Fix part of #632: Replace LanguageSelectionAdapter with BindableAdapter

app/BUILD.bazel

@@ -63,6 +63,7 @@ LISTENERS = [
     "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",
+    "src/main/java/org/oppia/android/app/options/LanguageRadioButtonListener.kt",
     "src/main/java/org/oppia/android/app/options/RouteToAppLanguageListListener.kt",
     "src/main/java/org/oppia/android/app/options/RouteToAudioLanguageListListener.kt",
     "src/main/java/org/oppia/android/app/options/RouteToReadingTextSizeListener.kt",
@@ -178,6 +179,8 @@ VIEW_MODELS = [
     "src/main/java/org/oppia/android/app/onboarding/ViewPagerSlide.kt",
     "src/main/java/org/oppia/android/app/ongoingtopiclist/OngoingTopicItemViewModel.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/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

@@ -14,7 +14,9 @@ private const val KEY_APP_LANGUAGE_PREFERENCE_SUMMARY_VALUE =
 private const val SELECTED_LANGUAGE_SAVED_KEY = "AppLanguageFragment.selected_language"
 
 /** The fragment to change the language of the app. */
-class AppLanguageFragment : InjectableFragment() {
+class AppLanguageFragment :
+  InjectableFragment(),
+  LanguageRadioButtonListener {
 
   @Inject
   lateinit var appLanguageFragmentPresenter: AppLanguageFragmentPresenter
@@ -63,4 +65,8 @@ class AppLanguageFragment : InjectableFragment() {
       appLanguageFragmentPresenter.getLanguageSelected()
     )
   }
+
+  override fun onLanguageSelected(selectedLanguage: String) {
+    appLanguageFragmentPresenter.onLanguageSelected(selectedLanguage)
+  }
 }

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

@@ -5,14 +5,19 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
+import org.oppia.android.app.recyclerview.BindableAdapter
+import org.oppia.android.app.viewmodel.ViewModelProvider
 import org.oppia.android.databinding.AppLanguageFragmentBinding
+import org.oppia.android.databinding.LanguageItemsBinding
 import javax.inject.Inject
 
 /** The presenter for [AppLanguageFragment]. */
-class AppLanguageFragmentPresenter @Inject constructor(private val fragment: Fragment) {
-  private lateinit var languageSelectionAdapter: LanguageSelectionAdapter
+class AppLanguageFragmentPresenter @Inject constructor(
+  private val fragment: Fragment,
+  private val viewModelProvider: ViewModelProvider<LanguageSelectionViewModel>
+) {
   private lateinit var prefSummaryValue: String
-
+  private lateinit var languageSelectionViewModel: LanguageSelectionViewModel
   fun handleOnCreateView(
     inflater: LayoutInflater,
     container: ViewGroup?,
@@ -25,25 +30,37 @@ class AppLanguageFragmentPresenter @Inject constructor(private val fragment: Fra
       /* attachToRoot= */ false
     )
     this.prefSummaryValue = prefSummaryValue
-    languageSelectionAdapter = LanguageSelectionAdapter(prefKey) {
-      updateAppLanguage(it)
-    }
+    languageSelectionViewModel = getLanguageSelectionViewModel()
+    binding.viewModel = languageSelectionViewModel
+    languageSelectionViewModel.selectedLanguage.value = prefSummaryValue
     binding.languageRecyclerView.apply {
-      adapter = languageSelectionAdapter
+      adapter = createRecyclerViewAdapter()
     }
 
     binding.appLanguageToolbar?.setNavigationOnClickListener {
-      val message = languageSelectionAdapter.getSelectedLanguage()
+      val message = languageSelectionViewModel.selectedLanguage.value
       val intent = Intent()
       intent.putExtra(MESSAGE_APP_LANGUAGE_ARGUMENT_KEY, message)
       (fragment.activity as AppLanguageActivity).setResult(REQUEST_CODE_APP_LANGUAGE, intent)
       (fragment.activity as AppLanguageActivity).finish()
     }
 
-    createAdapter()
     return binding.root
   }
 
+  fun getLanguageSelected(): String? {
+    return languageSelectionViewModel.selectedLanguage.value
+  }
+
+  private fun createRecyclerViewAdapter(): BindableAdapter<LanguageItemViewModel> {
+    return BindableAdapter.SingleTypeBuilder
+      .newBuilder<LanguageItemViewModel>()
+      .registerViewDataBinderWithSameModelType(
+        inflateDataBinding = LanguageItemsBinding::inflate,
+        setViewModel = LanguageItemsBinding::setViewModel
+      ).build()
+  }
+
   private fun updateAppLanguage(appLanguage: String) {
     // The first branch of (when) will be used in the case of multipane
     when (val parentActivity = fragment.activity) {
@@ -54,18 +71,11 @@ class AppLanguageFragmentPresenter @Inject constructor(private val fragment: Fra
     }
   }
 
-  fun getLanguageSelected(): String {
-    return languageSelectionAdapter.getSelectedLanguage()
+  fun onLanguageSelected(selectedLanguage: String) {
+    languageSelectionViewModel.selectedLanguage.value = selectedLanguage
   }
 
-  private fun createAdapter() {
-    // TODO(#669): Replace dummy list with actual language list from backend.
-    val languageList = ArrayList<String>()
-    languageList.add("English")
-    languageList.add("French")
-    languageList.add("Hindi")
-    languageList.add("Chinese")
-    languageSelectionAdapter.setLanguageList(languageList)
-    languageSelectionAdapter.setDefaultLanguageSelected(prefSummaryValue = prefSummaryValue)
+  private fun getLanguageSelectionViewModel(): LanguageSelectionViewModel {
+    return viewModelProvider.getForFragment(fragment, LanguageSelectionViewModel::class.java)
   }
 }

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

@@ -15,7 +15,9 @@ private const val SELECTED_AUDIO_LANGUAGE_SAVED_KEY =
   "AudioLanguageFragment.selected_audio_language"
 
 /** The fragment to change the default audio language of the app. */
-class AudioLanguageFragment : InjectableFragment() {
+class AudioLanguageFragment :
+  InjectableFragment(),
+  LanguageRadioButtonListener {
 
   @Inject
   lateinit var audioLanguageFragmentPresenter: AudioLanguageFragmentPresenter
@@ -68,4 +70,8 @@ class AudioLanguageFragment : InjectableFragment() {
       audioLanguageFragmentPresenter.getLanguageSelected()
     )
   }
+
+  override fun onLanguageSelected(selectedLanguage: String) {
+    audioLanguageFragmentPresenter.onLanguageSelected(selectedLanguage)
+  }
 }

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

@@ -5,15 +5,20 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
+import org.oppia.android.app.recyclerview.BindableAdapter
+import org.oppia.android.app.viewmodel.ViewModelProvider
 import org.oppia.android.databinding.AudioLanguageFragmentBinding
+import org.oppia.android.databinding.LanguageItemsBinding
 import javax.inject.Inject
 
 /** The presenter for [AudioLanguageFragment]. */
-class AudioLanguageFragmentPresenter @Inject constructor(private val fragment: Fragment) {
+class AudioLanguageFragmentPresenter @Inject constructor(
+  private val fragment: Fragment,
+  private val viewModelProvider: ViewModelProvider<LanguageSelectionViewModel>
+) {
 
   private lateinit var prefSummaryValue: String
-  private lateinit var languageSelectionAdapter: LanguageSelectionAdapter
-
+  private lateinit var languageSelectionViewModel: LanguageSelectionViewModel
   fun handleOnCreateView(
     inflater: LayoutInflater,
     container: ViewGroup?,
@@ -25,27 +30,36 @@ class AudioLanguageFragmentPresenter @Inject constructor(private val fragment: F
       container,
       /* attachToRoot= */ false
     )
+    languageSelectionViewModel = getLanguageSelectionViewModel()
+    binding.viewModel = languageSelectionViewModel
     prefSummaryValue = prefValue
-    languageSelectionAdapter = LanguageSelectionAdapter(prefKey) {
-      updateAudioLanguage(it)
-    }
+    languageSelectionViewModel.selectedLanguage.value = prefSummaryValue
     binding.audioLanguageRecyclerView.apply {
-      adapter = languageSelectionAdapter
+      adapter = createRecyclerViewAdapter()
     }
 
     binding.audioLanguageToolbar?.setNavigationOnClickListener {
-      val message = languageSelectionAdapter.getSelectedLanguage()
+      val message = languageSelectionViewModel.selectedLanguage.value
       val intent = Intent()
       intent.putExtra(MESSAGE_AUDIO_LANGUAGE_ARGUMENT_KEY, message)
       (fragment.activity as AudioLanguageActivity).setResult(REQUEST_CODE_AUDIO_LANGUAGE, intent)
       (fragment.activity as AudioLanguageActivity).finish()
     }
-    createAdapter()
+
     return binding.root
   }
 
-  fun getLanguageSelected(): String {
-    return languageSelectionAdapter.getSelectedLanguage()
+  fun getLanguageSelected(): String? {
+    return languageSelectionViewModel.selectedLanguage.value
+  }
+
+  private fun createRecyclerViewAdapter(): BindableAdapter<LanguageItemViewModel> {
+    return BindableAdapter.SingleTypeBuilder
+      .newBuilder<LanguageItemViewModel>()
+      .registerViewDataBinderWithSameModelType(
+        inflateDataBinding = LanguageItemsBinding::inflate,
+        setViewModel = LanguageItemsBinding::setViewModel
+      ).build()
   }
 
   private fun updateAudioLanguage(audioLanguage: String) {
@@ -58,15 +72,12 @@ class AudioLanguageFragmentPresenter @Inject constructor(private val fragment: F
     }
   }
 
-  private fun createAdapter() {
-    // TODO(#669): Replace dummy list with actual language list from backend.
-    val languageList = ArrayList<String>()
-    languageList.add("No Audio")
-    languageList.add("English")
-    languageList.add("French")
-    languageList.add("Hindi")
-    languageList.add("Chinese")
-    languageSelectionAdapter.setLanguageList(languageList)
-    languageSelectionAdapter.setDefaultLanguageSelected(prefSummaryValue = prefSummaryValue)
+  fun onLanguageSelected(selectedLanguage: String) {
+    languageSelectionViewModel.selectedLanguage.value = selectedLanguage
+    updateAudioLanguage(selectedLanguage)
+  }
+
+  private fun getLanguageSelectionViewModel(): LanguageSelectionViewModel {
+    return viewModelProvider.getForFragment(fragment, LanguageSelectionViewModel::class.java)
   }
 }

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

@@ -0,0 +1,22 @@
+package org.oppia.android.app.options
+
+import androidx.databinding.ObservableBoolean
+import androidx.lifecycle.LiveData
+import org.oppia.android.app.viewmodel.ObservableViewModel
+
+/**
+ * Language item view model for the recycler view in [AppLanguageFragment] and
+ * [AudioLanguageFragment].
+ */
+class LanguageItemViewModel(
+  val language: String,
+  selectedLanguage: LiveData<String>,
+  val languageRadioButtonListener: LanguageRadioButtonListener
+) : ObservableViewModel() {
+  val isLanguageSelected = ObservableBoolean()
+  init {
+    selectedLanguage.observeForever {
+      isLanguageSelected.set(it == language)
+    }
+  }
+}

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

@@ -0,0 +1,9 @@
+package org.oppia.android.app.options
+
+/**
+ * Listener for when the language is selected from the [AppLanguageFragment] or
+ * [AudioLanguageFragment].
+ */
+interface LanguageRadioButtonListener {
+  fun onLanguageSelected(selectedLanguage: String)
+}

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

@@ -0,0 +1,44 @@
+package org.oppia.android.app.options
+
+import androidx.appcompat.app.AppCompatActivity
+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] and
+ * [AudioLanguageFragment].
+ */
+@FragmentScope
+class LanguageSelectionViewModel @Inject constructor(
+  val activity: AppCompatActivity,
+  val fragment: Fragment
+) : ObservableViewModel() {
+
+  val selectedLanguage = MutableLiveData<String>()
+  val languageRadioButtonListener = fragment as LanguageRadioButtonListener
+
+  private val appLanguagesList = listOf<LanguageItemViewModel>(
+    LanguageItemViewModel("English", selectedLanguage, languageRadioButtonListener),
+    LanguageItemViewModel("French", selectedLanguage, languageRadioButtonListener),
+    LanguageItemViewModel("Hindi", selectedLanguage, languageRadioButtonListener),
+    LanguageItemViewModel("Chinese", selectedLanguage, languageRadioButtonListener)
+  )
+  private val audioLanguagesList = listOf<LanguageItemViewModel>(
+    LanguageItemViewModel("No Audio", selectedLanguage, languageRadioButtonListener),
+    LanguageItemViewModel("English", selectedLanguage, languageRadioButtonListener),
+    LanguageItemViewModel("French", selectedLanguage, languageRadioButtonListener),
+    LanguageItemViewModel("Hindi", selectedLanguage, languageRadioButtonListener),
+    LanguageItemViewModel("Chinese", selectedLanguage, languageRadioButtonListener)
+  )
+
+  val recyclerViewAudioLanguageList: List<LanguageItemViewModel> by lazy {
+    audioLanguagesList
+  }
+
+  val recyclerViewAppLanguageList: List<LanguageItemViewModel> by lazy {
+    appLanguagesList
+  }
+}