Add a HomeActivityViewModel, VisibleRoomHandler and Event classes to handle some navigation. Not perfect but ok for now

app/src/main/java/im/vector/riotredesign/core/extensions/LiveData.kt

@@ -0,0 +1,19 @@
+package im.vector.riotredesign.core.extensions
+
+import android.arch.lifecycle.LifecycleOwner
+import android.arch.lifecycle.LiveData
+import android.arch.lifecycle.Observer
+import im.vector.riotredesign.core.utils.Event
+import im.vector.riotredesign.core.utils.EventObserver
+
+inline fun <T> LiveData<T>.observeK(owner: LifecycleOwner, crossinline observer: (T?) -> Unit) {
+    this.observe(owner, Observer { observer(it) })
+}
+
+inline fun <T> LiveData<T>.observeNotNull(owner: LifecycleOwner, crossinline observer: (T) -> Unit) {
+    this.observe(owner, Observer { it?.run(observer) })
+}
+
+inline fun <T> LiveData<Event<T>>.observeEvent(owner: LifecycleOwner, crossinline observer: (T) -> Unit) {
+    this.observe(owner, EventObserver { it.run(observer) })
+}

app/src/main/java/im/vector/riotredesign/core/utils/Event.kt

@@ -0,0 +1,40 @@
+package im.vector.riotredesign.core.utils
+
+import android.arch.lifecycle.Observer
+
+open class Event<out T>(private val content: T) {
+
+    var hasBeenHandled = false
+        private set // Allow external read but not write
+
+    /**
+     * Returns the content and prevents its use again.
+     */
+    fun getContentIfNotHandled(): T? {
+        return if (hasBeenHandled) {
+            null
+        } else {
+            hasBeenHandled = true
+            content
+        }
+    }
+
+    /**
+     * Returns the content, even if it's already been handled.
+     */
+    fun peekContent(): T = content
+}
+
+/**
+ * An [Observer] for [Event]s, simplifying the pattern of checking if the [Event]'s content has
+ * already been handled.
+ *
+ * [onEventUnhandledContent] is *only* called if the [Event]'s contents has not been handled.
+ */
+class EventObserver<T>(private val onEventUnhandledContent: (T) -> Unit) : Observer<Event<T>> {
+    override fun onChanged(event: Event<T>?) {
+        event?.getContentIfNotHandled()?.let { value ->
+            onEventUnhandledContent(value)
+        }
+    }
+}

app/src/main/java/im/vector/riotredesign/features/home/HomeActivity.kt

@@ -9,7 +9,9 @@ import android.support.v7.app.ActionBarDrawerToggle
 import android.support.v7.widget.Toolbar
 import android.view.Gravity
 import android.view.MenuItem
+import com.airbnb.mvrx.viewModel
 import im.vector.riotredesign.R
+import im.vector.riotredesign.core.extensions.observeEvent
 import im.vector.riotredesign.core.extensions.replaceFragment
 import im.vector.riotredesign.core.platform.OnBackPressed
 import im.vector.riotredesign.core.platform.RiotActivity
@@ -22,6 +24,8 @@ import org.koin.standalone.StandAloneContext.loadKoinModules
 
 class HomeActivity : RiotActivity(), ToolbarConfigurable {
 
+
+    private val homeActivityViewModel: HomeActivityViewModel by viewModel()
     private val homeNavigator by inject<HomeNavigator>()
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -35,6 +39,9 @@ class HomeActivity : RiotActivity(), ToolbarConfigurable {
             replaceFragment(loadingDetail, R.id.homeDetailFragmentContainer)
             replaceFragment(homeDrawerFragment, R.id.homeDrawerFragmentContainer)
         }
+        homeActivityViewModel.openRoomLiveData.observeEvent(this) {
+            homeNavigator.openRoomDetail(it, null)
+        }
     }
 
     override fun onDestroy() {

app/src/main/java/im/vector/riotredesign/features/home/HomeActivityViewModel.kt

@@ -0,0 +1,61 @@
+package im.vector.riotredesign.features.home
+
+import android.arch.lifecycle.LiveData
+import android.arch.lifecycle.MutableLiveData
+import android.support.v4.app.FragmentActivity
+import com.airbnb.mvrx.MvRxState
+import com.airbnb.mvrx.MvRxViewModelFactory
+import im.vector.matrix.android.api.Matrix
+import im.vector.matrix.android.api.session.Session
+import im.vector.matrix.rx.rx
+import im.vector.riotredesign.core.platform.RiotViewModel
+import im.vector.riotredesign.core.utils.Event
+import im.vector.riotredesign.features.home.room.list.RoomSelectionRepository
+import io.reactivex.rxkotlin.subscribeBy
+import org.koin.android.ext.android.get
+
+class EmptyState : MvRxState
+
+class HomeActivityViewModel(state: EmptyState,
+                            private val session: Session,
+                            roomSelectionRepository: RoomSelectionRepository
+) : RiotViewModel<EmptyState>(state) {
+
+    companion object : MvRxViewModelFactory<EmptyState> {
+
+        @JvmStatic
+        override fun create(activity: FragmentActivity, state: EmptyState): HomeActivityViewModel {
+            val session = Matrix.getInstance().currentSession
+            val roomSelectionRepository = activity.get<RoomSelectionRepository>()
+            return HomeActivityViewModel(state, session, roomSelectionRepository)
+        }
+    }
+
+    private val _openRoomLiveData = MutableLiveData<Event<String>>()
+    val openRoomLiveData: LiveData<Event<String>>
+        get() = _openRoomLiveData
+
+    init {
+        val lastSelectedRoom = roomSelectionRepository.lastSelectedRoom()
+        if (lastSelectedRoom == null) {
+            getTheFirstRoomWhenAvailable()
+        } else {
+            _openRoomLiveData.postValue(Event(lastSelectedRoom))
+        }
+    }
+
+    private fun getTheFirstRoomWhenAvailable() {
+        session.rx().liveRoomSummaries()
+                .filter { it.isNotEmpty() }
+                .first(emptyList())
+                .subscribeBy {
+                    val firstRoom = it.firstOrNull()
+                    if (firstRoom != null) {
+                        _openRoomLiveData.postValue(Event(firstRoom.roomId))
+                    }
+                }
+                .disposeOnClear()
+    }
+
+
+}

app/src/main/java/im/vector/riotredesign/features/home/HomeModule.kt

@@ -1,6 +1,7 @@
 package im.vector.riotredesign.features.home
 
 import im.vector.riotredesign.features.home.group.SelectedGroupHolder
+import im.vector.riotredesign.features.home.room.VisibleRoomHolder
 import im.vector.riotredesign.features.home.room.detail.timeline.MessageItemFactory
 import im.vector.riotredesign.features.home.room.detail.timeline.TextItemFactory
 import im.vector.riotredesign.features.home.room.detail.timeline.TimelineDateFormatter
@@ -35,9 +36,14 @@ class HomeModule(private val homeActivity: HomeActivity) {
             SelectedGroupHolder()
         }
 
+        single {
+            VisibleRoomHolder()
+        }
+
         single {
             HomePermalinkHandler(get())
         }
 
+
     }
 }

app/src/main/java/im/vector/riotredesign/features/home/room/VisibleRoomHolder.kt

@@ -0,0 +1,19 @@
+package im.vector.riotredesign.features.home.room
+
+import io.reactivex.Observable
+import io.reactivex.subjects.BehaviorSubject
+
+class VisibleRoomHolder {
+
+    private val visibleRoomStream = BehaviorSubject.create<String>()
+
+    fun setVisibleRoom(roomId: String) {
+        visibleRoomStream.onNext(roomId)
+    }
+
+    fun visibleRoom(): Observable<String> {
+        return visibleRoomStream.hide()
+    }
+
+
+}

app/src/main/java/im/vector/riotredesign/features/home/room/detail/RoomDetailActions.kt

@@ -3,5 +3,6 @@ package im.vector.riotredesign.features.home.room.detail
 sealed class RoomDetailActions {
 
     data class SendMessage(val text: String) : RoomDetailActions()
+    object IsDisplayed : RoomDetailActions()
 
 }

app/src/main/java/im/vector/riotredesign/features/home/room/detail/RoomDetailFragment.kt

@@ -62,6 +62,11 @@ class RoomDetailFragment : RiotFragment(), TimelineEventController.Callback {
         roomDetailViewModel.subscribe { renderState(it) }
     }
 
+    override fun onResume() {
+        super.onResume()
+        roomDetailViewModel.accept(RoomDetailActions.IsDisplayed)
+    }
+
     private fun setupToolbar() {
         val parentActivity = riotActivity
         if (parentActivity is ToolbarConfigurable) {

app/src/main/java/im/vector/riotredesign/features/home/room/detail/RoomDetailViewModel.kt

@@ -8,9 +8,12 @@ import im.vector.matrix.android.api.session.Session
 import im.vector.matrix.android.api.session.events.model.Event
 import im.vector.matrix.rx.rx
 import im.vector.riotredesign.core.platform.RiotViewModel
+import im.vector.riotredesign.features.home.room.VisibleRoomHolder
+import org.koin.android.ext.android.get
 
 class RoomDetailViewModel(initialState: RoomDetailViewState,
-                          session: Session
+                          private val session: Session,
+                          private val visibleRoomHolder: VisibleRoomHolder
 ) : RiotViewModel<RoomDetailViewState>(initialState) {
 
     private val room = session.getRoom(initialState.roomId)!!
@@ -22,7 +25,8 @@ class RoomDetailViewModel(initialState: RoomDetailViewState,
         @JvmStatic
         override fun create(activity: FragmentActivity, state: RoomDetailViewState): RoomDetailViewModel {
             val currentSession = Matrix.getInstance().currentSession
-            return RoomDetailViewModel(state, currentSession)
+            val visibleRoomHolder = activity.get<VisibleRoomHolder>()
+            return RoomDetailViewModel(state, currentSession, visibleRoomHolder)
         }
     }
 
@@ -35,6 +39,7 @@ class RoomDetailViewModel(initialState: RoomDetailViewState,
     fun accept(action: RoomDetailActions) {
         when (action) {
             is RoomDetailActions.SendMessage -> handleSendMessage(action)
+            is RoomDetailActions.IsDisplayed -> visibleRoomHolder.setVisibleRoom(roomId)
         }
     }
 
@@ -54,7 +59,7 @@ class RoomDetailViewModel(initialState: RoomDetailViewState,
     private fun observeTimeline() {
         room.rx().timeline(eventId)
                 .execute { timelineData ->
-                    copy(asyncTimelineData= timelineData)
+                    copy(asyncTimelineData = timelineData)
                 }
     }
 

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

@@ -44,15 +44,12 @@ class RoomListFragment : RiotFragment(), RoomSummaryController.Callback {
     private fun renderState(state: RoomListViewState) {
         when (state.asyncRooms) {
             is Incomplete -> renderLoading()
-            is Success -> renderSuccess(state)
+            is Success    -> renderSuccess(state)
-            is Fail -> renderFailure(state.asyncRooms.error)
+            is Fail       -> renderFailure(state.asyncRooms.error)
         }
     }
 
     private fun renderSuccess(state: RoomListViewState) {
-        if (state.selectedRoomId != null) {
-            homeNavigator.openRoomDetail(state.selectedRoomId, null)
-        }
         if (state.asyncRooms().isNullOrEmpty()) {
             stateView.state = StateView.State.Empty(getString(R.string.room_list_empty))
         } else {
@@ -68,7 +65,7 @@ class RoomListFragment : RiotFragment(), RoomSummaryController.Callback {
     private fun renderFailure(error: Throwable) {
         val message = when (error) {
             is Failure.NetworkConnection -> getString(R.string.error_no_network)
-            else -> getString(R.string.error_common)
+            else                         -> getString(R.string.error_common)
         }
         stateView.state = StateView.State.Error(message)
     }

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

@@ -10,13 +10,16 @@ import im.vector.matrix.android.api.session.room.model.RoomSummary
 import im.vector.matrix.rx.rx
 import im.vector.riotredesign.core.platform.RiotViewModel
 import im.vector.riotredesign.features.home.group.SelectedGroupHolder
+import im.vector.riotredesign.features.home.room.VisibleRoomHolder
 import io.reactivex.Observable
 import io.reactivex.functions.BiFunction
+import io.reactivex.rxkotlin.subscribeBy
 import org.koin.android.ext.android.get
 
 class RoomListViewModel(initialState: RoomListViewState,
                         private val session: Session,
                         private val selectedGroupHolder: SelectedGroupHolder,
+                        private val visibleRoomHolder: VisibleRoomHolder,
                         private val roomSelectionRepository: RoomSelectionRepository)
     : RiotViewModel<RoomListViewState>(initialState) {
 
@@ -27,12 +30,14 @@ class RoomListViewModel(initialState: RoomListViewState,
             val currentSession = Matrix.getInstance().currentSession
             val roomSelectionRepository = activity.get<RoomSelectionRepository>()
             val selectedGroupHolder = activity.get<SelectedGroupHolder>()
-            return RoomListViewModel(state, currentSession, selectedGroupHolder, roomSelectionRepository)
+            val visibleRoomHolder = activity.get<VisibleRoomHolder>()
+            return RoomListViewModel(state, currentSession, selectedGroupHolder, visibleRoomHolder, roomSelectionRepository)
         }
     }
 
     init {
         observeRoomSummaries()
+        observeVisibleRoom()
     }
 
     fun accept(action: RoomListActions) {
@@ -46,10 +51,17 @@ class RoomListViewModel(initialState: RoomListViewState,
     private fun handleSelectRoom(action: RoomListActions.SelectRoom) = withState { state ->
         if (state.selectedRoomId != action.roomSummary.roomId) {
             roomSelectionRepository.saveLastSelectedRoom(action.roomSummary.roomId)
-            setState { copy(selectedRoomId = action.roomSummary.roomId) }
         }
     }
 
+    private fun observeVisibleRoom() {
+        visibleRoomHolder.visibleRoom()
+                .subscribeBy {
+                    setState { copy(selectedRoomId = it) }
+                }
+                .disposeOnClear()
+    }
+
     private fun observeRoomSummaries() {
         Observable.combineLatest<List<RoomSummary>, Option<GroupSummary>, RoomSummaries>(
                 session.rx().liveRoomSummaries(),
@@ -78,15 +90,8 @@ class RoomListViewModel(initialState: RoomListViewState,
                 }
         )
                 .execute { async ->
-                    val summaries = async()
-                    val selectedRoomId = selectedRoomId
-                            ?: roomSelectionRepository.lastSelectedRoom()
-                            ?: summaries?.directRooms?.firstOrNull()?.roomId
-                            ?: summaries?.groupRooms?.firstOrNull()?.roomId
-
                     copy(
-                            asyncRooms = async,
+                            asyncRooms = async
-                            selectedRoomId = selectedRoomId
                     )
                 }
     }