Add ui { } DSL to run stuff on the UI thread and check for valid

fragment and view

app/src/main/java/chat/rocket/android/authentication/registerusername/ui/RegisterUsernameFragment.kt

@@ -59,26 +59,36 @@ class RegisterUsernameFragment : Fragment(), RegisterUsernameView {
     }
 
     override fun alertBlankUsername() {
-        vibrateSmartPhone()
-        text_username.shake()
+        ui {
+            vibrateSmartPhone()
+            text_username.shake()
+        }
     }
 
     override fun showLoading() {
-        disableUserInput()
-        view_loading.setVisible(true)
+        ui {
+            disableUserInput()
+            view_loading.setVisible(true)
+        }
     }
 
     override fun hideLoading() {
-        view_loading.setVisible(false)
-        enableUserInput()
+        ui {
+            view_loading.setVisible(false)
+            enableUserInput()
+        }
     }
 
     override fun showMessage(resId: Int) {
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showGenericErrorMessage() {
@@ -86,10 +96,10 @@ class RegisterUsernameFragment : Fragment(), RegisterUsernameView {
     }
 
     private fun tintEditTextDrawableStart() {
-        activity?.apply {
-            val atDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_at_black_24dp, this)
+        ui {
+            val atDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_at_black_24dp, it)
             DrawableHelper.wrapDrawable(atDrawable)
-            DrawableHelper.tintDrawable(atDrawable, this, R.color.colorDrawableTintGrey)
+            DrawableHelper.tintDrawable(atDrawable, it, R.color.colorDrawableTintGrey)
             DrawableHelper.compoundDrawable(text_username, atDrawable)
         }
     }

app/src/main/java/chat/rocket/android/authentication/server/ui/ServerFragment.kt

@@ -47,21 +47,29 @@ class ServerFragment : Fragment(), ServerView {
     override fun showInvalidServerUrlMessage() = showMessage(getString(R.string.msg_invalid_server_url))
 
     override fun showLoading() {
-        enableUserInput(false)
-        view_loading.setVisible(true)
+        ui {
+            enableUserInput(false)
+            view_loading.setVisible(true)
+        }
     }
 
     override fun hideLoading() {
-        view_loading.setVisible(false)
-        enableUserInput(true)
+        ui {
+            view_loading.setVisible(false)
+            enableUserInput(true)
+        }
     }
 
     override fun showMessage(resId: Int){
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showGenericErrorMessage() {

app/src/main/java/chat/rocket/android/authentication/signup/ui/SignupFragment.kt

@@ -25,7 +25,7 @@ class SignupFragment : Fragment(), SignupView {
         } else {
             bottom_container.apply {
                 postDelayed({
-                    setVisible(true)
+                    ui { setVisible(true) }
                 }, 3)
             }
         }
@@ -64,45 +64,61 @@ class SignupFragment : Fragment(), SignupView {
     }
 
     override fun alertBlankName() {
-        vibrateSmartPhone()
-        text_name.shake()
-        text_name.requestFocus()
+        ui {
+            vibrateSmartPhone()
+            text_name.shake()
+            text_name.requestFocus()
+        }
     }
 
     override fun alertBlankUsername() {
-        vibrateSmartPhone()
-        text_username.shake()
-        text_username.requestFocus()
+        ui {
+            vibrateSmartPhone()
+            text_username.shake()
+            text_username.requestFocus()
+        }
     }
 
     override fun alertEmptyPassword() {
-        vibrateSmartPhone()
-        text_password.shake()
-        text_password.requestFocus()
+        ui {
+            vibrateSmartPhone()
+            text_password.shake()
+            text_password.requestFocus()
+        }
     }
 
     override fun alertBlankEmail() {
-        vibrateSmartPhone()
-        text_email.shake()
-        text_email.requestFocus()
+        ui {
+            vibrateSmartPhone()
+            text_email.shake()
+            text_email.requestFocus()
+        }
     }
 
     override fun showLoading() {
-        enableUserInput(false)
-        view_loading.setVisible(true)
+        ui {
+            enableUserInput(false)
+            view_loading.setVisible(true)
+        }
     }
 
     override fun hideLoading() {
-        view_loading.setVisible(false)
-        enableUserInput(true)
+        ui {
+            view_loading.setVisible(false)
+            enableUserInput(true)
+        }
     }
 
     override fun showMessage(resId: Int) {
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showGenericErrorMessage() {
@@ -110,15 +126,15 @@ class SignupFragment : Fragment(), SignupView {
     }
 
     private fun tintEditTextDrawableStart() {
-        activity?.apply {
-            val personDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_person_black_24dp, this)
-            val atDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_at_black_24dp, this)
-            val lockDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_lock_black_24dp, this)
-            val emailDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_email_black_24dp, this)
+        ui {
+            val personDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_person_black_24dp, it)
+            val atDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_at_black_24dp, it)
+            val lockDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_lock_black_24dp, it)
+            val emailDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_email_black_24dp, it)
 
             val drawables = arrayOf(personDrawable, atDrawable, lockDrawable, emailDrawable)
             DrawableHelper.wrapDrawables(drawables)
-            DrawableHelper.tintDrawables(drawables, this, R.color.colorDrawableTintGrey)
+            DrawableHelper.tintDrawables(drawables, it, R.color.colorDrawableTintGrey)
             DrawableHelper.compoundDrawables(arrayOf(text_name, text_username, text_password, text_email), drawables)
         }
     }

app/src/main/java/chat/rocket/android/authentication/twofactor/ui/TwoFAFragment.kt

@@ -63,8 +63,10 @@ class TwoFAFragment : Fragment(), TwoFAView {
     }
 
     override fun alertBlankTwoFactorAuthenticationCode() {
-        vibrateSmartPhone()
-        text_two_factor_auth.shake()
+        ui {
+            vibrateSmartPhone()
+            text_two_factor_auth.shake()
+        }
     }
 
     override fun alertInvalidTwoFactorAuthenticationCode() {
@@ -72,30 +74,38 @@ class TwoFAFragment : Fragment(), TwoFAView {
     }
 
     override fun showLoading() {
-        enableUserInput(false)
-        view_loading.setVisible(true)
+        ui {
+            enableUserInput(false)
+            view_loading.setVisible(true)
+        }
     }
 
     override fun hideLoading() {
-        view_loading.setVisible(false)
-        enableUserInput(true)
+        ui {
+            view_loading.setVisible(false)
+            enableUserInput(true)
+        }
     }
 
     override fun showMessage(resId: Int) {
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showGenericErrorMessage() = showMessage(getString(R.string.msg_generic_error))
 
     private fun tintEditTextDrawableStart() {
-        activity?.apply {
-            val lockDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_vpn_key_black_24dp, this)
+        ui {
+            val lockDrawable = DrawableHelper.getDrawableFromId(R.drawable.ic_vpn_key_black_24dp, it)
             DrawableHelper.wrapDrawable(lockDrawable)
-            DrawableHelper.tintDrawable(lockDrawable, this, R.color.colorDrawableTintGrey)
+            DrawableHelper.tintDrawable(lockDrawable, it, R.color.colorDrawableTintGrey)
             DrawableHelper.compoundDrawable(text_two_factor_auth, lockDrawable)
         }
     }

app/src/main/java/chat/rocket/android/chatroom/ui/ChatRoomFragment.kt

@@ -18,6 +18,7 @@ import android.support.v7.widget.DefaultItemAnimator
 import android.support.v7.widget.LinearLayoutManager
 import android.support.v7.widget.RecyclerView
 import android.view.*
+import androidx.core.content.systemService
 import chat.rocket.android.R
 import chat.rocket.android.chatroom.adapter.*
 import chat.rocket.android.chatroom.presentation.ChatRoomPresenter
@@ -183,28 +184,28 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
     }
 
     override fun showMessages(dataSet: List<BaseViewModel<*>>) {
-        // track the message sent immediately after the current message
-        var prevMessageViewModel: MessageViewModel? = null
-
-        // Loop over received messages to determine first unread
-        for (i in dataSet.indices) {
-            val msgModel = dataSet[i]
-
-            if (msgModel is MessageViewModel) {
-                val msg = msgModel.rawData
-                if (msg.timestamp < chatRoomLastSeen) {
-                    // This message was sent before the last seen of the room. Hence, it was seen.
-                    // if there is a message after (below) this, mark it firstUnread.
-                    if (prevMessageViewModel != null) {
-                        prevMessageViewModel.isFirstUnread = true
+        ui {
+            // track the message sent immediately after the current message
+            var prevMessageViewModel: MessageViewModel? = null
+
+            // Loop over received messages to determine first unread
+            for (i in dataSet.indices) {
+                val msgModel = dataSet[i]
+
+                if (msgModel is MessageViewModel) {
+                    val msg = msgModel.rawData
+                    if (msg.timestamp < chatRoomLastSeen) {
+                        // This message was sent before the last seen of the room. Hence, it was seen.
+                        // if there is a message after (below) this, mark it firstUnread.
+                        if (prevMessageViewModel != null) {
+                            prevMessageViewModel.isFirstUnread = true
+                        }
+                        break
                     }
-                    break
+                    prevMessageViewModel = msgModel
                 }
-                prevMessageViewModel = msgModel
             }
-        }
 
-        activity?.apply {
             if (recycler_view.adapter == null) {
                 adapter = ChatRoomAdapter(chatRoomType, chatRoomName, presenter,
                         reactionListener = this@ChatRoomFragment)
@@ -282,11 +283,13 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
     }
 
     override fun sendMessage(text: String) {
-        if (!text.isBlank()) {
-            if (!text.startsWith("/")) {
-                presenter.sendMessage(chatRoomId, text, editingMessageId)
-            } else {
-                presenter.runCommand(text, chatRoomId)
+        ui {
+            if (!text.isBlank()) {
+                if (!text.startsWith("/")) {
+                    presenter.sendMessage(chatRoomId, text, editingMessageId)
+                } else {
+                    presenter.runCommand(text, chatRoomId)
+                }
             }
         }
     }
@@ -301,43 +304,55 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
     }
 
     override fun showNewMessage(message: List<BaseViewModel<*>>) {
-        adapter.prependData(message)
-        recycler_view.scrollToPosition(0)
-        verticalScrollOffset.set(0)
+        ui {
+            adapter.prependData(message)
+            recycler_view.scrollToPosition(0)
+            verticalScrollOffset.set(0)
+        }
     }
 
     override fun disableSendMessageButton() {
-        button_send.isEnabled = false
+        ui {
+            button_send.isEnabled = false
+        }
     }
 
     override fun enableSendMessageButton(sendFailed: Boolean) {
-        button_send.isEnabled = true
-        text_message.isEnabled = true
-        if (!sendFailed) {
-            clearMessageComposition()
+        ui {
+            button_send.isEnabled = true
+            text_message.isEnabled = true
+            if (!sendFailed) {
+                clearMessageComposition()
+            }
         }
     }
 
     override fun clearMessageComposition() {
-        citation = null
-        editingMessageId = null
-        text_message.textContent = ""
-        actionSnackbar.dismiss()
+        ui {
+            citation = null
+            editingMessageId = null
+            text_message.textContent = ""
+            actionSnackbar.dismiss()
+        }
     }
 
     override fun dispatchUpdateMessage(index: Int, message: List<BaseViewModel<*>>) {
-        adapter.updateItem(message.last())
-        if (message.size > 1) {
-            adapter.prependData(listOf(message.first()))
+        ui {
+            adapter.updateItem(message.last())
+            if (message.size > 1) {
+                adapter.prependData(listOf(message.first()))
+            }
         }
     }
 
     override fun dispatchDeleteMessage(msgId: String) {
-        adapter.removeItem(msgId)
+        ui {
+            adapter.removeItem(msgId)
+        }
     }
 
     override fun showReplyingAction(username: String, replyMarkdown: String, quotedMessage: String) {
-        activity?.apply {
+        ui {
             citation = replyMarkdown
             actionSnackbar.title = username
             actionSnackbar.text = quotedMessage
@@ -352,41 +367,55 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
         }
     }
 
-    override fun showLoading() = view_loading.setVisible(true)
+    override fun showLoading() {
+        ui { view_loading.setVisible(true) }
+    }
 
-    override fun hideLoading() = view_loading.setVisible(false)
+    override fun hideLoading() {
+        ui { view_loading.setVisible(false) }
+    }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showMessage(resId: Int) {
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showGenericErrorMessage() = showMessage(getString(R.string.msg_generic_error))
 
     override fun populatePeopleSuggestions(members: List<PeopleSuggestionViewModel>) {
-        suggestions_view.addItems("@", members)
+        ui {
+            suggestions_view.addItems("@", members)
+        }
     }
 
     override fun populateRoomSuggestions(chatRooms: List<ChatRoomSuggestionViewModel>) {
-        suggestions_view.addItems("#", chatRooms)
+        ui {
+            suggestions_view.addItems("#", chatRooms)
+        }
     }
 
     override fun populateCommandSuggestions(commands: List<CommandSuggestionViewModel>) {
-        suggestions_view.addItems("/", commands)
+        ui {
+            suggestions_view.addItems("/", commands)
+        }
     }
 
     override fun copyToClipboard(message: String) {
-        activity?.apply {
-            val clipboard = getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
+        ui {
+            val clipboard: ClipboardManager  = it.systemService()
             clipboard.primaryClip = ClipData.newPlainText("", message)
         }
     }
 
     override fun showEditingAction(roomId: String, messageId: String, text: String) {
-        activity?.apply {
+        ui {
             actionSnackbar.title = getString(R.string.action_title_editing)
             actionSnackbar.text = text
             actionSnackbar.show()
@@ -422,7 +451,7 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
     }
 
     override fun showReactionsPopup(messageId: String) {
-        context?.let {
+        ui {
             val emojiPickerPopup = EmojiPickerPopup(it)
             emojiPickerPopup.listener = object : EmojiListenerAdapter() {
                 override fun onEmojiAdded(emoji: Emoji) {
@@ -435,11 +464,11 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
 
     private fun setReactionButtonIcon(@DrawableRes drawableId: Int) {
         button_add_reaction.setImageResource(drawableId)
-        button_add_reaction.setTag(drawableId)
+        button_add_reaction.tag = drawableId
     }
 
     override fun showFileSelection(filter: Array<String>) {
-        activity?.let {
+        ui {
             if (ContextCompat.checkSelfPermission(it, Manifest.permission.READ_EXTERNAL_STORAGE)
                     != PackageManager.PERMISSION_GRANTED) {
                 ActivityCompat.requestPermissions(it,
@@ -459,7 +488,7 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
             1 -> {
                 if (!(grantResults.isNotEmpty() && grantResults.first() == PackageManager.PERMISSION_GRANTED)) {
                     handler.postDelayed({
-                        hideAttachmentOptions()
+                        ui { hideAttachmentOptions() }
                     }, 400)
                 }
             }
@@ -471,7 +500,7 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
     }
 
     override fun showConnectionState(state: State) {
-        activity?.apply {
+        ui {
             connection_status_text.fadeIn()
             handler.removeCallbacks(dismissStatus)
             when (state) {
@@ -489,10 +518,12 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
     }
 
     override fun onJoined() {
-        input_container.setVisible(true)
-        button_join_chat.setVisible(false)
-        isSubscribed = true
-        setupMessageComposer()
+        ui {
+            input_container.setVisible(true)
+            button_join_chat.setVisible(false)
+            isSubscribed = true
+            setupMessageComposer()
+        }
     }
 
     private val dismissStatus = {

app/src/main/java/chat/rocket/android/chatroom/ui/PinnedMessagesFragment.kt

@@ -16,6 +16,7 @@ import chat.rocket.android.chatroom.viewmodel.BaseViewModel
 import chat.rocket.android.helper.EndlessRecyclerViewScrollListener
 import chat.rocket.android.util.extensions.setVisible
 import chat.rocket.android.util.extensions.showToast
+import chat.rocket.android.util.extensions.ui
 import dagger.android.support.AndroidSupportInjection
 import kotlinx.android.synthetic.main.fragment_pinned_messages.*
 import javax.inject.Inject
@@ -62,22 +63,30 @@ class PinnedMessagesFragment : Fragment(), PinnedMessagesView {
         presenter.loadPinnedMessages(chatRoomId)
     }
 
-    override fun showLoading() = view_loading.setVisible(true)
+    override fun showLoading() {
+        ui { view_loading.setVisible(true) }
+    }
 
-    override fun hideLoading() = view_loading.setVisible(false)
+    override fun hideLoading() {
+        ui { view_loading.setVisible(false) }
+    }
 
     override fun showMessage(resId: Int) {
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showGenericErrorMessage() = showMessage(getString(R.string.msg_generic_error))
 
     override fun showPinnedMessages(pinnedMessages: List<BaseViewModel<*>>) {
-        activity?.apply {
+        ui {
             if (recycler_view_pinned.adapter == null) {
                 // TODO - add a better constructor for this case...
                 adapter = ChatRoomAdapter(chatRoomType, chatRoomName, null, false)

app/src/main/java/chat/rocket/android/chatrooms/ui/ChatRoomsFragment.kt

@@ -32,6 +32,7 @@ import dagger.android.support.AndroidSupportInjection
 import kotlinx.android.synthetic.main.fragment_chat_rooms.*
 import kotlinx.coroutines.experimental.CommonPool
 import kotlinx.coroutines.experimental.Job
+import kotlinx.coroutines.experimental.NonCancellable.isActive
 import kotlinx.coroutines.experimental.android.UI
 import kotlinx.coroutines.experimental.async
 import kotlinx.coroutines.experimental.launch
@@ -101,8 +102,8 @@ class ChatRoomsFragment : Fragment(), ChatRoomsView {
     }
 
 
-    override fun onOptionsItemSelected(item: MenuItem?): Boolean {
-        when (item?.itemId) {
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        when (item.itemId) {
             R.id.action_sort -> {
                 val dialogLayout = layoutInflater.inflate(R.layout.chatroom_sort_dialog, null)
                 val sortType = SharedPreferenceHelper.getInt(Constants.CHATROOM_SORT_TYPE_KEY, ChatRoomsSortOrder.ACTIVITY)
@@ -154,50 +155,56 @@ class ChatRoomsFragment : Fragment(), ChatRoomsView {
     }
 
     override suspend fun updateChatRooms(newDataSet: List<ChatRoom>) {
-        activity?.apply {
-            listJob?.cancel()
-            listJob = launch(UI) {
-                val adapter = recycler_view.adapter as SimpleSectionedRecyclerViewAdapter
-                // FIXME https://fabric.io/rocketchat3/android/apps/chat.rocket.android/issues/5ac2916c36c7b235275ccccf
-                // TODO - fix this bug to re-enable DiffUtil
-                /*val diff = async(CommonPool) {
-                    DiffUtil.calculateDiff(RoomsDiffCallback(adapter.baseAdapter.dataSet, newDataSet))
-                }.await()*/
-
-                if (isActive) {
-                    adapter.baseAdapter.updateRooms(newDataSet)
-                    // TODO - fix crash to re-enable diff.dispatchUpdatesTo(adapter)
-                    adapter.notifyDataSetChanged()
-
-                    //Set sections always after data set is updated
-                    setSections()
-                }
+        listJob?.cancel()
+        listJob = ui {
+            val adapter = recycler_view.adapter as SimpleSectionedRecyclerViewAdapter
+            // FIXME https://fabric.io/rocketchat3/android/apps/chat.rocket.android/issues/5ac2916c36c7b235275ccccf
+            // TODO - fix this bug to re-enable DiffUtil
+            /*val diff = async(CommonPool) {
+                DiffUtil.calculateDiff(RoomsDiffCallback(adapter.baseAdapter.dataSet, newDataSet))
+            }.await()*/
+
+            if (isActive) {
+                adapter.baseAdapter.updateRooms(newDataSet)
+                // TODO - fix crash to re-enable diff.dispatchUpdatesTo(adapter)
+                adapter.notifyDataSetChanged()
+
+                //Set sections always after data set is updated
+                setSections()
             }
         }
     }
 
-    override fun showNoChatRoomsToDisplay() = text_no_data_to_display.setVisible(true)
+    override fun showNoChatRoomsToDisplay() {
+        ui { text_no_data_to_display.setVisible(true) }
+    }
 
-    override fun showLoading() = view_loading.setVisible(true)
+    override fun showLoading(){
+        ui { view_loading.setVisible(true) }
+    }
 
     override fun hideLoading() {
-        if (view_loading != null) {
+        ui {
             view_loading.setVisible(false)
         }
     }
 
     override fun showMessage(resId: Int) {
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showGenericErrorMessage() = showMessage(getString(R.string.msg_generic_error))
 
     override fun showConnectionState(state: State) {
-        activity?.apply {
+        ui {
             connection_status_text.fadeIn()
             handler.removeCallbacks(dismissStatus)
             when (state) {
@@ -221,22 +228,25 @@ class ChatRoomsFragment : Fragment(), ChatRoomsView {
     }
 
     private fun setupToolbar() {
-        (activity as AppCompatActivity).supportActionBar?.title = getString(R.string.title_chats)
+        (activity as AppCompatActivity?)?.supportActionBar?.title = getString(R.string.title_chats)
     }
 
     private fun setupRecyclerView() {
-        activity?.apply {
-            recycler_view.layoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
-            recycler_view.addItemDecoration(DividerItemDecoration(this,
+        ui {
+            recycler_view.layoutManager = LinearLayoutManager(it, LinearLayoutManager.VERTICAL, false)
+            recycler_view.addItemDecoration(DividerItemDecoration(it,
                     resources.getDimensionPixelSize(R.dimen.divider_item_decorator_bound_start),
                     resources.getDimensionPixelSize(R.dimen.divider_item_decorator_bound_end)))
             recycler_view.itemAnimator = DefaultItemAnimator()
             // TODO - use a ViewModel Mapper instead of using settings on the adapter
 
-            val baseAdapter = ChatRoomsAdapter(this,
-                    settingsRepository.get(serverInteractor.get()!!), localRepository) { chatRoom -> presenter.loadChatRoom(chatRoom) }
+            val baseAdapter = ChatRoomsAdapter(it,
+                    settingsRepository.get(serverInteractor.get()!!), localRepository) {
+                chatRoom -> presenter.loadChatRoom(chatRoom)
+            }
 
-            sectionedAdapter = SimpleSectionedRecyclerViewAdapter(this, R.layout.item_chatroom_header, R.id.text_chatroom_header, baseAdapter!!)
+            sectionedAdapter = SimpleSectionedRecyclerViewAdapter(it,
+                    R.layout.item_chatroom_header, R.id.text_chatroom_header, baseAdapter)
             recycler_view.adapter = sectionedAdapter
         }
     }

app/src/main/java/chat/rocket/android/members/presentation/MembersNavigator.kt

 package chat.rocket.android.members.presentation
 
 import chat.rocket.android.chatroom.ui.ChatRoomActivity
-import chat.rocket.android.member.ui.newInstance
+import chat.rocket.android.members.ui.newInstance
 
 class MembersNavigator(internal val activity: ChatRoomActivity) {
 

app/src/main/java/chat/rocket/android/member/ui/MemberBottomSheetFragment.kt → app/src/main/java/chat/rocket/android/members/ui/MemberBottomSheetFragment.kt

-package chat.rocket.android.member.ui
+package chat.rocket.android.members.ui
 
 import android.os.Bundle
 import android.support.design.widget.BottomSheetDialogFragment

app/src/main/java/chat/rocket/android/members/ui/MembersFragment.kt

@@ -19,6 +19,7 @@ import chat.rocket.android.members.viewmodel.MemberViewModel
 import chat.rocket.android.util.extensions.inflate
 import chat.rocket.android.util.extensions.setVisible
 import chat.rocket.android.util.extensions.showToast
+import chat.rocket.android.util.extensions.ui
 import chat.rocket.android.widget.DividerItemDecoration
 import dagger.android.support.AndroidSupportInjection
 import kotlinx.android.synthetic.main.fragment_members.*
@@ -70,7 +71,7 @@ class MembersFragment : Fragment(), MembersView {
     }
 
     override fun showMembers(dataSet: List<MemberViewModel>, total: Long) {
-        activity?.apply {
+        ui {
             setupToolbar(total)
             if (adapter.itemCount == 0) {
                 adapter.prependData(dataSet)
@@ -84,8 +85,8 @@ class MembersFragment : Fragment(), MembersView {
             } else {
                 adapter.appendData(dataSet)
             }
-            if (this is ChatRoomActivity) {
-                this.showRoomTypeIcon(false)
+            if (it is ChatRoomActivity) {
+                it.showRoomTypeIcon(false)
             }
         }
     }
@@ -98,29 +99,37 @@ class MembersFragment : Fragment(), MembersView {
         return super.onOptionsItemSelected(item)
     }
 
-    override fun showLoading() = view_loading.setVisible(true)
+    override fun showLoading() {
+        ui { view_loading.setVisible(true) }
+    }
 
-    override fun hideLoading() = view_loading.setVisible(false)
+    override fun hideLoading() {
+        ui { view_loading.setVisible(false) }
+    }
 
     override fun showMessage(resId: Int) {
-        showToast(resId)
+        ui {
+            showToast(resId)
+        }
     }
 
     override fun showMessage(message: String) {
-        showToast(message)
+        ui {
+            showToast(message)
+        }
     }
 
     override fun showGenericErrorMessage() = showMessage(getString(R.string.msg_generic_error))
 
     private fun setupRecyclerView() {
-        activity?.apply {
+        ui {
             recycler_view.layoutManager = linearLayoutManager
-            recycler_view.addItemDecoration(DividerItemDecoration(this))
+            recycler_view.addItemDecoration(DividerItemDecoration(it))
             recycler_view.adapter = adapter
         }
     }
 
     private fun setupToolbar(totalMembers: Long) {
-        (activity as ChatRoomActivity).setupToolbarTitle(getString(R.string.title_members, totalMembers))
+        (activity as ChatRoomActivity?)?.setupToolbarTitle(getString(R.string.title_members, totalMembers))
     }
 }
\ No newline at end of file

app/src/main/java/chat/rocket/android/util/extensions/Fragment.kt

+package chat.rocket.android.util.extensions
+
+import android.os.Looper
+import android.support.v4.app.Fragment
+import android.support.v4.app.FragmentActivity
+import kotlinx.coroutines.experimental.Job
+import kotlinx.coroutines.experimental.android.UI
+import kotlinx.coroutines.experimental.launch
+
+inline fun Fragment.ui(crossinline block: (activity: FragmentActivity) -> Unit): Job? {
+    // Checking first for activity and view saves us from some synchronyzed and thread local checks
+    if (activity != null && view != null) {
+        // If we already are running on the Main Thread (UI Thread), just go ahead and execute the block
+        return if (Looper.getMainLooper() == Looper.myLooper()) {
+            block(activity!!)
+            null
+        } else {
+            // Launch a Job on the UI context and check again if the activity and view are still valid
+            launch(UI) {
+                if (activity != null && view != null) {
+                    block(activity!!)
+                }
+            }
+        }
+    }
+
+    return null
+}
\ No newline at end of file