refactor: Reduce message list mapping and ViewModel scope overhead

app/src/main/kotlin/com/wire/android/mapper/RegularMessageContentMapper.kt

@@ -28,8 +28,6 @@
 import com.wire.android.ui.home.conversations.model.UIMessageContent
 import com.wire.android.ui.home.conversations.model.UIQuotedMessage
 import com.wire.android.ui.home.conversations.model.messagetypes.image.VisualMediaParams
-import com.wire.android.ui.markdown.toMarkdownDocument
-import com.wire.android.ui.markdown.toMarkdownTextWithMentions
 import com.wire.android.ui.theme.Accent
 import com.wire.android.util.time.ISOFormatter
 import com.wire.android.util.ui.UIText
@@ -110,11 +108,7 @@
 
                 MessageBody(
                     message = UIText.DynamicString(textContent.value, content.textContent?.mentions.orEmpty()),
-                    quotedMessage = quotedMessage,
-                    markdownDocument = UIText.DynamicString(
-                        textContent.value,
-                        content.textContent?.mentions.orEmpty()
-                    ).toMarkdownTextWithMentions().second.toMarkdownDocument()
+                    quotedMessage = quotedMessage
                 )
             }
 
@@ -199,16 +193,9 @@
                 else -> UIText.StringResource(R.string.sent_a_message_with_unknown_content)
         }
 
-        val markdownDocument = if (uiText is UIText.DynamicString) {
-            uiText.toMarkdownTextWithMentions().second.toMarkdownDocument()
-        } else {
-            null
-        }
-
         return MessageBody(
             message = uiText,
-            quotedMessage = quotedMessage,
-            markdownDocument = markdownDocument
+            quotedMessage = quotedMessage
         ).let { messageBody ->
             UIMessageContent.TextMessage(
                 messageBody = messageBody,

app/src/main/kotlin/com/wire/android/ui/home/conversations/ConversationScreen.kt

@@ -230,6 +230,8 @@ import com.wire.android.ui.common.R as commonR
  */
 private const val MAXIMUM_SCROLLED_MESSAGES_UNTIL_AUTOSCROLL_STOPS = 5
 
+private const val SCOPED_VIEW_MODEL_PREFETCH_WINDOW = 3
+
 /**
  * The maximum number of participants to start a call without showing a confirmation dialog.
  */
@@ -1349,11 +1351,22 @@ fun MessageList(
         }
     }
 
-    val audioMessageKeysInScope = remember(lazyPagingMessages.itemSnapshotList.items) {
-        lazyPagingMessages.itemSnapshotList.items.mapNotNull { it.audioMessageScopedKeyOrNull() }.distinct()
+    val scopedMessages by remember(lazyListState, lazyPagingMessages) {
+        derivedStateOf {
+            lazyPagingMessages.peekVisibleWindowItems(lazyListState, SCOPED_VIEW_MODEL_PREFETCH_WINDOW)
+        }
+    }
+    val playingAudioMessageKey = (playingAudioMessage as? PlayingAudioMessage.Some)?.let {
+        AudioMessageArgs(it.conversationId, it.messageId).key
     }
-    val assetLocalPathKeysInScope = remember(lazyPagingMessages.itemSnapshotList.items) {
-        lazyPagingMessages.itemSnapshotList.items
+    val audioMessageKeysInScope = remember(scopedMessages, playingAudioMessageKey) {
+        buildList {
+            scopedMessages.mapNotNullTo(this) { it.audioMessageScopedKeyOrNull() }
+            playingAudioMessageKey?.let(::add)
+        }.distinct()
+    }
+    val assetLocalPathKeysInScope = remember(scopedMessages) {
+        scopedMessages
             .flatMap { it.assetLocalPathScopedKeys() }
             .distinct()
     }
@@ -1651,6 +1664,27 @@ private fun BoxScope.ScrollDateOverlay(
 private fun LazyPagingItems<UIMessage>.peekOrNull(index: Int): UIMessage? =
     if (index in 0 until itemCount) peek(index) else null
 
+private fun LazyPagingItems<UIMessage>.peekVisibleWindowItems(
+    lazyListState: LazyListState,
+    prefetchWindow: Int
+): List<UIMessage> {
+    val visibleItems = lazyListState.layoutInfo.visibleItemsInfo
+    return if (itemCount == 0 || visibleItems.isEmpty()) {
+        emptyList()
+    } else {
+        val firstVisibleIndex = visibleItems.minOf { it.index }
+        val lastVisibleIndex = visibleItems.maxOf { it.index }
+        val firstIndex = (firstVisibleIndex - prefetchWindow).coerceAtLeast(0)
+        val lastIndex = (lastVisibleIndex + prefetchWindow).coerceAtMost(itemCount - 1)
+
+        if (firstIndex > lastIndex) {
+            emptyList()
+        } else {
+            (firstIndex..lastIndex).mapNotNull { index -> peekOrNull(index) }
+        }
+    }
+}
+
 @Composable
 private fun MessageGroupDateTime(
     now: Long,

app/src/main/kotlin/com/wire/android/ui/home/conversations/model/MessageTypes.kt

@@ -40,6 +40,7 @@ import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalInspectionMode
 import androidx.compose.ui.unit.DpSize
@@ -106,9 +107,14 @@ internal fun MessageBody(
     clickable: Boolean = true,
     messageStyle: MessageStyle = MessageStyle.NORMAL
 ) {
-    val (displayMentions, text) = messageBody?.message?.let {
-        mapToDisplayMentions(it, LocalContext.current.resources)
-    } ?: Pair(emptyList(), null)
+    val resources = LocalContext.current.resources
+    val configuration = LocalConfiguration.current
+    val message = messageBody?.message
+    val (displayMentions, text) = remember(message, configuration) {
+        message?.let {
+            mapToDisplayMentions(it, resources)
+        } ?: Pair(emptyList(), null)
+    }
 
     val color = when (messageStyle) {
         MessageStyle.BUBBLE_SELF -> colorsScheme().selfBubble.onPrimary

app/src/main/kotlin/com/wire/android/ui/home/conversations/model/UIMessage.kt

@@ -644,8 +644,18 @@ enum class MessageSource {
 
 @Serializable
 data class MessageTime(val instant: Instant) {
-    val utcISO: String = instant.toIsoDateTimeString()
-    val formattedDate: String = utcISO.uiMessageDateTime() ?: ""
+    @Transient
+    private val utcISOValue: Lazy<String> = lazy(LazyThreadSafetyMode.PUBLICATION) {
+        instant.toIsoDateTimeString()
+    }
+
+    @Transient
+    private val formattedDateValue: Lazy<String> = lazy(LazyThreadSafetyMode.PUBLICATION) {
+        utcISO.uiMessageDateTime() ?: ""
+    }
+
+    val utcISO: String get() = utcISOValue.value
+    val formattedDate: String get() = formattedDateValue.value
     fun getFormattedDateGroup(now: Long): MessageDateTimeGroup? = utcISO.groupedUIMessageDateTime(now = now)
     fun shouldDisplayDatesDifferenceDivider(previousDate: String): Boolean =
         utcISO.shouldDisplayDatesDifferenceDivider(previousDate = previousDate)

app/src/test/kotlin/com/wire/android/mapper/RegularMessageContentMapperTest.kt

@@ -52,6 +52,7 @@ import kotlinx.coroutines.test.runTest
 import okio.Path
 import okio.Path.Companion.toPath
 import okio.buffer
+import org.junit.jupiter.api.Assertions.assertNull
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.extension.ExtendWith
@@ -83,6 +84,18 @@ class RegularMessageContentMapperTest {
         }
     }
 
+    @Test
+    fun givenTextContent_whenMappingToTextMessageContent_thenMarkdownDocumentShouldBeParsedByUi() = runTest {
+        // Given
+        val (_, mapper) = Arrangement().arrange()
+
+        // When
+        val result = mapper.toText(TestConversation.ID, TestMessage.TEXT_MESSAGE.content, userMembers, DeliveryStatus.CompleteDelivery)
+
+        // Then
+        assertNull(result.messageBody.markdownDocument)
+    }
+
     @Test
     fun givenAssetContent_whenMappingToUIMessageContent_thenCorrectValuesShouldBeReturned() = runTest {
         // Given