Fix #936 & #2297 : Oppia Android Promoted Stories App Layer.

app/BUILD.bazel

@@ -123,6 +123,9 @@ VIEW_MODELS_WITH_RESOURCE_IMPORTS = [
     "src/main/java/org/oppia/android/app/help/HelpListViewModel.kt",
     "src/main/java/org/oppia/android/app/help/faq/FAQListViewModel.kt",
     "src/main/java/org/oppia/android/app/home/HomeViewModel.kt",
+    "src/main/java/org/oppia/android/app/home/topiclist/TopicSummaryViewModel.kt",
+    "src/main/java/org/oppia/android/app/home/promotedlist/ComingSoonTopicListViewModel.kt",
+    "src/main/java/org/oppia/android/app/home/promotedlist/ComingSoonTopicsViewModel.kt",
     "src/main/java/org/oppia/android/app/home/promotedlist/PromotedStoryListViewModel.kt",
     "src/main/java/org/oppia/android/app/home/promotedlist/PromotedStoryViewModel.kt",
     "src/main/java/org/oppia/android/app/home/topiclist/TopicSummaryViewModel.kt",
@@ -313,6 +316,7 @@ VIEWS = [
     "src/main/java/org/oppia/android/app/customview/interaction/NumericInputInteractionView.kt",
     "src/main/java/org/oppia/android/app/customview/interaction/TextInputInteractionView.kt",
     "src/main/java/org/oppia/android/app/customview/interaction/RatioInputInteractionView.kt",
+    "src/main/java/org/oppia/android/app/home/promotedlist/ComingSoonTopicsListView.kt",
     "src/main/java/org/oppia/android/app/home/promotedlist/PromotedStoryListView.kt",
     "src/main/java/org/oppia/android/app/player/state/DragDropSortInteractionView.kt",
     "src/main/java/org/oppia/android/app/player/state/ImageRegionSelectionInteractionView.kt",

app/src/main/java/org/oppia/android/app/home/HomeFragmentPresenter.kt

@@ -9,13 +9,15 @@ import androidx.recyclerview.widget.GridLayoutManager
 import org.oppia.android.R
 import org.oppia.android.app.drawer.KEY_NAVIGATION_PROFILE_ID
 import org.oppia.android.app.fragment.FragmentScope
+import org.oppia.android.app.home.promotedlist.ComingSoonTopicListViewModel
 import org.oppia.android.app.home.promotedlist.PromotedStoryListViewModel
 import org.oppia.android.app.home.topiclist.AllTopicsViewModel
 import org.oppia.android.app.home.topiclist.TopicSummaryViewModel
 import org.oppia.android.app.model.EventLog
 import org.oppia.android.app.model.TopicSummary
 import org.oppia.android.app.recyclerview.BindableAdapter
 import org.oppia.android.databinding.AllTopicsBinding
+import org.oppia.android.databinding.ComingSoonTopicListBinding
 import org.oppia.android.databinding.HomeFragmentBinding
 import org.oppia.android.databinding.PromotedStoryListBinding
 import org.oppia.android.databinding.TopicSummaryViewBinding
@@ -72,7 +74,7 @@ class HomeFragmentPresenter @Inject constructor(
     homeLayoutManager.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
       override fun getSpanSize(position: Int): Int {
         return if (position < homeAdapter.itemCount &&
-          homeAdapter.getItemViewType(position) === ViewType.TOPIC_LIST.ordinal
+          homeAdapter.getItemViewType(position) == ViewType.TOPIC_LIST.ordinal
         ) 1
         else spanCount
       }
@@ -96,6 +98,7 @@ class HomeFragmentPresenter @Inject constructor(
         when (viewModel) {
           is WelcomeViewModel -> ViewType.WELCOME_MESSAGE
           is PromotedStoryListViewModel -> ViewType.PROMOTED_STORY_LIST
+          is ComingSoonTopicListViewModel -> ViewType.COMING_SOON_TOPIC_LIST
           is AllTopicsViewModel -> ViewType.ALL_TOPICS
           is TopicSummaryViewModel -> ViewType.TOPIC_LIST
           else -> throw IllegalArgumentException("Encountered unexpected view model: $viewModel")
@@ -113,6 +116,12 @@ class HomeFragmentPresenter @Inject constructor(
         setViewModel = PromotedStoryListBinding::setViewModel,
         transformViewModel = { it as PromotedStoryListViewModel }
       )
+      .registerViewDataBinder(
+        viewType = ViewType.COMING_SOON_TOPIC_LIST,
+        inflateDataBinding = ComingSoonTopicListBinding::inflate,
+        setViewModel = ComingSoonTopicListBinding::setViewModel,
+        transformViewModel = { it as ComingSoonTopicListViewModel }
+      )
       .registerViewDataBinder(
         viewType = ViewType.ALL_TOPICS,
         inflateDataBinding = AllTopicsBinding::inflate,
@@ -131,6 +140,7 @@ class HomeFragmentPresenter @Inject constructor(
   private enum class ViewType {
     WELCOME_MESSAGE,
     PROMOTED_STORY_LIST,
+    COMING_SOON_TOPIC_LIST,
     ALL_TOPICS,
     TOPIC_LIST
   }

app/src/main/java/org/oppia/android/app/home/HomeViewModel.kt

@@ -7,14 +7,18 @@ import androidx.lifecycle.Transformations
 import androidx.lifecycle.ViewModel
 import org.oppia.android.R
 import org.oppia.android.app.fragment.FragmentScope
+import org.oppia.android.app.home.promotedlist.ComingSoonTopicListViewModel
+import org.oppia.android.app.home.promotedlist.ComingSoonTopicsViewModel
 import org.oppia.android.app.home.promotedlist.PromotedStoryListViewModel
 import org.oppia.android.app.home.promotedlist.PromotedStoryViewModel
 import org.oppia.android.app.home.topiclist.AllTopicsViewModel
 import org.oppia.android.app.home.topiclist.TopicSummaryClickListener
 import org.oppia.android.app.home.topiclist.TopicSummaryViewModel
-import org.oppia.android.app.model.OngoingStoryList
+import org.oppia.android.app.model.ComingSoonTopicList
 import org.oppia.android.app.model.Profile
 import org.oppia.android.app.model.ProfileId
+import org.oppia.android.app.model.PromotedActivityList
+import org.oppia.android.app.model.PromotedStoryList
 import org.oppia.android.app.model.TopicList
 import org.oppia.android.app.viewmodel.ObservableViewModel
 import org.oppia.android.domain.profile.ProfileManagementController
@@ -26,9 +30,12 @@ import org.oppia.android.util.logging.ConsoleLogger
 import org.oppia.android.util.parser.StoryHtmlParserEntityType
 import org.oppia.android.util.parser.TopicHtmlParserEntityType
 import org.oppia.android.util.system.OppiaClock
+import java.util.Collections
 
-private const val PROFILE_AND_ONGOING_STORY_COMBINED_PROVIDER_ID = "profile+ongoingStoryList"
-private const val HOME_FRAGMENT_COMBINED_PROVIDER_ID = "profile+ongoingStoryList+topicListProvider"
+private const val PROFILE_AND_PROMOTED_ACTIVITY_COMBINED_PROVIDER_ID =
+  "profile+promotedActivityList"
+private const val HOME_FRAGMENT_COMBINED_PROVIDER_ID =
+  "profile+promotedActivityList+topicListProvider"
 
 /** [ViewModel] for layouts in home fragment. */
 @FragmentScope
@@ -45,7 +52,6 @@ class HomeViewModel(
 ) : ObservableViewModel() {
 
   private val profileId: ProfileId = ProfileId.newBuilder().setInternalId(internalProfileId).build()
-
   private val promotedStoryListLimit = activity.resources.getInteger(
     R.integer.promoted_story_list_limit
   )
@@ -54,8 +60,8 @@ class HomeViewModel(
     profileManagementController.getProfile(profileId)
   }
 
-  private val ongoingStoryListSummaryDataProvider: DataProvider<OngoingStoryList> by lazy {
-    topicListController.getOngoingStoryList(profileId)
+  private val promotedActivityListSummaryDataProvider: DataProvider<PromotedActivityList> by lazy {
+    topicListController.getPromotedActivityList(profileId)
   }
 
   private val topicListSummaryDataProvider: DataProvider<TopicList> by lazy {
@@ -67,12 +73,12 @@ class HomeViewModel(
     // instances). If any of the data providers are pending or failed, the combined result will also
     // be pending or failed.
     profileDataProvider.combineWith(
-      ongoingStoryListSummaryDataProvider,
-      PROFILE_AND_ONGOING_STORY_COMBINED_PROVIDER_ID
-    ) { profile, ongoingStoryList ->
+      promotedActivityListSummaryDataProvider,
+      PROFILE_AND_PROMOTED_ACTIVITY_COMBINED_PROVIDER_ID
+    ) { profile, promotedActivityList ->
       listOfNotNull(
         computeWelcomeViewModel(profile),
-        computePromotedStoryListViewModel(ongoingStoryList)
+        computePromotedActivityListViewModel(promotedActivityList)
       )
     }.combineWith(
       topicListSummaryDataProvider,
@@ -111,20 +117,39 @@ class HomeViewModel(
   }
 
   /**
-   * Returns a [HomeItemViewModel] corresponding to the promoted stories to be displayed for this learner
-   * (see [PromotedStoryListViewModel]), or null if this profile does not have any promoted stories.
-   * Promoted stories are determined by any recent stories started by this profile.
+   * Returns a [HomeItemViewModel] corresponding to the promoted stories(Recommended, Recently-played and
+   * Last-played stories)[PromotedStoryListViewModel] and Upcoming topics [ComingSoonTopicListViewModel]
+   * to be displayed for this learner or null if this profile does not have any promoted stories.
+   * Promoted stories are determined by any recent stories last-played stories or suggested stories started by this profile.
    */
-  private fun computePromotedStoryListViewModel(
-    ongoingStoryList: OngoingStoryList
+  private fun computePromotedActivityListViewModel(
+    promotedActivityList: PromotedActivityList
   ): HomeItemViewModel? {
-    val storyViewModelList = computePromotedStoryViewModelList(ongoingStoryList)
-    return if (storyViewModelList.isNotEmpty()) {
-      return PromotedStoryListViewModel(
-        activity,
-        storyViewModelList
-      )
-    } else null
+    when (promotedActivityList.recommendationTypeCase) {
+      PromotedActivityList.RecommendationTypeCase.PROMOTED_STORY_LIST -> {
+        val storyViewModelList = computePromotedStoryViewModelList(
+          promotedActivityList.promotedStoryList
+        )
+        return if (storyViewModelList.isNotEmpty()) {
+          return PromotedStoryListViewModel(
+            activity,
+            storyViewModelList,
+            promotedActivityList
+          )
+        } else null
+      }
+      PromotedActivityList.RecommendationTypeCase.COMING_SOON_TOPIC_LIST -> {
+        val comingSoonTopicsList = computeComingSoonTopicViewModelList(
+          promotedActivityList.comingSoonTopicList
+        )
+        return if (comingSoonTopicsList.isNotEmpty()) {
+          return ComingSoonTopicListViewModel(
+            comingSoonTopicsList
+          )
+        } else null
+      }
+      else -> return null
+    }
   }
 
   /**
@@ -133,24 +158,76 @@ class HomeViewModel(
    * ongoing stories at all.
    */
   private fun computePromotedStoryViewModelList(
-    ongoingStoryList: OngoingStoryList
+    promotedStoryList: PromotedStoryList
   ): List<PromotedStoryViewModel> {
-    val storyList = if (ongoingStoryList.recentStoryCount != 0) {
-      ongoingStoryList.recentStoryList
-    } else {
-      // TODO(#936): Optimise this as part of recommended stories.
-      ongoingStoryList.olderStoryList
-    }
-    return storyList.take(promotedStoryListLimit)
-      .map { promotedStory ->
-        PromotedStoryViewModel(
-          activity,
-          internalProfileId,
-          storyList.size,
-          storyEntityType,
-          promotedStory
-        )
+    with(promotedStoryList) {
+      val storyList = when {
+        suggestedStoryCount != 0 -> {
+          if (recentlyPlayedStoryCount != 0 ||
+            olderPlayedStoryCount != 0
+          ) {
+            recentlyPlayedStoryList +
+              olderPlayedStoryList +
+              suggestedStoryList
+          } else {
+            suggestedStoryList
+          }
+        }
+        recentlyPlayedStoryCount != 0 -> {
+          recentlyPlayedStoryList
+        }
+        else -> {
+          olderPlayedStoryList
+        }
+      }
+
+      // Check if at least one story in topic is completed. Prioritize recommended story over completed story topic.
+      // Use swap function to change recommended and completed story topic position.
+      storyList.take(promotedStoryListLimit).mapIndexed { completedStoryIndex, promotedStory ->
+        if (promotedStory.isTopicLearned &&
+          suggestedStoryCount != 0
+        ) {
+          if (completedStoryIndex == 0 &&
+            (recentlyPlayedStoryCount > 1 || olderPlayedStoryCount > 1)
+          ) {
+            Collections.swap(storyList, completedStoryIndex, 1)
+          } else {
+            val swapWithSuggestedListIndex0 =
+              recentlyPlayedStoryList.size + olderPlayedStoryList.size
+            Collections.swap(storyList, completedStoryIndex, swapWithSuggestedListIndex0)
+          }
+        }
       }
+
+      return storyList.take(promotedStoryListLimit)
+        .map { promotedStory ->
+          PromotedStoryViewModel(
+            activity,
+            internalProfileId,
+            storyList.size,
+            storyEntityType,
+            promotedStory
+          )
+        }
+    }
+  }
+
+  /**
+   * Returns a list of [HomeItemViewModel]s corresponding to [ComingSoonTopicListViewModel]  all the upcoming topics available in future and to be
+   * displayed for this profile (see [ComingSoonTopicsViewModel]), or an empty list if the profile does not have any
+   * ongoing stories at all.
+   */
+  private fun computeComingSoonTopicViewModelList(
+    comingSoonTopicList: ComingSoonTopicList
+  ): List<ComingSoonTopicsViewModel> {
+    return comingSoonTopicList.upcomingTopicList.map { topicSummary ->
+      ComingSoonTopicsViewModel(
+        activity,
+        topicSummary,
+        topicEntityType,
+        comingSoonTopicList
+      )
+    }
   }
 
   /**

app/src/main/java/org/oppia/android/app/home/promotedlist/ComingSoonTopicListViewModel.kt

@@ -0,0 +1,20 @@
+package org.oppia.android.app.home.promotedlist
+
+import androidx.lifecycle.ViewModel
+import org.oppia.android.app.home.HomeItemViewModel
+import java.util.Objects
+
+/** [ViewModel] for the upcoming topic list displayed in [HomeFragment]. */
+class ComingSoonTopicListViewModel(
+  val comingSoonTopicList: List<ComingSoonTopicsViewModel>
+) : HomeItemViewModel() {
+  // Overriding equals is needed so that DataProvider combine functions used in the HomeViewModel
+  // will only rebind when the actual data in the data list changes, rather than when the ViewModel
+  // object changes.
+  override fun equals(other: Any?): Boolean {
+    return other is ComingSoonTopicListViewModel &&
+      other.comingSoonTopicList == this.comingSoonTopicList
+  }
+
+  override fun hashCode() = Objects.hash(comingSoonTopicList)
+}

app/src/main/java/org/oppia/android/app/home/promotedlist/ComingSoonTopicsListView.kt

@@ -0,0 +1,87 @@
+package org.oppia.android.app.home.promotedlist
+
+import android.content.Context
+import android.util.AttributeSet
+import android.view.LayoutInflater
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.FragmentManager
+import androidx.recyclerview.widget.RecyclerView
+import org.oppia.android.app.recyclerview.BindableAdapter
+import org.oppia.android.app.recyclerview.StartSnapHelper
+import org.oppia.android.app.shim.ViewBindingShim
+import org.oppia.android.app.shim.ViewComponentFactory
+import org.oppia.android.util.logging.ConsoleLogger
+import javax.inject.Inject
+
+private const val COMING_SOON_TOPIC_LIST_VIEW_TAG = "ComingSoonTopicsListView"
+
+/**
+ * A custom [RecyclerView] for displaying a variable list of Upcoming topics that snaps to
+ * a fixed position when being scrolled.
+ */
+class ComingSoonTopicsListView @JvmOverloads constructor(
+  context: Context,
+  attrs: AttributeSet? = null,
+  defStyleAttr: Int = 0
+) : RecyclerView(context, attrs, defStyleAttr) {
+
+  @Inject
+  lateinit var bindingInterface: ViewBindingShim
+
+  @Inject
+  lateinit var logger: ConsoleLogger
+
+  override fun onAttachedToWindow() {
+    super.onAttachedToWindow()
+
+    (FragmentManager.findFragment<Fragment>(this) as ViewComponentFactory)
+      .createViewComponent(this).inject(this)
+
+    // The StartSnapHelper is used to snap between items rather than smooth scrolling, so that
+    // the item is completely visible in [HomeFragment] as soon as learner lifts the finger
+    // after scrolling.
+    val snapHelper = StartSnapHelper()
+    onFlingListener = null
+    snapHelper.attachToRecyclerView(this)
+  }
+
+  /**
+   * Sets the list of coming soon topics that this view shows to the learner.
+   *
+   * @param newDataList the new list of topics to present
+   */
+  fun setComingSoonTopicList(newDataList: List<ComingSoonTopicsViewModel>?) {
+    // To reliably bind data only after the adapter is created, we manually set the data so we can first
+    // check for the adapter; when using an existing [RecyclerViewBindingAdapter] there is no reliable
+    // way to check that the adapter is created.
+    // This ensures that the adapter will only be created once and correctly rebinds the data.
+    // For more context:  https://github.com/oppia/oppia-android/pull/2246#pullrequestreview-565964462
+    if (adapter == null) {
+      adapter = createAdapter()
+    }
+    if (newDataList == null) {
+      logger.w(COMING_SOON_TOPIC_LIST_VIEW_TAG, "Failed to resolve upcoming topic list data")
+    } else {
+      (adapter as BindableAdapter<*>).setDataUnchecked(newDataList)
+    }
+  }
+
+  private fun createAdapter(): BindableAdapter<ComingSoonTopicsViewModel> {
+    return BindableAdapter.SingleTypeBuilder.newBuilder<ComingSoonTopicsViewModel>()
+      .registerViewBinder(
+        inflateView = { parent ->
+          bindingInterface.provideComingSoonTopicViewInflatedView(
+            LayoutInflater.from(parent.context),
+            parent,
+            attachToParent = false
+          )
+        },
+        bindView = { view, viewModel ->
+          bindingInterface.provideComingSoonTopicsViewViewModel(
+            view,
+            viewModel
+          )
+        }
+      ).build()
+  }
+}