Fixes #4470, #4471, #4472, #4473, #4474, #4708: Handle configuration change using on saved instance

app/src/main/java/org/oppia/android/app/player/state/StateFragment.kt

@@ -8,6 +8,7 @@ import android.view.ViewGroup
 import org.oppia.android.app.fragment.FragmentComponentImpl
 import org.oppia.android.app.fragment.InjectableFragment
 import org.oppia.android.app.model.HelpIndex
+import org.oppia.android.app.model.RawUserAnswer
 import org.oppia.android.app.model.UserAnswer
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerErrorOrAvailabilityCheckReceiver
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerHandler
@@ -19,7 +20,9 @@ import org.oppia.android.app.player.state.listener.PreviousResponsesHeaderClickL
 import org.oppia.android.app.player.state.listener.ReturnToTopicNavigationButtonListener
 import org.oppia.android.app.player.state.listener.ShowHintAvailabilityListener
 import org.oppia.android.app.player.state.listener.SubmitNavigationButtonListener
+import org.oppia.android.util.extensions.getProto
 import org.oppia.android.util.extensions.getStringFromBundle
+import org.oppia.android.util.extensions.putProto
 import javax.inject.Inject
 
 /** Fragment that represents the current state of an exploration. */
@@ -79,12 +82,17 @@ class StateFragment :
     val storyId = arguments!!.getStringFromBundle(STATE_FRAGMENT_STORY_ID_ARGUMENT_KEY)!!
     val explorationId =
       arguments!!.getStringFromBundle(STATE_FRAGMENT_EXPLORATION_ID_ARGUMENT_KEY)!!
+    var rawUserAnswer: RawUserAnswer? = null
+    if (savedInstanceState != null) {
+      rawUserAnswer = savedInstanceState.getProto("Answer", RawUserAnswer.getDefaultInstance())
+    }
     return stateFragmentPresenter.handleCreateView(
       inflater,
       container,
       internalProfileId,
       topicId,
       storyId,
+      rawUserAnswer,
       explorationId
     )
   }
@@ -129,6 +137,11 @@ class StateFragment :
     stateFragmentPresenter.revealHint(hintIndex)
   }
 
+  override fun onSaveInstanceState(outState: Bundle) {
+    super.onSaveInstanceState(outState)
+    outState.putProto("Answer", stateFragmentPresenter.handleOnSavedInstance())
+  }
+
   fun revealSolution() = stateFragmentPresenter.revealSolution()
 
   fun dismissConceptCard() = stateFragmentPresenter.dismissConceptCard()

app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt

@@ -1,6 +1,7 @@
 package org.oppia.android.app.player.state
 
 import android.content.Context
+import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -24,6 +25,7 @@ import org.oppia.android.app.model.CheckpointState
 import org.oppia.android.app.model.EphemeralState
 import org.oppia.android.app.model.HelpIndex
 import org.oppia.android.app.model.ProfileId
+import org.oppia.android.app.model.RawUserAnswer
 import org.oppia.android.app.model.State
 import org.oppia.android.app.model.UserAnswer
 import org.oppia.android.app.player.audio.AudioButtonListener
@@ -47,6 +49,8 @@ import org.oppia.android.util.data.DataProvider
 import org.oppia.android.util.data.DataProviders.Companion.toLiveData
 import org.oppia.android.util.gcsresource.DefaultResourceBucketName
 import org.oppia.android.util.parser.html.ExplorationHtmlParserEntityType
+import org.oppia.android.util.platformparameter.EnableInteractionConfigChangeStateRetention
+import org.oppia.android.util.platformparameter.PlatformParameterValue
 import org.oppia.android.util.system.OppiaClock
 import javax.inject.Inject
 
@@ -71,6 +75,8 @@ class StateFragmentPresenter @Inject constructor(
   private val storyProgressController: StoryProgressController,
   private val oppiaLogger: OppiaLogger,
   @DefaultResourceBucketName private val resourceBucketName: String,
+  @EnableInteractionConfigChangeStateRetention
+  private val isConfigChangeStateRetentionEnabled: PlatformParameterValue<Boolean>,
   private val assemblerBuilderFactory: StatePlayerRecyclerViewAssembler.Builder.Factory,
   private val splitScreenManager: SplitScreenManager,
   private val oppiaClock: OppiaClock
@@ -105,6 +111,7 @@ class StateFragmentPresenter @Inject constructor(
     internalProfileId: Int,
     topicId: String,
     storyId: String,
+    rawUserAnswer: RawUserAnswer?,
     explorationId: String
   ): View? {
     profileId = ProfileId.newBuilder().setInternalId(internalProfileId).build()
@@ -158,7 +165,7 @@ class StateFragmentPresenter @Inject constructor(
       )
     }
 
-    subscribeToCurrentState()
+    subscribeToCurrentState(rawUserAnswer)
     return binding.root
   }
 
@@ -278,25 +285,28 @@ class StateFragmentPresenter @Inject constructor(
     return getAudioFragment() as? AudioUiManager
   }
 
-  private fun subscribeToCurrentState() {
+  private fun subscribeToCurrentState(rawUserAnswer: RawUserAnswer?) {
     ephemeralStateLiveData.observe(
       fragment,
       { result ->
-        processEphemeralStateResult(result)
+        processEphemeralStateResult(result, rawUserAnswer)
       }
     )
   }
 
-  private fun processEphemeralStateResult(result: AsyncResult<EphemeralState>) {
+  private fun processEphemeralStateResult(
+    result: AsyncResult<EphemeralState>,
+    rawUserAnswer: RawUserAnswer?
+  ) {
     when (result) {
       is AsyncResult.Failure ->
         oppiaLogger.e("StateFragment", "Failed to retrieve ephemeral state", result.error)
       is AsyncResult.Pending -> {} // Display nothing until a valid result is available.
-      is AsyncResult.Success -> processEphemeralState(result.value)
+      is AsyncResult.Success -> processEphemeralState(result.value, rawUserAnswer)
     }
   }
 
-  private fun processEphemeralState(ephemeralState: EphemeralState) {
+  private fun processEphemeralState(ephemeralState: EphemeralState, rawUserAnswer: RawUserAnswer?) {
     explorationCheckpointState = ephemeralState.checkpointState
     val shouldSplit = splitScreenManager.shouldSplitScreen(ephemeralState.state.interaction.id)
     if (shouldSplit) {
@@ -307,6 +317,8 @@ class StateFragmentPresenter @Inject constructor(
       viewModel.centerGuidelinePercentage.set(1f)
     }
 
+    Log.d("testAnswer", "Ephemeral State Called")
+
     val isInNewState =
       ::currentStateName.isInitialized && currentStateName != ephemeralState.state.name
 
@@ -318,6 +330,7 @@ class StateFragmentPresenter @Inject constructor(
     val dataPair = recyclerViewAssembler.compute(
       ephemeralState,
       explorationId,
+      rawUserAnswer,
       shouldSplit
     )
 
@@ -451,6 +464,14 @@ class StateFragmentPresenter @Inject constructor(
   /** Returns the checkpoint state for the current exploration. */
   fun getExplorationCheckpointState() = explorationCheckpointState
 
+  fun handleOnSavedInstance(): RawUserAnswer {
+    return if (isConfigChangeStateRetentionEnabled.value) {
+      viewModel.getRawUserAnswer(recyclerViewAssembler::getPendingAnswerHandler)
+    } else {
+      RawUserAnswer.getDefaultInstance()
+    }
+  }
+
   private fun markExplorationCompleted() {
     storyProgressController.recordCompletedChapter(
       profileId,

app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt

@@ -25,6 +25,7 @@ import org.oppia.android.app.model.EphemeralState.StateTypeCase
 import org.oppia.android.app.model.HelpIndex
 import org.oppia.android.app.model.Interaction
 import org.oppia.android.app.model.ProfileId
+import org.oppia.android.app.model.RawUserAnswer
 import org.oppia.android.app.model.StringList
 import org.oppia.android.app.model.SubtitledHtml
 import org.oppia.android.app.model.UserAnswer
@@ -195,6 +196,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
   fun compute(
     ephemeralState: EphemeralState,
     gcsEntityId: String,
+    rawUserAnswer: RawUserAnswer?,
     isSplitView: Boolean
   ): Pair<List<StateItemViewModel>, List<StateItemViewModel>> {
     this.isSplitView.set(isSplitView)
@@ -231,6 +233,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
           interaction,
           hasPreviousState,
           gcsEntityId,
+          rawUserAnswer,
           ephemeralState.writtenTranslationContext
         )
       }
@@ -305,12 +308,14 @@ class StatePlayerRecyclerViewAssembler private constructor(
     interaction: Interaction,
     hasPreviousButton: Boolean,
     gcsEntityId: String,
+    rawUserAnswer: RawUserAnswer?,
     writtenTranslationContext: WrittenTranslationContext
   ) {
     val interactionViewModelFactory = interactionViewModelFactoryMap.getValue(interaction.id)
     pendingItemList += interactionViewModelFactory.create(
       gcsEntityId,
       hasConversationView,
+      rawUserAnswer,
       interaction,
       fragment as InteractionAnswerReceiver,
       fragment as InteractionAnswerErrorOrAvailabilityCheckReceiver,

app/src/main/java/org/oppia/android/app/player/state/StateViewModel.kt

@@ -4,6 +4,7 @@ import androidx.databinding.ObservableField
 import androidx.databinding.ObservableList
 import androidx.lifecycle.ViewModel
 import org.oppia.android.app.fragment.FragmentScope
+import org.oppia.android.app.model.RawUserAnswer
 import org.oppia.android.app.model.UserAnswer
 import org.oppia.android.app.player.state.answerhandling.AnswerErrorCategory
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerHandler
@@ -56,6 +57,16 @@ class StateViewModel @Inject constructor() : ObservableViewModel() {
     ) ?: UserAnswer.getDefaultInstance()
   }
 
+  fun getRawUserAnswer(
+    retrieveAnswerHandler: (List<StateItemViewModel>) -> InteractionAnswerHandler?
+  ): RawUserAnswer {
+    return getRawUserAnswerWithError(
+      retrieveAnswerHandler(
+        getAnswerItemList()
+      )
+    ) ?: RawUserAnswer.getDefaultInstance()
+  }
+
   private fun getPendingAnswerWithoutError(
     answerHandler: InteractionAnswerHandler?
   ): UserAnswer? {
@@ -66,6 +77,12 @@ class StateViewModel @Inject constructor() : ObservableViewModel() {
     }
   }
 
+  private fun getRawUserAnswerWithError(
+    answerHandler: InteractionAnswerHandler?
+  ): RawUserAnswer? {
+    return answerHandler?.getRawUserAnswer()
+  }
+
   private fun getAnswerItemList(): List<StateItemViewModel> {
     return if (isSplitView.get() == true) {
       rightItemList

app/src/main/java/org/oppia/android/app/player/state/answerhandling/InteractionAnswerHandler.kt

@@ -1,5 +1,6 @@
 package org.oppia.android.app.player.state.answerhandling
 
+import org.oppia.android.app.model.RawUserAnswer
 import org.oppia.android.app.model.UserAnswer
 
 /**
@@ -26,6 +27,11 @@ interface InteractionAnswerHandler {
   fun getPendingAnswer(): UserAnswer? {
     return null
   }
+
+  /** Return the last entered answer entered by user. */
+  fun getRawUserAnswer(): RawUserAnswer? {
+    return null
+  }
 }
 
 /**

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/ContinueInteractionViewModel.kt

@@ -3,6 +3,7 @@ package org.oppia.android.app.player.state.itemviewmodel
 import androidx.fragment.app.Fragment
 import org.oppia.android.app.model.Interaction
 import org.oppia.android.app.model.InteractionObject
+import org.oppia.android.app.model.RawUserAnswer
 import org.oppia.android.app.model.UserAnswer
 import org.oppia.android.app.model.WrittenTranslationContext
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerErrorOrAvailabilityCheckReceiver
@@ -24,6 +25,7 @@ private const val DEFAULT_CONTINUE_INTERACTION_TEXT_ANSWER = "Please continue."
 class ContinueInteractionViewModel private constructor(
   private val interactionAnswerReceiver: InteractionAnswerReceiver,
   val hasConversationView: Boolean,
+  rawUserAnswer: RawUserAnswer?,
   val hasPreviousButton: Boolean,
   val previousNavigationButtonListener: PreviousNavigationButtonListener,
   val isSplitView: Boolean,
@@ -41,6 +43,10 @@ class ContinueInteractionViewModel private constructor(
     this.writtenTranslationContext = [email protected]
   }.build()
 
+  override fun getRawUserAnswer(): RawUserAnswer? {
+    return RawUserAnswer.getDefaultInstance()
+  }
+
   fun handleButtonClicked() {
     interactionAnswerReceiver.onAnswerReadyForSubmission(getPendingAnswer())
   }
@@ -52,6 +58,7 @@ class ContinueInteractionViewModel private constructor(
     override fun create(
       entityId: String,
       hasConversationView: Boolean,
+      rawUserAnswer: RawUserAnswer?,
       interaction: Interaction,
       interactionAnswerReceiver: InteractionAnswerReceiver,
       answerErrorReceiver: InteractionAnswerErrorOrAvailabilityCheckReceiver,
@@ -62,6 +69,7 @@ class ContinueInteractionViewModel private constructor(
       return ContinueInteractionViewModel(
         interactionAnswerReceiver,
         hasConversationView,
+        rawUserAnswer,
         hasPreviousButton,
         fragment as PreviousNavigationButtonListener,
         isSplitView,

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/DragAndDropSortInteractionViewModel.kt

@@ -7,6 +7,7 @@ import org.oppia.android.app.model.Interaction
 import org.oppia.android.app.model.InteractionObject
 import org.oppia.android.app.model.ListOfSetsOfHtmlStrings
 import org.oppia.android.app.model.ListOfSetsOfTranslatableHtmlContentIds
+import org.oppia.android.app.model.RawUserAnswer
 import org.oppia.android.app.model.SetOfTranslatableHtmlContentIds
 import org.oppia.android.app.model.StringList
 import org.oppia.android.app.model.SubtitledHtml
@@ -27,6 +28,7 @@ import javax.inject.Inject
 class DragAndDropSortInteractionViewModel private constructor(
   val entityId: String,
   val hasConversationView: Boolean,
+  rawUserAnswer: RawUserAnswer?,
   interaction: Interaction,
   private val interactionAnswerErrorOrAvailabilityCheckReceiver: InteractionAnswerErrorOrAvailabilityCheckReceiver, // ktlint-disable max-line-length
   val isSplitView: Boolean,
@@ -129,6 +131,10 @@ class DragAndDropSortInteractionViewModel private constructor(
       this@DragAndDropSortInteractionViewModel.writtenTranslationContext
   }.build()
 
+  override fun getRawUserAnswer(): RawUserAnswer {
+    return RawUserAnswer.getDefaultInstance()
+  }
+
   /** Returns an HTML list containing all of the HTML string elements as items in the list. */
   private fun convertItemsToAnswer(htmlItems: List<StringList>): ListOfSetsOfHtmlStrings {
     return ListOfSetsOfHtmlStrings.newBuilder()
@@ -198,6 +204,7 @@ class DragAndDropSortInteractionViewModel private constructor(
     override fun create(
       entityId: String,
       hasConversationView: Boolean,
+      rawUserAnswer: RawUserAnswer?,
       interaction: Interaction,
       interactionAnswerReceiver: InteractionAnswerReceiver,
       answerErrorReceiver: InteractionAnswerErrorOrAvailabilityCheckReceiver,
@@ -208,6 +215,7 @@ class DragAndDropSortInteractionViewModel private constructor(
       return DragAndDropSortInteractionViewModel(
         entityId,
         hasConversationView,
+        rawUserAnswer,
         interaction,
         answerErrorReceiver,
         isSplitView,