fix #219, show a dialog about unsaved changes at exiting when appropriate

app/src/main/kotlin/com/simplemobiletools/notes/activities/MainActivity.kt

@@ -11,6 +11,7 @@ import android.view.ActionMode
 import android.view.Gravity
 import android.view.Menu
 import android.view.MenuItem
+import com.simplemobiletools.commons.dialogs.ConfirmationAdvancedDialog
 import com.simplemobiletools.commons.dialogs.FilePickerDialog
 import com.simplemobiletools.commons.dialogs.RadioGroupDialog
 import com.simplemobiletools.commons.extensions.*
@@ -177,6 +178,21 @@ class MainActivity : SimpleActivity(), ViewPager.OnPageChangeListener {
         }
     }
 
+    override fun onBackPressed() {
+        if (!config.autosaveNotes && mAdapter?.anyHasUnsavedChanges() == true) {
+            ConfirmationAdvancedDialog(this, "", R.string.unsaved_changes_warning, R.string.save, R.string.discard) {
+                if (it) {
+                    mAdapter?.saveAllFragmentTexts()
+                    super.onBackPressed()
+                } else {
+                    super.onBackPressed()
+                }
+            }
+        } else {
+            super.onBackPressed()
+        }
+    }
+
     private fun storeStateVariables() {
         config.apply {
             storedEnableLineWrap = enableLineWrap

app/src/main/kotlin/com/simplemobiletools/notes/adapters/NotesPagerAdapter.kt

@@ -42,6 +42,10 @@ class NotesPagerAdapter(fm: FragmentManager, val notes: List<Note>, val activity
 
     fun focusEditText(position: Int) = fragments[position]?.focusEditText()
 
+    fun anyHasUnsavedChanges() = fragments.values.any { it.hasUnsavedChanges() }
+
+    fun saveAllFragmentTexts() = fragments.values.forEach { it.saveText(false) }
+
     fun undo(position: Int) = fragments[position]?.undo()
 
     fun redo(position: Int) = fragments[position]?.redo()

app/src/main/kotlin/com/simplemobiletools/notes/fragments/NoteFragment.kt

@@ -155,6 +155,8 @@ class NoteFragment : Fragment() {
         }
     }
 
+    fun hasUnsavedChanges() = getCurrentNoteViewText() != note.getNoteStoredValue()
+
     fun focusEditText() {
         view.notes_view.requestFocus()
     }