Fix scroll to bottom button always visible if last item is taller than RecyclerView

app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationActivityV2.kt

@@ -211,10 +211,7 @@ class ConversationActivityV2 : PassphraseRequiredActionBarActivity(), InputBarDe
     var searchViewItem: MenuItem? = null
 
     private val isScrolledToBottom: Boolean
-        get() {
-            val position = layoutManager?.findFirstCompletelyVisibleItemPosition() ?: 0
-            return position == 0
-        }
+        get() = binding?.conversationRecyclerView?.isScrolledToBottom ?: true
 
     private val layoutManager: LinearLayoutManager?
         get() { return binding?.conversationRecyclerView?.layoutManager as LinearLayoutManager? }

libsession/src/main/java/org/session/libsession/utilities/ViewUtils.kt

@@ -4,6 +4,7 @@ import android.content.Context
 import android.util.TypedValue
 import androidx.annotation.AttrRes
 import androidx.annotation.ColorInt
+import androidx.recyclerview.widget.RecyclerView
 
 @ColorInt
 fun Context.getColorFromAttr(
@@ -13,4 +14,10 @@ fun Context.getColorFromAttr(
 ): Int {
     theme.resolveAttribute(attrColor, typedValue, resolveRefs)
     return typedValue.data
-}
+}
+
+val RecyclerView.isScrolledToBottom: Boolean
+    get() {
+        val contentHeight = height - (paddingTop + paddingBottom)
+        return computeVerticalScrollRange() == computeVerticalScrollOffset() + contentHeight
+    }