Fix #122: Introduce interface & partial implementation for Exploratio…

…nProgressController (#183)

* Introduce first pass interface for ExplorationProgressController.

* Fill in the stubbed logic for ExplorationProgressController. Still no
tests to verify correctness.

Also, added a method to facilitate notifying of DataProvider changes on
the UI thread.

* Fix lateinit issue in ExplorationProgressController due to wrongly ordered
initialization.

* Fix a variaty of issues in the exp progress controller, properly hook it up to
the data controller, and start adding tests.

* Created a separate ExplorationRetriever, hooked up
AnswerClassificationController, and attempted to make
ExplorationProgressController thread-safe.

The thread-safety led to significant interface changes in the progress
controller, and led to discovering some issues with the mediator live data
approach to interop coroutines and LiveData. This locking mechanism will
need to change since the optimal solution requires resolving #90.

* Change the locking mechanism for ExplorationProgressController to work
with the current MediatorLiveData implementation (see #90 for more
context). Fix existing progress controller tests and add a few more. All
current progress controller tests are passing.

* Finish tests for ExplorationProgressController and add test classification
support for the second test exploration (about_oppia).

domain/src/main/java/org/oppia/domain/classify/AnswerClassificationController.kt

@@ -3,24 +3,77 @@ package org.oppia.domain.classify
 import org.oppia.app.model.Interaction
 import org.oppia.app.model.InteractionObject
 import org.oppia.app.model.Outcome
+import org.oppia.app.model.State
 import javax.inject.Inject
 
 // TODO(#59): Restrict the visibility of this class to only other controllers.
 /**
  * Controller responsible for classifying user answers to a specific outcome based on Oppia's interaction rule engine.
  * This controller is not meant to be interacted with directly by the UI. Instead, UIs wanting to submit answers should
- * do so via various progress controllers, like [StoryProgressController].
+ * do so via various progress controllers, like [org.oppia.domain.topic.StoryProgressController].
  *
  * This controller should only be interacted with via background threads.
  */
 class AnswerClassificationController @Inject constructor() {
+  // TODO(#114): Add support for classifying answers based on an actual exploration. Also, classify() should take an
+  // Interaction, not a State.
+
   /**
    * Classifies the specified answer in the context of the specified [Interaction] and returns the [Outcome] that best
    * matches the learner's answer.
    */
-  internal fun classify(interaction: Interaction, answer: InteractionObject): Outcome {
-    // Assume only the default outcome is returned currently since this stubbed implementation is not actually used by
-    // downstream stubbed progress controllers.
-    return interaction.defaultOutcome
+  internal fun classify(currentState: State, answer: InteractionObject): Outcome {
+    return when (currentState.name) {
+      // Exp 5
+      "Welcome!" -> simulateMultipleChoiceForWelcomeStateExp5(currentState, answer)
+      "What language" -> simulateTextInputForWhatLanguageStateExp5(currentState, answer)
+      "Numeric input" -> simulateNumericInputForNumericInputStateExp5(currentState, answer)
+      "Things you can do" -> currentState.interaction.defaultOutcome
+      // Exp 6
+      "First State" -> currentState.interaction.defaultOutcome
+      "So what can I tell you" -> simulateMultipleChoiceForWelcomeStateExp6(currentState, answer)
+      "Example1" -> currentState.interaction.defaultOutcome // TextInput with ignored answer.
+      "Example3" -> currentState.interaction.defaultOutcome
+      "End Card" -> currentState.interaction.defaultOutcome
+      else -> throw Exception("Cannot submit answer to unexpected state: ${currentState.name}.")
+    }
+  }
+
+  private fun simulateMultipleChoiceForWelcomeStateExp5(currentState: State, answer: InteractionObject): Outcome {
+    return when {
+      answer.objectTypeCase != InteractionObject.ObjectTypeCase.NON_NEGATIVE_INT ->
+        throw Exception("Expected non-negative int answer, not $answer.")
+      answer.nonNegativeInt == 0 -> currentState.interaction.answerGroupsList[0].outcome
+      answer.nonNegativeInt == 2 -> currentState.interaction.answerGroupsList[1].outcome
+      else -> currentState.interaction.defaultOutcome
+    }
+  }
+
+  private fun simulateTextInputForWhatLanguageStateExp5(currentState: State, answer: InteractionObject): Outcome {
+    return when {
+      answer.objectTypeCase != InteractionObject.ObjectTypeCase.NORMALIZED_STRING ->
+        throw Exception("Expected string answer, not $answer.")
+      answer.normalizedString.toLowerCase() == "finnish" -> currentState.interaction.getAnswerGroups(6).outcome
+      else -> currentState.interaction.defaultOutcome
+    }
+  }
+
+  private fun simulateNumericInputForNumericInputStateExp5(currentState: State, answer: InteractionObject): Outcome {
+    return when {
+      answer.objectTypeCase != InteractionObject.ObjectTypeCase.SIGNED_INT ->
+        throw Exception("Expected signed int answer, not $answer.")
+      answer.signedInt == 121 -> currentState.interaction.answerGroupsList.first().outcome
+      else -> currentState.interaction.defaultOutcome
+    }
+  }
+
+  private fun simulateMultipleChoiceForWelcomeStateExp6(currentState: State, answer: InteractionObject): Outcome {
+    return when {
+      answer.objectTypeCase != InteractionObject.ObjectTypeCase.NON_NEGATIVE_INT ->
+        throw Exception("Expected non-negative int answer, not $answer.")
+      answer.nonNegativeInt == 3 -> currentState.interaction.answerGroupsList[1].outcome
+      answer.nonNegativeInt == 0 -> currentState.interaction.answerGroupsList[2].outcome
+      else -> currentState.interaction.defaultOutcome
+    }
   }
 }