#include <Wt/WApplication.h>
#include <Wt/WBootstrap5Theme.h>
#include <Wt/WServer.h>

#include <Wt/WContainerWidget.h>
#include <Wt/WHBoxLayout.h>
#include <Wt/WVBoxLayout.h>
#include <Wt/WMenu.h>
#include <Wt/WStackedWidget.h>
#include <Wt/WText.h>

using namespace Wt;


/*
 * A utility container widget which defers creation of its single
 * child widget until the container is loaded (which is done on-demand
 * by a WMenu). The constructor takes the create function for the
 * widget as a parameter.
 *
 * We use this to defer widget creation until needed, which also defers
 * loading auxiliary javascript libraries.
 */
#if !defined(WT_TARGET_JAVA)
    template <typename Function>
    class DeferredWidget : public Wt::WContainerWidget
    {
    public:
      DeferredWidget(Function f)
        : f_(f) { }

    private:
      void load()
      {
        addWidget(f_());
        Wt::WContainerWidget::load();
      }

      Function f_;
    };

    template <typename Function>
    std::unique_ptr<DeferredWidget<Function>> deferCreate(Function f)
    {
      return std::make_unique<DeferredWidget<Function>>(f);
    }
#else
    class DeferredWidget : public Wt::WContainerWidget
    {
    public:
      DeferredWidget(std::bound f) {}
    };
    std::unique_ptr<DeferredWidget> deferCreate(std::bound b)
    {
      return std::make_unique<DeferredWidget>(b);
    }
#endif



// -----------------------------------------------------------------------------------
std::unique_ptr<WContainerWidget> createSplitView()
{
    std::cerr << "*** Create Split View" << std::endl;

    auto flexCont = std::make_unique<WContainerWidget>();
    flexCont->setAttributeValue("style", "width: 100%; height: 100%; background-color: yellow;");

    auto vLayout = flexCont->setLayout(std::make_unique<WVBoxLayout>());

    auto splitHLayout = vLayout->addLayout(std::make_unique<WHBoxLayout>(), 1);
    splitHLayout->setPreferredImplementation(LayoutImplementation::JavaScript);

    auto leftCont = splitHLayout->addWidget(std::make_unique<WContainerWidget>());
    leftCont->setAttributeValue("style", "width: 100%; height: 100%;");
    leftCont->decorationStyle().setBackgroundColor(WColor("blue"));
    leftCont->setMinimumSize(WLength::Auto, 50);
    leftCont->addNew<WText>("Left Container");

    auto rightCont = splitHLayout->addWidget(std::make_unique<WContainerWidget>());
    rightCont->setAttributeValue("style", "width: 100%; height: 100%;");
    rightCont->decorationStyle().setBackgroundColor(WColor("green"));
    rightCont->setMinimumSize(WLength::Auto, 50);
    rightCont->addNew<WText>("Right Container");

    splitHLayout->setResizable(0, true, WLength(70, LengthUnit::Percentage));

    return flexCont;
}


// -----------------------------------------------------------------------------------
std::unique_ptr<WApplication> createHelloApplication(const WEnvironment &env)
{
    auto app = std::make_unique<WApplication>(env);

    auto theme = std::make_shared<WBootstrap5Theme>();
    app->setTheme(theme);

    app->root()->setAttributeValue("style", "width: 100%; height: 100%;");
    auto hLayout = app->root()->setLayout(std::make_unique<WHBoxLayout>());

    auto leftCont = hLayout->addWidget(std::make_unique<WContainerWidget>());
    leftCont->setAttributeValue("style", "background-color: #b3daff;");
    leftCont->setWidth(200);

    auto rightCont = hLayout->addWidget(std::make_unique<WContainerWidget>(), 1);
    rightCont->setAttributeValue("style", "background-color: grey;");

    auto rightVLayout = rightCont->setLayout(std::make_unique<WVBoxLayout>());

    auto stackUP = std::make_unique<WStackedWidget>();

    auto menu = leftCont->addNew<WMenu>(stackUP.get());

    rightVLayout->addWidget(std::move(stackUP), 1);

    menu->addItem("Stack Level 0", std::make_unique<WText>("Empty"));

    // This will work:
//     menu->addItem("Split Test", createSplitView());

    // This will not work:
    menu->addItem("Split Text", deferCreate(std::bind(&createSplitView)));

    return app;
}


// -----------------------------------------------------------------------------------
int main(int argc, char *argv[])
{
    try
    {
        WServer server(argc, argv, WTHTTP_CONFIGURATION);

        server.addEntryPoint(EntryPointType::Application,
                             std::bind(&createHelloApplication, std::placeholders::_1));

        if (server.start())
        {
          int sig = WServer::waitForShutdown();

          std::cerr << "*** Shutdown (signal = " << sig << ")" << std::endl;
          server.stop();

          if (sig == 1) // SIGHUP
            WServer::restart(argc, argv, environ);

          return 0;
        }
    }
    catch (WServer::Exception &e)
    {
        std::cerr << "*** Server Exception: " << e.what() << std::endl;
    }
    catch (std::exception &e)
    {
        std::cerr << "*** Std Exception: " << e.what() << std::endl;
    }
}