Improve Dropdown Behavior in Questionnaire Items

datacapture/src/main/java/com/google/android/fhir/datacapture/views/factories/DropDownViewHolderFactory.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022-2023 Google LLC
+ * Copyright 2022-2024 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,10 @@ package com.google.android.fhir.datacapture.views.factories
 
 import android.content.Context
 import android.graphics.drawable.Drawable
+import android.os.Handler
+import android.os.Looper
+import android.text.Editable
+import android.text.TextWatcher
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -48,6 +52,7 @@ internal object DropDownViewHolderFactory :
       private lateinit var autoCompleteTextView: MaterialAutoCompleteTextView
       override lateinit var questionnaireViewItem: QuestionnaireViewItem
       private lateinit var context: Context
+      private var isDropdownEditable = true
 
       override fun init(itemView: View) {
         header = itemView.findViewById(R.id.header)
@@ -97,32 +102,69 @@ internal object DropDownViewHolderFactory :
               null,
             )
           }
+
         autoCompleteTextView.setAdapter(adapter)
         autoCompleteTextView.onItemClickListener =
           AdapterView.OnItemClickListener { _, _, position, _ ->
-            val selectedItem = adapter.getItem(position)
-            autoCompleteTextView.setText(selectedItem?.answerOptionString, false)
-            autoCompleteTextView.setCompoundDrawablesRelative(
-              adapter.getItem(position)?.answerOptionImage,
-              null,
-              null,
-              null,
-            )
-            val selectedAnswer =
-              questionnaireViewItem.enabledAnswerOptions
-                .firstOrNull { it.value.identifierString(context) == selectedItem?.answerId }
-                ?.value
-
-            if (selectedAnswer == null) {
-              questionnaireViewItem.clearAnswer()
-            } else {
-              questionnaireViewItem.setAnswer(
-                QuestionnaireResponse.QuestionnaireResponseItemAnswerComponent()
-                  .setValue(selectedAnswer),
+            if (isDropdownEditable) {
+              val selectedItem = adapter.getItem(position)
+              autoCompleteTextView.setText(selectedItem?.answerOptionString, false)
+              autoCompleteTextView.setCompoundDrawablesRelative(
+                adapter.getItem(position)?.answerOptionImage,
+                null,
+                null,
+                null,
               )
+
+              isDropdownEditable = false
+              val selectedAnswer =
+                questionnaireViewItem.enabledAnswerOptions
+                  .firstOrNull { it.value.identifierString(context) == selectedItem?.answerId }
+                  ?.value
+
+              if (selectedAnswer == null) {
+                questionnaireViewItem.clearAnswer()
+              } else {
+                questionnaireViewItem.setAnswer(
+                  QuestionnaireResponse.QuestionnaireResponseItemAnswerComponent()
+                    .setValue(selectedAnswer),
+                )
+              }
             }
           }
 
+        autoCompleteTextView.addTextChangedListener(
+          object : TextWatcher {
+            override fun beforeTextChanged(
+              charSequence: CharSequence?,
+              start: Int,
+              count: Int,
+              after: Int,
+            ) {}
+
+            override fun onTextChanged(
+              charSequence: CharSequence?,
+              start: Int,
+              before: Int,
+              count: Int,
+            ) {}
+
+            override fun afterTextChanged(editable: Editable?) {
+              if (editable.isNullOrBlank()) {
+                Handler(Looper.getMainLooper())
+                  .postDelayed(
+                    {
+                      if (autoCompleteTextView.isPopupShowing.not()) {
+                        autoCompleteTextView.showDropDown()
+                      }
+                    },
+                    100,
+                  )
+              }
+            }
+          },
+        )
+
         displayValidationResult(questionnaireViewItem.validationResult)
       }
 
@@ -137,6 +179,7 @@ internal object DropDownViewHolderFactory :
 
       override fun setReadOnly(isReadOnly: Boolean) {
         textInputLayout.isEnabled = !isReadOnly
+        autoCompleteTextView.isEnabled = isDropdownEditable
       }
 
       private fun cleanupOldState() {