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feat(chat): add message pagination with cursor-based loading

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Load initial 200 messages, auto-load older messages on scroll to top.
Uses cursor-based DAO queries for stable scroll position.
Also fixes pre-existing ackMessage compile errors in test fakes.

Closes #113
This commit is contained in:
Jens Reinemann 2026-05-18 21:32:47 +02:00
parent 7b21394cc6
commit 975976fd06
10 changed files with 203 additions and 6 deletions
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36
app/src/main/java/de/bollwerk/app/data/db/dao/MessageDao.kt
View file

@ -45,4 +45,40 @@ internal interface MessageDao {
@Query("UPDATE messages SET is_read = 1 WHERE receiver_id = :myId AND sender_id = :senderId")
suspend fun markConversationAsRead(myId: String, senderId: String)
@Query("""
SELECT * FROM messages
WHERE (sender_id = :myId AND receiver_id = :otherId)
OR (sender_id = :otherId AND receiver_id = :myId)
ORDER BY sent_at DESC
LIMIT :limit
""")
suspend fun getLatestMessages(myId: String, otherId: String, limit: Int): List<MessageEntity>
@Query("""
SELECT * FROM messages
WHERE ((sender_id = :myId AND receiver_id = :otherId)
OR (sender_id = :otherId AND receiver_id = :myId))
AND sent_at < :beforeTimestamp
ORDER BY sent_at DESC
LIMIT :limit
""")
suspend fun getMessagesBefore(myId: String, otherId: String, beforeTimestamp: Long, limit: Int): List<MessageEntity>
@Query("""
SELECT COUNT(*) FROM messages
WHERE ((sender_id = :myId AND receiver_id = :otherId)
OR (sender_id = :otherId AND receiver_id = :myId))
AND sent_at < :beforeTimestamp
""")
suspend fun countOlderMessages(myId: String, otherId: String, beforeTimestamp: Long): Int
@Query("""
SELECT * FROM messages
WHERE ((sender_id = :myId AND receiver_id = :otherId)
OR (sender_id = :otherId AND receiver_id = :myId))
AND sent_at > :afterTimestamp
ORDER BY sent_at ASC
""")
fun getNewMessagesAfter(myId: String, otherId: String, afterTimestamp: Long): Flow<List<MessageEntity>>
}

12
app/src/main/java/de/bollwerk/app/data/repository/MessageRepositoryImpl.kt
View file

@ -115,6 +115,18 @@ internal class MessageRepositoryImpl @Inject constructor(
override fun getConversation(myId: String, otherId: String): Flow<List<MessageEntity>> =
dao.getConversation(myId, otherId)
override suspend fun getLatestMessages(myId: String, otherId: String, limit: Int): List<MessageEntity> =
withContext(Dispatchers.IO) { dao.getLatestMessages(myId, otherId, limit) }
override suspend fun getMessagesBefore(myId: String, otherId: String, beforeTimestamp: Long, limit: Int): List<MessageEntity> =
withContext(Dispatchers.IO) { dao.getMessagesBefore(myId, otherId, beforeTimestamp, limit) }
override suspend fun countOlderMessages(myId: String, otherId: String, beforeTimestamp: Long): Int =
withContext(Dispatchers.IO) { dao.countOlderMessages(myId, otherId, beforeTimestamp) }
override fun getNewMessagesAfter(myId: String, otherId: String, afterTimestamp: Long): Flow<List<MessageEntity>> =
dao.getNewMessagesAfter(myId, otherId, afterTimestamp)
override suspend fun sendMessage(recipientId: String, body: String) {
val myId = settingsRepository.getStringOrNull(StringKey.AuthUserId) ?: return
val myUsername = settingsRepository.getString(StringKey.AuthUsername)

4
app/src/main/java/de/bollwerk/app/domain/repository/MessageRepository.kt
View file

@ -6,6 +6,10 @@ import kotlinx.coroutines.flow.Flow
internal interface MessageRepository {
fun getConversation(myId: String, otherId: String): Flow<List<MessageEntity>>
suspend fun getLatestMessages(myId: String, otherId: String, limit: Int): List<MessageEntity>
suspend fun getMessagesBefore(myId: String, otherId: String, beforeTimestamp: Long, limit: Int): List<MessageEntity>
suspend fun countOlderMessages(myId: String, otherId: String, beforeTimestamp: Long): Int
fun getNewMessagesAfter(myId: String, otherId: String, afterTimestamp: Long): Flow<List<MessageEntity>>
suspend fun sendMessage(recipientId: String, body: String)
suspend fun fetchUsers(): Result<List<UserListItemDto>>
suspend fun getMyUserId(): String?

46
app/src/main/java/de/bollwerk/app/ui/messaging/ChatScreen.kt
View file

@ -1,6 +1,7 @@
package de.bollwerk.app.ui.messaging
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Row
@ -9,6 +10,7 @@ import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.imePadding
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.layout.widthIn
import androidx.compose.foundation.lazy.LazyColumn
@ -18,6 +20,7 @@ import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.automirrored.filled.ArrowBack
import androidx.compose.material.icons.automirrored.filled.Send
import androidx.compose.material3.CircularProgressIndicator
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
@ -29,14 +32,18 @@ import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.derivedStateOf
import androidx.compose.runtime.getValue
import androidx.compose.runtime.remember
import androidx.compose.runtime.snapshotFlow
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import androidx.hilt.navigation.compose.hiltViewModel
import androidx.lifecycle.compose.collectAsStateWithLifecycle
import de.bollwerk.app.data.db.entity.MessageEntity
import kotlinx.coroutines.flow.distinctUntilChanged
import kotlinx.coroutines.flow.filter
import java.text.SimpleDateFormat
import java.util.Date
import java.util.Locale
@ -48,14 +55,39 @@ internal fun ChatScreen(
viewModel: ChatViewModel = hiltViewModel()
) {
val uiState by viewModel.uiState.collectAsStateWithLifecycle()
val prependedCount by viewModel.prependedCount.collectAsStateWithLifecycle()
val listState = rememberLazyListState()
// Scroll to bottom when new messages arrive (only if already near bottom)
val isNearBottom by remember {
derivedStateOf {
val lastVisible = listState.layoutInfo.visibleItemsInfo.lastOrNull()?.index ?: 0
lastVisible >= listState.layoutInfo.totalItemsCount - 3
}
}
LaunchedEffect(uiState.messages.size) {
if (uiState.messages.isNotEmpty()) {
if (uiState.messages.isNotEmpty() && isNearBottom) {
listState.animateScrollToItem(uiState.messages.size - 1)
}
}
// Maintain scroll position after prepending older messages
LaunchedEffect(prependedCount) {
if (prependedCount > 0) {
val targetIndex = listState.firstVisibleItemIndex + prependedCount
listState.scrollToItem(targetIndex, listState.firstVisibleItemScrollOffset)
viewModel.onPrependHandled()
}
}
// Auto-load more when scrolled to top
LaunchedEffect(listState) {
snapshotFlow { listState.firstVisibleItemIndex }
.distinctUntilChanged()
.filter { it == 0 }
.collect { viewModel.loadMore() }
}
Scaffold(
topBar = {
TopAppBar(
@ -83,6 +115,18 @@ internal fun ChatScreen(
contentPadding = PaddingValues(horizontal = 8.dp, vertical = 8.dp),
verticalArrangement = Arrangement.spacedBy(4.dp)
) {
if (uiState.isLoadingMore) {
item(key = "loading_indicator") {
Box(
modifier = Modifier
.fillMaxWidth()
.padding(8.dp),
contentAlignment = Alignment.Center
) {
CircularProgressIndicator(modifier = Modifier.size(24.dp))
}
}
}
items(uiState.messages, key = { it.id }) { message ->
MessageBubble(
message = message,

76
app/src/main/java/de/bollwerk/app/ui/messaging/ChatViewModel.kt
View file

@ -18,7 +18,9 @@ internal data class ChatUiState(
val myUserId: String = "",
val recipientUsername: String = "",
val inputText: String = "",
val isSending: Boolean = false
val isSending: Boolean = false,
val isLoadingMore: Boolean = false,
val hasOlderMessages: Boolean = true
)
@HiltViewModel
@ -34,6 +36,14 @@ internal class ChatViewModel @Inject constructor(
private val _uiState = MutableStateFlow(ChatUiState(recipientUsername = recipientUsername))
val uiState: StateFlow<ChatUiState> = _uiState
private val loadedMessages = mutableListOf<MessageEntity>()
private var oldestTimestamp: Long = Long.MAX_VALUE
private var newestTimestamp: Long = 0L
/** Number of items prepended in the last loadMore call, consumed by the UI for scroll adjustment. */
private val _prependedCount = MutableStateFlow(0)
val prependedCount: StateFlow<Int> = _prependedCount
init {
notificationHelper.setActiveChat(recipientId)
notificationHelper.cancelNotificationForSender(recipientId)
@ -41,14 +51,66 @@ internal class ChatViewModel @Inject constructor(
val myId = messageRepository.getMyUserId() ?: ""
_uiState.update { it.copy(myUserId = myId) }
if (myId.isNotEmpty()) {
messageRepository.getConversation(myId, recipientId).collect { messages ->
_uiState.update { it.copy(messages = messages) }
messageRepository.markConversationAsRead(recipientId)
}
loadInitialMessages(myId)
observeNewMessages(myId)
}
}
}
private suspend fun loadInitialMessages(myId: String) {
val initial = messageRepository.getLatestMessages(myId, recipientId, PAGE_SIZE)
// getLatestMessages returns DESC order, reverse to ASC for display
val sorted = initial.sortedBy { it.sentAt }
loadedMessages.addAll(sorted)
if (sorted.isNotEmpty()) {
oldestTimestamp = sorted.first().sentAt
newestTimestamp = sorted.last().sentAt
}
val hasOlder = if (sorted.isNotEmpty()) {
messageRepository.countOlderMessages(myId, recipientId, oldestTimestamp) > 0
} else {
false
}
_uiState.update { it.copy(messages = loadedMessages.toList(), hasOlderMessages = hasOlder) }
messageRepository.markConversationAsRead(recipientId)
}
private suspend fun observeNewMessages(myId: String) {
messageRepository.getNewMessagesAfter(myId, recipientId, newestTimestamp).collect { newMessages ->
val truly = newMessages.filter { msg -> loadedMessages.none { it.id == msg.id } }
if (truly.isNotEmpty()) {
loadedMessages.addAll(truly)
newestTimestamp = loadedMessages.maxOf { it.sentAt }
_uiState.update { it.copy(messages = loadedMessages.toList()) }
messageRepository.markConversationAsRead(recipientId)
}
}
}
fun loadMore() {
if (_uiState.value.isLoadingMore || !_uiState.value.hasOlderMessages) return
val myId = _uiState.value.myUserId
if (myId.isEmpty()) return
viewModelScope.launch {
_uiState.update { it.copy(isLoadingMore = true) }
val older = messageRepository.getMessagesBefore(myId, recipientId, oldestTimestamp, PAGE_SIZE)
val sorted = older.sortedBy { it.sentAt }
if (sorted.isNotEmpty()) {
oldestTimestamp = sorted.first().sentAt
loadedMessages.addAll(0, sorted)
val hasOlder = messageRepository.countOlderMessages(myId, recipientId, oldestTimestamp) > 0
_prependedCount.value = sorted.size
_uiState.update { it.copy(messages = loadedMessages.toList(), isLoadingMore = false, hasOlderMessages = hasOlder) }
} else {
_uiState.update { it.copy(isLoadingMore = false, hasOlderMessages = false) }
}
}
}
fun onPrependHandled() {
_prependedCount.value = 0
}
override fun onCleared() {
super.onCleared()
notificationHelper.setActiveChat(null)
@ -67,4 +129,8 @@ internal class ChatViewModel @Inject constructor(
_uiState.update { it.copy(isSending = false) }
}
}
private companion object {
const val PAGE_SIZE = 200
}
}

1
app/src/test/java/de/bollwerk/app/data/repository/ItemRepositoryImplTest.kt
View file

@ -176,6 +176,7 @@ private class FakeWebSocketClient : WebSocketClient {
suspend fun emit(event: WebSocketEvent) { _events.emit(event) }
override fun connect(serverUrl: String, accessToken: String) {}
override fun disconnect() {}
override fun ackMessage(messageId: String) = Unit
}
private fun buildItem(

21
app/src/test/java/de/bollwerk/app/data/repository/MessageRepositoryImplTest.kt
View file

@ -68,6 +68,26 @@ private class FakeMessageDao : MessageDao {
override suspend fun markConversationAsRead(myId: String, senderId: String) {
markedAsRead.add(myId to senderId)
}
override suspend fun getLatestMessages(myId: String, otherId: String, limit: Int): List<MessageEntity> =
upserted.filter {
(it.senderId == myId && it.receiverId == otherId) ||
(it.senderId == otherId && it.receiverId == myId)
}.sortedByDescending { it.sentAt }.take(limit)
override suspend fun getMessagesBefore(myId: String, otherId: String, beforeTimestamp: Long, limit: Int): List<MessageEntity> =
upserted.filter {
((it.senderId == myId && it.receiverId == otherId) ||
(it.senderId == otherId && it.receiverId == myId)) && it.sentAt < beforeTimestamp
}.sortedByDescending { it.sentAt }.take(limit)
override suspend fun countOlderMessages(myId: String, otherId: String, beforeTimestamp: Long): Int =
upserted.count {
((it.senderId == myId && it.receiverId == otherId) ||
(it.senderId == otherId && it.receiverId == myId)) && it.sentAt < beforeTimestamp
}
override fun getNewMessagesAfter(myId: String, otherId: String, afterTimestamp: Long): Flow<List<MessageEntity>> =
flowOf(upserted.filter {
((it.senderId == myId && it.receiverId == otherId) ||
(it.senderId == otherId && it.receiverId == myId)) && it.sentAt > afterTimestamp
})
}
private class FakeMessageSettingsRepository : SettingsRepository {
@ -100,6 +120,7 @@ private class FakeMessageWsClient : WebSocketClient {
_connectionState
override fun connect(serverUrl: String, accessToken: String) = Unit
override fun disconnect() = Unit
override fun ackMessage(messageId: String) = Unit
}
private fun buildFakeE2EEKeyManager(): E2EEKeyManager = mockk<E2EEKeyManager>(relaxed = true).also {

8
app/src/test/java/de/bollwerk/app/ui/messaging/ChatViewModelTest.kt
View file

@ -32,6 +32,14 @@ private class FakeChatMessageRepository(
override val totalUnreadCount: Flow<Int> = flowOf(0)
override fun getConversation(myId: String, otherId: String): Flow<List<MessageEntity>> = conversation
override suspend fun getLatestMessages(myId: String, otherId: String, limit: Int): List<MessageEntity> =
conversation.value.sortedByDescending { it.sentAt }.take(limit)
override suspend fun getMessagesBefore(myId: String, otherId: String, beforeTimestamp: Long, limit: Int): List<MessageEntity> =
conversation.value.filter { it.sentAt < beforeTimestamp }.sortedByDescending { it.sentAt }.take(limit)
override suspend fun countOlderMessages(myId: String, otherId: String, beforeTimestamp: Long): Int =
conversation.value.count { it.sentAt < beforeTimestamp }
override fun getNewMessagesAfter(myId: String, otherId: String, afterTimestamp: Long): Flow<List<MessageEntity>> =
flowOf(emptyList())
override fun getUnreadCountsBySender(): Flow<Map<String, Int>> = flowOf(emptyMap())
override suspend fun markConversationAsRead(senderId: String) = Unit
override suspend fun sendMessage(recipientId: String, body: String) {

4
app/src/test/java/de/bollwerk/app/ui/messaging/UserListViewModelTest.kt
View file

@ -31,6 +31,10 @@ private class FakeUserListMessageRepository(
override val totalUnreadCount: Flow<Int> = flowOf(0)
override fun getConversation(myId: String, otherId: String): Flow<List<MessageEntity>> =
MutableStateFlow(emptyList())
override suspend fun getLatestMessages(myId: String, otherId: String, limit: Int): List<MessageEntity> = emptyList()
override suspend fun getMessagesBefore(myId: String, otherId: String, beforeTimestamp: Long, limit: Int): List<MessageEntity> = emptyList()
override suspend fun countOlderMessages(myId: String, otherId: String, beforeTimestamp: Long): Int = 0
override fun getNewMessagesAfter(myId: String, otherId: String, afterTimestamp: Long): Flow<List<MessageEntity>> = flowOf(emptyList())
override fun getUnreadCountsBySender(): Flow<Map<String, Int>> = flowOf(emptyMap())
override suspend fun markConversationAsRead(senderId: String) = Unit
override suspend fun sendMessage(recipientId: String, body: String) = Unit

1
app/src/test/java/de/bollwerk/app/ui/settings/SettingsViewModelTest.kt
View file

@ -912,6 +912,7 @@ private class FakeWebSocketClient : WebSocketClient {
var connectedUrl: String? = null
override fun connect(serverUrl: String, accessToken: String) { connectedUrl = serverUrl }
override fun disconnect() { connectedUrl = null }
override fun ackMessage(messageId: String) = Unit
}
// endregion