Show a dialog when preloading assets for offline support.

This does a bunch of refactoring & hacky workarounds to keep asset
priming support fully isolated (just a few files now need to be deleted
to clean things up). This also:
1. Fixes actual asset downloading (the GCS asset path templates have
changed, so priming didn't actually work anymore).
2. Disables audio file caching since we can't play audio when offline,
anyway (there's a dialog that prevents this in-player).
3. Fixes #1340 and #1341 by accounting for error cases when trying to
play audio. It turns out that playing audio crashes if you didn't have
internet access when going into an exploration (the no connectivity
dialog only appears if you lose connectivity within a lesson). There's
also some issues with existing view model code that wrongly assumed
audio couldn't be in a failure state at that point. This has been fixed.
4. Moves the list of topics to cache to be in the same position as the
flag enabling/disabling this functionality.

The download experience isn't perfect, but it's meant to be a helper for
user study coordinators so that they know when lessons can be brought
offline.

Note that the UI aspects of this change are really hacky. This is by
design--I didn't want to overcomplicate the solution, and I wanted to
keep the priming changes fully isolated to make future cleanup easier.

Finally, no new tests were added. I clarified in StateFragmentTest that
the edge cases fixed in this PR need to have corresponding tests, but
I'm actually not sure offhand how to test that audio's playing. I think
this will require additional work. I prefer to push this off to #388,
but I will follow up with tests if anyone wants to push back on this.

app/src/main/java/org/oppia/app/application/ApplicationComponent.kt

@@ -17,6 +17,7 @@ import org.oppia.domain.classify.rules.numericinput.NumericInputRuleModule
 import org.oppia.domain.classify.rules.textinput.TextInputRuleModule
 import org.oppia.domain.oppialogger.LogStorageModule
 import org.oppia.domain.question.QuestionModule
+import org.oppia.domain.topic.PrimeTopicAssetsControllerModule
 import org.oppia.util.accessibility.AccessibilityModule
 import org.oppia.util.caching.CachingModule
 import org.oppia.util.gcsresource.GcsResourceModule
@@ -29,22 +30,21 @@ import org.oppia.util.threading.DispatcherModule
 import javax.inject.Provider
 import javax.inject.Singleton
 
-/** Root Dagger component for the application. All application-scoped modules should be included in this component. */
+/**
+ * Root Dagger component for the application. All application-scoped modules should be included in
+ * this component.
+ */
 @Singleton
 @Component(
   modules = [
-    ApplicationModule::class, DispatcherModule::class,
-    NetworkModule::class, LoggerModule::class,
-    ContinueModule::class, FractionInputModule::class,
-    ItemSelectionInputModule::class, MultipleChoiceInputModule::class,
-    NumberWithUnitsRuleModule::class, NumericInputRuleModule::class,
-    TextInputRuleModule::class, DragDropSortInputModule::class,
-    InteractionsModule::class, GcsResourceModule::class,
-    GlideImageLoaderModule::class, ImageParsingModule::class,
-    HtmlParserEntityTypeModule::class, CachingModule::class,
-    QuestionModule::class, LogReportingModule::class,
-    AccessibilityModule::class, ImageClickInputModule::class,
-    LogStorageModule::class
+    ApplicationModule::class, DispatcherModule::class, NetworkModule::class, LoggerModule::class,
+    ContinueModule::class, FractionInputModule::class, ItemSelectionInputModule::class,
+    MultipleChoiceInputModule::class, NumberWithUnitsRuleModule::class,
+    NumericInputRuleModule::class, TextInputRuleModule::class, DragDropSortInputModule::class,
+    InteractionsModule::class, GcsResourceModule::class, GlideImageLoaderModule::class,
+    ImageParsingModule::class, HtmlParserEntityTypeModule::class, CachingModule::class,
+    QuestionModule::class, LogReportingModule::class, AccessibilityModule::class,
+    ImageClickInputModule::class, LogStorageModule::class, PrimeTopicAssetsControllerModule::class
   ]
 )
 

app/src/main/java/org/oppia/app/player/audio/AudioFragmentPresenter.kt

@@ -21,6 +21,7 @@ import org.oppia.app.model.CellularDataPreference
 import org.oppia.app.model.Profile
 import org.oppia.app.model.ProfileId
 import org.oppia.app.model.State
+import org.oppia.app.player.audio.AudioViewModel.UiAudioPlayStatus
 import org.oppia.app.viewmodel.ViewModelProvider
 import org.oppia.domain.audio.CellularAudioDialogController
 import org.oppia.domain.profile.ProfileManagementController
@@ -95,7 +96,7 @@ class AudioFragmentPresenter @Inject constructor(
     viewModel.playStatusLiveData.observe(
       fragment,
       Observer {
-        prepared = it != AudioViewModel.UiAudioPlayStatus.LOADING
+        prepared = it != UiAudioPlayStatus.LOADING && it != UiAudioPlayStatus.FAILED
         binding.sbAudioProgress.isEnabled = prepared
       }
     )

app/src/main/java/org/oppia/app/player/audio/AudioViewModel.kt

@@ -143,14 +143,14 @@ class AudioViewModel @Inject constructor(
   }
 
   private fun processDurationResultLiveData(playProgressResult: AsyncResult<PlayProgress>): Int {
-    if (playProgressResult.isPending()) {
+    if (!playProgressResult.isSuccess()) {
       return 0
     }
     return playProgressResult.getOrThrow().duration
   }
 
   private fun processPositionResultLiveData(playProgressResult: AsyncResult<PlayProgress>): Int {
-    if (playProgressResult.isPending()) {
+    if (!playProgressResult.isSuccess()) {
       return 0
     }
     return playProgressResult.getOrThrow().position
@@ -159,20 +159,22 @@ class AudioViewModel @Inject constructor(
   private fun processPlayStatusResultLiveData(
     playProgressResult: AsyncResult<PlayProgress>
   ): UiAudioPlayStatus {
-    if (playProgressResult.isPending()) return UiAudioPlayStatus.LOADING
-    if (playProgressResult.isFailure()) return UiAudioPlayStatus.FAILED
-    return when (playProgressResult.getOrThrow().type) {
-      PlayStatus.PREPARED -> {
-        if (autoPlay) audioPlayerController.play()
-        autoPlay = false
-        UiAudioPlayStatus.PREPARED
-      }
-      PlayStatus.PLAYING -> UiAudioPlayStatus.PLAYING
-      PlayStatus.PAUSED -> UiAudioPlayStatus.PAUSED
-      PlayStatus.COMPLETED -> {
-        if (hasFeedback) loadAudio(null, false)
-        hasFeedback = false
-        UiAudioPlayStatus.COMPLETED
+    return when {
+      playProgressResult.isPending() -> UiAudioPlayStatus.LOADING
+      playProgressResult.isFailure() -> UiAudioPlayStatus.FAILED
+      else -> when (playProgressResult.getOrThrow().type) {
+        PlayStatus.PREPARED -> {
+          if (autoPlay) audioPlayerController.play()
+          autoPlay = false
+          UiAudioPlayStatus.PREPARED
+        }
+        PlayStatus.PLAYING -> UiAudioPlayStatus.PLAYING
+        PlayStatus.PAUSED -> UiAudioPlayStatus.PAUSED
+        PlayStatus.COMPLETED -> {
+          if (hasFeedback) loadAudio(null, false)
+          hasFeedback = false
+          UiAudioPlayStatus.COMPLETED
+        }
       }
     }
   }

app/src/main/java/org/oppia/app/splash/SplashActivityPresenter.kt

@@ -11,6 +11,7 @@ import org.oppia.app.model.OnboardingFlow
 import org.oppia.app.onboarding.OnboardingActivity
 import org.oppia.app.profile.ProfileActivity
 import org.oppia.domain.onboarding.OnboardingFlowController
+import org.oppia.domain.topic.PrimeTopicAssetsController
 import org.oppia.util.data.AsyncResult
 import org.oppia.util.logging.ConsoleLogger
 import javax.inject.Inject
@@ -20,7 +21,8 @@ import javax.inject.Inject
 class SplashActivityPresenter @Inject constructor(
   private val activity: AppCompatActivity,
   private val logger: ConsoleLogger,
-  private val onboardingFlowController: OnboardingFlowController
+  private val onboardingFlowController: OnboardingFlowController,
+  private val primeTopicAssetsController: PrimeTopicAssetsController
 ) {
 
   fun handleOnCreate() {
@@ -29,6 +31,8 @@ class SplashActivityPresenter @Inject constructor(
       WindowManager.LayoutParams.FLAG_FULLSCREEN,
       WindowManager.LayoutParams.FLAG_FULLSCREEN
     )
+    // Initiate download support before any additional processing begins.
+    primeTopicAssetsController.downloadAssets(R.style.AlertDialogTheme)
     subscribeToOnboardingFlow()
   }
 

app/src/sharedTest/java/org/oppia/app/player/state/StateFragmentTest.kt

@@ -119,7 +119,7 @@ class StateFragmentTest {
   //  10. Testing interactions with custom Oppia tags (including images) render correctly (when manually inspected) and are correctly functional.
   //  11. Update the tests to work properly on Robolectric (requires idling resource + replacing the dispatchers to leverage a coordinated test dispatcher library).
   //  12. Add tests for hints & solutions.
-  //  13. Add tests for audio states.
+  //  13. Add tests for audio states, including: audio playing & having an error, or no-network connectivity scenarios. See the PR introducing this comment & #1340 / #1341 for context.
   // TODO(#56): Add support for testing that previous/next button states are properly retained on config changes.
 
   @Test

domain/src/main/java/org/oppia/domain/topic/PrimeTopicAssetsController.kt

@@ -0,0 +1,18 @@
+package org.oppia.domain.topic
+
+// TODO(#169): Remove this controller & download priming once downloads are properly supported.
+
+/**
+ * Controller for conditionally pre-priming assets to enable full download support. Whether
+ * downloading is enabled is gated by the [org.oppia.util.caching.CacheAssetsLocally] annotation.
+ */
+interface PrimeTopicAssetsController {
+  /**
+   * Initiates asset downloading in the background. UI affordances will be shown before and after
+   * priming, if it's enabled (otherwise nothing will show).
+   *
+   * @param dialogStyleResId the resource ID for the alert dialog style used for the dialog-based UI
+   *     affordances
+   */
+  fun downloadAssets(dialogStyleResId: Int)
+}