- (void)insertText:(id)string replacementRange:(NSRange)range {
  if (_activeModel == nullptr) {
    return;
  }
  _eventProducedOutput |= true;

  FML_LOG(INFO) << "insertText"
   << " string=" << string;
   << " range=" << range.location << " " << range.length;

  if (range.location != NSNotFound) {
    // The selected range can actually have negative numbers, since it can start
    // at the end of the range if the user selected the text going backwards.
    // Cast to a signed type to determine whether or not the selection is reversed.
    long signedLength = static_cast<long>(range.length);
    long location = range.location;
    long textLength = _activeModel->text_range().end();

    size_t base = std::clamp(location, 0L, textLength);
    size_t extent = std::clamp(location + signedLength, 0L, textLength);

    _activeModel->SetSelection(flutter::TextRange(base, extent));
  }

  flutter::TextRange oldSelection = _activeModel->selection();
  flutter::TextRange composingBeforeChange = _activeModel->composing_range();
  flutter::TextRange replacedRange(-1, -1);

  std::string textBeforeChange = _activeModel->GetText().c_str();
  std::string utf8String = [string UTF8String];

  FML_LOG(INFO) << "textBeforeChange=" << textBeforeChange;
  FML_LOG(INFO) << "utf8String=" << utf8String;

  _activeModel->AddText(utf8String);

  FML_LOG(INFO) << "textAfterChange=" << _activeModel->GetText().c_str();

  if (_activeModel->composing()) {
    replacedRange = composingBeforeChange;
    _activeModel->CommitComposing();
    _activeModel->EndComposing();
  } else {
    replacedRange = range.location == NSNotFound
                        ? flutter::TextRange(oldSelection.base(), oldSelection.extent())
                        : flutter::TextRange(range.location, range.location + range.length);
  }

  if (_enableDeltaModel) {
    [self updateEditStateWithDelta:flutter::TextEditingDelta(textBeforeChange, replacedRange, utf8String)];
  } else {
    [self updateEditState];
  }
}

- (void)insertText:(id)string replacementRange:(NSRange)range {
  if (_activeModel == nullptr) {
    return;
  }
  _eventProducedOutput |= true;

  if (range.location != NSNotFound) {
    // The selected range can actually have negative numbers, since it can start
    // at the end of the range if the user selected the text going backwards.
    // Cast to a signed type to determine whether or not the selection is reversed.
    long signedLength = static_cast<long>(range.length);
    long location = range.location;
    long textLength = _activeModel->text_range().end();

    size_t base = std::clamp(location, 0L, textLength);
    size_t extent = std::clamp(location + signedLength, 0L, textLength);

    _activeModel->SetSelection(flutter::TextRange(base, extent));
  }
+ else if (_activeModel->composing() && !(_activeModel->composing_range() == _activeModel->selection())) {
+   // When confirmed by Japanese IME, string replaces range of composing_range.
+   // If selection == composing_range there is no problem.
+   // If selection ! = composing_range the range of selection is only a part of composing_range.
+   // Since _activeModel->AddText is processed first for selection, the finalization of the conversion 
+   // cannot be processed correctly unless selection == composing_range or selection.collapsed().
+   // Since _activeModel->SetSelection fails if (composing_ && !range.collapsed()), 
+   // selection == composing_range will failed.
+   // Therefore, the selection cursor should only be placed at the beginning of composing_range.
+   flutter::TextRange composing_range = _activeModel->composing_range();
+   _activeModel->SetSelection(flutter::TextRange(composing_range.start()));
+ }

  flutter::TextRange oldSelection = _activeModel->selection();
  flutter::TextRange composingBeforeChange = _activeModel->composing_range();
  flutter::TextRange replacedRange(-1, -1);

  std::string textBeforeChange = _activeModel->GetText().c_str();
  std::string utf8String = [string UTF8String];

  _activeModel->AddText(utf8String);

  if (_activeModel->composing()) {
    replacedRange = composingBeforeChange;
    _activeModel->CommitComposing();
    _activeModel->EndComposing();
  } else {
    replacedRange = range.location == NSNotFound
                        ? flutter::TextRange(oldSelection.base(), oldSelection.extent())
                        : flutter::TextRange(range.location, range.location + range.length);
  }

  if (_enableDeltaModel) {
    [self updateEditStateWithDelta:flutter::TextEditingDelta(textBeforeChange, replacedRange,
                                                             utf8String)];
  } else {
    [self updateEditState];
  }
}