From 98099e2bd8036389df86b5b791d9b75867d2785b Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Mon, 25 Jan 2021 01:12:25 +0530
Subject: [PATCH 01/14] Fixed Revealing Second hint

---
 .../state/StatePlayerRecyclerViewAssembler.kt |  2 +-
 .../app/player/state/StateFragmentTest.kt     | 96 +++++++++++++++++++
 2 files changed, 97 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 578cd23ff3c..978f86f80e8 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -1376,7 +1376,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
         }
       } else {
         // See if the learner's new wrong answer justifies showing a hint.
-        if (isFirstHint) {
+        if (isFirstHint && nextUnrevealedHintIndex.hintIndex == 0) {
           if (wrongAnswerCount > 1) {
             // If more than one answer has been submitted and no hint has yet been shown, show a
             // hint immediately since the learner is probably stuck.
diff --git a/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt b/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
index 4db6235e830..b39d6df957d 100644
--- a/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
@@ -20,6 +20,7 @@ import androidx.test.espresso.action.GeneralLocation
 import androidx.test.espresso.action.Press
 import androidx.test.espresso.action.ViewActions.click
 import androidx.test.espresso.action.ViewActions.closeSoftKeyboard
+import androidx.test.espresso.action.ViewActions.pressBack
 import androidx.test.espresso.assertion.ViewAssertions.doesNotExist
 import androidx.test.espresso.assertion.ViewAssertions.matches
 import androidx.test.espresso.contrib.RecyclerViewActions.scrollToHolder
@@ -103,6 +104,7 @@ import org.oppia.android.domain.oppialogger.LogStorageModule
 import org.oppia.android.domain.oppialogger.loguploader.LogUploadWorkerModule
 import org.oppia.android.domain.oppialogger.loguploader.WorkManagerConfigurationModule
 import org.oppia.android.domain.question.QuestionModule
+import org.oppia.android.domain.topic.FRACTIONS_EXPLORATION_ID_0
 import org.oppia.android.domain.topic.FRACTIONS_EXPLORATION_ID_1
 import org.oppia.android.domain.topic.PrimeTopicAssetsControllerModule
 import org.oppia.android.domain.topic.TEST_EXPLORATION_ID_0
@@ -905,6 +907,100 @@ class StateFragmentTest {
     }
   }
 
+  @Test
+  fun testStateFragment_forTwoWrongAnswers_revealHint() {
+    launchForExploration(FRACTIONS_EXPLORATION_ID_0).use {
+      startPlayingExploration()
+      clickContinueInteractionButton()
+      clickContinueInteractionButton()
+      clickContinueInteractionButton()
+      selectMultipleChoiceOption(optionPosition = 2)
+      clickContinueNavigationButton()
+      selectMultipleChoiceOption(optionPosition = 1)
+      clickContinueNavigationButton()
+      selectMultipleChoiceOption(optionPosition = 1)
+      clickContinueNavigationButton()
+      onView(withId(R.id.hints_and_solution_fragment_container)).check(
+        matches(
+          not(isDisplayed())
+        )
+      )
+      selectMultipleChoiceOption(optionPosition = 1)
+      selectMultipleChoiceOption(optionPosition = 1)
+      onView(withId(R.id.hints_and_solution_fragment_container)).check(
+        matches(
+          isDisplayed()
+        )
+      )
+    }
+  }
+
+  @Test
+  fun testStateFragment_forTwoWrongAnswers_revealHint_dotDisappears() {
+    launchForExploration(FRACTIONS_EXPLORATION_ID_0).use {
+      startPlayingExploration()
+      clickContinueInteractionButton()
+      clickContinueInteractionButton()
+      clickContinueInteractionButton()
+      selectMultipleChoiceOption(optionPosition = 2)
+      clickContinueNavigationButton()
+      selectMultipleChoiceOption(optionPosition = 1)
+      clickContinueNavigationButton()
+      selectMultipleChoiceOption(optionPosition = 1)
+      clickContinueNavigationButton()
+
+      selectMultipleChoiceOption(optionPosition = 1)
+      selectMultipleChoiceOption(optionPosition = 1)
+      onView(withId(R.id.dot_hint)).check(
+        matches(
+          isDisplayed()
+        )
+      )
+      onView(withId(R.id.hints_and_solution_fragment_container)).perform(click())
+      onView(withId(R.id.reveal_hint_button)).perform(click())
+      onView(isRoot()).perform(pressBack())
+      onView(withId(R.id.dot_hint)).check(
+        matches(
+          not(isDisplayed())
+        )
+      )
+    }
+  }
+
+  @Test
+  fun testStateFragment_forTwoWrongAnswers_revealHint_configurationChange_newHintNotRevealed() {
+    launchForExploration(FRACTIONS_EXPLORATION_ID_0).use {
+      startPlayingExploration()
+      clickContinueInteractionButton()
+      clickContinueInteractionButton()
+      clickContinueInteractionButton()
+      selectMultipleChoiceOption(optionPosition = 2)
+      clickContinueNavigationButton()
+      selectMultipleChoiceOption(optionPosition = 1)
+      clickContinueNavigationButton()
+      selectMultipleChoiceOption(optionPosition = 1)
+      clickContinueNavigationButton()
+
+      selectMultipleChoiceOption(optionPosition = 1)
+      selectMultipleChoiceOption(optionPosition = 1)
+      onView(withId(R.id.dot_hint)).check(
+        matches(
+          isDisplayed()
+        )
+      )
+      onView(withId(R.id.hints_and_solution_fragment_container)).perform(click())
+      onView(withId(R.id.reveal_hint_button)).perform(click())
+      onView(isRoot()).perform(pressBack())
+      rotateToLandscape()
+      onView(withId(R.id.dot_hint)).check(
+        matches(
+          not(isDisplayed())
+        )
+      )
+    }
+  }
+
+
   @Test
   fun testStateFragment_forMisconception_showsLinkTextForConceptCard() {
     launchForExploration(FRACTIONS_EXPLORATION_ID_1).use {

From eb761b7cd70641fc950ed3b030a88b1ae93b858c Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Mon, 25 Jan 2021 01:19:06 +0530
Subject: [PATCH 02/14] ktlint fix

---
 .../java/org/oppia/android/app/player/state/StateFragmentTest.kt | 1 -
 1 file changed, 1 deletion(-)

diff --git a/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt b/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
index b39d6df957d..b74bcc3a8e9 100644
--- a/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
@@ -1000,7 +1000,6 @@ class StateFragmentTest {
     }
   }
 
-
   @Test
   fun testStateFragment_forMisconception_showsLinkTextForConceptCard() {
     launchForExploration(FRACTIONS_EXPLORATION_ID_1).use {

From 54c9e9e2de4c52084358ac0d8ee82648f63ad86c Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Fri, 5 Feb 2021 21:59:39 +0530
Subject: [PATCH 03/14] making HintHandler life cycle aware

---
 .../android/app/player/state/StateFragment.kt |  8 ++++-
 .../player/state/StateFragmentPresenter.kt    | 12 +++++++-
 .../state/StatePlayerRecyclerViewAssembler.kt | 29 +++++++++++++++----
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StateFragment.kt b/app/src/main/java/org/oppia/android/app/player/state/StateFragment.kt
index 1eff9e90ff0..211732cfdcb 100755
--- a/app/src/main/java/org/oppia/android/app/player/state/StateFragment.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StateFragment.kt
@@ -82,10 +82,16 @@ class StateFragment :
       internalProfileId,
       topicId,
       storyId,
-      explorationId
+      explorationId,
+      savedInstanceState
     )
   }
 
+  override fun onSaveInstanceState(outState: Bundle) {
+    super.onSaveInstanceState(outState)
+    stateFragmentPresenter.handleOnSaveInstanceState(outState)
+  }
+
   override fun onAnswerReadyForSubmission(answer: UserAnswer) {
     stateFragmentPresenter.handleAnswerReadyForSubmission(answer)
   }
diff --git a/app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt b/app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt
index 43737cab4be..21710bca62f 100755
--- a/app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt
+++ b/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.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -88,13 +89,18 @@ class StateFragmentPresenter @Inject constructor(
     internalProfileId: Int,
     topicId: String,
     storyId: String,
-    explorationId: String
+    explorationId: String,
+    savedInstanceState: Bundle?
   ): View? {
     profileId = ProfileId.newBuilder().setInternalId(internalProfileId).build()
     this.topicId = topicId
     this.storyId = storyId
     this.explorationId = explorationId
 
+    savedInstanceState?.let {
+      recyclerViewAssembler.restoreState(savedInstanceState)
+    }
+
     binding = StateFragmentBinding.inflate(
       inflater,
       container,
@@ -145,6 +151,10 @@ class StateFragmentPresenter @Inject constructor(
     return binding.root
   }
 
+  fun handleOnSaveInstanceState(bundle: Bundle) {
+    recyclerViewAssembler.saveState(bundle)
+  }
+
   fun handleAnswerReadyForSubmission(answer: UserAnswer) {
     // An interaction has indicated that an answer is ready for submission.
     handleSubmitAnswer(answer)
diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 978f86f80e8..c4ed7fbdb81 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -1,5 +1,6 @@
 package org.oppia.android.app.player.state
 
+import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.animation.AccelerateInterpolator
@@ -92,6 +93,10 @@ private typealias AudioUiManagerRetriever = () -> AudioUiManager?
 
 /** The fragment tag corresponding to the concept card dialog fragment. */
 const val CONCEPT_CARD_DIALOG_FRAGMENT_TAG = "CONCEPT_CARD_FRAGMENT"
+const val KEY_TRACKED_WRONG_ANSWER_COUNT = "TRACKED_WRONG_ANSWER_COUNT"
+const val KEY_PREVIOUS_HELP_INDEX = "PREVIOUS_HELP_INDEX"
+const val KEY_HINT_SEQUENCE_NUMBER = "HINT_SEQUENCE_NUMBER"
+const val KEY_IS_HINT_VISIBLE_IN_LATEST_STATE = "IS_HINT_VISIBLE_IN_LATEST_STATE"
 
 /**
  * An assembler for generating the list of view models to bind to the state player recycler view.
@@ -150,6 +155,20 @@ class StatePlayerRecyclerViewAssembler private constructor(
 
   val isCorrectAnswer = ObservableField<Boolean>(false)
 
+  fun saveState(bundle: Bundle) {
+    bundle.putInt(KEY_TRACKED_WRONG_ANSWER_COUNT, hintHandler.trackedWrongAnswerCount)
+    // bundle.putSerializable(KEY_PREVIOUS_HELP_INDEX, hintHandler.previousHelpIndex as Serializable)
+    bundle.putInt(KEY_HINT_SEQUENCE_NUMBER, hintHandler.hintSequenceNumber)
+    bundle.putBoolean(KEY_IS_HINT_VISIBLE_IN_LATEST_STATE, hintHandler.isHintVisibleInLatestState)
+  }
+
+  fun restoreState(bundle: Bundle) {
+    hintHandler.trackedWrongAnswerCount = bundle.getInt(KEY_TRACKED_WRONG_ANSWER_COUNT)
+    // hintHandler.previousHelpIndex = bundle.get(KEY_PREVIOUS_HELP_INDEX) as HelpIndex
+    hintHandler.hintSequenceNumber = bundle.getInt(KEY_HINT_SEQUENCE_NUMBER)
+    hintHandler.isHintVisibleInLatestState = bundle.getBoolean(KEY_IS_HINT_VISIBLE_IN_LATEST_STATE)
+  }
+
   private val lifecycleSafeTimerFactory = LifecycleSafeTimerFactory(backgroundCoroutineDispatcher)
 
   private val hintHandler = HintHandler(
@@ -1309,10 +1328,10 @@ class StatePlayerRecyclerViewAssembler private constructor(
     private val delayShowAdditionalHintsMs: Long,
     private val delayShowAdditionalHintsFromWrongAnswerMs: Long
   ) {
-    private var trackedWrongAnswerCount = 0
-    private var previousHelpIndex: HelpIndex = HelpIndex.getDefaultInstance()
-    private var hintSequenceNumber = 0
-    private var isHintVisibleInLatestState = false
+    var trackedWrongAnswerCount = 0
+    var previousHelpIndex: HelpIndex = HelpIndex.getDefaultInstance()
+    var hintSequenceNumber = 0
+    var isHintVisibleInLatestState = false
 
     /** Resets this handler to prepare it for a new state, cancelling any pending hints. */
     fun reset() {
@@ -1376,7 +1395,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
         }
       } else {
         // See if the learner's new wrong answer justifies showing a hint.
-        if (isFirstHint && nextUnrevealedHintIndex.hintIndex == 0) {
+        if (isFirstHint) {
           if (wrongAnswerCount > 1) {
             // If more than one answer has been submitted and no hint has yet been shown, show a
             // hint immediately since the learner is probably stuck.

From 4dcedf12b0289de90c1eaf64fefb4737a66b82a5 Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Fri, 5 Feb 2021 22:08:54 +0530
Subject: [PATCH 04/14] ktlint fix

---
 .../app/player/state/StatePlayerRecyclerViewAssembler.kt        | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 7d3dfb1aac8..0db279d5b8c 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -1,7 +1,7 @@
 package org.oppia.android.app.player.state
 
-import android.os.Bundle
 import android.content.Context
+import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.animation.AccelerateInterpolator

From 96b3c482ed863b5e8d07c5cb3b791530e8166d64 Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Fri, 5 Feb 2021 23:17:34 +0530
Subject: [PATCH 05/14] NIT fix

---
 .../player/state/StateFragmentPresenter.kt    |  8 +++----
 .../state/StatePlayerRecyclerViewAssembler.kt | 22 +++++++++----------
 2 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt b/app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt
index 3de113aa4d1..a3525fcb374 100755
--- a/app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StateFragmentPresenter.kt
@@ -101,11 +101,6 @@ class StateFragmentPresenter @Inject constructor(
     this.topicId = topicId
     this.storyId = storyId
     this.explorationId = explorationId
-
-    savedInstanceState?.let {
-      recyclerViewAssembler.restoreState(savedInstanceState)
-    }
-
     binding = StateFragmentBinding.inflate(
       inflater,
       container,
@@ -117,6 +112,9 @@ class StateFragmentPresenter @Inject constructor(
       binding.congratulationsTextConfettiView,
       binding.fullScreenConfettiView
     )
+    savedInstanceState?.let {
+      recyclerViewAssembler.restoreState(savedInstanceState)
+    }
 
     val stateRecyclerViewAdapter = recyclerViewAssembler.adapter
     val rhsStateRecyclerViewAdapter = recyclerViewAssembler.rhsAdapter
diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 0db279d5b8c..9984eecf6fc 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -765,9 +765,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
       yPosition = height / 2,
       minAngle = 180.0,
       maxAngle = 270.0,
-      timeToLiveMs,
+      timeToLiveMs = timeToLiveMs,
       delayMs = 0L,
-      colorsList
+      colorsList = colorsList
     )
     config.startConfettiBurst(
       confettiView,
@@ -775,9 +775,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
       yPosition = height / 2,
       minAngle = 270.0,
       maxAngle = 370.0,
-      timeToLiveMs,
+      timeToLiveMs = timeToLiveMs,
       delayMs = 0L,
-      colorsList
+      colorsList = colorsList
     )
   }
 
@@ -821,9 +821,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
       yPosition = 0f,
       minAngle = -90.0,
       maxAngle = 90.0,
-      timeToLiveMillis,
-      delayMillis,
-      colorsList
+      timeToLiveMs = timeToLiveMillis,
+      delayMs = delayMillis,
+      colorsList = colorsList
     )
     config.startConfettiBurst(
       confettiView,
@@ -831,9 +831,9 @@ class StatePlayerRecyclerViewAssembler private constructor(
       yPosition = 0f,
       minAngle = 90.0,
       maxAngle = 270.0,
-      timeToLiveMillis,
-      delayMillis,
-      colorsList
+      timeToLiveMs = timeToLiveMillis,
+      delayMs = delayMillis,
+      colorsList = colorsList
     )
   }
 
@@ -1269,7 +1269,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
      */
     fun hasConversationView(hasConversationView: Boolean): Builder {
       this.hasConversationView = hasConversationView
-      featureSets += PlayerFeatureSet(showCongratulationsOnCorrectAnswer = true)
+      featureSets += PlayerFeatureSet(showCelebrationOnCorrectAnswer = true)
       return this
     }
 

From 76745762108b55ac85bb57d2208fa671796092df Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Sat, 6 Feb 2021 15:08:09 +0530
Subject: [PATCH 06/14] Using proto in bundle

---
 .../app/player/state/StatePlayerRecyclerViewAssembler.kt | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 9984eecf6fc..6c544fe5b06 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -89,6 +89,8 @@ import org.oppia.android.databinding.SubmittedAnswerItemBinding
 import org.oppia.android.databinding.SubmittedAnswerListItemBinding
 import org.oppia.android.databinding.SubmittedHtmlAnswerItemBinding
 import org.oppia.android.databinding.TextInputInteractionItemBinding
+import org.oppia.android.util.extensions.getProto
+import org.oppia.android.util.extensions.putProto
 import org.oppia.android.util.parser.HtmlParser
 import org.oppia.android.util.threading.BackgroundDispatcher
 import javax.inject.Inject
@@ -169,14 +171,17 @@ class StatePlayerRecyclerViewAssembler private constructor(
 
   fun saveState(bundle: Bundle) {
     bundle.putInt(KEY_TRACKED_WRONG_ANSWER_COUNT, hintHandler.trackedWrongAnswerCount)
-    // bundle.putSerializable(KEY_PREVIOUS_HELP_INDEX, hintHandler.previousHelpIndex as Serializable)
+    bundle.putProto(KEY_PREVIOUS_HELP_INDEX, hintHandler.previousHelpIndex)
     bundle.putInt(KEY_HINT_SEQUENCE_NUMBER, hintHandler.hintSequenceNumber)
     bundle.putBoolean(KEY_IS_HINT_VISIBLE_IN_LATEST_STATE, hintHandler.isHintVisibleInLatestState)
   }
 
   fun restoreState(bundle: Bundle) {
     hintHandler.trackedWrongAnswerCount = bundle.getInt(KEY_TRACKED_WRONG_ANSWER_COUNT)
-    // hintHandler.previousHelpIndex = bundle.get(KEY_PREVIOUS_HELP_INDEX) as HelpIndex
+    hintHandler.previousHelpIndex = bundle.getProto(
+      KEY_PREVIOUS_HELP_INDEX,
+      HelpIndex.getDefaultInstance()
+    )
     hintHandler.hintSequenceNumber = bundle.getInt(KEY_HINT_SEQUENCE_NUMBER)
     hintHandler.isHintVisibleInLatestState = bundle.getBoolean(KEY_IS_HINT_VISIBLE_IN_LATEST_STATE)
   }

From 0a566c3844d54b23f14ff8fc4f739ebf3311ba45 Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Wed, 10 Feb 2021 14:18:41 +0530
Subject: [PATCH 07/14] Added single proto for to handle the hint related
 configuration changes.

---
 .../state/StatePlayerRecyclerViewAssembler.kt | 31 ++++++++++---------
 model/src/main/proto/exploration.proto        |  7 +++++
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 6c544fe5b06..7a4b728171f 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -22,8 +22,11 @@ import nl.dionsegijn.konfetti.KonfettiView
 import org.oppia.android.app.model.AnswerAndResponse
 import org.oppia.android.app.model.EphemeralState
 import org.oppia.android.app.model.EphemeralState.StateTypeCase
+import org.oppia.android.app.model.Exploration
 import org.oppia.android.app.model.HelpIndex
 import org.oppia.android.app.model.HelpIndex.IndexTypeCase.INDEXTYPE_NOT_SET
+import org.oppia.android.app.model.Hint
+import org.oppia.android.app.model.HintState
 import org.oppia.android.app.model.Interaction
 import org.oppia.android.app.model.PendingState
 import org.oppia.android.app.model.State
@@ -99,10 +102,7 @@ private typealias AudioUiManagerRetriever = () -> AudioUiManager?
 
 /** The fragment tag corresponding to the concept card dialog fragment. */
 const val CONCEPT_CARD_DIALOG_FRAGMENT_TAG = "CONCEPT_CARD_FRAGMENT"
-const val KEY_TRACKED_WRONG_ANSWER_COUNT = "TRACKED_WRONG_ANSWER_COUNT"
-const val KEY_PREVIOUS_HELP_INDEX = "PREVIOUS_HELP_INDEX"
-const val KEY_HINT_SEQUENCE_NUMBER = "HINT_SEQUENCE_NUMBER"
-const val KEY_IS_HINT_VISIBLE_IN_LATEST_STATE = "IS_HINT_VISIBLE_IN_LATEST_STATE"
+const val KEY_HINT_STATE = "HINT_STATE"
 
 private const val CONGRATULATIONS_TEXT_VIEW_FADE_MILLIS: Long = 600
 private const val CONGRATULATIONS_TEXT_VIEW_VISIBLE_MILLIS: Long = 800
@@ -170,20 +170,21 @@ class StatePlayerRecyclerViewAssembler private constructor(
   val isCorrectAnswer = ObservableField<Boolean>(false)
 
   fun saveState(bundle: Bundle) {
-    bundle.putInt(KEY_TRACKED_WRONG_ANSWER_COUNT, hintHandler.trackedWrongAnswerCount)
-    bundle.putProto(KEY_PREVIOUS_HELP_INDEX, hintHandler.previousHelpIndex)
-    bundle.putInt(KEY_HINT_SEQUENCE_NUMBER, hintHandler.hintSequenceNumber)
-    bundle.putBoolean(KEY_IS_HINT_VISIBLE_IN_LATEST_STATE, hintHandler.isHintVisibleInLatestState)
+    val hintState:HintState = HintState.newBuilder().apply {
+      wrongAnswerCount = hintHandler.trackedWrongAnswerCount
+      helpIndex = hintHandler.previousHelpIndex
+      hintSequenceNumber = hintHandler.hintSequenceNumber
+      isHintVisibleInLatestState = hintHandler.isHintVisibleInLatestState
+    }.build()
+    bundle.putProto(KEY_HINT_STATE, hintState)
   }
 
   fun restoreState(bundle: Bundle) {
-    hintHandler.trackedWrongAnswerCount = bundle.getInt(KEY_TRACKED_WRONG_ANSWER_COUNT)
-    hintHandler.previousHelpIndex = bundle.getProto(
-      KEY_PREVIOUS_HELP_INDEX,
-      HelpIndex.getDefaultInstance()
-    )
-    hintHandler.hintSequenceNumber = bundle.getInt(KEY_HINT_SEQUENCE_NUMBER)
-    hintHandler.isHintVisibleInLatestState = bundle.getBoolean(KEY_IS_HINT_VISIBLE_IN_LATEST_STATE)
+    val hintState = bundle.getProto(KEY_HINT_STATE, HintState.newBuilder().build())
+    hintHandler.trackedWrongAnswerCount = hintState.wrongAnswerCount
+    hintHandler.previousHelpIndex = hintState.helpIndex
+    hintHandler.hintSequenceNumber = hintState.hintSequenceNumber
+    hintHandler.isHintVisibleInLatestState = hintState.isHintVisibleInLatestState
   }
 
   private val lifecycleSafeTimerFactory = LifecycleSafeTimerFactory(backgroundCoroutineDispatcher)
diff --git a/model/src/main/proto/exploration.proto b/model/src/main/proto/exploration.proto
index 0135b2d95c0..bf2094abdf5 100644
--- a/model/src/main/proto/exploration.proto
+++ b/model/src/main/proto/exploration.proto
@@ -253,6 +253,13 @@ message UserAnswer {
   string content_description = 5;
 }
 
+message HintState {
+  int32 wrongAnswerCount = 1;
+  HelpIndex helpIndex = 2;
+  int32 hintSequenceNumber = 3;
+  bool isHintVisibleInLatestState = 4;
+}
+
 message AnswerAndResponse {
   // A previous answer the learner submitted.
   UserAnswer user_answer = 1;

From e8789f5c4111b6ad431bba96b133df18fb906a6d Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Wed, 10 Feb 2021 14:19:54 +0530
Subject: [PATCH 08/14] Ktlint fix

---
 .../app/player/state/StatePlayerRecyclerViewAssembler.kt      | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 7a4b728171f..304e2660598 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -22,10 +22,8 @@ import nl.dionsegijn.konfetti.KonfettiView
 import org.oppia.android.app.model.AnswerAndResponse
 import org.oppia.android.app.model.EphemeralState
 import org.oppia.android.app.model.EphemeralState.StateTypeCase
-import org.oppia.android.app.model.Exploration
 import org.oppia.android.app.model.HelpIndex
 import org.oppia.android.app.model.HelpIndex.IndexTypeCase.INDEXTYPE_NOT_SET
-import org.oppia.android.app.model.Hint
 import org.oppia.android.app.model.HintState
 import org.oppia.android.app.model.Interaction
 import org.oppia.android.app.model.PendingState
@@ -170,7 +168,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
   val isCorrectAnswer = ObservableField<Boolean>(false)
 
   fun saveState(bundle: Bundle) {
-    val hintState:HintState = HintState.newBuilder().apply {
+    val hintState: HintState = HintState.newBuilder().apply {
       wrongAnswerCount = hintHandler.trackedWrongAnswerCount
       helpIndex = hintHandler.previousHelpIndex
       hintSequenceNumber = hintHandler.hintSequenceNumber

From e601ff9972a38b0d2360eb9e2971b2488b7dceac Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Wed, 10 Feb 2021 15:32:11 +0530
Subject: [PATCH 09/14] protobuf fix

---
 model/src/main/proto/exploration.proto | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/model/src/main/proto/exploration.proto b/model/src/main/proto/exploration.proto
index bf2094abdf5..95bb0c26065 100644
--- a/model/src/main/proto/exploration.proto
+++ b/model/src/main/proto/exploration.proto
@@ -254,10 +254,10 @@ message UserAnswer {
 }
 
 message HintState {
-  int32 wrongAnswerCount = 1;
-  HelpIndex helpIndex = 2;
-  int32 hintSequenceNumber = 3;
-  bool isHintVisibleInLatestState = 4;
+  int32 wrong_answer_count = 1;
+  HelpIndex help_index = 2;
+  int32 hint_sequence_number = 3;
+  bool is_hint_visible_in_latest_state = 4;
 }
 
 message AnswerAndResponse {

From b63e7ce020d9df5dfa995c376ab59058e54a9be5 Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Fri, 12 Feb 2021 03:22:09 +0530
Subject: [PATCH 10/14] Resolving requested changes

---
 .../state/StatePlayerRecyclerViewAssembler.kt | 24 +++--
 .../questionplayer/QuestionPlayerFragment.kt  |  7 +-
 .../QuestionPlayerFragmentPresenter.kt        | 15 ++-
 .../app/player/state/StateFragmentTest.kt     | 95 -------------------
 model/src/main/proto/exploration.proto        |  7 --
 model/src/main/proto/ui_state.proto           | 20 ++++
 6 files changed, 58 insertions(+), 110 deletions(-)
 create mode 100644 model/src/main/proto/ui_state.proto

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 304e2660598..d49ab235725 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -24,10 +24,10 @@ import org.oppia.android.app.model.EphemeralState
 import org.oppia.android.app.model.EphemeralState.StateTypeCase
 import org.oppia.android.app.model.HelpIndex
 import org.oppia.android.app.model.HelpIndex.IndexTypeCase.INDEXTYPE_NOT_SET
-import org.oppia.android.app.model.HintState
 import org.oppia.android.app.model.Interaction
 import org.oppia.android.app.model.PendingState
 import org.oppia.android.app.model.State
+import org.oppia.android.app.model.StatePlayerSavedHintState
 import org.oppia.android.app.model.StringList
 import org.oppia.android.app.model.SubtitledHtml
 import org.oppia.android.app.model.UserAnswer
@@ -100,7 +100,7 @@ private typealias AudioUiManagerRetriever = () -> AudioUiManager?
 
 /** The fragment tag corresponding to the concept card dialog fragment. */
 const val CONCEPT_CARD_DIALOG_FRAGMENT_TAG = "CONCEPT_CARD_FRAGMENT"
-const val KEY_HINT_STATE = "HINT_STATE"
+private const val KEY_HINT_STATE = "HINT_STATE"
 
 private const val CONGRATULATIONS_TEXT_VIEW_FADE_MILLIS: Long = 600
 private const val CONGRATULATIONS_TEXT_VIEW_VISIBLE_MILLIS: Long = 800
@@ -167,18 +167,26 @@ class StatePlayerRecyclerViewAssembler private constructor(
 
   val isCorrectAnswer = ObservableField<Boolean>(false)
 
+  /*
+    Saves the StatePlayerSavedHintState in the onSavedInstance called
+    in the onSaveInstanceState of the StateFragment.
+   */
   fun saveState(bundle: Bundle) {
-    val hintState: HintState = HintState.newBuilder().apply {
+    val statePlayerSavedHintState = StatePlayerSavedHintState.newBuilder().apply {
       wrongAnswerCount = hintHandler.trackedWrongAnswerCount
       helpIndex = hintHandler.previousHelpIndex
       hintSequenceNumber = hintHandler.hintSequenceNumber
       isHintVisibleInLatestState = hintHandler.isHintVisibleInLatestState
     }.build()
-    bundle.putProto(KEY_HINT_STATE, hintState)
+    bundle.putProto(KEY_HINT_STATE, statePlayerSavedHintState)
   }
 
+  /*
+    Restores the StatePlayerSavedHintState in the onCreate called
+    in the onCreateView of the StateFragment.
+   */
   fun restoreState(bundle: Bundle) {
-    val hintState = bundle.getProto(KEY_HINT_STATE, HintState.newBuilder().build())
+    val hintState = bundle.getProto(KEY_HINT_STATE, StatePlayerSavedHintState.getDefaultInstance())
     hintHandler.trackedWrongAnswerCount = hintState.wrongAnswerCount
     hintHandler.previousHelpIndex = hintState.helpIndex
     hintHandler.hintSequenceNumber = hintState.hintSequenceNumber
@@ -306,13 +314,17 @@ class StatePlayerRecyclerViewAssembler private constructor(
       }
     }
 
+    if (isTerminalState && playerFeatureSet.showCelebrationAtEndOfSession) {
+      maybeShowCelebrationForEndOfSession()
+    }
+
     maybeAddNavigationButtons(
       conversationPendingItemList,
       extraInteractionPendingItemList,
       hasPreviousState,
       canContinueToNextState,
       hasGeneralContinueButton,
-      ephemeralState.stateTypeCase == EphemeralState.StateTypeCase.TERMINAL_STATE
+      isTerminalState
     )
     return Pair(conversationPendingItemList, extraInteractionPendingItemList)
   }
diff --git a/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragment.kt b/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragment.kt
index 399a5388cbf..61802173df5 100644
--- a/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragment.kt
+++ b/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragment.kt
@@ -45,7 +45,12 @@ class QuestionPlayerFragment :
     container: ViewGroup?,
     savedInstanceState: Bundle?
   ): View? {
-    return questionPlayerFragmentPresenter.handleCreateView(inflater, container)
+    return questionPlayerFragmentPresenter.handleCreateView(inflater, container, savedInstanceState)
+  }
+
+  override fun onSaveInstanceState(outState: Bundle) {
+    super.onSaveInstanceState(outState)
+    questionPlayerFragmentPresenter.handleOnSaveInstanceState(outState)
   }
 
   override fun onAnswerReadyForSubmission(answer: UserAnswer) {
diff --git a/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragmentPresenter.kt b/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragmentPresenter.kt
index f5adf68904c..5445161ff54 100644
--- a/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragmentPresenter.kt
+++ b/app/src/main/java/org/oppia/android/app/topic/questionplayer/QuestionPlayerFragmentPresenter.kt
@@ -1,6 +1,7 @@
 package org.oppia.android.app.topic.questionplayer
 
 import android.content.Context
+import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -70,7 +71,11 @@ class QuestionPlayerFragmentPresenter @Inject constructor(
   private lateinit var questionId: String
   private lateinit var currentQuestionState: State
 
-  fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
+  fun handleCreateView(
+    inflater: LayoutInflater,
+    container: ViewGroup?,
+    savedInstanceState: Bundle?
+  ): View? {
     binding = QuestionPlayerFragmentBinding.inflate(
       inflater,
       container,
@@ -83,6 +88,10 @@ class QuestionPlayerFragmentPresenter @Inject constructor(
       binding.congratulationsTextConfettiView
     )
 
+    savedInstanceState?.let {
+      recyclerViewAssembler.restoreState(savedInstanceState)
+    }
+
     binding.apply {
       lifecycleOwner = fragment
       viewModel = questionViewModel
@@ -105,6 +114,10 @@ class QuestionPlayerFragmentPresenter @Inject constructor(
     return binding.root
   }
 
+  fun handleOnSaveInstanceState(bundle: Bundle) {
+    recyclerViewAssembler.saveState(bundle)
+  }
+
   fun revealHint(saveUserChoice: Boolean, hintIndex: Int) {
     subscribeToHint(
       questionAssessmentProgressController.submitHintIsRevealed(
diff --git a/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt b/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
index dd39a511252..9dec15c4c99 100644
--- a/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/android/app/player/state/StateFragmentTest.kt
@@ -20,7 +20,6 @@ import androidx.test.espresso.action.GeneralLocation
 import androidx.test.espresso.action.Press
 import androidx.test.espresso.action.ViewActions.click
 import androidx.test.espresso.action.ViewActions.closeSoftKeyboard
-import androidx.test.espresso.action.ViewActions.pressBack
 import androidx.test.espresso.assertion.ViewAssertions.doesNotExist
 import androidx.test.espresso.assertion.ViewAssertions.matches
 import androidx.test.espresso.contrib.RecyclerViewActions.scrollToHolder
@@ -104,7 +103,6 @@ import org.oppia.android.domain.oppialogger.LogStorageModule
 import org.oppia.android.domain.oppialogger.loguploader.LogUploadWorkerModule
 import org.oppia.android.domain.oppialogger.loguploader.WorkManagerConfigurationModule
 import org.oppia.android.domain.question.QuestionModule
-import org.oppia.android.domain.topic.FRACTIONS_EXPLORATION_ID_0
 import org.oppia.android.domain.topic.FRACTIONS_EXPLORATION_ID_1
 import org.oppia.android.domain.topic.PrimeTopicAssetsControllerModule
 import org.oppia.android.domain.topic.TEST_EXPLORATION_ID_0
@@ -907,99 +905,6 @@ class StateFragmentTest {
     }
   }
 
-  @Test
-  fun testStateFragment_forTwoWrongAnswers_revealHint() {
-    launchForExploration(FRACTIONS_EXPLORATION_ID_0).use {
-      startPlayingExploration()
-      clickContinueInteractionButton()
-      clickContinueInteractionButton()
-      clickContinueInteractionButton()
-      selectMultipleChoiceOption(optionPosition = 2)
-      clickContinueNavigationButton()
-      selectMultipleChoiceOption(optionPosition = 1)
-      clickContinueNavigationButton()
-      selectMultipleChoiceOption(optionPosition = 1)
-      clickContinueNavigationButton()
-      onView(withId(R.id.hints_and_solution_fragment_container)).check(
-        matches(
-          not(isDisplayed())
-        )
-      )
-      selectMultipleChoiceOption(optionPosition = 1)
-      selectMultipleChoiceOption(optionPosition = 1)
-      onView(withId(R.id.hints_and_solution_fragment_container)).check(
-        matches(
-          isDisplayed()
-        )
-      )
-    }
-  }
-
-  @Test
-  fun testStateFragment_forTwoWrongAnswers_revealHint_dotDisappears() {
-    launchForExploration(FRACTIONS_EXPLORATION_ID_0).use {
-      startPlayingExploration()
-      clickContinueInteractionButton()
-      clickContinueInteractionButton()
-      clickContinueInteractionButton()
-      selectMultipleChoiceOption(optionPosition = 2)
-      clickContinueNavigationButton()
-      selectMultipleChoiceOption(optionPosition = 1)
-      clickContinueNavigationButton()
-      selectMultipleChoiceOption(optionPosition = 1)
-      clickContinueNavigationButton()
-
-      selectMultipleChoiceOption(optionPosition = 1)
-      selectMultipleChoiceOption(optionPosition = 1)
-      onView(withId(R.id.dot_hint)).check(
-        matches(
-          isDisplayed()
-        )
-      )
-      onView(withId(R.id.hints_and_solution_fragment_container)).perform(click())
-      onView(withId(R.id.reveal_hint_button)).perform(click())
-      onView(isRoot()).perform(pressBack())
-      onView(withId(R.id.dot_hint)).check(
-        matches(
-          not(isDisplayed())
-        )
-      )
-    }
-  }
-
-  @Test
-  fun testStateFragment_forTwoWrongAnswers_revealHint_configurationChange_newHintNotRevealed() {
-    launchForExploration(FRACTIONS_EXPLORATION_ID_0).use {
-      startPlayingExploration()
-      clickContinueInteractionButton()
-      clickContinueInteractionButton()
-      clickContinueInteractionButton()
-      selectMultipleChoiceOption(optionPosition = 2)
-      clickContinueNavigationButton()
-      selectMultipleChoiceOption(optionPosition = 1)
-      clickContinueNavigationButton()
-      selectMultipleChoiceOption(optionPosition = 1)
-      clickContinueNavigationButton()
-
-      selectMultipleChoiceOption(optionPosition = 1)
-      selectMultipleChoiceOption(optionPosition = 1)
-      onView(withId(R.id.dot_hint)).check(
-        matches(
-          isDisplayed()
-        )
-      )
-      onView(withId(R.id.hints_and_solution_fragment_container)).perform(click())
-      onView(withId(R.id.reveal_hint_button)).perform(click())
-      onView(isRoot()).perform(pressBack())
-      rotateToLandscape()
-      onView(withId(R.id.dot_hint)).check(
-        matches(
-          not(isDisplayed())
-        )
-      )
-    }
-  }
-
   @Test
   fun testStateFragment_forMisconception_showsLinkTextForConceptCard() {
     launchForExploration(FRACTIONS_EXPLORATION_ID_1).use {
diff --git a/model/src/main/proto/exploration.proto b/model/src/main/proto/exploration.proto
index 95bb0c26065..0135b2d95c0 100644
--- a/model/src/main/proto/exploration.proto
+++ b/model/src/main/proto/exploration.proto
@@ -253,13 +253,6 @@ message UserAnswer {
   string content_description = 5;
 }
 
-message HintState {
-  int32 wrong_answer_count = 1;
-  HelpIndex help_index = 2;
-  int32 hint_sequence_number = 3;
-  bool is_hint_visible_in_latest_state = 4;
-}
-
 message AnswerAndResponse {
   // A previous answer the learner submitted.
   UserAnswer user_answer = 1;
diff --git a/model/src/main/proto/ui_state.proto b/model/src/main/proto/ui_state.proto
new file mode 100644
index 00000000000..0fdcf8bc27f
--- /dev/null
+++ b/model/src/main/proto/ui_state.proto
@@ -0,0 +1,20 @@
+syntax = "proto3";
+
+package model;
+
+option java_package = "org.oppia.android.app.model";
+option java_multiple_files = true;
+
+import "exploration.proto";
+
+// Corresponds to HintHandler in the exploration to make it life cycle aware
+message StatePlayerSavedHintState {
+  // Wrong answer count in the current state
+  int32 wrong_answer_count = 1;
+  // HelpIndex of the current state
+  HelpIndex help_index = 2;
+  // nth hint of the current state
+  int32 hint_sequence_number = 3;
+  // A boolean that which toggles the visibility of the hint bulb
+  bool is_hint_visible_in_latest_state = 4;
+}

From 376a9bb5de7e2b0f4edc45af7528d88e3e2a7abe Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Fri, 12 Feb 2021 17:07:40 +0530
Subject: [PATCH 11/14] Resolving requested changes

---
 .../state/StatePlayerRecyclerViewAssembler.kt   | 17 +++++++++--------
 model/src/main/proto/ui_state.proto             | 10 +++++-----
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index d49ab235725..04cb403342e 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -100,7 +100,7 @@ private typealias AudioUiManagerRetriever = () -> AudioUiManager?
 
 /** The fragment tag corresponding to the concept card dialog fragment. */
 const val CONCEPT_CARD_DIALOG_FRAGMENT_TAG = "CONCEPT_CARD_FRAGMENT"
-private const val KEY_HINT_STATE = "HINT_STATE"
+private const val KEY_HINT_STATE = "KEY_HINT_STATE"
 
 private const val CONGRATULATIONS_TEXT_VIEW_FADE_MILLIS: Long = 600
 private const val CONGRATULATIONS_TEXT_VIEW_VISIBLE_MILLIS: Long = 800
@@ -167,9 +167,10 @@ class StatePlayerRecyclerViewAssembler private constructor(
 
   val isCorrectAnswer = ObservableField<Boolean>(false)
 
-  /*
-    Saves the StatePlayerSavedHintState in the onSavedInstance called
-    in the onSaveInstanceState of the StateFragment.
+  /**
+   * Saves transient state that the assembler depends on.
+   * This should be used to retain state across configuration changes,
+   * and state saved through this method should be restored via [restoreState].
    */
   fun saveState(bundle: Bundle) {
     val statePlayerSavedHintState = StatePlayerSavedHintState.newBuilder().apply {
@@ -181,9 +182,10 @@ class StatePlayerRecyclerViewAssembler private constructor(
     bundle.putProto(KEY_HINT_STATE, statePlayerSavedHintState)
   }
 
-  /*
-    Restores the StatePlayerSavedHintState in the onCreate called
-    in the onCreateView of the StateFragment.
+  /**
+   * Restores transient state that the assembler depends on.
+   * This should be used to retain state across configuration changes,
+   * and state saved through this method should be saved via [saveState].
    */
   fun restoreState(bundle: Bundle) {
     val hintState = bundle.getProto(KEY_HINT_STATE, StatePlayerSavedHintState.getDefaultInstance())
@@ -1285,7 +1287,6 @@ class StatePlayerRecyclerViewAssembler private constructor(
      */
     fun hasConversationView(hasConversationView: Boolean): Builder {
       this.hasConversationView = hasConversationView
-      featureSets += PlayerFeatureSet(showCelebrationOnCorrectAnswer = true)
       return this
     }
 
diff --git a/model/src/main/proto/ui_state.proto b/model/src/main/proto/ui_state.proto
index 0fdcf8bc27f..22cf4b026e9 100644
--- a/model/src/main/proto/ui_state.proto
+++ b/model/src/main/proto/ui_state.proto
@@ -7,14 +7,14 @@ option java_multiple_files = true;
 
 import "exploration.proto";
 
-// Corresponds to HintHandler in the exploration to make it life cycle aware
+// Represents savable state for the hint & solution handler in the state player.
 message StatePlayerSavedHintState {
-  // Wrong answer count in the current state
+  // Wrong answer count in the current state.
   int32 wrong_answer_count = 1;
-  // HelpIndex of the current state
+  // HelpIndex of the current state.
   HelpIndex help_index = 2;
-  // nth hint of the current state
+  // nth hint of the current state.
   int32 hint_sequence_number = 3;
-  // A boolean that which toggles the visibility of the hint bulb
+  // Whether the hint bulb is current visible.
   bool is_hint_visible_in_latest_state = 4;
 }

From cae556764ee95088b2001e5b1e63203f74328e26 Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Fri, 12 Feb 2021 17:49:42 +0530
Subject: [PATCH 12/14] Using defaults for the StatePlayerSavedHintState

---
 .../state/StatePlayerRecyclerViewAssembler.kt    | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 04cb403342e..74ec5297e6a 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -105,6 +105,10 @@ private const val KEY_HINT_STATE = "KEY_HINT_STATE"
 private const val CONGRATULATIONS_TEXT_VIEW_FADE_MILLIS: Long = 600
 private const val CONGRATULATIONS_TEXT_VIEW_VISIBLE_MILLIS: Long = 800
 
+private const val DEFAULT_WRONG_ANSWER_COUNT = 0
+private const val DEFAULT_HINT_SEQUENCE_NUMBER = 0
+private const val DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE = false
+
 /**
  * An assembler for generating the list of view models to bind to the state player recycler view.
  * This class also handles some non-recycler view feature management, such as the congratulations
@@ -188,7 +192,11 @@ class StatePlayerRecyclerViewAssembler private constructor(
    * and state saved through this method should be saved via [saveState].
    */
   fun restoreState(bundle: Bundle) {
-    val hintState = bundle.getProto(KEY_HINT_STATE, StatePlayerSavedHintState.getDefaultInstance())
+    val hintState = bundle.getProto(KEY_HINT_STATE, StatePlayerSavedHintState.newBuilder().apply {
+      wrongAnswerCount = DEFAULT_WRONG_ANSWER_COUNT
+      hintSequenceNumber = DEFAULT_HINT_SEQUENCE_NUMBER
+      isHintVisibleInLatestState = DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE
+    }.build())
     hintHandler.trackedWrongAnswerCount = hintState.wrongAnswerCount
     hintHandler.previousHelpIndex = hintState.helpIndex
     hintHandler.hintSequenceNumber = hintState.hintSequenceNumber
@@ -1487,10 +1495,10 @@ class StatePlayerRecyclerViewAssembler private constructor(
     private val delayShowAdditionalHintsMs: Long,
     private val delayShowAdditionalHintsFromWrongAnswerMs: Long
   ) {
-    var trackedWrongAnswerCount = 0
+    var trackedWrongAnswerCount = DEFAULT_WRONG_ANSWER_COUNT
     var previousHelpIndex: HelpIndex = HelpIndex.getDefaultInstance()
-    var hintSequenceNumber = 0
-    var isHintVisibleInLatestState = false
+    var hintSequenceNumber = DEFAULT_HINT_SEQUENCE_NUMBER
+    var isHintVisibleInLatestState = DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE
 
     /** Resets this handler to prepare it for a new state, cancelling any pending hints. */
     fun reset() {

From 39814de1dabc512913a14a2aa994f5407ce7b149 Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Sat, 13 Feb 2021 11:22:52 +0530
Subject: [PATCH 13/14] Resolving requested changes

---
 .../state/StatePlayerRecyclerViewAssembler.kt     | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index 74ec5297e6a..dc20b6983d7 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -173,6 +173,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
 
   /**
    * Saves transient state that the assembler depends on.
+   *
    * This should be used to retain state across configuration changes,
    * and state saved through this method should be restored via [restoreState].
    */
@@ -188,15 +189,19 @@ class StatePlayerRecyclerViewAssembler private constructor(
 
   /**
    * Restores transient state that the assembler depends on.
+   *
    * This should be used to retain state across configuration changes,
    * and state saved through this method should be saved via [saveState].
    */
   fun restoreState(bundle: Bundle) {
-    val hintState = bundle.getProto(KEY_HINT_STATE, StatePlayerSavedHintState.newBuilder().apply {
-      wrongAnswerCount = DEFAULT_WRONG_ANSWER_COUNT
-      hintSequenceNumber = DEFAULT_HINT_SEQUENCE_NUMBER
-      isHintVisibleInLatestState = DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE
-    }.build())
+    val hintState = bundle.getProto(
+      KEY_HINT_STATE,
+      StatePlayerSavedHintState.newBuilder().apply {
+        wrongAnswerCount = DEFAULT_WRONG_ANSWER_COUNT
+        hintSequenceNumber = DEFAULT_HINT_SEQUENCE_NUMBER
+        isHintVisibleInLatestState = DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE
+      }.build()
+    )
     hintHandler.trackedWrongAnswerCount = hintState.wrongAnswerCount
     hintHandler.previousHelpIndex = hintState.helpIndex
     hintHandler.hintSequenceNumber = hintState.hintSequenceNumber

From b8bc619147a8c9f347d798586c34c3c3bec77ff8 Mon Sep 17 00:00:00 2001
From: farees <fareezzhussain@gmail.com>
Date: Wed, 17 Feb 2021 11:17:28 +0530
Subject: [PATCH 14/14] Resolving requested changes

---
 .../player/state/StatePlayerRecyclerViewAssembler.kt   | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
index dc20b6983d7..8f3b66f974e 100644
--- a/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
+++ b/app/src/main/java/org/oppia/android/app/player/state/StatePlayerRecyclerViewAssembler.kt
@@ -107,6 +107,7 @@ private const val CONGRATULATIONS_TEXT_VIEW_VISIBLE_MILLIS: Long = 800
 
 private const val DEFAULT_WRONG_ANSWER_COUNT = 0
 private const val DEFAULT_HINT_SEQUENCE_NUMBER = 0
+private val DEFAULT_PREVIOUS_HINT_INDEX = HelpIndex.getDefaultInstance()
 private const val DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE = false
 
 /**
@@ -198,6 +199,7 @@ class StatePlayerRecyclerViewAssembler private constructor(
       KEY_HINT_STATE,
       StatePlayerSavedHintState.newBuilder().apply {
         wrongAnswerCount = DEFAULT_WRONG_ANSWER_COUNT
+        helpIndex = DEFAULT_PREVIOUS_HINT_INDEX
         hintSequenceNumber = DEFAULT_HINT_SEQUENCE_NUMBER
         isHintVisibleInLatestState = DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE
       }.build()
@@ -1501,19 +1503,19 @@ class StatePlayerRecyclerViewAssembler private constructor(
     private val delayShowAdditionalHintsFromWrongAnswerMs: Long
   ) {
     var trackedWrongAnswerCount = DEFAULT_WRONG_ANSWER_COUNT
-    var previousHelpIndex: HelpIndex = HelpIndex.getDefaultInstance()
+    var previousHelpIndex: HelpIndex = DEFAULT_PREVIOUS_HINT_INDEX
     var hintSequenceNumber = DEFAULT_HINT_SEQUENCE_NUMBER
     var isHintVisibleInLatestState = DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE
 
     /** Resets this handler to prepare it for a new state, cancelling any pending hints. */
     fun reset() {
-      trackedWrongAnswerCount = 0
-      previousHelpIndex = HelpIndex.getDefaultInstance()
+      trackedWrongAnswerCount = DEFAULT_WRONG_ANSWER_COUNT
+      previousHelpIndex = DEFAULT_PREVIOUS_HINT_INDEX
       // Cancel any potential pending hints by advancing the sequence number. Note that this isn't
       // reset to 0 to ensure that all previous hint tasks are cancelled, and new tasks can be
       // scheduled without overlapping with past sequence numbers.
       hintSequenceNumber++
-      isHintVisibleInLatestState = false
+      isHintVisibleInLatestState = DEFAULT_IS_HINT_VISIBLE_IN_LATEST_STATE
     }
 
     /** Hide hint when moving to any previous state. */