#include <guecs/ui.hpp>
#include <flat_map>
#include <cassert>

namespace gui {
  template<typename SCREEN_TYPE>
    struct UIStack {
      using UIStackMap = std::flat_map<std::string, std::shared_ptr<SCREEN_TYPE>>;

      UIStackMap screens{};
      bool visible = false;

      UIStackMap::iterator $current{screens.begin()};
      SCREEN_TYPE* $active = nullptr;

      void add(const std::string& name, std::shared_ptr<SCREEN_TYPE> screen) {
        screens.insert_or_assign(name, screen);
        update_active(screens.begin());
      }

      void update_active(const UIStackMap::iterator& itr) {
        $current = itr;
        $active = (*$current).second.get();
      }

      void set_active(const std::string& name) {
        assert(screens.contains(name) && "no screen with that name");
        update_active(screens.find(name));
      }

      void set_visible(bool new_value) {
        visible = new_value;
      }

      bool is_visible() {
        return visible;
      }

      void render(sf::RenderTarget& target) {
        assert($active != nullptr && "you didn't set active");
        $active->render(target);
      }

      void update() {
        assert($active != nullptr && "you didn't set active");
        $active->update();
      }

      bool mouse(float x, float y, guecs::Modifiers mods = guecs::NO_MODS) {
        assert($active != nullptr && "you didn't set active");
        return $active->mouse(x, y, mods);
      }

      bool move(const UIStackMap::iterator& itr, const UIStackMap::iterator& avoid, const UIStackMap::iterator& result) {
        if(itr != avoid) {
          update_active(result);
          return true;
        } else {
          return false;
        }
      }

      bool next() {
        return move($current + 1, screens.end(), $current + 1);
      }

      bool prev() {
        return move($current, screens.begin(), $current - 1);
      }

      void first() {
        update_active(screens.begin());
      }

      void last() {
        update_active(screens.end() - 1);
      }

      const std::string& active_name() {
        assert($active != nullptr && "you didn't set active");
        return (*$current).first;
      }

      std::shared_ptr<SCREEN_TYPE> active_ui() {
        assert($active != nullptr && "you didn't set active");
        return (*$current).second;
      }

      std::shared_ptr<SCREEN_TYPE> at(const std::string& name) {
        return screens.at(name);
      }

      const UIStackMap::key_container_type& names() {
        return screens.keys();
      }
    };
}