Fix #3821: Ensure Portuguese can be a default audio language (#4575)

## Explanation
Fixes #3821

This PR introduces the following end-user visible changes:
- It adds Brazilian Portuguese as an option when selecting a default audio language.
- It removes the 'No Audio' option from the list since it's confusing and presently defaults to 'English' when playing audio voiceovers, anyway.
- It changes the display names of the default audio languages to be localized to their own locale to make the languages easier to read by native speakers.
- It fixes a bug in the tablet version of OptionsActivity wherein switching between audio & reading text would result in fragment stacking (i.e. you could see the bottom of the longer fragment when on the shorter one). This entailed changing fragment 'adds' to 'replaces' for the options fragment transactions.

Technical details:
- This PR migrates the audio language pattern from using a string over to using the AudioLanguage proto enum, similar to the recent change for ReadingTextSize. This was preferred since changing everywhere to support a localized name of each language seemed non-ideal.
- A few models & listeners needed to be split between app & audio languages due to the previous approaching having a lot of codesharing between the two that's no longer applicable with strong types.

Exemptions:
- AppLanguageResourceHandler is now allowed to use ``Locale`` directly so that it can produce localized display names for each audio language. In the future, this could be moved to MachineLocale maybe.
- AppLanguageResourceHandlerTest is now allowed to use parameterized tests. The new parameterized tests that were added are technically violating the principle of now parameterizing the expected output of the test, but these are medium-term tests that will go away when the new language selector is added.
- The test file exemptions aren't technically "new" in the sense that they're just preserving the existing exemptions except that the exemptions are now split in the same way as the new app/audio versions of the classes.

## Essential Checklist
- [x] The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
- [x] Any changes to [scripts/assets](https://github.com/oppia/oppia-android/tree/develop/scripts/assets) files have their rationale included in the PR explanation.
- [x] The PR follows the [style guide](https://github.com/oppia/oppia-android/wiki/Coding-style-guide).
- [x] The PR does not contain any unnecessary code changes from Android Studio ([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#undo-unnecessary-changes)).
- [x] The PR is made from a branch that's **not** called "develop" and is up-to-date with "develop".
- [x] The PR is **assigned** to the appropriate reviewers ([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#clarification-regarding-assignees-and-reviewers-section)).

## For UI-specific PRs only
This section will be filled in post-merge (#4567 is tracking ensuring that the description is finished later).

Commits:

* Add pt-Br as option for default voiceover audio.

This also makes some infrastructural improvements, a small UX
improvement (removing the 'No Audio' option), and fixed a tablet bug in
the options menu.

* Update app/src/main/java/org/oppia/android/app/translation/AppLanguageResourceHandler.kt

app/BUILD.bazel

@@ -124,7 +124,8 @@ LISTENERS = [
     "src/main/java/org/oppia/android/app/home/topiclist/TopicSummaryClickListener.kt",
     "src/main/java/org/oppia/android/app/onboarding/OnboardingNavigationListener.kt",
     "src/main/java/org/oppia/android/app/onboarding/RouteToProfileListListener.kt",
-    "src/main/java/org/oppia/android/app/options/LanguageRadioButtonListener.kt",
+    "src/main/java/org/oppia/android/app/options/AppLanguageRadioButtonListener.kt",
+    "src/main/java/org/oppia/android/app/options/AudioLanguageRadioButtonListener.kt",
     "src/main/java/org/oppia/android/app/options/LoadAppLanguageListListener.kt",
     "src/main/java/org/oppia/android/app/options/LoadAudioLanguageListListener.kt",
     "src/main/java/org/oppia/android/app/options/LoadReadingTextSizeListener.kt",
@@ -293,8 +294,10 @@ VIEW_MODELS = [
     "src/main/java/org/oppia/android/app/onboarding/OnboardingViewPagerViewModel.kt",
     "src/main/java/org/oppia/android/app/onboarding/ViewPagerSlide.kt",
     "src/main/java/org/oppia/android/app/ongoingtopiclist/OngoingTopicListViewModel.kt",
-    "src/main/java/org/oppia/android/app/options/LanguageItemViewModel.kt",
-    "src/main/java/org/oppia/android/app/options/LanguageSelectionViewModel.kt",
+    "src/main/java/org/oppia/android/app/options/AppLanguageItemViewModel.kt",
+    "src/main/java/org/oppia/android/app/options/AppLanguageSelectionViewModel.kt",
+    "src/main/java/org/oppia/android/app/options/AudioLanguageItemViewModel.kt",
+    "src/main/java/org/oppia/android/app/options/AudioLanguageSelectionViewModel.kt",
     "src/main/java/org/oppia/android/app/options/OptionControlsViewModel.kt",
     "src/main/java/org/oppia/android/app/options/OptionsAppLanguageViewModel.kt",
     "src/main/java/org/oppia/android/app/options/OptionsAudioLanguageViewModel.kt",

app/src/main/java/org/oppia/android/app/options/AppLanguageFragment.kt

@@ -17,9 +17,7 @@ private const val APP_LANGUAGE_PREFERENCE_SUMMARY_VALUE_ARGUMENT_KEY =
 private const val SELECTED_LANGUAGE_SAVED_KEY = "AppLanguageFragment.selected_language"
 
 /** The fragment to change the language of the app. */
-class AppLanguageFragment :
-  InjectableFragment(),
-  LanguageRadioButtonListener {
+class AppLanguageFragment : InjectableFragment(), AppLanguageRadioButtonListener {
 
   @Inject
   lateinit var appLanguageFragmentPresenter: AppLanguageFragmentPresenter

app/src/main/java/org/oppia/android/app/options/AppLanguageFragmentPresenter.kt

@@ -6,13 +6,13 @@ import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import org.oppia.android.app.recyclerview.BindableAdapter
 import org.oppia.android.databinding.AppLanguageFragmentBinding
-import org.oppia.android.databinding.LanguageItemsBinding
+import org.oppia.android.databinding.AppLanguageItemBinding
 import javax.inject.Inject
 
 /** The presenter for [AppLanguageFragment]. */
 class AppLanguageFragmentPresenter @Inject constructor(
   private val fragment: Fragment,
-  private val languageSelectionViewModel: LanguageSelectionViewModel
+  private val appLanguageSelectionViewModel: AppLanguageSelectionViewModel
 ) {
   private lateinit var prefSummaryValue: String
   fun handleOnCreateView(
@@ -27,8 +27,8 @@ class AppLanguageFragmentPresenter @Inject constructor(
       /* attachToRoot= */ false
     )
     this.prefSummaryValue = prefSummaryValue
-    binding.viewModel = languageSelectionViewModel
-    languageSelectionViewModel.selectedLanguage.value = prefSummaryValue
+    binding.viewModel = appLanguageSelectionViewModel
+    appLanguageSelectionViewModel.selectedLanguage.value = prefSummaryValue
     binding.languageRecyclerView.apply {
       adapter = createRecyclerViewAdapter()
     }
@@ -37,16 +37,16 @@ class AppLanguageFragmentPresenter @Inject constructor(
   }
 
   fun getLanguageSelected(): String? {
-    return languageSelectionViewModel.selectedLanguage.value
+    return appLanguageSelectionViewModel.selectedLanguage.value
   }
 
-  private fun createRecyclerViewAdapter(): BindableAdapter<LanguageItemViewModel> {
+  private fun createRecyclerViewAdapter(): BindableAdapter<AppLanguageItemViewModel> {
     return BindableAdapter.SingleTypeBuilder
-      .newBuilder<LanguageItemViewModel>()
+      .newBuilder<AppLanguageItemViewModel>()
       .setLifecycleOwner(fragment)
       .registerViewDataBinderWithSameModelType(
-        inflateDataBinding = LanguageItemsBinding::inflate,
-        setViewModel = LanguageItemsBinding::setViewModel
+        inflateDataBinding = AppLanguageItemBinding::inflate,
+        setViewModel = AppLanguageItemBinding::setViewModel
       ).build()
   }
 
@@ -61,7 +61,7 @@ class AppLanguageFragmentPresenter @Inject constructor(
   }
 
   fun onLanguageSelected(selectedLanguage: String) {
-    languageSelectionViewModel.selectedLanguage.value = selectedLanguage
+    appLanguageSelectionViewModel.selectedLanguage.value = selectedLanguage
     updateAppLanguage(selectedLanguage)
   }
 }

app/src/main/java/org/oppia/android/app/options/AppLanguageItemViewModel.kt

@@ -0,0 +1,27 @@
+package org.oppia.android.app.options
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.Transformations
+import org.oppia.android.app.viewmodel.ObservableViewModel
+
+/**
+ * Language item view model for the recycler view in [AppLanguageFragment] and.
+ *
+ * @property language the app language corresponding to this language item to be displayed
+ * @property currentSelectedLanguage the [LiveData] tracking the currently selected language
+ * @property appLanguageRadioButtonListener the listener which will be called if this language is
+ *     selected by the user
+ */
+class AppLanguageItemViewModel(
+  val language: String,
+  private val currentSelectedLanguage: LiveData<String>,
+  val appLanguageRadioButtonListener: AppLanguageRadioButtonListener
+) : ObservableViewModel() {
+  /**
+   * Indicates whether the language corresponding to this view model is _currently_ selected in the
+   * radio button list.
+   */
+  val isLanguageSelected: LiveData<Boolean> by lazy {
+    Transformations.map(currentSelectedLanguage) { it == language }
+  }
+}

app/src/main/java/org/oppia/android/app/options/AppLanguageRadioButtonListener.kt

@@ -0,0 +1,7 @@
+package org.oppia.android.app.options
+
+/** Listener for when a language is selected for the [AppLanguageFragment]. */
+interface AppLanguageRadioButtonListener {
+  /** Called when the user selected a new app language to use as their default preference. */
+  fun onLanguageSelected(appLanguage: String)
+}

app/src/main/java/org/oppia/android/app/options/AppLanguageSelectionViewModel.kt

@@ -0,0 +1,27 @@
+package org.oppia.android.app.options
+
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.MutableLiveData
+import org.oppia.android.app.fragment.FragmentScope
+import org.oppia.android.app.viewmodel.ObservableViewModel
+import javax.inject.Inject
+
+/** Language list view model for the recycler view in [AppLanguageFragment]. */
+@FragmentScope
+class AppLanguageSelectionViewModel @Inject constructor(
+  val fragment: Fragment
+) : ObservableViewModel() {
+  /** The name of the app language currently selected in the radio button list. */
+  val selectedLanguage = MutableLiveData<String>()
+  private val appLanguageRadioButtonListener = fragment as AppLanguageRadioButtonListener
+
+  private val appLanguagesList = listOf(
+    AppLanguageItemViewModel("English", selectedLanguage, appLanguageRadioButtonListener),
+    AppLanguageItemViewModel("French", selectedLanguage, appLanguageRadioButtonListener),
+    AppLanguageItemViewModel("Hindi", selectedLanguage, appLanguageRadioButtonListener),
+    AppLanguageItemViewModel("Chinese", selectedLanguage, appLanguageRadioButtonListener)
+  )
+
+  /** The list of [AppLanguageItemViewModel]s which can be bound to a recycler view. */
+  val recyclerViewAppLanguageList: List<AppLanguageItemViewModel> by lazy { appLanguagesList }
+}

app/src/main/java/org/oppia/android/app/options/AudioLanguageActivity.kt

@@ -5,72 +5,64 @@ import android.content.Intent
 import android.os.Bundle
 import org.oppia.android.app.activity.ActivityComponentImpl
 import org.oppia.android.app.activity.InjectableAppCompatActivity
+import org.oppia.android.app.model.AudioLanguage
+import org.oppia.android.app.model.AudioLanguageActivityParams
+import org.oppia.android.app.model.AudioLanguageActivityStateBundle
+import org.oppia.android.util.extensions.getProto
+import org.oppia.android.util.extensions.getProtoExtra
+import org.oppia.android.util.extensions.putProto
+import org.oppia.android.util.extensions.putProtoExtra
 import javax.inject.Inject
 
 /** The activity to change the Default Audio language of the app. */
 class AudioLanguageActivity : InjectableAppCompatActivity() {
-
-  @Inject
-  lateinit var audioLanguageActivityPresenter: AudioLanguageActivityPresenter
-  private lateinit var prefKey: String
-  private lateinit var prefSummaryValue: String
+  @Inject lateinit var audioLanguageActivityPresenter: AudioLanguageActivityPresenter
 
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     (activityComponent as ActivityComponentImpl).inject(this)
-    prefKey = checkNotNull(intent.getStringExtra(AUDIO_LANGUAGE_PREFERENCE_TITLE_EXTRA_KEY)) {
-      "Expected $AUDIO_LANGUAGE_PREFERENCE_TITLE_EXTRA_KEY to be in intent extras."
-    }
-    prefSummaryValue = if (savedInstanceState != null) {
-      savedInstanceState.get(AUDIO_LANGUAGE_PREFERENCE_SUMMARY_VALUE_EXTRA_KEY) as String
-    } else {
-      checkNotNull(intent.getStringExtra(AUDIO_LANGUAGE_PREFERENCE_SUMMARY_VALUE_EXTRA_KEY)) {
-        "Expected $AUDIO_LANGUAGE_PREFERENCE_SUMMARY_VALUE_EXTRA_KEY to be in intent extras."
-      }
-    }
-    audioLanguageActivityPresenter.handleOnCreate(prefKey, prefSummaryValue)
+    audioLanguageActivityPresenter.handleOnCreate(
+      savedInstanceState?.retrieveLanguageFromSavedState() ?: intent.retrieveLanguageFromParams()
+    )
+  }
+
+  override fun onSaveInstanceState(outState: Bundle) {
+    super.onSaveInstanceState(outState)
+    val state = AudioLanguageActivityStateBundle.newBuilder().apply {
+      audioLanguage = audioLanguageActivityPresenter.getLanguageSelected()
+    }.build()
+    outState.putProto(ACTIVITY_SAVED_STATE_KEY, state)
   }
 
+  override fun onBackPressed() = audioLanguageActivityPresenter.finishWithResult()
+
   companion object {
-    internal const val AUDIO_LANGUAGE_PREFERENCE_TITLE_EXTRA_KEY =
-      "AudioLanguageActivity.audio_language_preference_title"
-    const val AUDIO_LANGUAGE_PREFERENCE_SUMMARY_VALUE_EXTRA_KEY =
-      "AudioLanguageActivity.audio_language_preference_summary_value"
+    private const val ACTIVITY_PARAMS_KEY = "AudioLanguageActivity.params"
+    private const val ACTIVITY_SAVED_STATE_KEY = "AudioLanguageActivity.saved_state"
 
     /** Returns a new [Intent] to route to [AudioLanguageActivity]. */
     fun createAudioLanguageActivityIntent(
       context: Context,
-      prefKey: String,
-      summaryValue: String?
+      audioLanguage: AudioLanguage
     ): Intent {
-      val intent = Intent(context, AudioLanguageActivity::class.java)
-      intent.putExtra(AUDIO_LANGUAGE_PREFERENCE_TITLE_EXTRA_KEY, prefKey)
-      intent.putExtra(AUDIO_LANGUAGE_PREFERENCE_SUMMARY_VALUE_EXTRA_KEY, summaryValue)
-      return intent
+      return Intent(context, AudioLanguageActivity::class.java).apply {
+        val arguments = AudioLanguageActivityParams.newBuilder().apply {
+          this.audioLanguage = audioLanguage
+        }.build()
+        putProtoExtra(ACTIVITY_PARAMS_KEY, arguments)
+      }
     }
 
-    fun getKeyAudioLanguagePreferenceTitle(): String {
-      return AUDIO_LANGUAGE_PREFERENCE_TITLE_EXTRA_KEY
+    private fun Intent.retrieveLanguageFromParams(): AudioLanguage {
+      return getProtoExtra(
+        ACTIVITY_PARAMS_KEY, AudioLanguageActivityParams.getDefaultInstance()
+      ).audioLanguage
     }
 
-    fun getKeyAudioLanguagePreferenceSummaryValue(): String {
-      return AUDIO_LANGUAGE_PREFERENCE_SUMMARY_VALUE_EXTRA_KEY
+    private fun Bundle.retrieveLanguageFromSavedState(): AudioLanguage {
+      return getProto(
+        ACTIVITY_SAVED_STATE_KEY, AudioLanguageActivityStateBundle.getDefaultInstance()
+      ).audioLanguage
     }
   }
-
-  override fun onSaveInstanceState(outState: Bundle) {
-    super.onSaveInstanceState(outState)
-    outState.putString(
-      AUDIO_LANGUAGE_PREFERENCE_SUMMARY_VALUE_EXTRA_KEY,
-      audioLanguageActivityPresenter.getLanguageSelected()
-    )
-  }
-
-  override fun onBackPressed() {
-    val message = audioLanguageActivityPresenter.getLanguageSelected()
-    val intent = Intent()
-    intent.putExtra(MESSAGE_AUDIO_LANGUAGE_ARGUMENT_KEY, message)
-    setResult(REQUEST_CODE_AUDIO_LANGUAGE, intent)
-    finish()
-  }
 }

app/src/main/java/org/oppia/android/app/options/AudioLanguageActivityPresenter.kt

@@ -5,46 +5,60 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.databinding.DataBindingUtil
 import org.oppia.android.R
 import org.oppia.android.app.activity.ActivityScope
+import org.oppia.android.app.model.AudioLanguage
+import org.oppia.android.app.model.AudioLanguageActivityResultBundle
 import org.oppia.android.databinding.AudioLanguageActivityBinding
+import org.oppia.android.util.extensions.putProtoExtra
 import javax.inject.Inject
 
 /** The presenter for [AudioLanguageActivity]. */
 @ActivityScope
 class AudioLanguageActivityPresenter @Inject constructor(private val activity: AppCompatActivity) {
+  private lateinit var audioLanguage: AudioLanguage
 
-  private lateinit var prefSummaryValue: String
-
-  fun handleOnCreate(prefKey: String, prefValue: String) {
-    val binding: AudioLanguageActivityBinding = DataBindingUtil.setContentView(
-      activity,
-      R.layout.audio_language_activity,
-    )
-    val toolbar = binding.audioLanguageToolbar
-    toolbar.setNavigationOnClickListener {
-      val intent = Intent().apply {
-        putExtra(MESSAGE_AUDIO_LANGUAGE_ARGUMENT_KEY, prefSummaryValue)
-      }
-      (activity as AudioLanguageActivity).setResult(REQUEST_CODE_AUDIO_LANGUAGE, intent)
-      activity.finish()
+  /** Handles when the activity is first created. */
+  fun handleOnCreate(audioLanguage: AudioLanguage) {
+    this.audioLanguage = audioLanguage
+
+    val binding: AudioLanguageActivityBinding =
+      DataBindingUtil.setContentView(activity, R.layout.audio_language_activity)
+    binding.audioLanguageToolbar.setNavigationOnClickListener {
+      finishWithResult()
     }
-    setLanguageSelected(prefValue)
     if (getAudioLanguageFragment() == null) {
-      val audioLanguageFragment = AudioLanguageFragment.newInstance(prefKey, prefValue)
+      val audioLanguageFragment = AudioLanguageFragment.newInstance(audioLanguage)
       activity.supportFragmentManager.beginTransaction()
         .add(R.id.audio_language_fragment_container, audioLanguageFragment).commitNow()
     }
   }
 
-  fun setLanguageSelected(audioLanguage: String) {
-    prefSummaryValue = audioLanguage
+  /** Updates the currently selected [AudioLanguage] to the specified [audioLanguage]. */
+  fun setLanguageSelected(audioLanguage: AudioLanguage) {
+    this.audioLanguage = audioLanguage
   }
 
-  fun getLanguageSelected(): String {
-    return prefSummaryValue
+  /** Returns the current [AudioLanguage] selected in the activity. */
+  fun getLanguageSelected(): AudioLanguage = audioLanguage
+
+  /**
+   * Finishes the current activity with a result (specifically, an intent result with
+   * [AudioLanguageActivityResultBundle] populated with the [AudioLanguage] that was selected in the
+   * activity).
+   */
+  fun finishWithResult() {
+    val intent = Intent().apply {
+      val result = AudioLanguageActivityResultBundle.newBuilder().apply {
+        this.audioLanguage = this@AudioLanguageActivityPresenter.audioLanguage
+      }.build()
+      putProtoExtra(MESSAGE_AUDIO_LANGUAGE_RESULTS_KEY, result)
+    }
+
+    activity.setResult(REQUEST_CODE_AUDIO_LANGUAGE, intent)
+    activity.finish()
   }
 
   private fun getAudioLanguageFragment(): AudioLanguageFragment? {
     return activity.supportFragmentManager
-      .findFragmentById(R.id.audio_language_fragment_container) as AudioLanguageFragment?
+      .findFragmentById(R.id.audio_language_fragment_container) as? AudioLanguageFragment
   }
 }