Fix part of #5571: Support practice questions

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

@@ -21,7 +21,8 @@ import org.oppia.android.app.ui.R
 import org.oppia.android.domain.oppialogger.OppiaLogger
 import org.oppia.android.domain.oppialogger.analytics.AnalyticsController
 import org.oppia.android.util.accessibility.AccessibilityService
-import org.oppia.android.util.platformparameter.EnableExtraTopicTabsUi
+import org.oppia.android.util.platformparameter.EnableTopicInfoTab
+import org.oppia.android.util.platformparameter.EnableTopicPracticeTab
 import org.oppia.android.util.platformparameter.PlatformParameterValue
 import javax.inject.Inject
 
@@ -33,7 +34,8 @@ class TopicFragmentPresenter @Inject constructor(
   private val viewModel: TopicViewModel,
   private val oppiaLogger: OppiaLogger,
   private val analyticsController: AnalyticsController,
-  @EnableExtraTopicTabsUi private val enableExtraTopicTabsUi: PlatformParameterValue<Boolean>,
+  @EnableTopicInfoTab private val enableTopicInfoTabFlag: PlatformParameterValue<Boolean>,
+  @EnableTopicPracticeTab private val enableTopicPracticeTabFlag: PlatformParameterValue<Boolean>,
   private val resourceHandler: AppLanguageResourceHandler
 ) {
   @Inject
@@ -45,6 +47,12 @@ class TopicFragmentPresenter @Inject constructor(
   private lateinit var storyId: String
   private lateinit var viewPager: ViewPager2
 
+  private var enableTopicInfoTab: Boolean = enableTopicInfoTabFlag.value
+  private var enableTopicPracticeTab: Boolean = false
+    set(hasPracticeQuestions) {
+      field = enableTopicPracticeTabFlag.value && hasPracticeQuestions
+    }
+
   fun handleCreateView(
     inflater: LayoutInflater,
     container: ViewGroup?,
@@ -76,7 +84,17 @@ class TopicFragmentPresenter @Inject constructor(
     viewModel.setTopicId(topicId)
     binding.viewModel = viewModel
 
-    setUpViewPager(viewPager, classroomId, topicId, isConfigChanged)
+    viewModel.hasPracticeQuestions.observe(fragment) { hasPracticeQuestions ->
+      enableTopicPracticeTab = hasPracticeQuestions
+
+      setUpViewPager(
+        viewPager,
+        classroomId,
+        topicId,
+        isConfigChanged
+      )
+    }
+
     return binding.root
   }
 
@@ -120,7 +138,7 @@ class TopicFragmentPresenter @Inject constructor(
   }
 
   private fun computeTabPosition(tab: TopicTab): Int {
-    return if (enableExtraTopicTabsUi.value) tab.positionWithFourTabs else tab.positionWithTwoTabs
+    return tab.getPosition(enableTopicInfoTab, enableTopicPracticeTab)
   }
 
   private fun setUpViewPager(
@@ -136,25 +154,36 @@ class TopicFragmentPresenter @Inject constructor(
         classroomId,
         topicId,
         storyId,
-        enableExtraTopicTabsUi.value
+        enableTopicInfoTab,
+        enableTopicPracticeTab
       )
     viewPager2.adapter = adapter
     TabLayoutMediator(tabLayout, viewPager2) { tab, position ->
-      val topicTab = TopicTab.getTabForPosition(position, enableExtraTopicTabsUi.value)
+      val topicTab = TopicTab.getTabForPosition(
+        position,
+        enableTopicInfoTab,
+        enableTopicPracticeTab
+      )
       tab.text = resourceHandler.getStringInLocale(topicTab.tabLabelResId)
       tab.icon = ContextCompat.getDrawable(activity, topicTab.tabIconResId)
       tab.contentDescription = resourceHandler.getStringInLocale(topicTab.contentDescriptionResId)
     }.attach()
     if (!isConfigChanged && topicId.isNotEmpty()) {
-      if (enableExtraTopicTabsUi.value) {
+      if (enableTopicInfoTab) {
         setCurrentTab(if (storyId.isNotEmpty()) TopicTab.LEARN else TopicTab.INFO)
       } else {
         setCurrentTab(TopicTab.LEARN)
       }
     }
     viewPager2.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
       override fun onPageSelected(position: Int) {
-        logTopicEvents(TopicTab.getTabForPosition(position, enableExtraTopicTabsUi.value))
+        logTopicEvents(
+          TopicTab.getTabForPosition(
+            position,
+            enableTopicInfoTab,
+            enableTopicPracticeTab
+          )
+        )
       }
     })
   }

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

@@ -6,58 +6,102 @@ import org.oppia.android.app.ui.R
 
 /** Enum to store the tabs of [TopicFragment] and get tab by position. */
 enum class TopicTab(
-  val positionWithTwoTabs: Int,
-  val positionWithFourTabs: Int,
   @StringRes val tabLabelResId: Int,
   @DrawableRes val tabIconResId: Int,
-  @StringRes val contentDescriptionResId: Int
+  @StringRes val contentDescriptionResId: Int,
+  val positions: Map<TabConfig, Int>
 ) {
   INFO(
-    positionWithTwoTabs = -1,
-    positionWithFourTabs = 0,
     tabLabelResId = R.string.info,
     tabIconResId = R.drawable.ic_info_icon_24dp,
-    contentDescriptionResId = R.string.info_tab_content_description
+    contentDescriptionResId = R.string.info_tab_content_description,
+    positions = mapOf(
+      TabConfig.TwoTabs to -1,
+      TabConfig.ThreeTabsWithInfo to 0,
+      TabConfig.ThreeTabsWithPractice to -1,
+      TabConfig.FourTabs to 0
+    )
   ),
   LEARN(
-    positionWithTwoTabs = 0,
-    positionWithFourTabs = 1,
     tabLabelResId = R.string.learn,
     tabIconResId = R.drawable.ic_lessons_icon_24dp,
-    contentDescriptionResId = R.string.lessons_tab_content_description
+    contentDescriptionResId = R.string.lessons_tab_content_description,
+    positions = mapOf(
+      TabConfig.TwoTabs to 0,
+      TabConfig.ThreeTabsWithInfo to 1,
+      TabConfig.ThreeTabsWithPractice to 0,
+      TabConfig.FourTabs to 1
+    )
   ),
   PRACTICE(
-    positionWithTwoTabs = -1,
-    positionWithFourTabs = 2,
     tabLabelResId = R.string.practice,
     tabIconResId = R.drawable.ic_practice_icon_24dp,
-    contentDescriptionResId = R.string.practice_tab_content_description
+    contentDescriptionResId = R.string.practice_tab_content_description,
+    positions = mapOf(
+      TabConfig.TwoTabs to -1,
+      TabConfig.ThreeTabsWithInfo to -1,
+      TabConfig.ThreeTabsWithPractice to 1,
+      TabConfig.FourTabs to 2
+    )
   ),
   STUDY(
-    positionWithTwoTabs = 1,
-    positionWithFourTabs = 3,
     tabLabelResId = R.string.study,
     tabIconResId = R.drawable.ic_revision_icon_24dp,
-    contentDescriptionResId = R.string.revision_tab_content_description
+    contentDescriptionResId = R.string.revision_tab_content_description,
+    positions = mapOf(
+      TabConfig.TwoTabs to 1,
+      TabConfig.ThreeTabsWithInfo to 2,
+      TabConfig.ThreeTabsWithPractice to 2,
+      TabConfig.FourTabs to 3
+    )
   );
 
+  /** Enum representing different tab configurations. */
+  enum class TabConfig {
+    TwoTabs,
+    ThreeTabsWithInfo,
+    ThreeTabsWithPractice,
+    FourTabs;
+
+    companion object {
+      fun getConfig(enableInfo: Boolean, enablePractice: Boolean) = when {
+        enableInfo && enablePractice -> FourTabs
+        enableInfo -> ThreeTabsWithInfo
+        enablePractice -> ThreeTabsWithPractice
+        else -> TwoTabs
+      }
+    }
+  }
+
+  /** Returns the tab position based on enabled tabs. */
+  fun getPosition(enableTopicInfoTab: Boolean, enableTopicPracticeTab: Boolean): Int {
+    val config = TabConfig.getConfig(enableTopicInfoTab, enableTopicPracticeTab)
+    return positions[config] ?: -1 // -1 indicates that the tab is not available
+  }
+
   companion object {
     /**
      * Returns the [TopicTab] corresponding to the specified tab position, considering whether the
-     * info and practice tabs are enabled per [enableExtraTopicTabsUi].
+     * info and practice tabs are enabled per [enableTopicInfoTab] and [enableTopicPracticeTab]
+     * respectively.
      */
-    fun getTabForPosition(position: Int, enableExtraTopicTabsUi: Boolean): TopicTab {
-      return checkNotNull(
-        values().find {
-          position == if (enableExtraTopicTabsUi) {
-            it.positionWithFourTabs
-          } else it.positionWithTwoTabs
-        }
-      ) { "No tab corresponding to position: $position" }
+    fun getTabForPosition(
+      position: Int,
+      enableTopicInfoTab: Boolean,
+      enableTopicPracticeTab: Boolean
+    ): TopicTab {
+      return values().find {
+        it.getPosition(enableTopicInfoTab, enableTopicPracticeTab) == position
+      } ?: error("No tab corresponding to position: $position")
     }
 
-    /** Returns the number of active tabs considering [enableExtraTopicTabsUi]. */
-    fun getTabCount(enableExtraTopicTabsUi: Boolean) =
-      if (enableExtraTopicTabsUi) values().size else values().size - 2
+    /**
+     *  Returns the number of active tabs considering [enableTopicInfoTab] and
+     *  [enableTopicPracticeTab].
+     */
+    fun getTabCount(enableTopicInfoTab: Boolean, enableTopicPracticeTab: Boolean): Int {
+      val config = TabConfig.getConfig(enableTopicInfoTab, enableTopicPracticeTab)
+      return values().count { it.positions[config] != -1 } // -1 indicates that the tab is disabled
+    }
   }
 }

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

@@ -78,6 +78,12 @@ class TopicViewModel @Inject constructor(
     }
   }
 
+  val hasPracticeQuestions: LiveData<Boolean> by lazy {
+    Transformations.map(topicLiveData) { ephemeralTopic ->
+      ephemeralTopic.topic.hasPracticeQuestions
+    }
+  }
+
   fun setProfileId(profileId: ProfileId) {
     this.profileId = profileId
   }

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

@@ -15,13 +15,15 @@ class ViewPagerAdapter(
   private val classroomId: String,
   private val topicId: String,
   private val storyId: String,
-  private val enableExtraTopicTabsUi: Boolean
+  private val enableTopicInfoTab: Boolean,
+  private val enableTopicPracticeTab: Boolean
 ) : FragmentStateAdapter(fragment) {
 
-  override fun getItemCount(): Int = TopicTab.getTabCount(enableExtraTopicTabsUi)
+  override fun getItemCount(): Int =
+    TopicTab.getTabCount(enableTopicInfoTab, enableTopicPracticeTab)
 
   override fun createFragment(position: Int): Fragment {
-    return when (TopicTab.getTabForPosition(position, enableExtraTopicTabsUi)) {
+    return when (TopicTab.getTabForPosition(position, enableTopicInfoTab, enableTopicPracticeTab)) {
       TopicTab.INFO -> {
         TopicInfoFragment.newInstance(profileId, topicId)
       }

app/src/sharedTest/java/org/oppia/android/app/devoptions/featureflags/FeatureFlagsFragmentTest.kt

@@ -167,7 +167,7 @@ class FeatureFlagsFragmentTest {
 
       // Note to developers: if you add/remove a feature flag, please update the expected count.
       onView(withId(R.id.feature_flags_recycler_view))
-        .check(RecyclerViewMatcher.hasItemCount(count = 14))
+        .check(RecyclerViewMatcher.hasItemCount(count = 15))
     }
   }
 

app/src/sharedTest/java/org/oppia/android/app/testing/TopicTestActivityForStoryTest.kt

@@ -92,7 +92,8 @@ import org.oppia.android.util.networking.NetworkConnectionUtilDebugModule
 import org.oppia.android.util.parser.html.HtmlParserEntityTypeModule
 import org.oppia.android.util.parser.image.GlideImageLoaderModule
 import org.oppia.android.util.parser.image.ImageParsingModule
-import org.oppia.android.util.platformparameter.EnableExtraTopicTabsUi
+import org.oppia.android.util.platformparameter.EnableTopicInfoTab
+import org.oppia.android.util.platformparameter.EnableTopicPracticeTab
 import org.oppia.android.util.platformparameter.PlatformParameterValue
 import org.robolectric.annotation.Config
 import org.robolectric.annotation.LooperMode
@@ -116,12 +117,16 @@ class TopicTestActivityForStoryTest {
   @Inject
   lateinit var testCoroutineDispatchers: TestCoroutineDispatchers
 
-  @field:[Inject EnableExtraTopicTabsUi]
-  lateinit var enableExtraTopicTabsUiValue: PlatformParameterValue<Boolean>
+  @field:[Inject EnableTopicInfoTab]
+  lateinit var enableTopicInfoTab: PlatformParameterValue<Boolean>
+
+  @field:[Inject EnableTopicPracticeTab]
+  lateinit var enableTopicPracticeTab: PlatformParameterValue<Boolean>
 
   @Before
   fun setUp() {
-    TestPlatformParameterModule.forceEnableExtraTopicTabsUi(true)
+    TestPlatformParameterModule.forceEnableTopicInfoTab(true)
+    TestPlatformParameterModule.forceEnableTopicPracticeTab(true)
     setUpTestApplicationComponent()
     testCoroutineDispatchers.registerIdlingResource()
   }
@@ -145,7 +150,8 @@ class TopicTestActivityForStoryTest {
           matchCurrentTabTitle(
             TopicTab.getTabForPosition(
               position = 1,
-              enableExtraTopicTabsUiValue.value
+              enableTopicInfoTab.value,
+              enableTopicPracticeTab.value
             ).name
           )
         )

app/src/sharedTest/java/org/oppia/android/app/topic/TopicActivityTest.kt

@@ -171,7 +171,8 @@ class TopicActivityTest {
 
   @Test
   fun testTopicActivity_hasCorrectActivityLabel() {
-    TestPlatformParameterModule.forceEnableExtraTopicTabsUi(true)
+    TestPlatformParameterModule.forceEnableTopicInfoTab(true)
+    TestPlatformParameterModule.forceEnableTopicPracticeTab(true)
     launchTopicActivity(
       profileId, TEST_CLASSROOM_ID_1, FRACTIONS_TOPIC_ID
     ).use { scenario ->
@@ -187,7 +188,8 @@ class TopicActivityTest {
   @Test
   @RunOn(TestPlatform.ROBOLECTRIC) // TODO(#3858): Enable for Espresso.
   fun testTopicActivity_startPracticeSession_questionActivityStartedWithProfileId() {
-    TestPlatformParameterModule.forceEnableExtraTopicTabsUi(true)
+    TestPlatformParameterModule.forceEnableTopicInfoTab(true)
+    TestPlatformParameterModule.forceEnableTopicPracticeTab(true)
     launchTopicActivity(profileId, TEST_CLASSROOM_ID_1, FRACTIONS_TOPIC_ID).use {
       // Open the practice tab and select a skill.
       onView(withText("Practice")).perform(click())