Improve the actual and perceived speed of thread loading (#3118)

* Improve the actual and perceived speed of thread loading

To improve the actual speed, note that if the user has opened a thread from
their home timeline then the initial status is cached in the database. Other
statuses in the same thread may be cached as well.

So try and load the initial status from the database, falling back to the
network if it's not present (e.g., the user has opened a thread from the
local or federated timelines, or a search).

Introduce a new loading state to deal with this case.

In typical cases this allows the UI to display the initial status immediately
with no need to show a progress indicator.

To improve the perceived speed, delay showing the initial loading circular
progress indicators by 500ms. If loading the initial status completes within
that time no spinner is shown and the user will perceive the action as
close-to-immediate
(https://www.nngroup.com/articles/response-times-3-important-limits/).

Additionally, introduce an extra indeterminate progress indicator.

The new indicator is linear, anchored to the bottom of the screen, and shows
progress loading ancestor/descendant statuses. Like the other indicator is
also delayed 500ms from when ancestor/descendant status information is
fetched, and if the fetch completes in that time it will not be shown.

* Mark `getStatus` as suspend so it doesn't run on the main thread

* Save an allocation, use an isDetailed parameter to TimelineStatusWithAccount.toViewData

Rename Status.toViewData's "detailed" parameter to "isDetailed" for
consistency with other uses.

* Ensure suspend functions run to completion when testing

* Delay-load the status from the network even if it's cached

This speeds up the UI while ensuring it will eventually contain accurate data
from the remote.

* Load the network status before updating the list

Avoids excess animations if the network copy has changes

* Fix UI flicker when loading reblogged statuses

* Lint

* Fixup tests

app/src/main/java/com/keylesspalace/tusky/components/timeline/TimelineTypeMappers.kt

@@ -149,7 +149,7 @@ fun Status.toEntity(
     )
 }
 
-fun TimelineStatusWithAccount.toViewData(gson: Gson): StatusViewData {
+fun TimelineStatusWithAccount.toViewData(gson: Gson, isDetailed: Boolean = false): StatusViewData {
     if (this.status.authorServerId == null) {
         return StatusViewData.Placeholder(this.status.serverId, this.status.expanded)
     }
@@ -261,6 +261,7 @@ fun TimelineStatusWithAccount.toViewData(gson: Gson): StatusViewData {
         status = status,
         isExpanded = this.status.expanded,
         isShowingContent = this.status.contentShowing,
-        isCollapsed = this.status.contentCollapsed
+        isCollapsed = this.status.contentCollapsed,
+        isDetailed = isDetailed
     )
 }

app/src/main/java/com/keylesspalace/tusky/components/viewthread/ThreadAdapter.kt

@@ -62,6 +62,7 @@ class ThreadAdapter(
     }
 
     companion object {
+        private const val TAG = "ThreadAdapter"
         private const val VIEW_TYPE_STATUS = 0
         private const val VIEW_TYPE_STATUS_DETAILED = 1
 

app/src/main/java/com/keylesspalace/tusky/components/viewthread/ViewThreadFragment.kt

@@ -21,6 +21,7 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.widget.LinearLayout
+import androidx.annotation.CheckResult
 import androidx.fragment.app.commit
 import androidx.fragment.app.viewModels
 import androidx.lifecycle.lifecycleScope
@@ -50,6 +51,9 @@ import com.keylesspalace.tusky.util.show
 import com.keylesspalace.tusky.util.viewBinding
 import com.keylesspalace.tusky.viewdata.AttachmentViewData.Companion.list
 import com.keylesspalace.tusky.viewdata.StatusViewData
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.awaitCancellation
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import java.io.IOException
 import javax.inject.Inject
@@ -142,24 +146,50 @@ class ViewThreadFragment : SFragment(), OnRefreshListener, StatusActionListener,
 
         (binding.recyclerView.itemAnimator as SimpleItemAnimator).supportsChangeAnimations = false
 
+        var initialProgressBar = getProgressBarJob(binding.initialProgressBar, 500)
+        var threadProgressBar = getProgressBarJob(binding.threadProgressBar, 500)
+
         viewLifecycleOwner.lifecycleScope.launch {
             viewModel.uiState.collect { uiState ->
                 when (uiState) {
                     is ThreadUiState.Loading -> {
                         updateRevealButton(RevealButtonState.NO_BUTTON)
+
                         binding.recyclerView.hide()
                         binding.statusView.hide()
-                        binding.progressBar.show()
+
+                        initialProgressBar = getProgressBarJob(binding.initialProgressBar, 500)
+                        initialProgressBar.start()
+                    }
+                    is ThreadUiState.LoadingThread -> {
+                        if (uiState.statusViewDatum == null) {
+                            // no detailed statuses available, e.g. because author is blocked
+                            activity?.finish()
+                            return@collect
+                        }
+
+                        initialProgressBar.cancel()
+                        threadProgressBar = getProgressBarJob(binding.threadProgressBar, 500)
+                        threadProgressBar.start()
+
+                        adapter.submitList(listOf(uiState.statusViewDatum))
+
+                        updateRevealButton(uiState.revealButton)
+                        binding.swipeRefreshLayout.isRefreshing = false
+
+                        binding.recyclerView.show()
+                        binding.statusView.hide()
                     }
                     is ThreadUiState.Error -> {
                         Log.w(TAG, "failed to load status", uiState.throwable)
+                        initialProgressBar.cancel()
+                        threadProgressBar.cancel()
 
                         updateRevealButton(RevealButtonState.NO_BUTTON)
                         binding.swipeRefreshLayout.isRefreshing = false
 
                         binding.recyclerView.hide()
                         binding.statusView.show()
-                        binding.progressBar.hide()
 
                         if (uiState.throwable is IOException) {
                             binding.statusView.setup(R.drawable.elephant_offline, R.string.error_network) {
@@ -172,28 +202,21 @@ class ViewThreadFragment : SFragment(), OnRefreshListener, StatusActionListener,
                         }
                     }
                     is ThreadUiState.Success -> {
-                        if (uiState.statuses.none { viewData -> viewData.isDetailed }) {
+                        threadProgressBar.cancel()
-                            // no detailed statuses available, e.g. because author is blocked
-                            activity?.finish()
-                            return@collect
-                        }
 
-                        adapter.submitList(uiState.statuses) {
+                        adapter.submitList(uiState.statusViewData) {
-                            if (viewModel.isInitialLoad) {
+                            // Ensure the top of the status is visible
-                                viewModel.isInitialLoad = false
+                            (binding.recyclerView.layoutManager as LinearLayoutManager).scrollToPositionWithOffset(uiState.detailedStatusPosition, 0)
-                                val detailedPosition = adapter.currentList.indexOfFirst { viewData ->
-                                    viewData.isDetailed
-                                }
-                                binding.recyclerView.scrollToPosition(detailedPosition)
-                            }
                         }
 
                         updateRevealButton(uiState.revealButton)
-                        binding.swipeRefreshLayout.isRefreshing = uiState.refreshing
+                        binding.swipeRefreshLayout.isRefreshing = false
 
                         binding.recyclerView.show()
                         binding.statusView.hide()
-                        binding.progressBar.hide()
+                    }
+                    is ThreadUiState.Refreshing -> {
+                        threadProgressBar.cancel()
                     }
                 }
             }
@@ -213,6 +236,28 @@ class ViewThreadFragment : SFragment(), OnRefreshListener, StatusActionListener,
         viewModel.loadThread(thisThreadsStatusId)
     }
 
+    /**
+     * Create a job to implement a delayed-visible progress bar.
+     *
+     * Delaying the visibility of the progress bar can improve user perception of UI speed because
+     * fewer UI elements are appearing and disappearing.
+     *
+     * When started the job will wait `delayMs` then show `view`. If the job is cancelled at
+     * any time `view` is hidden.
+     */
+    @CheckResult()
+    private fun getProgressBarJob(view: View, delayMs: Long) = viewLifecycleOwner.lifecycleScope.launch(
+        start = CoroutineStart.LAZY
+    ) {
+        try {
+            delay(delayMs)
+            view.show()
+            awaitCancellation()
+        } finally {
+            view.hide()
+        }
+    }
+
     private fun updateRevealButton(state: RevealButtonState) {
         val menuItem = binding.toolbar.menu.findItem(R.id.action_reveal)
 

app/src/main/java/com/keylesspalace/tusky/components/viewthread/ViewThreadViewModel.kt

@@ -20,6 +20,7 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import at.connyduck.calladapter.networkresult.fold
 import at.connyduck.calladapter.networkresult.getOrElse
+import com.google.gson.Gson
 import com.keylesspalace.tusky.appstore.BlockEvent
 import com.keylesspalace.tusky.appstore.BookmarkEvent
 import com.keylesspalace.tusky.appstore.EventHub
@@ -28,8 +29,10 @@ import com.keylesspalace.tusky.appstore.PinEvent
 import com.keylesspalace.tusky.appstore.ReblogEvent
 import com.keylesspalace.tusky.appstore.StatusComposedEvent
 import com.keylesspalace.tusky.appstore.StatusDeletedEvent
+import com.keylesspalace.tusky.components.timeline.toViewData
 import com.keylesspalace.tusky.components.timeline.util.ifExpected
 import com.keylesspalace.tusky.db.AccountManager
+import com.keylesspalace.tusky.db.AppDatabase
 import com.keylesspalace.tusky.entity.Filter
 import com.keylesspalace.tusky.entity.Status
 import com.keylesspalace.tusky.network.FilterModel
@@ -54,7 +57,9 @@ class ViewThreadViewModel @Inject constructor(
     private val filterModel: FilterModel,
     private val timelineCases: TimelineCases,
     eventHub: EventHub,
-    accountManager: AccountManager
+    accountManager: AccountManager,
+    private val db: AppDatabase,
+    private val gson: Gson
 ) : ViewModel() {
 
     private val _uiState: MutableStateFlow<ThreadUiState> = MutableStateFlow(ThreadUiState.Loading)
@@ -65,8 +70,6 @@ class ViewThreadViewModel @Inject constructor(
     val errors: Flow<Throwable>
         get() = _errors
 
-    var isInitialLoad: Boolean = true
-
     private val alwaysShowSensitiveMedia: Boolean
     private val alwaysOpenSpoiler: Boolean
 
@@ -95,36 +98,70 @@ class ViewThreadViewModel @Inject constructor(
     }
 
     fun loadThread(id: String) {
+        _uiState.value = ThreadUiState.Loading
+
         viewModelScope.launch {
+            Log.d(TAG, "Finding status with: $id")
             val contextCall = async { api.statusContext(id) }
-            val statusCall = async { api.statusAsync(id) }
+            val timelineStatus = db.timelineDao().getStatus(id)
+
+            var detailedStatus = if (timelineStatus != null) {
+                Log.d(TAG, "Loaded status from local timeline")
+                val viewData = timelineStatus.toViewData(
+                    gson,
+                    isDetailed = true
+                ) as StatusViewData.Concrete
+
+                // Return the correct status, depending on which one matched. If you do not do
+                // this the status IDs will be different between the status that's displayed with
+                // ThreadUiState.LoadingThread and ThreadUiState.Success, even though the apparent
+                // status content is the same. Then the status flickers as it is drawn twice.
+                if (viewData.actionableId == id) {
+                    viewData.actionable.toViewData(isDetailed = true)
+                } else {
+                    viewData
+                }
+            } else {
+                Log.d(TAG, "Loaded status from network")
+                val result = api.status(id).getOrElse { exception ->
+                    _uiState.value = ThreadUiState.Error(exception)
+                    return@launch
+                }
+                result.toViewData(isDetailed = true)
+            }
 
-            val contextResult = contextCall.await()
+            _uiState.value = ThreadUiState.LoadingThread(
-            val statusResult = statusCall.await()
+                statusViewDatum = detailedStatus,
+                revealButton = detailedStatus.getRevealButtonState()
+            )
 
-            val status = statusResult.getOrElse { exception ->
+            // If the detailedStatus was loaded from the database it might be out-of-date
-                _uiState.value = ThreadUiState.Error(exception)
+            // compared to the remote one. Now the user has a working UI do a background fetch
-                return@launch
+            // for the status. Ignore errors, the user still has a functioning UI if the fetch
+            // failed.
+            if (timelineStatus != null) {
+                val viewData = api.status(id).getOrNull()?.toViewData(isDetailed = true)
+                if (viewData != null) { detailedStatus = viewData }
             }
 
-            contextResult.fold({ statusContext ->
+            val contextResult = contextCall.await()
 
+            contextResult.fold({ statusContext ->
                 val ancestors = statusContext.ancestors.map { status -> status.toViewData() }.filter()
-                val detailedStatus = status.toViewData(true)
                 val descendants = statusContext.descendants.map { status -> status.toViewData() }.filter()
                 val statuses = ancestors + detailedStatus + descendants
 
                 _uiState.value = ThreadUiState.Success(
-                    statuses = statuses,
+                    statusViewData = statuses,
-                    revealButton = statuses.getRevealButtonState(),
+                    detailedStatusPosition = ancestors.size,
-                    refreshing = false
+                    revealButton = statuses.getRevealButtonState()
                 )
             }, { throwable ->
                 _errors.emit(throwable)
                 _uiState.value = ThreadUiState.Success(
-                    statuses = listOf(status.toViewData(true)),
+                    statusViewData = listOf(detailedStatus),
+                    detailedStatusPosition = 0,
                     revealButton = RevealButtonState.NO_BUTTON,
-                    refreshing = false
                 )
             })
         }
@@ -136,14 +173,12 @@ class ViewThreadViewModel @Inject constructor(
     }
 
     fun refresh(id: String) {
-        updateSuccess { uiState ->
+        _uiState.value = ThreadUiState.Refreshing
-            uiState.copy(refreshing = true)
-        }
         loadThread(id)
     }
 
     fun detailedStatus(): StatusViewData.Concrete? {
-        return (_uiState.value as ThreadUiState.Success?)?.statuses?.find { status ->
+        return (_uiState.value as ThreadUiState.Success?)?.statusViewData?.find { status ->
             status.isDetailed
         }
     }
@@ -201,14 +236,14 @@ class ViewThreadViewModel @Inject constructor(
     fun removeStatus(statusToRemove: StatusViewData.Concrete) {
         updateSuccess { uiState ->
             uiState.copy(
-                statuses = uiState.statuses.filterNot { status -> status == statusToRemove }
+                statusViewData = uiState.statusViewData.filterNot { status -> status == statusToRemove }
             )
         }
     }
 
     fun changeExpanded(expanded: Boolean, status: StatusViewData.Concrete) {
         updateSuccess { uiState ->
-            val statuses = uiState.statuses.map { viewData ->
+            val statuses = uiState.statusViewData.map { viewData ->
                 if (viewData.id == status.id) {
                     viewData.copy(isExpanded = expanded)
                 } else {
@@ -216,7 +251,7 @@ class ViewThreadViewModel @Inject constructor(
                 }
             }
             uiState.copy(
-                statuses = statuses,
+                statusViewData = statuses,
                 revealButton = statuses.getRevealButtonState()
             )
         }
@@ -261,7 +296,7 @@ class ViewThreadViewModel @Inject constructor(
     private fun removeAllByAccountId(accountId: String) {
         updateSuccess { uiState ->
             uiState.copy(
-                statuses = uiState.statuses.filter { viewData ->
+                statusViewData = uiState.statusViewData.filter { viewData ->
                     viewData.status.account.id != accountId
                 }
             )
@@ -271,7 +306,7 @@ class ViewThreadViewModel @Inject constructor(
     private fun handleStatusComposedEvent(event: StatusComposedEvent) {
         val eventStatus = event.status
         updateSuccess { uiState ->
-            val statuses = uiState.statuses
+            val statuses = uiState.statusViewData
             val detailedIndex = statuses.indexOfFirst { status -> status.isDetailed }
             val repliedIndex = statuses.indexOfFirst { status -> eventStatus.inReplyToId == status.id }
             if (detailedIndex != -1 && repliedIndex >= detailedIndex) {
@@ -279,7 +314,7 @@ class ViewThreadViewModel @Inject constructor(
                 val newStatuses = statuses.subList(0, repliedIndex + 1) +
                     eventStatus.toViewData() +
                     statuses.subList(repliedIndex + 1, statuses.size)
-                uiState.copy(statuses = newStatuses)
+                uiState.copy(statusViewData = newStatuses)
             } else {
                 uiState
             }
@@ -289,7 +324,7 @@ class ViewThreadViewModel @Inject constructor(
     private fun handleStatusDeletedEvent(event: StatusDeletedEvent) {
         updateSuccess { uiState ->
             uiState.copy(
-                statuses = uiState.statuses.filter { status ->
+                statusViewData = uiState.statusViewData.filter { status ->
                     status.id != event.statusId
                 }
             )
@@ -300,13 +335,13 @@ class ViewThreadViewModel @Inject constructor(
         updateSuccess { uiState ->
             when (uiState.revealButton) {
                 RevealButtonState.HIDE -> uiState.copy(
-                    statuses = uiState.statuses.map { viewData ->
+                    statusViewData = uiState.statusViewData.map { viewData ->
                         viewData.copy(isExpanded = false)
                     },
                     revealButton = RevealButtonState.REVEAL
                 )
                 RevealButtonState.REVEAL -> uiState.copy(
-                    statuses = uiState.statuses.map { viewData ->
+                    statusViewData = uiState.statusViewData.map { viewData ->
                         viewData.copy(isExpanded = true)
                     },
                     revealButton = RevealButtonState.HIDE
@@ -316,16 +351,11 @@ class ViewThreadViewModel @Inject constructor(
         }
     }
 
-    private fun List<StatusViewData.Concrete>.getRevealButtonState(): RevealButtonState {
+    private fun StatusViewData.Concrete.getRevealButtonState(): RevealButtonState {
-        val hasWarnings = any { viewData ->
+        val hasWarnings = status.spoilerText.isNotEmpty()
-            viewData.status.spoilerText.isNotEmpty()
-        }
 
         return if (hasWarnings) {
-            val allExpanded = none { viewData ->
+            if (isExpanded) {
-                !viewData.isExpanded
-            }
-            if (allExpanded) {
                 RevealButtonState.HIDE
             } else {
                 RevealButtonState.REVEAL
@@ -335,6 +365,31 @@ class ViewThreadViewModel @Inject constructor(
         }
     }
 
+    /**
+     * Get the reveal button state based on the state of all the statuses in the list.
+     *
+     * - If any status sets it to REVEAL, use REVEAL
+     * - If no status sets it to REVEAL, but at least one uses HIDE, use HIDE
+     * - Otherwise use NO_BUTTON
+     */
+    private fun List<StatusViewData.Concrete>.getRevealButtonState(): RevealButtonState {
+        var seenHide = false
+
+        forEach {
+            when (val state = it.getRevealButtonState()) {
+                RevealButtonState.NO_BUTTON -> return@forEach
+                RevealButtonState.REVEAL -> return state
+                RevealButtonState.HIDE -> seenHide = true
+            }
+        }
+
+        if (seenHide) {
+            return RevealButtonState.HIDE
+        }
+
+        return RevealButtonState.NO_BUTTON
+    }
+
     private fun loadFilters() {
         viewModelScope.launch {
             val filters = api.getFilters().getOrElse {
@@ -349,9 +404,9 @@ class ViewThreadViewModel @Inject constructor(
             )
 
             updateSuccess { uiState ->
-                val statuses = uiState.statuses.filter()
+                val statuses = uiState.statusViewData.filter()
                 uiState.copy(
-                    statuses = statuses,
+                    statusViewData = statuses,
                     revealButton = statuses.getRevealButtonState()
                 )
             }
@@ -365,14 +420,14 @@ class ViewThreadViewModel @Inject constructor(
     }
 
     private fun Status.toViewData(
-        detailed: Boolean = false
+        isDetailed: Boolean = false
     ): StatusViewData.Concrete {
-        val oldStatus = (_uiState.value as? ThreadUiState.Success)?.statuses?.find { it.id == this.id }
+        val oldStatus = (_uiState.value as? ThreadUiState.Success)?.statusViewData?.find { it.id == this.id }
         return toViewData(
             isShowingContent = oldStatus?.isShowingContent ?: (alwaysShowSensitiveMedia || !actionableStatus.sensitive),
             isExpanded = oldStatus?.isExpanded ?: alwaysOpenSpoiler,
-            isCollapsed = oldStatus?.isCollapsed ?: !detailed,
+            isCollapsed = oldStatus?.isCollapsed ?: !isDetailed,
-            isDetailed = oldStatus?.isDetailed ?: detailed
+            isDetailed = oldStatus?.isDetailed ?: isDetailed
         )
     }
 
@@ -389,7 +444,7 @@ class ViewThreadViewModel @Inject constructor(
     private fun updateStatusViewData(statusId: String, updater: (StatusViewData.Concrete) -> StatusViewData.Concrete) {
         updateSuccess { uiState ->
             uiState.copy(
-                statuses = uiState.statuses.map { viewData ->
+                statusViewData = uiState.statusViewData.map { viewData ->
                     if (viewData.id == statusId) {
                         updater(viewData)
                     } else {
@@ -414,13 +469,27 @@ class ViewThreadViewModel @Inject constructor(
 }
 
 sealed interface ThreadUiState {
+    /** The initial load of the detailed status for this thread */
     object Loading : ThreadUiState
+
+    /** Loading the detailed status has completed, now loading ancestors/descendants */
+    data class LoadingThread(
+        val statusViewDatum: StatusViewData.Concrete?,
+        val revealButton: RevealButtonState
+    ) : ThreadUiState
+
+    /** An error occurred at any point */
     class Error(val throwable: Throwable) : ThreadUiState
+
+    /** Successfully loaded the full thread */
     data class Success(
-        val statuses: List<StatusViewData.Concrete>,
+        val statusViewData: List<StatusViewData.Concrete>,
         val revealButton: RevealButtonState,
-        val refreshing: Boolean
+        val detailedStatusPosition: Int
     ) : ThreadUiState
+
+    /** Refreshing the thread with a swipe */
+    object Refreshing : ThreadUiState
 }
 
 enum class RevealButtonState {

app/src/main/java/com/keylesspalace/tusky/components/viewthread/edits/ViewEditsFragment.kt

@@ -82,14 +82,14 @@ class ViewEditsFragment : Fragment(R.layout.fragment_view_thread), LinkListener,
                     EditsUiState.Loading -> {
                         binding.recyclerView.hide()
                         binding.statusView.hide()
-                        binding.progressBar.show()
+                        binding.initialProgressBar.show()
                     }
                     is EditsUiState.Error -> {
                         Log.w(TAG, "failed to load edits", uiState.throwable)
 
                         binding.recyclerView.hide()
                         binding.statusView.show()
-                        binding.progressBar.hide()
+                        binding.initialProgressBar.hide()
 
                         if (uiState.throwable is IOException) {
                             binding.statusView.setup(R.drawable.elephant_offline, R.string.error_network) {
@@ -104,7 +104,7 @@ class ViewEditsFragment : Fragment(R.layout.fragment_view_thread), LinkListener,
                     is EditsUiState.Success -> {
                         binding.recyclerView.show()
                         binding.statusView.hide()
-                        binding.progressBar.hide()
+                        binding.initialProgressBar.hide()
 
                         binding.recyclerView.adapter = ViewEditsAdapter(
                             edits = uiState.edits,

app/src/main/java/com/keylesspalace/tusky/db/TimelineDao.kt

@@ -53,6 +53,28 @@ ORDER BY LENGTH(s.serverId) DESC, s.serverId DESC"""
     )
     abstract fun getStatuses(account: Long): PagingSource<Int, TimelineStatusWithAccount>
 
+    @Query(
+        """
+SELECT s.serverId, s.url, s.timelineUserId,
+s.authorServerId, s.inReplyToId, s.inReplyToAccountId, s.createdAt, s.editedAt,
+s.emojis, s.reblogsCount, s.favouritesCount, s.repliesCount, s.reblogged, s.favourited, s.bookmarked, s.sensitive,
+s.spoilerText, s.visibility, s.mentions, s.tags, s.application, s.reblogServerId,s.reblogAccountId,
+s.content, s.attachments, s.poll, s.card, s.muted, s.expanded, s.contentShowing, s.contentCollapsed, s.pinned, s.language,  
+a.serverId as 'a_serverId', a.timelineUserId as 'a_timelineUserId',
+a.localUsername as 'a_localUsername', a.username as 'a_username',
+a.displayName as 'a_displayName', a.url as 'a_url', a.avatar as 'a_avatar',
+a.emojis as 'a_emojis', a.bot as 'a_bot',
+rb.serverId as 'rb_serverId', rb.timelineUserId 'rb_timelineUserId',
+rb.localUsername as 'rb_localUsername', rb.username as 'rb_username',
+rb.displayName as 'rb_displayName', rb.url as 'rb_url', rb.avatar as 'rb_avatar',
+rb.emojis as 'rb_emojis', rb.bot as 'rb_bot'
+FROM TimelineStatusEntity s
+LEFT JOIN TimelineAccountEntity a ON (s.timelineUserId = a.timelineUserId AND s.authorServerId = a.serverId)
+LEFT JOIN TimelineAccountEntity rb ON (s.timelineUserId = rb.timelineUserId AND s.reblogAccountId = rb.serverId)
+WHERE s.serverId = :statusId OR s.reblogServerId = :statusId"""
+    )
+    abstract suspend fun getStatus(statusId: String): TimelineStatusWithAccount?
+
     @Query(
         """DELETE FROM TimelineStatusEntity WHERE timelineUserId = :accountId AND
         (LENGTH(serverId) < LENGTH(:maxId) OR LENGTH(serverId) == LENGTH(:maxId) AND serverId <= :maxId)

app/src/main/res/layout-sw640dp/fragment_view_thread.xml

@@ -27,20 +27,37 @@
         android:layout_gravity="center_horizontal|top"
         app:layout_behavior="com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior">
 
-        <androidx.recyclerview.widget.RecyclerView
+        <LinearLayout
-            android:id="@+id/recyclerView"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
-            android:background="?android:attr/colorBackground"
+            android:orientation="vertical">
-            android:scrollbars="vertical" />
 
+            <androidx.recyclerview.widget.RecyclerView
+                android:id="@+id/recyclerView"
+                android:layout_width="match_parent"
+                android:layout_height="0dp"
+                android:layout_weight="1"
+                android:background="?android:attr/colorBackground"
+                android:scrollbars="vertical" />
+
+            <com.google.android.material.progressindicator.LinearProgressIndicator
+                android:id="@+id/threadProgressBar"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:visibility="gone"
+                android:indeterminate="true"
+                android:contentDescription="@string/a11y_label_loading_thread" />
+        </LinearLayout>
     </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
 
     <ProgressBar
-        android:id="@+id/progressBar"
+        android:id="@+id/initialProgressBar"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_gravity="center" />
+        android:visibility="gone"
+        android:indeterminate="true"
+        android:layout_gravity="center"
+        android:contentDescription="@string/a11y_label_loading_thread" />
 
     <com.keylesspalace.tusky.view.BackgroundMessageView
         android:id="@+id/statusView"

app/src/main/res/layout/fragment_view_thread.xml

@@ -24,23 +24,39 @@
         android:id="@+id/swipeRefreshLayout"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:layout_gravity="top"
         app:layout_behavior="com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior">
 
-        <androidx.recyclerview.widget.RecyclerView
+        <LinearLayout
-            android:id="@+id/recyclerView"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
-            android:background="?android:attr/colorBackground"
+            android:orientation="vertical">
-            android:scrollbars="vertical" />
 
+            <androidx.recyclerview.widget.RecyclerView
+                android:id="@+id/recyclerView"
+                android:layout_width="match_parent"
+                android:layout_height="0dp"
+                android:layout_weight="1"
+                android:background="?android:attr/colorBackground"
+                android:scrollbars="vertical" />
+
+            <com.google.android.material.progressindicator.LinearProgressIndicator
+                android:id="@+id/threadProgressBar"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:visibility="gone"
+                android:indeterminate="true"
+                android:contentDescription="@string/a11y_label_loading_thread" />
+        </LinearLayout>
     </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
 
     <ProgressBar
-        android:id="@+id/progressBar"
+        android:id="@+id/initialProgressBar"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_gravity="center" />
+        android:visibility="gone"
+        android:indeterminate="true"
+        android:layout_gravity="center"
+        android:contentDescription="@string/a11y_label_loading_thread" />
 
     <com.keylesspalace.tusky.view.BackgroundMessageView
         android:id="@+id/statusView"

app/src/main/res/values/strings.xml

@@ -722,4 +722,5 @@
     <!--@Tusky created 19th December 2022 13:12 -->
     <string name="status_created_info">%1$s created %2$s</string>
 
+    <string name="a11y_label_loading_thread">Loading thread</string>
 </resources>

app/src/test/java/com/keylesspalace/tusky/components/viewthread/ViewThreadViewModelTest.kt

@@ -1,8 +1,12 @@
 package com.keylesspalace.tusky.components.viewthread
 
 import android.os.Looper.getMainLooper
+import androidx.arch.core.executor.testing.InstantTaskExecutorRule
+import androidx.room.Room
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
 import at.connyduck.calladapter.networkresult.NetworkResult
+import com.google.gson.Gson
 import com.keylesspalace.tusky.appstore.BookmarkEvent
 import com.keylesspalace.tusky.appstore.EventHub
 import com.keylesspalace.tusky.appstore.FavoriteEvent
@@ -11,14 +15,18 @@ import com.keylesspalace.tusky.components.timeline.mockStatus
 import com.keylesspalace.tusky.components.timeline.mockStatusViewData
 import com.keylesspalace.tusky.db.AccountEntity
 import com.keylesspalace.tusky.db.AccountManager
+import com.keylesspalace.tusky.db.AppDatabase
+import com.keylesspalace.tusky.db.Converters
 import com.keylesspalace.tusky.entity.StatusContext
 import com.keylesspalace.tusky.network.FilterModel
 import com.keylesspalace.tusky.network.MastodonApi
 import com.keylesspalace.tusky.usecase.TimelineCases
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.runBlocking
+import org.junit.After
 import org.junit.Assert.assertEquals
 import org.junit.Before
+import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.kotlin.doReturn
@@ -35,9 +43,38 @@ class ViewThreadViewModelTest {
     private lateinit var api: MastodonApi
     private lateinit var eventHub: EventHub
     private lateinit var viewModel: ViewThreadViewModel
+    private lateinit var db: AppDatabase
 
     private val threadId = "1234"
 
+    /**
+     * Execute each task synchronously.
+     *
+     * If you do not do this, and you have code like this under test:
+     *
+     * ```
+     * fun someFunc() = viewModelScope.launch {
+     *     _uiState.value = "initial value"
+     *     // ...
+     *     call_a_suspend_fun()
+     *     // ...
+     *     _uiState.value = "new value"
+     * }
+     * ```
+     *
+     * and a test like:
+     *
+     * ```
+     * someFunc()
+     * assertEquals("new value", viewModel.uiState.value)
+     * ```
+     *
+     * The test will fail, because someFunc() yields at the `call_a_suspend_func()` point,
+     * and control returns to the test before `_uiState.value` has been changed.
+     */
+    @get:Rule
+    val instantTaskRule = InstantTaskExecutorRule()
+
     @Before
     fun setup() {
         shadowOf(getMainLooper()).idle()
@@ -56,7 +93,19 @@ class ViewThreadViewModelTest {
                 isActive = true
             )
         }
-        viewModel = ViewThreadViewModel(api, filterModel, timelineCases, eventHub, accountManager)
+        val context = InstrumentationRegistry.getInstrumentation().targetContext
+        db = Room.inMemoryDatabaseBuilder(context, AppDatabase::class.java)
+            .addTypeConverter(Converters(Gson()))
+            .allowMainThreadQueries()
+            .build()
+
+        val gson = Gson()
+        viewModel = ViewThreadViewModel(api, filterModel, timelineCases, eventHub, accountManager, db, gson)
+    }
+
+    @After
+    fun closeDb() {
+        db.close()
     }
 
     @Test
@@ -68,13 +117,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test"),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test"),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test")
                     ),
-                    revealButton = RevealButtonState.REVEAL,
+                    detailedStatusPosition = 1,
-                    refreshing = false
+                    revealButton = RevealButtonState.REVEAL
                 ),
                 viewModel.uiState.first()
             )
@@ -84,7 +133,7 @@ class ViewThreadViewModelTest {
     @Test
     fun `should emit status even if context fails to load`() {
         api.stub {
-            onBlocking { statusAsync(threadId) } doReturn NetworkResult.success(mockStatus(id = "2", inReplyToId = "1", inReplyToAccountId = "1"))
+            onBlocking { status(threadId) } doReturn NetworkResult.success(mockStatus(id = "2", inReplyToId = "1", inReplyToAccountId = "1"))
             onBlocking { statusContext(threadId) } doReturn NetworkResult.failure(IOException())
         }
 
@@ -93,11 +142,11 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true)
                     ),
+                    detailedStatusPosition = 0,
                     revealButton = RevealButtonState.NO_BUTTON,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -107,7 +156,7 @@ class ViewThreadViewModelTest {
     @Test
     fun `should emit error when status and context fail to load`() {
         api.stub {
-            onBlocking { statusAsync(threadId) } doReturn NetworkResult.failure(IOException())
+            onBlocking { status(threadId) } doReturn NetworkResult.failure(IOException())
             onBlocking { statusContext(threadId) } doReturn NetworkResult.failure(IOException())
         }
 
@@ -124,7 +173,7 @@ class ViewThreadViewModelTest {
     @Test
     fun `should emit error when status fails to load`() {
         api.stub {
-            onBlocking { statusAsync(threadId) } doReturn NetworkResult.failure(IOException())
+            onBlocking { status(threadId) } doReturn NetworkResult.failure(IOException())
             onBlocking { statusContext(threadId) } doReturn NetworkResult.success(
                 StatusContext(
                     ancestors = listOf(mockStatus(id = "1")),
@@ -153,13 +202,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test", isExpanded = true),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test", isExpanded = true),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test", isExpanded = true)
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.HIDE,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -177,13 +226,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test", favourited = false),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test"),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test")
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.REVEAL,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -201,13 +250,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test"),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test", reblogged = true),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test")
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.REVEAL,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -225,13 +274,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test"),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test"),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test", bookmarked = false)
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.REVEAL,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -249,12 +298,12 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test"),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test")
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.REVEAL,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -275,13 +324,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test"),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test", isExpanded = true),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test")
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.REVEAL,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -302,13 +351,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test"),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test", isCollapsed = true),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test")
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.REVEAL,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -329,13 +378,13 @@ class ViewThreadViewModelTest {
         runBlocking {
             assertEquals(
                 ThreadUiState.Success(
-                    statuses = listOf(
+                    statusViewData = listOf(
                         mockStatusViewData(id = "1", spoilerText = "Test"),
                         mockStatusViewData(id = "2", inReplyToId = "1", inReplyToAccountId = "1", isDetailed = true, spoilerText = "Test", isShowingContent = true),
                         mockStatusViewData(id = "3", inReplyToId = "2", inReplyToAccountId = "1", spoilerText = "Test")
                     ),
+                    detailedStatusPosition = 1,
                     revealButton = RevealButtonState.REVEAL,
-                    refreshing = false
                 ),
                 viewModel.uiState.first()
             )
@@ -344,7 +393,7 @@ class ViewThreadViewModelTest {
 
     private fun mockSuccessResponses() {
         api.stub {
-            onBlocking { statusAsync(threadId) } doReturn NetworkResult.success(mockStatus(id = "2", inReplyToId = "1", inReplyToAccountId = "1", spoilerText = "Test"))
+            onBlocking { status(threadId) } doReturn NetworkResult.success(mockStatus(id = "2", inReplyToId = "1", inReplyToAccountId = "1", spoilerText = "Test"))
             onBlocking { statusContext(threadId) } doReturn NetworkResult.success(
                 StatusContext(
                     ancestors = listOf(mockStatus(id = "1", spoilerText = "Test")),