#include <Wt/WGlobal>
#include <Wt/WCompositeWidget>
#include <Wt/WContainerWidget>
#include <Wt/WVBoxLayout>
#include <Wt/WTreeView>
#include <Wt/WPushButton>
#include <Wt/WStandardItemModel>
#include <Wt/WStandardItem>

#include <boost/filesystem.hpp>


const char* pathToWTDev = "C:\\Wt";

class __Test_LargeTree : public Wt::WCompositeWidget {
   Wt::WTreeView* tree;
   bool toogle;

   void DoFolder (const boost::filesystem::path& path, Wt::WStandardItem* parent);
   void Toogle ();

public:
   __Test_LargeTree (Wt::WContainerWidget* parent = nullptr);
};


__Test_LargeTree::__Test_LargeTree (Wt::WContainerWidget* parent)
   : WCompositeWidget(parent), tree(nullptr), toogle(false)
{
   auto impl = new Wt::WContainerWidget;
   setImplementation(impl);

   auto layout = new Wt::WVBoxLayout(impl);

   tree = new Wt::WTreeView;
   layout->addWidget(tree, 1);

   auto model = new Wt::WStandardItemModel(0, 1, tree);
   model->setHeaderData(0, Wt::Horizontal, "name");

   tree->setAlternatingRowColors(true);
   tree->setModel(model);

   auto btnToogle = new Wt::WPushButton("Toogle");;
   layout->addWidget(btnToogle, 0, Wt::AlignCenter);

   btnToogle->clicked().connect(this, &__Test_LargeTree::Toogle);

   DoFolder(boost::filesystem::path(pathToWTDev), model->invisibleRootItem());
}

void __Test_LargeTree::DoFolder (const boost::filesystem::path& path, Wt::WStandardItem* parent)
{
   boost::filesystem::directory_iterator end;

   for (auto it = boost::filesystem::directory_iterator(path); it != end; ++it) {

      if (boost::filesystem::is_directory(it->path())) {
         auto row = new Wt::WStandardItem(it->path().string());
         parent->appendRow(row);
         DoFolder(*it, row);
      }
      else {
         parent->appendRow(new Wt::WStandardItem(it->path().string()));
      }

   }
}

static void ExpandNodeRecursive (Wt::WTreeView* tree, const Wt::WModelIndex& index, bool expand)
{
   int rowCount = tree->model()->rowCount(index);

   // ignore invisible root item
   if (index.isValid() && rowCount > 0) tree->setExpanded(index, expand);

   for (int i = 0; i < rowCount; ++i) {
      ExpandNodeRecursive(tree, tree->model()->index(i, 0, index), expand);
   }
}

void __Test_LargeTree::Toogle ()
{
   toogle = !toogle;
   ExpandNodeRecursive(tree, Wt::WModelIndex(), toogle);
}