Experimental: Swipe to switch between root spaces

Change-Id: I8849a4a2fd2cea0a7904f8c4259adf8c09f6864a

vector/src/main/java/de/spiritcroc/viewpager/ViewPager2.kt

@@ -0,0 +1,22 @@
+package de.spiritcroc.viewpager
+
+import androidx.recyclerview.widget.RecyclerView
+import androidx.viewpager2.widget.ViewPager2
+import timber.log.Timber
+import java.lang.Exception
+
+// Mainly taken from https://stackoverflow.com/a/63455547
+fun ViewPager2.reduceDragSensitivity(factor: Int) {
+    try {
+        val recyclerViewField = ViewPager2::class.java.getDeclaredField("mRecyclerView")
+        recyclerViewField.isAccessible = true
+       val recyclerView = recyclerViewField.get(this) as RecyclerView
+
+        val touchSlopField = RecyclerView::class.java.getDeclaredField("mTouchSlop")
+        touchSlopField.isAccessible = true
+        val touchSlop = touchSlopField.get(recyclerView) as Int
+        touchSlopField.set(recyclerView, touchSlop * factor)
+    } catch (e: Exception) {
+        Timber.e("Cannot reduce viewpager drag sensitivity: $e")
+    }
+}

vector/src/main/java/im/vector/app/features/home/HomeDetailFragment.kt

@@ -24,14 +24,16 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.core.view.isVisible
 import androidx.fragment.app.Fragment
+import androidx.viewpager2.adapter.FragmentStateAdapter
+import androidx.viewpager2.widget.ViewPager2
 import com.airbnb.mvrx.activityViewModel
 import com.airbnb.mvrx.fragmentViewModel
 import com.airbnb.mvrx.withState
 import com.google.android.material.badge.BadgeDrawable
+import de.spiritcroc.viewpager.reduceDragSensitivity
 import im.vector.app.AppStateHandler
 import im.vector.app.R
 import im.vector.app.RoomGroupingMethod
-import im.vector.app.core.extensions.commitTransaction
 import im.vector.app.core.extensions.restart
 import im.vector.app.core.extensions.toMvRxBundle
 import im.vector.app.core.platform.ToolbarConfigurable
@@ -48,6 +50,7 @@ import im.vector.app.features.call.dialpad.DialPadFragment
 import im.vector.app.features.call.webrtc.WebRtcCallManager
 import im.vector.app.features.home.room.list.RoomListFragment
 import im.vector.app.features.home.room.list.RoomListParams
+import im.vector.app.features.home.room.list.RoomListSectionBuilderSpace.Companion.SPACE_ID_FOLLOW_APP
 import im.vector.app.features.home.room.list.UnreadCounterBadgeView
 import im.vector.app.features.popup.PopupAlertManager
 import im.vector.app.features.popup.VerificationVectorAlert
@@ -60,6 +63,7 @@ import im.vector.app.features.workers.signout.ServerBackupStatusViewModel
 import org.matrix.android.sdk.api.session.group.model.GroupSummary
 import org.matrix.android.sdk.api.session.room.model.RoomSummary
 import org.matrix.android.sdk.internal.crypto.model.rest.DeviceInfo
+import timber.log.Timber
 import javax.inject.Inject
 
 class HomeDetailFragment @Inject constructor(
@@ -73,6 +77,10 @@ class HomeDetailFragment @Inject constructor(
         KeysBackupBanner.Delegate,
         CurrentCallsView.Callback {
 
+    companion object {
+        const val DEBUG_VIEW_PAGER = true
+    }
+
     private val viewModel: HomeDetailViewModel by fragmentViewModel()
     private val unknownDeviceDetectorSharedViewModel: UnknownDeviceDetectorSharedViewModel by activityViewModel()
     private val unreadMessagesSharedViewModel: UnreadMessagesSharedViewModel by activityViewModel()
@@ -93,6 +101,12 @@ class HomeDetailFragment @Inject constructor(
             }
         }
 
+    private var initialPageSelected = false
+    private var pagerSpaces: List<String?>? = null
+    private var pagerTab: HomeTab? = null
+    private var pagerPagingEnabled: Boolean = false
+    private val pendingSpaceIds = mutableListOf<String?>()
+
     override fun getMenuRes() = R.menu.room_list
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
@@ -131,6 +145,29 @@ class HomeDetailFragment @Inject constructor(
 
         checkNotificationTabStatus()
 
+        // Reduce sensitivity of viewpager to avoid scrolling horizontally by accident too easily
+        views.roomListContainerPager.reduceDragSensitivity(4)
+
+        // space pager: update appStateHandler's current page to update rest of the UI accordingly
+        views.roomListContainerPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
+            override fun onPageSelected(position: Int) {
+                if (DEBUG_VIEW_PAGER) Timber.i("Home pager: selected page $position $initialPageSelected")
+                super.onPageSelected(position)
+                if (!initialPageSelected) {
+                    // Do not apply before we have restored the previous value
+                    if (position == 0) {
+                        return
+                    } else {
+                        // User has swiped, store it anyways
+                        initialPageSelected = true
+                    }
+                }
+                val selectedId = getSpaceIdForPageIndex(position)
+                pendingSpaceIds.add(selectedId)
+                appStateHandler.setCurrentSpace(selectedId)
+            }
+        })
+
         viewModel.onEach(HomeDetailViewState::roomGroupingMethod) { roomGroupingMethod ->
             when (roomGroupingMethod) {
                 is RoomGroupingMethod.ByLegacyGroup -> {
@@ -188,6 +225,10 @@ class HomeDetailFragment @Inject constructor(
             )
         }
 
+        viewModel.onEach(HomeDetailViewState::roomGroupingMethod, HomeDetailViewState::rootSpacesOrdered, HomeDetailViewState::currentTab) { roomGroupingMethod, rootSpacesOrdered, currentTab ->
+            setupViewPager(roomGroupingMethod, rootSpacesOrdered, currentTab)
+        }
+
         sharedCallActionViewModel
                 .liveKnownCalls
                 .observe(viewLifecycleOwner) {
@@ -438,12 +479,13 @@ class HomeDetailFragment @Inject constructor(
     private fun updateUIForTab(tab: HomeTab) {
         views.bottomNavigationView.menu.findItem(tab.toMenuId()).isChecked = true
         views.groupToolbarTitleView.setText(tab.titleRes)
-        updateSelectedFragment(tab)
+        //updateSelectedFragment(tab)
         invalidateOptionsMenu()
     }
 
     private fun HomeTab.toFragmentTag() = "FRAGMENT_TAG_$this"
 
+    /*
     private fun updateSelectedFragment(tab: HomeTab) {
         val fragmentTag = tab.toFragmentTag()
         val fragmentToShow = childFragmentManager.findFragmentByTag(fragmentTag)
@@ -471,6 +513,120 @@ class HomeDetailFragment @Inject constructor(
             }
         }
     }
+     */
+
+    private fun setupViewPager(roomGroupingMethod: RoomGroupingMethod, spaces: List<RoomSummary>?, tab: HomeTab) {
+        val oldAdapter = views.roomListContainerPager.adapter as? FragmentStateAdapter
+        val pagingAllowed = vectorPreferences.enableSpacePager()
+        if (DEBUG_VIEW_PAGER) Timber.i("Home pager: setup, old adapter: $oldAdapter")
+        val unsafeSpaces = spaces?.map { it.roomId } ?: listOf()
+        val selectedSpaceId = (roomGroupingMethod as? RoomGroupingMethod.BySpace)?.spaceSummary?.roomId
+        val selectedIndex = getPageIndexForSpaceId(selectedSpaceId, unsafeSpaces)
+        val pagingEnabled = pagingAllowed && roomGroupingMethod is RoomGroupingMethod.BySpace && unsafeSpaces.size > 0 && selectedIndex != null
+        val safeSpaces = if (pagingEnabled) unsafeSpaces else listOf()
+        // Check if we need to recreate the adapter for a new tab
+        if (oldAdapter != null) {
+            val changed = pagerTab != tab || pagerSpaces != safeSpaces || pagerPagingEnabled != pagingEnabled
+            if (DEBUG_VIEW_PAGER) Timber.i("Home pager: has changed: $changed (${pagerTab != tab} ${pagerSpaces != safeSpaces} ${pagerPagingEnabled != pagingEnabled} $selectedIndex ${views.roomListContainerPager.currentItem}) | $safeSpaces")
+            if (!changed) {
+                if (pagingEnabled) {
+                    // No need to re-setup pager, just check for selected page
+                    // Discard state changes that we created ourselves by swiping on the pager
+                    while (pendingSpaceIds.size > 0) {
+                        val pendingSpaceId = pendingSpaceIds.removeAt(0)
+                        if (pendingSpaceId == selectedSpaceId) {
+                            return
+                        }
+                    }
+                    if (selectedIndex != null) {
+                        if (selectedIndex != views.roomListContainerPager.currentItem) {
+                            // post() mitigates a case where we could end up in an endless loop circling around the same few spaces
+                            views.roomListContainerPager.post {
+                                views.roomListContainerPager.currentItem = selectedIndex
+                            }
+                        }
+                        return
+                    }
+                } else {
+                    // Nothing to change
+                    return
+                }
+            } else {
+                // Clean up old fragments
+                val transaction = childFragmentManager.beginTransaction()
+                childFragmentManager.fragments
+                        .forEach {
+                            transaction.detach(it)
+                        }
+                transaction.commit()
+            }
+        }
+        pagerSpaces = safeSpaces
+        pagerTab = tab
+        pagerPagingEnabled = pagingEnabled
+        initialPageSelected = false
+        pendingSpaceIds.clear()
+
+        views.roomListContainerPager.offscreenPageLimit = 2
+
+        val adapter = object: FragmentStateAdapter(this@HomeDetailFragment) {
+            override fun getItemCount(): Int {
+                if (!pagingEnabled) {
+                    return 1
+                }
+                return when (tab) {
+                    is HomeTab.DialPad -> 1
+                    else -> safeSpaces.size + 1
+                }
+            }
+
+            override fun createFragment(position: Int): Fragment {
+                if (DEBUG_VIEW_PAGER) Timber.i("Home pager: create fragment for position $position")
+                return when (tab) {
+                    is HomeTab.DialPad -> createDialPadFragment()
+                    is HomeTab.RoomList -> {
+                        val params = if (pagingEnabled) {
+                            RoomListParams(tab.displayMode, getSpaceIdForPageIndex(position)).toMvRxBundle()
+                        } else {
+                            RoomListParams(tab.displayMode, SPACE_ID_FOLLOW_APP).toMvRxBundle()
+                        }
+                        childFragmentManager.fragmentFactory.instantiate(activity!!.classLoader, RoomListFragment::class.java.name).apply {
+                            arguments = params
+                        }
+                    }
+                }
+            }
+        }
+
+        views.roomListContainerPager.adapter = adapter
+        if (pagingEnabled) {
+            views.roomListContainerPager.post {
+                try {
+                    if (DEBUG_VIEW_PAGER) Timber.i("Home pager: set initial page $selectedIndex")
+                    views.roomListContainerPager.setCurrentItem(selectedIndex ?: 0, false)
+                    initialPageSelected = true
+                } catch (e: Exception) {
+                    Timber.e("Home pager: Could not set initial page after creating adapter: $e")
+                }
+            }
+        }
+    }
+
+    private fun getPageIndexForSpaceId(spaceId: String?, spaces: List<String?>? = pagerSpaces): Int? {
+        if (spaceId == null) {
+            return 0
+        }
+        val indexInList = spaces?.indexOf(spaceId)
+        return when (indexInList) {
+            null, -1 -> null
+            else -> indexInList + 1
+        }
+    }
+
+    private fun getSpaceIdForPageIndex(position: Int, spaces: List<String?>? = pagerSpaces): String? {
+        val safeSpaces = spaces ?: return null
+        return if (position == 0) null else safeSpaces[position-1]
+    }
 
     private fun createDialPadFragment(): Fragment {
         val fragment = childFragmentManager.fragmentFactory.instantiate(vectorBaseActivity.classLoader, DialPadFragment::class.java.name)

vector/src/main/java/im/vector/app/features/home/HomeDetailViewModel.kt

@@ -38,19 +38,26 @@ import im.vector.app.features.invite.showInvites
 import im.vector.app.features.settings.VectorDataStore
 import im.vector.app.features.ui.UiStateRepository
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.filterIsInstance
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import org.matrix.android.sdk.api.query.ActiveSpaceFilter
+import org.matrix.android.sdk.api.query.QueryStringValue
 import org.matrix.android.sdk.api.query.RoomCategoryFilter
 import org.matrix.android.sdk.api.session.Session
+import org.matrix.android.sdk.api.session.events.model.toModel
 import org.matrix.android.sdk.api.session.initsync.SyncStatusService
 import org.matrix.android.sdk.api.session.room.RoomSortOrder
+import org.matrix.android.sdk.api.session.room.accountdata.RoomAccountDataTypes
 import org.matrix.android.sdk.api.session.room.model.Membership
 import org.matrix.android.sdk.api.session.room.roomSummaryQueryParams
+import org.matrix.android.sdk.api.session.space.model.SpaceOrderContent
+import org.matrix.android.sdk.api.session.space.model.TopLevelSpaceComparator
 import org.matrix.android.sdk.api.util.toMatrixItem
 import org.matrix.android.sdk.flow.flow
 import timber.log.Timber
@@ -92,6 +99,7 @@ class HomeDetailViewModel @AssistedInject constructor(
         observeRoomSummaries()
         updatePstnSupportFlag()
         observeDataStore()
+        observeRootSpaces()
         callManager.addProtocolsCheckerListener(this)
         session.flow().liveUser(session.myUserId).execute {
             copy(
@@ -276,4 +284,46 @@ class HomeDetailViewModel @AssistedInject constructor(
                 }
                 .launchIn(viewModelScope)
     }
+
+    // Taken from SpaceListViewModel.observeSpaceSummaries()
+    private fun observeRootSpaces() {
+        val spaceSummaryQueryParams = roomSummaryQueryParams {
+            memberships = listOf(Membership.JOIN, Membership.INVITE)
+            displayName = QueryStringValue.IsNotEmpty
+            excludeType = listOf(/**RoomType.MESSAGING,$*/
+                    null)
+        }
+
+        val flowSession = session.flow()
+
+        combine(
+                flowSession
+                        .liveUser(session.myUserId)
+                        .map {
+                            it.getOrNull()
+                        },
+                flowSession
+                        .liveSpaceSummaries(spaceSummaryQueryParams),
+                session
+                        .accountDataService()
+                        .getLiveRoomAccountDataEvents(setOf(RoomAccountDataTypes.EVENT_TYPE_SPACE_ORDER))
+                        .asFlow()
+        ) { _, communityGroups, _ ->
+            communityGroups
+        }
+                .execute { //async ->
+                    val rootSpaces = session.spaceService().getRootSpaceSummaries()
+                    val orders = rootSpaces.map {
+                        it.roomId to session.getRoom(it.roomId)
+                                ?.getAccountDataEvent(RoomAccountDataTypes.EVENT_TYPE_SPACE_ORDER)
+                                ?.content.toModel<SpaceOrderContent>()
+                                ?.safeOrder()
+                    }.toMap()
+                    copy(
+                            //asyncSpaces = async,
+                            rootSpacesOrdered = rootSpaces.sortedWith(TopLevelSpaceComparator(orders)),
+                            //spaceOrderInfo = orders
+                    )
+                }
+    }
 }

vector/src/main/java/im/vector/app/features/home/HomeDetailViewState.kt

@@ -32,6 +32,7 @@ data class HomeDetailViewState(
         val myMatrixItem: MatrixItem? = null,
         val asyncRooms: Async<List<RoomSummary>> = Uninitialized,
         val currentTab: HomeTab = HomeTab.RoomList(RoomListDisplayMode.ALL),
+        val rootSpacesOrdered: List<RoomSummary>? = null,
         val notificationCountCatchup: Int = 0,
         val notificationHighlightCatchup: Boolean = false,
         val notificationCountPeople: Int = 0,

vector/src/main/java/im/vector/app/features/home/room/list/RoomListFragment.kt

@@ -47,6 +47,7 @@ import im.vector.app.core.resources.UserPreferencesProvider
 import im.vector.app.databinding.FragmentRoomListBinding
 import im.vector.app.features.home.RoomListDisplayMode
 import im.vector.app.features.home.room.filtered.FilteredRoomFooterItem
+import im.vector.app.features.home.room.list.RoomListSectionBuilderSpace.Companion.SPACE_ID_FOLLOW_APP
 import im.vector.app.features.home.room.list.actions.RoomListActionsArgs
 import im.vector.app.features.home.room.list.actions.RoomListQuickActionsBottomSheet
 import im.vector.app.features.home.room.list.actions.RoomListQuickActionsSharedAction
@@ -66,7 +67,8 @@ import javax.inject.Inject
 
 @Parcelize
 data class RoomListParams(
-        val displayMode: RoomListDisplayMode
+        val displayMode: RoomListDisplayMode,
+        val explicitSpaceId: String? = SPACE_ID_FOLLOW_APP
 ) : Parcelable
 
 class RoomListFragment @Inject constructor(
@@ -559,6 +561,9 @@ class RoomListFragment @Inject constructor(
     }
 
     override fun onSwitchSpace(spaceId: String?) {
+        if (roomListParams.explicitSpaceId == SPACE_ID_FOLLOW_APP) {
+            return
+        }
         if (spaceId != expandStatusSpaceId) {
             persistExpandStatus()
             expandStatusSpaceId = spaceId

vector/src/main/java/im/vector/app/features/home/room/list/RoomListSectionBuilder.kt

@@ -19,5 +19,5 @@ package im.vector.app.features.home.room.list
 import im.vector.app.features.home.RoomListDisplayMode
 
 interface RoomListSectionBuilder {
-    fun buildSections(mode: RoomListDisplayMode): List<RoomsSection>
+    fun buildSections(mode: RoomListDisplayMode, explicitSpaceId: String?): List<RoomsSection>
 }

vector/src/main/java/im/vector/app/features/home/room/list/RoomListSectionBuilderGroup.kt

@@ -47,7 +47,7 @@ class RoomListSectionBuilderGroup(
         private val onUpdatable: (UpdatableLivePageResult) -> Unit
 ) : RoomListSectionBuilder {
 
-    override fun buildSections(mode: RoomListDisplayMode): List<RoomsSection> {
+    override fun buildSections(mode: RoomListDisplayMode, explicitSpaceId: String?): List<RoomsSection> {
         val activeGroupAwareQueries = mutableListOf<UpdatableLivePageResult>()
         val sections = mutableListOf<RoomsSection>()
         val actualGroupId = appStateHandler.safeActiveGroupId()

vector/src/main/java/im/vector/app/features/home/room/list/RoomListSectionBuilderSpace.kt

@@ -49,6 +49,7 @@ import org.matrix.android.sdk.api.session.room.UpdatableLivePageResult
 import org.matrix.android.sdk.api.session.room.model.Membership
 import org.matrix.android.sdk.api.session.room.summary.RoomAggregateNotificationCount
 import timber.log.Timber
+import kotlin.math.exp
 
 class RoomListSectionBuilderSpace(
         private val session: Session,
@@ -61,6 +62,10 @@ class RoomListSectionBuilderSpace(
         private val onlyOrphansInHome: Boolean = false
 ) : RoomListSectionBuilder {
 
+    companion object {
+        const val SPACE_ID_FOLLOW_APP = "de.spiritcroc.riotx.SPACE_ID_FOLLOW_APP"
+    }
+
     private val pagedListConfig = PagedList.Config.Builder()
             .setPageSize(10)
             .setInitialLoadSizeHint(20)
@@ -68,20 +73,20 @@ class RoomListSectionBuilderSpace(
             .setPrefetchDistance(10)
             .build()
 
-    override fun buildSections(mode: RoomListDisplayMode): List<RoomsSection> {
+    override fun buildSections(mode: RoomListDisplayMode, explicitSpaceId: String?): List<RoomsSection> {
         val sections = mutableListOf<RoomsSection>()
         val activeSpaceAwareQueries = mutableListOf<RoomListViewModel.ActiveSpaceQueryUpdater>()
         when (mode) {
             RoomListDisplayMode.PEOPLE        -> {
                 // 4 sections Invites / Fav / Dms / Low Priority
-                buildDmSections(sections, activeSpaceAwareQueries)
+                buildDmSections(sections, activeSpaceAwareQueries, explicitSpaceId)
             }
             RoomListDisplayMode.ROOMS         -> {
                 // 6 sections invites / Fav / Rooms / Low Priority / Server notice / Suggested rooms
-                buildRoomsSections(sections, activeSpaceAwareQueries)
+                buildRoomsSections(sections, activeSpaceAwareQueries, explicitSpaceId)
             }
             RoomListDisplayMode.ALL           -> {
-                buildUnifiedSections(sections, activeSpaceAwareQueries)
+                buildUnifiedSections(sections, activeSpaceAwareQueries, explicitSpaceId)
             }
             RoomListDisplayMode.FILTERED      -> {
                 // Used when searching for rooms
@@ -106,6 +111,7 @@ class RoomListSectionBuilderSpace(
                             activeSpaceUpdaters = activeSpaceAwareQueries,
                             nameRes = R.string.invitations_header,
                             notifyOfLocalEcho = true,
+                            explicitSpaceId = explicitSpaceId,
                             spaceFilterStrategy = if (onlyOrphansInHome) {
                                 RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                             } else {
@@ -123,6 +129,7 @@ class RoomListSectionBuilderSpace(
                         activeSpaceUpdaters = activeSpaceAwareQueries,
                         nameRes = R.string.bottom_action_rooms,
                         notifyOfLocalEcho = false,
+                        explicitSpaceId = explicitSpaceId,
                         spaceFilterStrategy = if (onlyOrphansInHome) {
                             RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                         } else {
@@ -135,24 +142,31 @@ class RoomListSectionBuilderSpace(
             }
         }
 
-        appStateHandler.selectedRoomGroupingObservable
+        if (explicitSpaceId == SPACE_ID_FOLLOW_APP) {
-                .distinctUntilChanged()
+            appStateHandler.selectedRoomGroupingObservable
-                .onEach { groupingMethod ->
+                    .distinctUntilChanged()
-                    val selectedSpace = groupingMethod.orNull()?.space()
+                    .onEach { groupingMethod ->
-                    activeSpaceAwareQueries.onEach { updater ->
+                        val selectedSpace = groupingMethod.orNull()?.space()
-                        updater.updateForSpaceId(selectedSpace?.roomId)
+                        activeSpaceAwareQueries.onEach { updater ->
-                    }
+                            updater.updateForSpaceId(selectedSpace?.roomId)
-                }.launchIn(viewModelScope)
+                        }
+                    }.launchIn(viewModelScope)
+        } else {
+            activeSpaceAwareQueries.onEach { updater ->
+                updater.updateForSpaceId(explicitSpaceId)
+            }
+        }
 
         return sections
     }
 
-    private fun buildUnifiedSections(sections: MutableList<RoomsSection>, activeSpaceAwareQueries: MutableList<RoomListViewModel.ActiveSpaceQueryUpdater>) {
+    private fun buildUnifiedSections(sections: MutableList<RoomsSection>, activeSpaceAwareQueries: MutableList<RoomListViewModel.ActiveSpaceQueryUpdater>, explicitSpaceId: String?) {
         addSection(
                 sections = sections,
                 activeSpaceUpdaters = activeSpaceAwareQueries,
                 nameRes = R.string.invitations_header,
                 notifyOfLocalEcho = true,
+                explicitSpaceId = explicitSpaceId,
                 spaceFilterStrategy = RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
                 countRoomAsNotif = true
         ) {
@@ -164,7 +178,8 @@ class RoomListSectionBuilderSpace(
                 activeSpaceAwareQueries,
                 R.string.bottom_action_favourites,
                 false,
-                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL
+                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
+                explicitSpaceId = explicitSpaceId,
         ) {
             it.memberships = listOf(Membership.JOIN)
             it.roomTagQueryFilter = RoomTagQueryFilter(true, null, null)
@@ -175,6 +190,7 @@ class RoomListSectionBuilderSpace(
                 activeSpaceUpdaters = activeSpaceAwareQueries,
                 nameRes = R.string.normal_priority_header,
                 notifyOfLocalEcho = false,
+                explicitSpaceId = explicitSpaceId,
                 spaceFilterStrategy = if (onlyOrphansInHome) {
                     RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                 } else {
@@ -190,6 +206,7 @@ class RoomListSectionBuilderSpace(
                 activeSpaceUpdaters = activeSpaceAwareQueries,
                 nameRes = R.string.low_priority_header,
                 notifyOfLocalEcho = false,
+                explicitSpaceId = explicitSpaceId,
                 spaceFilterStrategy = if (onlyOrphansInHome) {
                     RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                 } else {
@@ -205,6 +222,7 @@ class RoomListSectionBuilderSpace(
                 activeSpaceUpdaters = activeSpaceAwareQueries,
                 nameRes = R.string.system_alerts_header,
                 notifyOfLocalEcho = false,
+                explicitSpaceId = explicitSpaceId,
                 spaceFilterStrategy = if (onlyOrphansInHome) {
                     RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                 } else {
@@ -215,17 +233,19 @@ class RoomListSectionBuilderSpace(
             it.roomTagQueryFilter = RoomTagQueryFilter(null, null, true)
         }
 
-        addSuggestedRoomsSection(sections)
+        addSuggestedRoomsSection(sections, explicitSpaceId)
     }
 
     private fun buildRoomsSections(sections: MutableList<RoomsSection>,
-                                   activeSpaceAwareQueries: MutableList<RoomListViewModel.ActiveSpaceQueryUpdater>) {
+                                   activeSpaceAwareQueries: MutableList<RoomListViewModel.ActiveSpaceQueryUpdater>,
+                                   explicitSpaceId: String?) {
         if (autoAcceptInvites.showInvites()) {
             addSection(
                     sections = sections,
                     activeSpaceUpdaters = activeSpaceAwareQueries,
                     nameRes = R.string.invitations_header,
                     notifyOfLocalEcho = true,
+                    explicitSpaceId = explicitSpaceId,
                     spaceFilterStrategy = RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
                     countRoomAsNotif = true
             ) {
@@ -239,7 +259,8 @@ class RoomListSectionBuilderSpace(
                 activeSpaceAwareQueries,
                 R.string.bottom_action_favourites,
                 false,
-                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL
+                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
+                explicitSpaceId = explicitSpaceId,
         ) {
             it.memberships = listOf(Membership.JOIN)
             it.roomCategoryFilter = RoomCategoryFilter.ONLY_ROOMS
@@ -251,6 +272,7 @@ class RoomListSectionBuilderSpace(
                 activeSpaceUpdaters = activeSpaceAwareQueries,
                 nameRes = R.string.bottom_action_rooms,
                 notifyOfLocalEcho = false,
+                explicitSpaceId = explicitSpaceId,
                 spaceFilterStrategy = if (onlyOrphansInHome) {
                     RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                 } else {
@@ -267,6 +289,7 @@ class RoomListSectionBuilderSpace(
                 activeSpaceUpdaters = activeSpaceAwareQueries,
                 nameRes = R.string.low_priority_header,
                 notifyOfLocalEcho = false,
+                explicitSpaceId = explicitSpaceId,
                 spaceFilterStrategy = if (onlyOrphansInHome) {
                     RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                 } else {
@@ -283,6 +306,7 @@ class RoomListSectionBuilderSpace(
                 activeSpaceUpdaters = activeSpaceAwareQueries,
                 nameRes = R.string.system_alerts_header,
                 notifyOfLocalEcho = false,
+                explicitSpaceId = explicitSpaceId,
                 spaceFilterStrategy = if (onlyOrphansInHome) {
                     RoomListViewModel.SpaceFilterStrategy.ORPHANS_IF_SPACE_NULL
                 } else {
@@ -294,12 +318,13 @@ class RoomListSectionBuilderSpace(
             it.roomTagQueryFilter = RoomTagQueryFilter(null, null, true)
         }
 
-        addSuggestedRoomsSection(sections)
+        addSuggestedRoomsSection(sections, explicitSpaceId)
     }
 
-    private fun addSuggestedRoomsSection(sections: MutableList<RoomsSection>) {
+    private fun addSuggestedRoomsSection(sections: MutableList<RoomsSection>,
+                                         explicitSpaceId: String?) {
         // add suggested rooms
-        val suggestedRoomsFlow = // MutableLiveData<List<SpaceChildInfo>>()
+        val suggestedRoomsFlow = if (explicitSpaceId == SPACE_ID_FOLLOW_APP) { // MutableLiveData<List<SpaceChildInfo>>()
                 appStateHandler.selectedRoomGroupingObservable
                         .distinctUntilChanged()
                         .flatMapLatest { groupingMethod ->
@@ -321,6 +346,24 @@ class RoomListSectionBuilderSpace(
                                 }.asFlow()
                             }
                         }
+        } else {
+            if (explicitSpaceId == null) {
+                flowOf(emptyList())
+            } else {
+                liveData(context = viewModelScope.coroutineContext + Dispatchers.IO) {
+                    val spaceSum = tryOrNull {
+                        session.spaceService()
+                                .querySpaceChildren(explicitSpaceId, suggestedOnly = true, null, null)
+                    }
+                    val value = spaceSum?.children.orEmpty().distinctBy { it.childRoomId }
+                    // i need to check if it's already joined.
+                    val filtered = value.filter {
+                        session.getRoomSummary(it.childRoomId)?.membership?.isActive() != true
+                    }
+                    emit(filtered)
+                }.asFlow()
+            }
+        }
 
         val liveSuggestedRooms = MutableLiveData<SuggestedRoomInfo>()
         combine(
@@ -345,13 +388,15 @@ class RoomListSectionBuilderSpace(
     }
 
     private fun buildDmSections(sections: MutableList<RoomsSection>,
-                                activeSpaceAwareQueries: MutableList<RoomListViewModel.ActiveSpaceQueryUpdater>) {
+                                activeSpaceAwareQueries: MutableList<RoomListViewModel.ActiveSpaceQueryUpdater>,
+                                explicitSpaceId: String?) {
         if (autoAcceptInvites.showInvites()) {
             addSection(
                     sections = sections,
                     activeSpaceUpdaters = activeSpaceAwareQueries,
                     nameRes = R.string.invitations_header,
                     notifyOfLocalEcho = true,
+                    explicitSpaceId = explicitSpaceId,
                     spaceFilterStrategy = RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
                     countRoomAsNotif = true
             ) {
@@ -365,7 +410,8 @@ class RoomListSectionBuilderSpace(
                 activeSpaceAwareQueries,
                 R.string.bottom_action_favourites,
                 false,
-                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL
+                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
+                explicitSpaceId = explicitSpaceId
         ) {
             it.memberships = listOf(Membership.JOIN)
             it.roomCategoryFilter = RoomCategoryFilter.ONLY_DM
@@ -377,7 +423,8 @@ class RoomListSectionBuilderSpace(
                 activeSpaceAwareQueries,
                 R.string.bottom_action_people_x,
                 false,
-                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL
+                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
+                explicitSpaceId = explicitSpaceId
         ) {
             it.memberships = listOf(Membership.JOIN)
             it.roomCategoryFilter = RoomCategoryFilter.ONLY_DM
@@ -389,7 +436,8 @@ class RoomListSectionBuilderSpace(
                 activeSpaceAwareQueries,
                 R.string.low_priority_header,
                 false,
-                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL
+                RoomListViewModel.SpaceFilterStrategy.ALL_IF_SPACE_NULL,
+                explicitSpaceId = explicitSpaceId
         ) {
             it.memberships = listOf(Membership.JOIN)
             it.roomCategoryFilter = RoomCategoryFilter.ONLY_DM
@@ -398,19 +446,28 @@ class RoomListSectionBuilderSpace(
 
     }
 
+    private fun AppStateHandler.explicitOrSafeActiveSpaceId(explicitSpaceId: String?): String? {
+        return if (explicitSpaceId == SPACE_ID_FOLLOW_APP) {
+            safeActiveSpaceId()
+        } else {
+            explicitSpaceId
+        }
+    }
+
     private fun addSection(sections: MutableList<RoomsSection>,
                            activeSpaceUpdaters: MutableList<RoomListViewModel.ActiveSpaceQueryUpdater>,
                            @StringRes nameRes: Int,
                            notifyOfLocalEcho: Boolean = false,
                            spaceFilterStrategy: RoomListViewModel.SpaceFilterStrategy = RoomListViewModel.SpaceFilterStrategy.NONE,
                            countRoomAsNotif: Boolean = false,
+                           explicitSpaceId: String?,
                            query: (RoomSummaryQueryParams.Builder) -> Unit) {
         withQueryParams(
                 { query.invoke(it) },
                 { roomQueryParams ->
                     val name = stringProvider.getString(nameRes)
                     session.getFilteredPagedRoomSummariesLive(
-                            roomQueryParams.process(spaceFilterStrategy, appStateHandler.safeActiveSpaceId()),
+                            roomQueryParams.process(spaceFilterStrategy, appStateHandler.explicitOrSafeActiveSpaceId(explicitSpaceId)),
                             pagedListConfig
                     ).also {
                         when (spaceFilterStrategy) {
@@ -461,7 +518,7 @@ class RoomListSectionBuilderSpace(
                                                                 RoomAggregateNotificationCount(it.size, it.size, 0)
                                                             } else {
                                                                 session.getNotificationCountForRooms(
-                                                                        roomQueryParams.process(spaceFilterStrategy, appStateHandler.safeActiveSpaceId())
+                                                                        roomQueryParams.process(spaceFilterStrategy, appStateHandler.explicitOrSafeActiveSpaceId(explicitSpaceId))
                                                                 )
                                                             }
                                                     )

vector/src/main/java/im/vector/app/features/home/room/list/RoomListViewModel.kt

@@ -146,7 +146,7 @@ class RoomListViewModel @AssistedInject constructor(
     }
 
     val sections: List<RoomsSection> by lazy {
-        roomListSectionBuilder.buildSections(initialState.displayMode)
+        roomListSectionBuilder.buildSections(initialState.displayMode, initialState.explicitSpaceId)
     }
 
     override fun handle(action: RoomListAction) {

vector/src/main/java/im/vector/app/features/home/room/list/RoomListViewState.kt

@@ -30,8 +30,10 @@ data class RoomListViewState(
         val roomMembershipChanges: Map<String, ChangeMembershipState> = emptyMap(),
         val asyncSuggestedRooms: Async<List<SpaceChildInfo>> = Uninitialized,
         val currentUserName: String? = null,
-        val currentRoomGrouping: Async<RoomGroupingMethod> = Uninitialized
+        val currentRoomGrouping: Async<RoomGroupingMethod> = Uninitialized,
+        // In comparison to currentRoomGrouping, the explicit space id fixes a filter method that should not change afterwards
+        val explicitSpaceId: String? = null
 ) : MavericksState {
 
-    constructor(args: RoomListParams) : this(displayMode = args.displayMode)
+    constructor(args: RoomListParams) : this(displayMode = args.displayMode, explicitSpaceId = args.explicitSpaceId)
 }

vector/src/main/java/im/vector/app/features/settings/VectorPreferences.kt

@@ -214,6 +214,7 @@ class VectorPreferences @Inject constructor(private val context: Context): Stati
         const val SETTINGS_FORCE_ALLOW_BACKGROUND_SYNC = "SETTINGS_FORCE_ALLOW_BACKGROUND_SYNC"
         private const val SETTINGS_JUMP_TO_BOTTOM_ON_SEND = "SETTINGS_JUMP_TO_BOTTOM_ON_SEND"
         private const val SETTINGS_SPACE_MEMBERS_IN_SPACE_ROOMS = "SETTINGS_SPACE_MEMBERS_IN_SPACE_ROOMS"
+        private const val SETTINGS_ENABLE_SPACE_PAGER = "SETTINGS_ENABLE_SPACE_PAGER"
 
         private const val DID_ASK_TO_ENABLE_SESSION_PUSH = "DID_ASK_TO_ENABLE_SESSION_PUSH"
         private const val DID_PROMOTE_NEW_RESTRICTED_JOIN_RULE = "DID_PROMOTE_NEW_RESTRICTED_JOIN_RULE"
@@ -1043,18 +1044,26 @@ class VectorPreferences @Inject constructor(private val context: Context): Stati
         return Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP && defaultPrefs.getBoolean(SETTINGS_VOICE_MESSAGE, true)
     }
 
+    // SC addition
     fun jumpToBottomOnSend(): Boolean {
         return defaultPrefs.getBoolean(SETTINGS_JUMP_TO_BOTTOM_ON_SEND, true)
     }
 
+    // SC addition
     fun forceUseCustomUpGateway(): Boolean {
         return defaultPrefs.getBoolean(SETTINGS_UNIFIED_PUSH_FORCE_CUSTOM_GATEWAY, false)
     }
 
+    // SC addition
     fun forceAllowBackgroundSync(): Boolean {
         return defaultPrefs.getBoolean(SETTINGS_FORCE_ALLOW_BACKGROUND_SYNC, false)
     }
 
+    // SC addition
+    fun enableSpacePager(): Boolean {
+        return defaultPrefs.getBoolean(SETTINGS_ENABLE_SPACE_PAGER, false)
+    }
+
     /**
      * I likely do more fresh installs of the app than anyone else, so a shortcut to change some of the default settings to
      * my preferred values can safe me some time
@@ -1077,6 +1086,7 @@ class VectorPreferences @Inject constructor(private val context: Context): Stati
                 .putBoolean(SETTINGS_USE_RAGE_SHAKE_KEY, true)
                 .putBoolean(SETTINGS_UNIFIED_PUSH_FORCE_CUSTOM_GATEWAY, true)
                 .putBoolean(SETTINGS_AGGREGATE_UNREAD_COUNTS, false)
+                .putBoolean(SETTINGS_ENABLE_SPACE_PAGER, true)
                 .apply()
     }
 

vector/src/main/res/layout/fragment_home_detail.xml

@@ -137,12 +137,21 @@
         app:layout_constraintTop_toBottomOf="@id/syncStateView"
         tools:visibility="visible" />
 
+<!--
     <androidx.fragment.app.FragmentContainerView
         android:id="@+id/roomListContainer"
         android:layout_width="match_parent"
         android:layout_height="0dp"
         app:layout_constraintBottom_toTopOf="@+id/bottomNavigationView"
         app:layout_constraintTop_toBottomOf="@+id/homeKeysBackupBanner" />
+-->
+
+    <androidx.viewpager2.widget.ViewPager2
+        android:id="@+id/roomListContainerPager"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        app:layout_constraintBottom_toTopOf="@+id/bottomNavigationView"
+        app:layout_constraintTop_toBottomOf="@+id/homeKeysBackupBanner" />
 
     <com.google.android.material.bottomnavigation.BottomNavigationView
         android:id="@+id/bottomNavigationView"

vector/src/main/res/values/strings_sc.xml

@@ -151,4 +151,7 @@
     <string name="settings_include_space_members_as_rooms">Show people in spaces</string>
     <string name="settings_include_space_members_as_rooms_summary">If disabled, you can still add Direct Messages to Personal Spaces. If enabled, you\'ll automatically see everyone who is a member of the Space.</string>
 
+    <string name="settings_enable_space_pager">Swipe chat list to switch space</string>
+    <string name="settings_enable_space_pager_summary">Allow to switch between root spaces by swiping horizontally in the chat list</string>
+
 </resources>

vector/src/main/res/xml/vector_settings_labs.xml

@@ -74,6 +74,12 @@
         android:key="SETTINGS_LABS_UNREAD_NOTIFICATIONS_AS_TAB"
         android:title="@string/labs_show_unread_notifications_as_tab" />
 
+    <im.vector.app.core.preference.VectorSwitchPreference
+        android:defaultValue="false"
+        android:key="SETTINGS_ENABLE_SPACE_PAGER"
+        android:title="@string/settings_enable_space_pager"
+        android:summary="@string/settings_enable_space_pager_summary" />
+
 
     <im.vector.app.core.preference.VectorSwitchPreference
         android:defaultValue="false"