Add replaceRegexWithBlank function

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/ContentViewModel.kt

@@ -1,10 +1,38 @@
 package org.oppia.android.app.player.state.itemviewmodel
 
+import android.text.Spannable
+import android.text.SpannableStringBuilder
+
 /** [StateItemViewModel] for content-card state. */
 class ContentViewModel(
   val htmlContent: CharSequence,
   val gcsEntityId: String,
   val hasConversationView: Boolean,
   val isSplitView: Boolean,
   val supportsConceptCards: Boolean
-) : StateItemViewModel(ViewType.CONTENT)
+) : StateItemViewModel(ViewType.CONTENT) {
+
+  private val underscoreRegex = Regex("(?<=\\s|[,.;?!])_{3,}(?=\\s|[,.;?!])")
+  private val replacementText = "Blank"
+
+  /**
+   * Replaces "2+ underscores, with space/punctuation on both sides" in the input text with a
+   * replacement string "blank", returning a Spannable.
+   * Adjusts offsets to handle text length changes during replacements.
+   */
+  fun replaceRegexWithBlank(inputText: CharSequence): Spannable {
+    val spannableStringBuilder = SpannableStringBuilder(inputText)
+    val matches = underscoreRegex.findAll(inputText)
+    var lengthOffset = 0
+
+    for (match in matches) {
+      val matchStart = match.range.first + lengthOffset
+      val matchEnd = match.range.last + 1 + lengthOffset
+      spannableStringBuilder.replace(matchStart, matchEnd, replacementText)
+
+      // Adjust offset due to change in length (difference between old and new text length)
+      lengthOffset += replacementText.length - (matchEnd - matchStart)
+    }
+    return spannableStringBuilder
+  }
+}

app/src/main/res/layout/content_item.xml

@@ -48,6 +48,7 @@
       android:minWidth="48dp"
       android:minHeight="48dp"
       android:text="@{htmlContent}"
+      android:contentDescription="@{viewModel.replaceRegexWithBlank(htmlContent)}"
       android:textColor="@color/component_color_shared_primary_text_color"
       android:textColorLink="@color/component_color_shared_link_text_color"
       android:textSize="16sp"