Fix part of #134: Home fragment low fi with TopicList (#289)

* HomeFragment xml introduction

* Promoted Story ViewModel

* PromotedStoryViewModel

* Basic promoted story

* Promoted story data display

* Promoted card display

* GridLayoutManager

* Functional HomeFragment

* Click listeners

* Click listeners final

* Chapter name issue fixed

* Fully functional with click listeners

* Introduce ContinuePlayingActivity

* Click listener integration

* Test for ContinuePlayingActivity

* HomeTest cases

* Nit changes

* Nit suggested changes

* Code updated as per suggestions

* Added HomeItemViewModel

* Nit changes

* Orientation Change

* EOF

* Test fix

app/build.gradle

@@ -73,6 +73,7 @@ dependencies {
   )
   testImplementation(
       'androidx.test:core:1.2.0',
+      'androidx.test.espresso:espresso-contrib:3.1.0',
       'androidx.test.espresso:espresso-core:3.2.0',
       'androidx.test.espresso:espresso-intents:3.1.0',
       'androidx.test.ext:junit:1.1.1',
@@ -82,6 +83,7 @@ dependencies {
   )
   androidTestImplementation(
       'androidx.test:core:1.2.0',
+      'androidx.test.espresso:espresso-contrib:3.1.0',
       'androidx.test.espresso:espresso-core:3.2.0',
       'androidx.test.espresso:espresso-intents:3.1.0',
       'androidx.test.ext:junit:1.1.1',

app/src/main/AndroidManifest.xml

@@ -11,6 +11,7 @@
     android:roundIcon="@mipmap/ic_launcher_round"
     android:supportsRtl="true"
     android:theme="@style/OppiaTheme">
+    <activity android:name=".home.ContinuePlayingActivity" />
     <activity android:name=".topic.conceptcard.testing.ConceptCardFragmentTestActivity" />
     <activity android:name=".testing.ContentCardTestActivity" />
     <activity android:name=".player.state.testing.StateFragmentTestActivity" />

app/src/main/java/org/oppia/app/activity/ActivityComponent.kt

@@ -4,6 +4,7 @@ import androidx.appcompat.app.AppCompatActivity
 import dagger.BindsInstance
 import dagger.Subcomponent
 import org.oppia.app.fragment.FragmentComponent
+import org.oppia.app.home.ContinuePlayingActivity
 import org.oppia.app.home.HomeActivity
 import org.oppia.app.player.audio.testing.AudioFragmentTestActivity
 import org.oppia.app.player.exploration.ExplorationActivity
@@ -34,9 +35,10 @@ interface ActivityComponent {
   fun inject(bindableAdapterTestActivity: BindableAdapterTestActivity)
   fun inject(conceptCardFragmentTestActivity: ConceptCardFragmentTestActivity)
   fun inject(contentCardTestActivity: ContentCardTestActivity)
+  fun inject(continuePlayingActivity: ContinuePlayingActivity)
   fun inject(explorationActivity: ExplorationActivity)
   fun inject(homeActivity: HomeActivity)
-  fun inject(htmlParserTestActivty: HtmlParserTestActivity)
+  fun inject(htmlParserTestActivity: HtmlParserTestActivity)
   fun inject(profileActivity: ProfileActivity)
   fun inject(questionPlayerActivity: QuestionPlayerActivity)
   fun inject(stateFragmentTestActivity: StateFragmentTestActivity)

app/src/main/java/org/oppia/app/databinding/DrawableBindingAdapters.kt

@@ -0,0 +1,15 @@
+package org.oppia.app.databinding
+
+import android.graphics.drawable.GradientDrawable
+import android.view.View
+import androidx.annotation.ColorInt
+import androidx.databinding.BindingAdapter
+import org.oppia.app.R
+
+/** Used to set a rounded-rect background drawable with a data-bound color. */
+@BindingAdapter("app:roundedRectDrawableWithColor")
+fun setBackgroundDrawable(view: View, @ColorInt colorRgb: Int) {
+  view.setBackgroundResource(R.drawable.rounded_rect_background)
+  // The input color needs to have alpha channel prepended to it.
+  (view.background as GradientDrawable).setColor((0xff000000 or colorRgb.toLong()).toInt())
+}

app/src/main/java/org/oppia/app/fragment/FragmentComponent.kt

@@ -3,6 +3,7 @@ package org.oppia.app.fragment
 import androidx.fragment.app.Fragment
 import dagger.BindsInstance
 import dagger.Subcomponent
+import org.oppia.app.home.ContinuePlayingFragment
 import org.oppia.app.home.HomeFragment
 import org.oppia.app.player.exploration.ExplorationFragment
 import org.oppia.app.player.state.StateFragment
@@ -37,6 +38,7 @@ interface FragmentComponent {
   fun inject(audioFragment: AudioFragment)
   fun inject(bindableAdapterTestFragment: BindableAdapterTestFragment)
   fun inject(conceptCardFragment: ConceptCardFragment)
+  fun inject(continuePlayingFragment: ContinuePlayingFragment)
   fun inject(explorationFragment: ExplorationFragment)
   fun inject(homeFragment: HomeFragment)
   fun inject(profileChooserFragment: ProfileChooserFragment)

app/src/main/java/org/oppia/app/home/ContinuePlayingActivity.kt

@@ -0,0 +1,25 @@
+package org.oppia.app.home
+
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import org.oppia.app.activity.InjectableAppCompatActivity
+import javax.inject.Inject
+
+/** Activity for recent stories. */
+class ContinuePlayingActivity : InjectableAppCompatActivity() {
+  @Inject lateinit var continuePlayingActivityPresenter: ContinuePlayingActivityPresenter
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    activityComponent.inject(this)
+    continuePlayingActivityPresenter.handleOnCreate()
+  }
+
+  companion object {
+    /** Returns a new [Intent] to route to [ContinuePlayingActivity]. */
+    fun createContinuePlayingActivityIntent(context: Context): Intent {
+      return Intent(context, ContinuePlayingActivity::class.java)
+    }
+  }
+}

app/src/main/java/org/oppia/app/home/ContinuePlayingActivityPresenter.kt

@@ -0,0 +1,24 @@
+package org.oppia.app.home
+
+import androidx.appcompat.app.AppCompatActivity
+import org.oppia.app.R
+import org.oppia.app.activity.ActivityScope
+import javax.inject.Inject
+
+/** The presenter for [ContinuePlayingActivity]. */
+@ActivityScope
+class ContinuePlayingActivityPresenter @Inject constructor(private val activity: AppCompatActivity) {
+  fun handleOnCreate() {
+    activity.setContentView(R.layout.continue_playing_activity)
+    if (getContinuePlayingFragment() == null) {
+      activity.supportFragmentManager.beginTransaction().add(
+        R.id.continue_playing_fragment_placeholder,
+        ContinuePlayingFragment()
+      ).commitNow()
+    }
+  }
+
+  private fun getContinuePlayingFragment(): ContinuePlayingFragment? {
+    return activity.supportFragmentManager.findFragmentById(R.id.continue_playing_fragment_placeholder) as ContinuePlayingFragment?
+  }
+}

app/src/main/java/org/oppia/app/home/ContinuePlayingFragment.kt

@@ -0,0 +1,23 @@
+package org.oppia.app.home
+
+import android.content.Context
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import org.oppia.app.fragment.InjectableFragment
+import javax.inject.Inject
+
+/** Fragment that contains all recently played stories. */
+class ContinuePlayingFragment : InjectableFragment() {
+  @Inject lateinit var continuePlayingFragmentPresenter: ContinuePlayingFragmentPresenter
+
+  override fun onAttach(context: Context?) {
+    super.onAttach(context)
+    fragmentComponent.inject(this)
+  }
+
+  override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+    return continuePlayingFragmentPresenter.handleCreateView(inflater, container)
+  }
+}

app/src/main/java/org/oppia/app/home/ContinuePlayingFragmentPresenter.kt

@@ -0,0 +1,16 @@
+package org.oppia.app.home
+
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import org.oppia.app.databinding.ContinuePlayingFragmentBinding
+import org.oppia.app.fragment.FragmentScope
+import javax.inject.Inject
+
+/** The presenter for [ContinuePlayingFragment]. */
+@FragmentScope
+class ContinuePlayingFragmentPresenter @Inject constructor() {
+  fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
+    return ContinuePlayingFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false).root
+  }
+}

app/src/main/java/org/oppia/app/home/HomeActivity.kt

@@ -3,18 +3,24 @@ package org.oppia.app.home
 import android.os.Bundle
 import org.oppia.app.activity.InjectableAppCompatActivity
 import org.oppia.app.player.exploration.ExplorationActivity
+import org.oppia.app.topic.TopicActivity
 import javax.inject.Inject
 
 /** The central activity for all users entering the app. */
-class HomeActivity : InjectableAppCompatActivity(), RouteToExplorationListener {
-  @Inject lateinit var homeActivityPresenter: HomeActivityPresenter
+class HomeActivity : InjectableAppCompatActivity(), RouteToTopicListener, RouteToExplorationListener {
+  @Inject
+  lateinit var homeActivityPresenter: HomeActivityPresenter
 
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     activityComponent.inject(this)
     homeActivityPresenter.handleOnCreate()
   }
 
+  override fun routeToTopic(topicId: String) {
+    startActivity(TopicActivity.createTopicActivityIntent(this, topicId))
+  }
+
   override fun routeToExploration(explorationId: String) {
     startActivity(ExplorationActivity.createExplorationActivityIntent(this, explorationId))
   }

app/src/main/java/org/oppia/app/home/HomeActivityPresenter.kt

@@ -5,7 +5,7 @@ import org.oppia.app.R
 import org.oppia.app.activity.ActivityScope
 import javax.inject.Inject
 
-/** The controller for [HomeActivity]. */
+/** The presenter for [HomeActivity]. */
 @ActivityScope
 class HomeActivityPresenter @Inject constructor(private val activity: AppCompatActivity) {
   fun handleOnCreate() {

app/src/main/java/org/oppia/app/home/HomeFragment.kt

@@ -6,10 +6,12 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import org.oppia.app.fragment.InjectableFragment
+import org.oppia.app.home.topiclist.TopicSummaryClickListener
+import org.oppia.app.model.TopicSummary
 import javax.inject.Inject
 
 /** Fragment that contains an introduction to the app. */
-class HomeFragment : InjectableFragment() {
+class HomeFragment : InjectableFragment(), TopicSummaryClickListener {
   @Inject lateinit var homeFragmentPresenter: HomeFragmentPresenter
 
   override fun onAttach(context: Context?) {
@@ -20,4 +22,8 @@ class HomeFragment : InjectableFragment() {
   override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
     return homeFragmentPresenter.handleCreateView(inflater, container)
   }
+
+  override fun onTopicSummaryClicked(topicSummary: TopicSummary) {
+    homeFragmentPresenter.onTopicSummaryClicked(topicSummary)
+  }
 }

app/src/main/java/org/oppia/app/home/HomeFragmentPresenter.kt

@@ -5,49 +5,85 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.app.AppCompatActivity
 import androidx.fragment.app.Fragment
+import androidx.lifecycle.LiveData
 import androidx.lifecycle.Observer
+import androidx.lifecycle.Transformations
+import androidx.recyclerview.widget.GridLayoutManager
 import org.oppia.app.databinding.HomeFragmentBinding
 import org.oppia.app.fragment.FragmentScope
+import org.oppia.app.home.topiclist.PromotedStoryViewModel
+import org.oppia.app.home.topiclist.TopicListAdapter
+import org.oppia.app.home.topiclist.TopicSummaryClickListener
+import org.oppia.app.home.topiclist.TopicSummaryViewModel
+import org.oppia.app.model.TopicList
+import org.oppia.app.model.TopicSummary
+import org.oppia.app.model.UserAppHistory
 import org.oppia.app.viewmodel.ViewModelProvider
 import org.oppia.domain.UserAppHistoryController
 import org.oppia.domain.exploration.ExplorationDataController
 import org.oppia.domain.exploration.TEST_EXPLORATION_ID_5
+import org.oppia.domain.topic.TopicListController
 import org.oppia.util.data.AsyncResult
 import org.oppia.util.logging.Logger
 import javax.inject.Inject
 
 private const val EXPLORATION_ID = TEST_EXPLORATION_ID_5
 
-/** The controller for [HomeFragment]. */
+/** The presenter for [HomeFragment]. */
 @FragmentScope
 class HomeFragmentPresenter @Inject constructor(
-  activity: AppCompatActivity,
+  private val activity: AppCompatActivity,
   private val fragment: Fragment,
   private val viewModelProvider: ViewModelProvider<UserAppHistoryViewModel>,
   private val userAppHistoryController: UserAppHistoryController,
+  private val topicListController: TopicListController,
   private val explorationDataController: ExplorationDataController,
   private val logger: Logger
 ) {
 
   private val routeToExplorationListener = activity as RouteToExplorationListener
+  private val routeToTopicListener = activity as RouteToTopicListener
+
+  private val itemList: MutableList<HomeItemViewModel> = ArrayList()
+
+  private lateinit var topicListAdapter: TopicListAdapter
+
+  private lateinit var binding: HomeFragmentBinding
 
   fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
-    val binding = HomeFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false)
+    binding = HomeFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false)
     // NB: Both the view model and lifecycle owner must be set in order to correctly bind LiveData elements to
     // data-bound view models.
+
+    topicListAdapter = TopicListAdapter(itemList)
+
+    val homeLayoutManager = GridLayoutManager(activity.applicationContext, 2)
+    homeLayoutManager.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
+      override fun getSpanSize(position: Int): Int {
+        return if (position == 0 || position == 1) {
+          /* number of spaces this item should occupy = */ 2
+        } else {
+          /* number of spaces this item should occupy = */ 1
+        }
+      }
+    }
+
+    binding.homeRecyclerView.apply {
+      adapter = topicListAdapter
+      // https://stackoverflow.com/a/32763434/32763621
+      layoutManager = homeLayoutManager
+    }
     binding.let {
-      it.viewModel = getUserAppHistoryViewModel()
       it.presenter = this
       it.lifecycleOwner = fragment
     }
 
     userAppHistoryController.markUserOpenedApp()
 
-    return binding.root
-  }
+    subscribeToUserAppHistory()
+    subscribeToTopicList()
 
-  private fun getUserAppHistoryViewModel(): UserAppHistoryViewModel {
-    return viewModelProvider.getForFragment(fragment, UserAppHistoryViewModel::class.java)
+    return binding.root
   }
 
   fun playExplorationButton(v: View) {
@@ -64,4 +100,55 @@ class HomeFragmentPresenter @Inject constructor(
       }
     })
   }
+
+  private fun getUserAppHistoryViewModel(): UserAppHistoryViewModel {
+    return viewModelProvider.getForFragment(fragment, UserAppHistoryViewModel::class.java)
+  }
+
+  private val topicListSummaryResultLiveData: LiveData<AsyncResult<TopicList>> by lazy {
+    topicListController.getTopicList()
+  }
+
+  private fun subscribeToTopicList() {
+    getAssumedSuccessfulTopicList().observe(fragment, Observer<TopicList> { result ->
+
+      val promotedStoryViewModel = PromotedStoryViewModel(activity)
+      promotedStoryViewModel.setPromotedStory(result.promotedStory)
+      itemList.add(promotedStoryViewModel)
+      for (topicSummary in result.topicSummaryList) {
+        val topicSummaryViewModel = TopicSummaryViewModel(topicSummary, fragment as TopicSummaryClickListener)
+        itemList.add(topicSummaryViewModel)
+      }
+      topicListAdapter.notifyDataSetChanged()
+    })
+  }
+
+  private fun getAssumedSuccessfulTopicList(): LiveData<TopicList> {
+    // If there's an error loading the data, assume the default.
+    return Transformations.map(topicListSummaryResultLiveData) { it.getOrDefault(TopicList.getDefaultInstance()) }
+  }
+
+  private fun subscribeToUserAppHistory() {
+    getUserAppHistory().observe(fragment, Observer<UserAppHistory> { result ->
+      getUserAppHistoryViewModel().setAlreadyAppOpened(result.alreadyOpenedApp)
+      itemList.add(0, getUserAppHistoryViewModel())
+      topicListAdapter.notifyDataSetChanged()
+    })
+  }
+
+  private fun getUserAppHistory(): LiveData<UserAppHistory> {
+    // If there's an error loading the data, assume the default.
+    return Transformations.map(userAppHistoryController.getUserAppHistory(), ::processUserAppHistoryResult)
+  }
+
+  private fun processUserAppHistoryResult(appHistoryResult: AsyncResult<UserAppHistory>): UserAppHistory {
+    if (appHistoryResult.isFailure()) {
+      logger.e("HomeFragment", "Failed to retrieve user app history" + appHistoryResult.getErrorOrNull())
+    }
+    return appHistoryResult.getOrDefault(UserAppHistory.getDefaultInstance())
+  }
+
+  fun onTopicSummaryClicked(topicSummary: TopicSummary) {
+    routeToTopicListener.routeToTopic(topicSummary.topicId)
+  }
 }

app/src/main/java/org/oppia/app/home/HomeItemViewModel.kt

@@ -0,0 +1,6 @@
+package org.oppia.app.home
+
+import org.oppia.app.viewmodel.ObservableViewModel
+
+/** The root [ViewModel] for all individual items that may be displayed in home fragment recycler view. */
+abstract class HomeItemViewModel: ObservableViewModel()

app/src/main/java/org/oppia/app/home/RouteToContinuePlayingListener.kt

@@ -0,0 +1,6 @@
+package org.oppia.app.home
+
+/** Listener for when an activity should route to [ContinuePlayingActivity]. */
+interface RouteToContinuePlayingListener {
+  fun routeToContinuePlaying()
+}

app/src/main/java/org/oppia/app/home/RouteToTopicListener.kt

@@ -0,0 +1,6 @@
+package org.oppia.app.home
+
+/** Listener for when an activity should route to a topic. */
+interface RouteToTopicListener {
+  fun routeToTopic(topicId: String)
+}