Add a View to show the beginning of the timeline (parity with iOS)

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/MatrixTimeline.kt

@@ -24,7 +24,8 @@ interface MatrixTimeline {
 
     data class PaginationState(
         val isBackPaginating: Boolean,
-        val hasMoreToLoadBackwards: Boolean
+        val hasMoreToLoadBackwards: Boolean,
+        val beginningOfRoomReached: Boolean,
     ) {
         val canBackPaginate = !isBackPaginating && hasMoreToLoadBackwards
     }

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/RustMatrixTimeline.kt

@@ -72,7 +72,11 @@ class RustMatrixTimeline(
         MutableStateFlow(emptyList())
 
     private val _paginationState = MutableStateFlow(
-        MatrixTimeline.PaginationState(hasMoreToLoadBackwards = true, isBackPaginating = false)
+        MatrixTimeline.PaginationState(
+            hasMoreToLoadBackwards = true,
+            isBackPaginating = false,
+            beginningOfRoomReached = false,
+        )
     )
 
     private val encryptedHistoryPostProcessor = TimelineEncryptedHistoryPostProcessor(
@@ -155,6 +159,7 @@ class RustMatrixTimeline(
                 return@getAndUpdate currentPaginationState.copy(
                     isBackPaginating = false,
                     hasMoreToLoadBackwards = false,
+                    beginningOfRoomReached = false,
                 )
             }
             when (status) {
@@ -173,7 +178,8 @@ class RustMatrixTimeline(
                 BackPaginationStatus.TIMELINE_START_REACHED -> {
                     currentPaginationState.copy(
                         isBackPaginating = false,
-                        hasMoreToLoadBackwards = false
+                        hasMoreToLoadBackwards = false,
+                        beginningOfRoomReached = true,
                     )
                 }
             }

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/TimelineEncryptedHistoryPostProcessor.kt

@@ -45,7 +45,8 @@ class TimelineEncryptedHistoryPostProcessor(
             paginationStateFlow.getAndUpdate {
                 it.copy(
                     isBackPaginating = false,
-                    hasMoreToLoadBackwards = false
+                    hasMoreToLoadBackwards = false,
+                    beginningOfRoomReached = false,
                 )
             }
         }

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/TimelineEncryptedHistoryPostProcessorTest.kt

@@ -98,7 +98,13 @@ class TimelineEncryptedHistoryPostProcessorTest {
 
     @Test
     fun `given a list with several with lower or equal timestamps than lastLoginTimestamp, they're replaced and the user can't back paginate`() = runTest {
-        val paginationStateFlow = MutableStateFlow(MatrixTimeline.PaginationState(hasMoreToLoadBackwards = true, isBackPaginating = false))
+        val paginationStateFlow = MutableStateFlow(
+            MatrixTimeline.PaginationState(
+                hasMoreToLoadBackwards = true,
+                isBackPaginating = false,
+                beginningOfRoomReached = false,
+            )
+        )
         val processor = createPostProcessor(paginationStateFlow = paginationStateFlow)
         val items = listOf(
             MatrixTimelineItem.Event(0L, anEventTimelineItem(timestamp = defaultLastLoginTimestamp.time - 1)),
@@ -111,7 +117,13 @@ class TimelineEncryptedHistoryPostProcessorTest {
                 MatrixTimelineItem.Event(0L, anEventTimelineItem(timestamp = defaultLastLoginTimestamp.time + 1))
             )
         )
-        assertThat(paginationStateFlow.value).isEqualTo(MatrixTimeline.PaginationState(hasMoreToLoadBackwards = false, isBackPaginating = false))
+        assertThat(paginationStateFlow.value).isEqualTo(
+            MatrixTimeline.PaginationState(
+                hasMoreToLoadBackwards = false,
+                isBackPaginating = false,
+                beginningOfRoomReached = false,
+            )
+        )
     }
 
     private fun TestScope.createPostProcessor(
@@ -119,7 +131,13 @@ class TimelineEncryptedHistoryPostProcessorTest {
         isRoomEncrypted: Boolean = true,
         isKeyBackupEnabled: Boolean = false,
         paginationStateFlow: MutableStateFlow<MatrixTimeline.PaginationState> =
-            MutableStateFlow(MatrixTimeline.PaginationState(hasMoreToLoadBackwards = true, isBackPaginating = false))
+            MutableStateFlow(
+                MatrixTimeline.PaginationState(
+                    hasMoreToLoadBackwards = true,
+                    isBackPaginating = false,
+                    beginningOfRoomReached = false,
+                )
+            )
     ) = TimelineEncryptedHistoryPostProcessor(
         lastLoginTimestamp = lastLoginTimestamp,
         isRoomEncrypted = isRoomEncrypted,

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/timeline/FakeMatrixTimeline.kt

@@ -29,7 +29,11 @@ import kotlinx.coroutines.flow.getAndUpdate
 
 class FakeMatrixTimeline(
     initialTimelineItems: List<MatrixTimelineItem> = emptyList(),
-    initialPaginationState: MatrixTimeline.PaginationState = MatrixTimeline.PaginationState(hasMoreToLoadBackwards = true, isBackPaginating = false)
+    initialPaginationState: MatrixTimeline.PaginationState = MatrixTimeline.PaginationState(
+        hasMoreToLoadBackwards = true,
+        isBackPaginating = false,
+        beginningOfRoomReached = false,
+    )
 ) : MatrixTimeline {
 
     private val _paginationState: MutableStateFlow<MatrixTimeline.PaginationState> = MutableStateFlow(initialPaginationState)