == current.map { it.id }.toSet()) {
+            "Reorder IDs must match current profile IDs exactly"
+        }
+        val byId = current.associateBy { it.id }
+        val reordered = orderedIds.map { byId.getValue(it) }
+        settings.profiles.valueBlocking = DeviceProfilesContainer(reordered)
+        log(VERBOSE) { "Reordered ${reordered.size} device profiles by ID" }
     }
 
-    suspend fun clear() {
+    suspend fun clear() = mutex.withLock {
         settings.profiles.valueBlocking = DeviceProfilesContainer(emptyList())
         deviceStateCache.deleteAll()
     }

app/src/main/java/eu/darken/capod/profiles/ui/DeviceManagerScreen.kt

@@ -12,11 +12,13 @@ import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.lazy.LazyColumn
-import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.twotone.ArrowBack
 import androidx.compose.material.icons.twotone.Add
+import androidx.compose.material.icons.twotone.DragHandle
 import androidx.compose.material3.Card
 import androidx.compose.material3.FloatingActionButton
 import androidx.compose.material3.Icon
@@ -27,6 +29,7 @@ import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.material3.TopAppBar
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -38,11 +41,15 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import eu.darken.capod.R
 import eu.darken.capod.common.compose.Preview2
 import eu.darken.capod.common.compose.PreviewWrapper
+import eu.darken.capod.common.compose.ReorderableAutoScroll
 import eu.darken.capod.common.compose.preview.MockPodDataProvider
+import eu.darken.capod.common.compose.reorderableItemModifier
+import eu.darken.capod.common.compose.rememberReorderableState
 import eu.darken.capod.common.error.ErrorEventHandler
 import eu.darken.capod.common.navigation.NavigationEventHandler
 import eu.darken.capod.pods.core.apple.PodModel
 import eu.darken.capod.profiles.core.DeviceProfile
+import eu.darken.capod.profiles.core.ProfileId
 
 @Composable
 fun DeviceManagerScreenHost(vm: DeviceManagerViewModel = hiltViewModel()) {
@@ -56,6 +63,7 @@ fun DeviceManagerScreenHost(vm: DeviceManagerViewModel = hiltViewModel()) {
             onBack = { vm.navUp() },
             onAddDevice = { vm.onAddDevice() },
             onEditProfile = { profile -> vm.onEditProfile(profile) },
+            onReorder = { ids -> vm.onReorder(ids) },
         )
     }
 }
@@ -66,7 +74,17 @@ fun DeviceManagerScreen(
     onBack: () -> Unit,
     onAddDevice: () -> Unit,
     onEditProfile: (DeviceProfile) -> Unit,
+    onReorder: (List<ProfileId>) -> Unit = {},
 ) {
+    val lazyListState = rememberLazyListState()
+    val reorderableState = rememberReorderableState(lazyListState, state.profiles) { it.id }
+
+    LaunchedEffect(state.profiles) {
+        reorderableState.syncItems(state.profiles)
+    }
+
+    ReorderableAutoScroll(reorderableState)
+
     Scaffold(
         topBar = {
             TopAppBar(
@@ -98,18 +116,33 @@ fun DeviceManagerScreen(
                 onAddDevice = onAddDevice,
             )
         } else {
+            val showDragHandles = reorderableState.items.size >= 2
             LazyColumn(
+                state = lazyListState,
                 modifier = Modifier
                     .fillMaxSize()
                     .padding(innerPadding),
             ) {
-                items(
+                itemsIndexed(
-                    items = state.profiles,
+                    items = reorderableState.items,
-                    key = { it.id },
+                    key = { _, profile -> profile.id },
-                ) { profile ->
+                ) { index, profile ->
+                    val isDraggingThis = reorderableState.draggedIndex == index
                     ProfileRow(
+                        modifier = Modifier
+                            .then(if (!isDraggingThis) Modifier.animateItem() else Modifier)
+                            .then(
+                                reorderableItemModifier(
+                                    state = reorderableState,
+                                    index = index,
+                                    item = profile,
+                                    enabled = showDragHandles,
+                                    onReorder = { reordered -> onReorder(reordered.map { it.id }) },
+                                )
+                            ),
                         profile = profile,
-                        onClick = { onEditProfile(profile) },
+                        onClick = { if (!reorderableState.isDragging) onEditProfile(profile) },
+                        showDragHandle = showDragHandles,
                     )
                 }
 
@@ -194,11 +227,13 @@ private fun EmptyState(
 
 @Composable
 private fun ProfileRow(
+    modifier: Modifier = Modifier,
     profile: DeviceProfile,
     onClick: () -> Unit,
+    showDragHandle: Boolean = false,
 ) {
     Row(
-        modifier = Modifier
+        modifier = modifier
             .fillMaxWidth()
             .clickable(onClick = onClick)
             .padding(horizontal = 16.dp, vertical = 12.dp),
@@ -221,6 +256,16 @@ private fun ProfileRow(
                 color = MaterialTheme.colorScheme.onSurfaceVariant,
             )
         }
+        if (showDragHandle) {
+            Icon(
+                imageVector = Icons.TwoTone.DragHandle,
+                contentDescription = stringResource(R.string.profiles_drag_handle_description),
+                modifier = Modifier
+                    .size(48.dp)
+                    .padding(12.dp),
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
     }
 }
 

app/src/main/java/eu/darken/capod/profiles/ui/DeviceManagerViewModel.kt

@@ -9,6 +9,7 @@ import eu.darken.capod.common.navigation.Nav
 import eu.darken.capod.common.uix.ViewModel4
 import eu.darken.capod.profiles.core.DeviceProfile
 import eu.darken.capod.profiles.core.DeviceProfilesRepo
+import eu.darken.capod.profiles.core.ProfileId
 import kotlinx.coroutines.flow.map
 import javax.inject.Inject
 
@@ -36,9 +37,9 @@ class DeviceManagerViewModel @Inject constructor(
         navTo(Nav.Main.DeviceProfileCreation(profileId = profile.id))
     }
 
-    fun onReorder(profiles: List<DeviceProfile>) = launch {
+    fun onReorder(profileIds: List<ProfileId>) = launch {
-        log(TAG) { "onReorder(): ${profiles.size} profiles" }
+        log(TAG) { "onReorder(): ${profileIds.size} profiles" }
-        deviceProfilesRepo.reorderProfiles(profiles)
+        deviceProfilesRepo.reorderProfilesById(profileIds)
     }
 
     companion object {

app/src/test/java/eu/darken/capod/profiles/core/DeviceProfilesRepoReorderTest.kt

@@ -0,0 +1,81 @@
+package eu.darken.capod.profiles.core
+
+import io.kotest.matchers.shouldBe
+import io.mockk.every
+import io.mockk.mockk
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.flow.flowOf
+import org.junit.jupiter.api.Test
+import testhelpers.BaseTest
+import testhelpers.coroutine.runTest2
+import testhelpers.datastore.FakeDataStoreValue
+
+class DeviceProfilesRepoReorderTest : BaseTest() {
+
+    private fun createRepo(
+        initialProfiles: List<DeviceProfile>,
+        scope: CoroutineScope,
+    ): Pair<DeviceProfilesRepo, FakeDataStoreValue<DeviceProfilesContainer>> {
+        val fakeProfiles = FakeDataStoreValue(DeviceProfilesContainer(initialProfiles))
+
+        val settings = mockk<DeviceProfilesSettings> {
+            every { profiles } returns fakeProfiles.mock
+            every { defaultProfileCreated } returns FakeDataStoreValue(true).mock
+        }
+
+        val repo = DeviceProfilesRepo(
+            scope = scope,
+            context = mockk(relaxed = true),
+            generalSettings = mockk(relaxed = true),
+            settings = settings,
+            deviceStateCache = mockk(relaxed = true),
+        )
+
+        return repo to fakeProfiles
+    }
+
+    @Test
+    fun `reorderProfilesById reorders profiles correctly`() = runTest2 {
+        val p1 = AppleDeviceProfile(id = "1", label = "First")
+        val p2 = AppleDeviceProfile(id = "2", label = "Second")
+        val p3 = AppleDeviceProfile(id = "3", label = "Third")
+
+        val (repo, fakeProfiles) = createRepo(listOf(p1, p2, p3), this)
+
+        repo.reorderProfilesById(listOf("3", "1", "2"))
+
+        fakeProfiles.value.profiles.map { it.id } shouldBe listOf("3", "1", "2")
+    }
+
+    @Test
+    fun `reorderProfilesById preserves profile data`() = runTest2 {
+        val p1 = AppleDeviceProfile(id = "1", label = "First", minimumSignalQuality = 0.5f)
+        val p2 = AppleDeviceProfile(id = "2", label = "Second", minimumSignalQuality = 0.8f)
+
+        val (repo, fakeProfiles) = createRepo(listOf(p1, p2), this)
+
+        repo.reorderProfilesById(listOf("2", "1"))
+
+        fakeProfiles.value.profiles shouldBe listOf(p2, p1)
+    }
+
+    @Test
+    fun `reorderProfilesById rejects mismatched IDs`() = runTest2(expectedError = IllegalArgumentException::class) {
+        val p1 = AppleDeviceProfile(id = "1", label = "First")
+        val p2 = AppleDeviceProfile(id = "2", label = "Second")
+
+        val (repo, _) = createRepo(listOf(p1, p2), this)
+
+        repo.reorderProfilesById(listOf("1", "3"))
+    }
+
+    @Test
+    fun `reorderProfilesById rejects wrong count`() = runTest2(expectedError = IllegalArgumentException::class) {
+        val p1 = AppleDeviceProfile(id = "1", label = "First")
+        val p2 = AppleDeviceProfile(id = "2", label = "Second")
+
+        val (repo, _) = createRepo(listOf(p1, p2), this)
+
+        repo.reorderProfilesById(listOf("1"))
+    }
+}