add a menu button for deleting the whole opened conversation

app/src/main/kotlin/com/simplemobiletools/smsmessenger/activities/ThreadActivity.kt

@@ -12,6 +12,7 @@ import android.view.View
 import android.view.inputmethod.EditorInfo
 import android.widget.LinearLayout
 import android.widget.RelativeLayout
+import com.simplemobiletools.commons.dialogs.ConfirmationDialog
 import com.simplemobiletools.commons.extensions.*
 import com.simplemobiletools.commons.helpers.ensureBackgroundThread
 import com.simplemobiletools.smsmessenger.R
@@ -91,6 +92,7 @@ class ThreadActivity : SimpleActivity() {
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
         when (item.itemId) {
+            R.id.delete -> askConfirmDelete()
             R.id.manage_people -> managePeople()
             else -> return super.onOptionsItemSelected(item)
         }
@@ -148,6 +150,14 @@ class ThreadActivity : SimpleActivity() {
         }
     }
 
+    private fun askConfirmDelete() {
+        ConfirmationDialog(this, getString(R.string.delete_whole_conversation_confirmation)) {
+            deleteThread(threadId)
+            refreshMessages()
+            finish()
+        }
+    }
+
     private fun managePeople() {
         if (thread_add_contacts.isVisible()) {
             hideKeyboard()

app/src/main/res/menu/menu_thread.xml

@@ -1,6 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
 <menu xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/delete"
+        android:icon="@drawable/ic_delete_vector"
+        android:title="@string/delete"
+        app:showAsAction="ifRoom" />
     <item
         android:id="@+id/manage_people"
         android:icon="@drawable/add_person_vector"

app/src/main/res/values/strings.xml

@@ -14,6 +14,7 @@
     <string name="new_message">New message</string>
 
     <!-- Confirmation dialog -->
+    <string name="delete_whole_conversation_confirmation">Are you sure you want to delete all messages of this conversation?</string>
     <string name="delete_conversations_confirmation">Are you sure you want to delete %s?</string>    <!-- Are you sure you want to delete 5 conversations? -->
 
     <!-- Are you sure you want to delete 5 conversations? -->