Fix #4450: Add next and previous card options on revision screen

app/src/main/AndroidManifest.xml

@@ -236,7 +236,7 @@
     <activity
       android:name=".app.topic.revisioncard.RevisionCardActivity"
       android:label="@string/revision_card_activity_title"
-      android:theme="@style/OppiaThemeWithoutActionBar" />
+      android:theme="@style/RevisionCardActivityTheme" />
     <activity android:name=".app.testing.SplashTestActivity" />
     <activity
       android:name=".app.topic.TopicActivity"

app/src/main/java/org/oppia/android/app/customview/LessonThumbnailImageView.kt

@@ -66,9 +66,11 @@ class LessonThumbnailImageView @JvmOverloads constructor(
     checkIfLoadingIsPossible()
   }
 
-  fun setLessonThumbnail(lessonThumbnail: LessonThumbnail) {
-    this.lessonThumbnail = lessonThumbnail
-    checkIfLoadingIsPossible()
+  fun setLessonThumbnail(lessonThumbnail: LessonThumbnail?) {
+    if (lessonThumbnail != null) {
+      this.lessonThumbnail = lessonThumbnail
+      checkIfLoadingIsPossible()
+    }
   }
 
   fun setIsBlurred(isBlurred: Boolean) {

app/src/main/java/org/oppia/android/app/testing/TopicRevisionTestActivity.kt

@@ -20,13 +20,19 @@ class TopicRevisionTestActivity : InjectableAppCompatActivity(), RouteToRevision
     topicRevisionTestActivityPresenter.handleOnCreate()
   }
 
-  override fun routeToRevisionCard(internalProfileId: Int, topicId: String, subtopicId: Int) {
+  override fun routeToRevisionCard(
+    internalProfileId: Int,
+    topicId: String,
+    subtopicId: Int,
+    subtopicListSize: Int
+  ) {
     startActivity(
       RevisionCardActivity.createRevisionCardActivityIntent(
         this,
         internalProfileId,
         topicId,
-        subtopicId
+        subtopicId,
+        subtopicListSize
       )
     )
   }

app/src/main/java/org/oppia/android/app/testing/TopicTestActivity.kt

@@ -79,10 +79,15 @@ class TopicTestActivity :
     )
   }
 
-  override fun routeToRevisionCard(internalProfileId: Int, topicId: String, subtopicId: Int) {
+  override fun routeToRevisionCard(
+    internalProfileId: Int,
+    topicId: String,
+    subtopicId: Int,
+    subtopicListSize: Int
+  ) {
     startActivity(
       RevisionCardActivity.createRevisionCardActivityIntent(
-        this, internalProfileId, topicId, subtopicId
+        this, internalProfileId, topicId, subtopicId, subtopicListSize
       )
     )
   }

app/src/main/java/org/oppia/android/app/testing/TopicTestActivityForStory.kt

@@ -105,10 +105,15 @@ class TopicTestActivityForStory :
     )
   }
 
-  override fun routeToRevisionCard(internalProfileId: Int, topicId: String, subtopicId: Int) {
+  override fun routeToRevisionCard(
+    internalProfileId: Int,
+    topicId: String,
+    subtopicId: Int,
+    subtopicListSize: Int
+  ) {
     startActivity(
       RevisionCardActivity.createRevisionCardActivityIntent(
-        this, internalProfileId, topicId, subtopicId
+        this, internalProfileId, topicId, subtopicId, subtopicListSize
       )
     )
   }

app/src/main/java/org/oppia/android/app/topic/RouteToRevisionCardListener.kt

@@ -2,5 +2,10 @@ package org.oppia.android.app.topic
 
 /** Listener for when an [TopicActivity] should route to a [RevisionCardFragment]. */
 interface RouteToRevisionCardListener {
-  fun routeToRevisionCard(internalProfileId: Int, topicId: String, subtopicId: Int)
+  fun routeToRevisionCard(
+    internalProfileId: Int,
+    topicId: String,
+    subtopicId: Int,
+    subtopicListSize: Int
+  )
 }

app/src/main/java/org/oppia/android/app/topic/TopicActivity.kt

@@ -72,13 +72,19 @@ class TopicActivity :
     )
   }
 
-  override fun routeToRevisionCard(internalProfileId: Int, topicId: String, subtopicId: Int) {
+  override fun routeToRevisionCard(
+    internalProfileId: Int,
+    topicId: String,
+    subtopicId: Int,
+    subtopicListSize: Int
+  ) {
     startActivity(
       RevisionCardActivity.createRevisionCardActivityIntent(
         this,
         internalProfileId,
         topicId,
-        subtopicId
+        subtopicId,
+        subtopicListSize
       )
     )
   }

app/src/main/java/org/oppia/android/app/topic/revision/TopicRevisionFragmentPresenter.kt

@@ -27,6 +27,7 @@ class TopicRevisionFragmentPresenter @Inject constructor(
   private var internalProfileId: Int = -1
   private lateinit var topicId: String
   private val routeToReviewListener = activity as RouteToRevisionCardListener
+  private var subtopicListSize: Int? = null
 
   fun handleCreateView(
     inflater: LayoutInflater,
@@ -55,11 +56,20 @@ class TopicRevisionFragmentPresenter @Inject constructor(
       this.viewModel = [email protected]
       lifecycleOwner = fragment
     }
+
+    viewModel.subtopicLiveData.observe(fragment) {
+      this.subtopicListSize = it.size
+    }
     return binding.root
   }
 
   override fun onTopicRevisionSummaryClicked(subtopic: Subtopic) {
-    routeToReviewListener.routeToRevisionCard(internalProfileId, topicId, subtopic.subtopicId)
+    routeToReviewListener.routeToRevisionCard(
+      internalProfileId,
+      topicId,
+      subtopic.subtopicId,
+      checkNotNull(subtopicListSize) { "Subtopic list size not found." }
+    )
   }
 
   private fun createRecyclerViewAdapter(): BindableAdapter<TopicRevisionItemViewModel> {

app/src/main/java/org/oppia/android/app/topic/revisioncard/RevisionCardActivity.kt

@@ -7,6 +7,7 @@ import org.oppia.android.app.activity.ActivityComponentImpl
 import org.oppia.android.app.activity.InjectableAppCompatActivity
 import org.oppia.android.app.model.ScreenName.REVISION_CARD_ACTIVITY
 import org.oppia.android.app.player.exploration.BottomSheetOptionsMenuItemClickListener
+import org.oppia.android.app.topic.RouteToRevisionCardListener
 import org.oppia.android.app.topic.conceptcard.ConceptCardListener
 import org.oppia.android.util.logging.CurrentAppScreenNameIntentDecorator.decorateWithScreenName
 import javax.inject.Inject
@@ -16,6 +17,7 @@ class RevisionCardActivity :
   InjectableAppCompatActivity(),
   ReturnToTopicClickListener,
   ConceptCardListener,
+  RouteToRevisionCardListener,
   BottomSheetOptionsMenuItemClickListener {
 
   @Inject
@@ -30,7 +32,13 @@ class RevisionCardActivity :
         "Expected topic ID to be included in intent for RevisionCardActivity."
       }
       val subtopicId = intent.getIntExtra(SUBTOPIC_ID_EXTRA_KEY, -1)
-      revisionCardActivityPresenter.handleOnCreate(internalProfileId, topicId, subtopicId)
+      val subtopicListSize = intent.getIntExtra(SUBTOPIC_LIST_SIZE_EXTRA_KEY, -1)
+      revisionCardActivityPresenter.handleOnCreate(
+        internalProfileId,
+        topicId,
+        subtopicId,
+        subtopicListSize
+      )
     }
   }
 
@@ -42,23 +50,44 @@ class RevisionCardActivity :
     internal const val INTERNAL_PROFILE_ID_EXTRA_KEY = "RevisionCardActivity.internal_profile_id"
     internal const val TOPIC_ID_EXTRA_KEY = "RevisionCardActivity.topic_id"
     internal const val SUBTOPIC_ID_EXTRA_KEY = "RevisionCardActivity.subtopic_id"
+    internal const val SUBTOPIC_LIST_SIZE_EXTRA_KEY = "RevisionCardActivity.subtopic_list_size"
 
     /** Returns a new [Intent] to route to [RevisionCardActivity]. */
     fun createRevisionCardActivityIntent(
       context: Context,
       internalProfileId: Int,
       topicId: String,
-      subtopicId: Int
+      subtopicId: Int,
+      subtopicListSize: Int
     ): Intent {
       return Intent(context, RevisionCardActivity::class.java).apply {
         putExtra(INTERNAL_PROFILE_ID_EXTRA_KEY, internalProfileId)
         putExtra(TOPIC_ID_EXTRA_KEY, topicId)
         putExtra(SUBTOPIC_ID_EXTRA_KEY, subtopicId)
+        putExtra(SUBTOPIC_LIST_SIZE_EXTRA_KEY, subtopicListSize)
         decorateWithScreenName(REVISION_CARD_ACTIVITY)
       }
     }
   }
 
+  override fun routeToRevisionCard(
+    internalProfileId: Int,
+    topicId: String,
+    subtopicId: Int,
+    subtopicListSize: Int
+  ) {
+    startActivity(
+      createRevisionCardActivityIntent(
+        this,
+        internalProfileId,
+        topicId,
+        subtopicId,
+        subtopicListSize
+      )
+    )
+    this.finish()
+  }
+
   override fun onReturnToTopicClicked() {
     onBackPressed()
   }

app/src/main/java/org/oppia/android/app/topic/revisioncard/RevisionCardActivityPresenter.kt

@@ -38,7 +38,12 @@ class RevisionCardActivityPresenter @Inject constructor(
   private lateinit var topicId: String
   private var subtopicId: Int = 0
 
-  fun handleOnCreate(internalProfileId: Int, topicId: String, subtopicId: Int) {
+  fun handleOnCreate(
+    internalProfileId: Int,
+    topicId: String,
+    subtopicId: Int,
+    subtopicListSize: Int
+  ) {
     val binding = DataBindingUtil.setContentView<RevisionCardActivityBinding>(
       activity,
       R.layout.revision_card_activity
@@ -72,7 +77,7 @@ class RevisionCardActivityPresenter @Inject constructor(
     if (getReviewCardFragment() == null) {
       activity.supportFragmentManager.beginTransaction().add(
         R.id.revision_card_fragment_placeholder,
-        RevisionCardFragment.newInstance(topicId, subtopicId, profileId)
+        RevisionCardFragment.newInstance(topicId, subtopicId, profileId, subtopicListSize)
       ).commitNow()
     }
   }

app/src/main/java/org/oppia/android/app/topic/revisioncard/RevisionCardFragment.kt

@@ -18,21 +18,24 @@ class RevisionCardFragment : InjectableDialogFragment() {
   companion object {
     private const val TOPIC_ID_ARGUMENT_KEY = "RevisionCardFragment.topic_id"
     private const val SUBTOPIC_ID_ARGUMENT_KEY = "RevisionCardFragment.subtopic_id"
+    private const val SUBTOPIC_LIST_SIZE_ARGUMENT_KEY = "RevisionCardFragment.subtopic_list_size"
     private const val PROFILE_ID_ARGUMENT_KEY = "RevisionCardFragment.profile_id"
 
     /**
      * Returns a new [RevisionCardFragment] to display the specific subtopic for the given topic &
      * profile.
      */
-    fun newInstance(topicId: String, subtopicId: Int, profileId: ProfileId): RevisionCardFragment {
-      return RevisionCardFragment().apply {
-        arguments = Bundle().apply {
-          putString(TOPIC_ID_ARGUMENT_KEY, topicId)
-          putInt(SUBTOPIC_ID_ARGUMENT_KEY, subtopicId)
-          putProto(PROFILE_ID_ARGUMENT_KEY, profileId)
+    fun newInstance(topicId: String, subtopicId: Int, profileId: ProfileId, subtopicListSize: Int):
+      RevisionCardFragment {
+        return RevisionCardFragment().apply {
+          arguments = Bundle().apply {
+            putString(TOPIC_ID_ARGUMENT_KEY, topicId)
+            putInt(SUBTOPIC_ID_ARGUMENT_KEY, subtopicId)
+            putProto(PROFILE_ID_ARGUMENT_KEY, profileId)
+            putInt(SUBTOPIC_LIST_SIZE_ARGUMENT_KEY, subtopicListSize)
+          }
         }
       }
-    }
   }
 
   @Inject
@@ -58,8 +61,9 @@ class RevisionCardFragment : InjectableDialogFragment() {
       }
     val subtopicId = args.getInt(SUBTOPIC_ID_ARGUMENT_KEY, -1)
     val profileId = args.getProto(PROFILE_ID_ARGUMENT_KEY, ProfileId.getDefaultInstance())
+    val subtopicListSize = args.getInt(SUBTOPIC_LIST_SIZE_ARGUMENT_KEY, -1)
     return revisionCardFragmentPresenter.handleCreateView(
-      inflater, container, topicId, subtopicId, profileId
+      inflater, container, topicId, subtopicId, profileId, subtopicListSize
     )
   }
 

app/src/main/java/org/oppia/android/app/topic/revisioncard/RevisionCardFragmentPresenter.kt

@@ -9,7 +9,6 @@ import org.oppia.android.app.model.ProfileId
 import org.oppia.android.app.topic.conceptcard.ConceptCardFragment
 import org.oppia.android.app.topic.conceptcard.ConceptCardFragment.Companion.CONCEPT_CARD_DIALOG_FRAGMENT_TAG
 import org.oppia.android.app.translation.AppLanguageResourceHandler
-import org.oppia.android.app.viewmodel.ViewModelProvider
 import org.oppia.android.databinding.RevisionCardFragmentBinding
 import org.oppia.android.domain.oppialogger.OppiaLogger
 import org.oppia.android.domain.translation.TranslationController
@@ -26,9 +25,9 @@ class RevisionCardFragmentPresenter @Inject constructor(
   private val htmlParserFactory: HtmlParser.Factory,
   @DefaultResourceBucketName private val resourceBucketName: String,
   @TopicHtmlParserEntityType private val entityType: String,
-  private val viewModelProvider: ViewModelProvider<RevisionCardViewModel>,
   private val translationController: TranslationController,
-  private val appLanguageResourceHandler: AppLanguageResourceHandler
+  private val appLanguageResourceHandler: AppLanguageResourceHandler,
+  private val revisionCardViewModelFactory: RevisionCardViewModel.Factory
 ) : HtmlParser.CustomOppiaTagActionListener {
   private lateinit var profileId: ProfileId
 
@@ -37,7 +36,8 @@ class RevisionCardFragmentPresenter @Inject constructor(
     container: ViewGroup?,
     topicId: String,
     subtopicId: Int,
-    profileId: ProfileId
+    profileId: ProfileId,
+    subtopicListSize: Int
   ): View? {
     this.profileId = profileId
 
@@ -48,9 +48,13 @@ class RevisionCardFragmentPresenter @Inject constructor(
         /* attachToRoot= */ false
       )
     val view = binding.revisionCardExplanationText
-    val viewModel = getReviewCardViewModel()
+    val viewModel = revisionCardViewModelFactory.create(
+      topicId,
+      subtopicId,
+      profileId,
+      subtopicListSize
+    )
 
-    viewModel.initialize(topicId, subtopicId, profileId)
     logRevisionCardEvent(topicId, subtopicId)
 
     binding.let {
@@ -59,22 +63,21 @@ class RevisionCardFragmentPresenter @Inject constructor(
     }
 
     viewModel.revisionCardLiveData.observe(
-      fragment,
-      { ephemeralRevisionCard ->
-        val pageContentsHtml =
-          translationController.extractString(
-            ephemeralRevisionCard.revisionCard.pageContents,
-            ephemeralRevisionCard.writtenTranslationContext
-          )
-        view.text = htmlParserFactory.create(
-          resourceBucketName, entityType, topicId, imageCenterAlign = true,
-          customOppiaTagActionListener = this,
-          displayLocale = appLanguageResourceHandler.getDisplayLocale()
-        ).parseOppiaHtml(
-          pageContentsHtml, view, supportsLinks = true, supportsConceptCards = true
+      fragment
+    ) { ephemeralRevisionCard ->
+      val pageContentsHtml =
+        translationController.extractString(
+          ephemeralRevisionCard.revisionCard.pageContents,
+          ephemeralRevisionCard.writtenTranslationContext
         )
-      }
-    )
+      view.text = htmlParserFactory.create(
+        resourceBucketName, entityType, topicId, imageCenterAlign = true,
+        customOppiaTagActionListener = this,
+        displayLocale = appLanguageResourceHandler.getDisplayLocale()
+      ).parseOppiaHtml(
+        pageContentsHtml, view, supportsLinks = true, supportsConceptCards = true
+      )
+    }
 
     return binding.root
   }
@@ -88,10 +91,6 @@ class RevisionCardFragmentPresenter @Inject constructor(
     }
   }
 
-  private fun getReviewCardViewModel(): RevisionCardViewModel {
-    return viewModelProvider.getForFragment(fragment, RevisionCardViewModel::class.java)
-  }
-
   private fun logRevisionCardEvent(topicId: String, subTopicId: Int) {
     oppiaLogger.logImportantEvent(oppiaLogger.createOpenRevisionCardContext(topicId, subTopicId))
   }