View.hpp

/*
** EPITECH PROJECT, 2023
** View.hpp
** File description:
** View.hpp
*/
 
#ifndef URANUS_VIEW_HPP
#define URANUS_VIEW_HPP
 
#include "Registry.hpp"
 
namespace uranus::ecs {
    template<typename... Components>
    class View {
    public:
        using Tuple = std::tuple<size_t, Components &...>; 
        explicit View(ecs::Registry &registry) : _registry(registry) {}
 
        class Iterator {
        public:
            explicit Iterator(ecs::Registry &registry) : _registry(registry)
            {
                idx = 0;
                skipInvalidEntities<Components...>();
            }
 
            Iterator &operator++()
            {
                idx++;
                skipInvalidEntities<Components...>();
                return *this;
            }
 
            Tuple operator->() { return Tuple(idx, (*_registry.getComponent<Components>(idx))...); }
 
            Tuple operator*() { return Tuple(idx, (*_registry.getComponent<Components>(idx))...); }
 
            bool operator==(const Iterator &other) const { return idx == other.idx; }
 
            bool operator!=(const Iterator &other) const { return !(other == *this); /* NOLINT */ }
 
            std::size_t idx;
 
        private:
            ecs::Registry _registry; 
            template<typename Component, typename... Others>
            void skipInvalidEntities()
            {
                while (idx < _registry.getEntityCounter()) {
                    bool hasAllComponents = true;
                    auto &component = _registry.getComponent<Component>(idx);
                    if (component == nullptr) {
                        hasAllComponents = false;
                    }
                    if (hasAllComponents) {
                        if constexpr (sizeof...(Others) > 0) {
                            skipInvalidEntities<Others...>();
                        }
                    }
                    if (hasAllComponents) return;
                    if (idx == _registry.getEntityCounter()) break;
                    idx++;
                }
            }
        };
 
        Iterator begin() { return Iterator(_registry); }
 
        Iterator end()
        {
            Iterator it(_registry);
            it.idx = _registry.getEntityCounter();
            return it;
        }
 
    private:
        Registry _registry; 
    };
} // namespace uranus::ecs
 
#endif // URANUS_VIEW_HPP