world.hpp

/*
 * MIT License
 *
 * Copyright (c) 2024 Giovanni Santini
 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
 
#pragma once
 
#include "ecs.hpp"
#include "ecs_types.hpp"
#include "engine_logger.hpp"
 
#include <algorithm>
#include <memory>
#include <set>
#include <typeindex>
#include <typeinfo>
#include <unordered_map>
#include <vector>
 
namespace Brenta
{
 
namespace ECS
{
 
using namespace Types;
using namespace Brenta::Utils;
 
class World
{
  public:
    World() = delete;
 
    static void Init();
    static void Delete();
    static void Tick();
 
    static std::set<Entity> *getEntities();
    static UMap<std::type_index, Resource> *getResources();
    static UMapVec<std::type_index, Component> *getComponents();
 
    static Entity NewEntity();
 
    template <typename R> static R *GetResource()
    {
        if (!resources)
        {
            ERROR("Cannot get resource: world not initialized");
            return nullptr;
        }
 
        if (!resources->count(std::type_index(typeid(R))))
        {
            ERROR("Resource not found: ", std::type_index(typeid(R)).name());
            return nullptr;
        }
 
        auto ret = resources->at(std::type_index(typeid(R)));
        if (ret)
            return static_cast<R *>(ret.get());
        return nullptr;
    }
 
    template <typename C>
    static void AddComponent(Entity entity, C new_component)
    {
        if (!components)
        {
            ERROR("Cannot add component: world not initialized");
            return;
        }
 
        auto component = std::make_shared<C>(new_component);
 
        component->entity = entity;
 
        if (!components->count(std::type_index(typeid(C))))
        {
            components->insert({std::type_index(typeid(C)), {component}});
        }
        else
        {
            components->at(std::type_index(typeid(C))).push_back(component);
        }
 
        INFO("Added component: ", std::type_index(typeid(C)).name());
    }
 
    template <typename R> static void AddResource(R resource)
    {
        if (!resources)
        {
            ERROR("Cannot add resource: world not initialized");
            return;
        }
 
        resources->insert(
            {std::type_index(typeid(R)), std::make_shared<R>(resource)});
        INFO("Added Resource: ", std::type_index(typeid(R)).name());
    }
 
    static void RemoveEntity(Entity entity);
 
    template <typename R> static void RemoveResource()
    {
        if (!resources)
        {
            ERROR("Cannot remove resource: world not initialized");
            return;
        }
 
        if (!resources->count(std::type_index(typeid(R))))
        {
            ERROR("Resource not found: ", std::type_index(typeid(R)).name());
            return;
        }
 
        resources->erase(std::type_index(typeid(R)));
    }
 
    template <typename C> static C *EntityToComponent(Entity entity)
    {
        if (!components)
        {
            ERROR("Cannot get component: world not initialized");
            return nullptr;
        }
 
        if (!components->count(std::type_index(typeid(C))))
        {
            ERROR("Component not found: ", std::type_index(typeid(C)).name());
            return nullptr;
        }
 
        for (auto component : components->at(std::type_index(typeid(C))))
        {
            if (component->entity == entity)
            {
                return static_cast<C *>(component.get());
            }
        }
 
        return nullptr;
    }
 
    static void RunSystems();
 
  private:
    static SetPtr<Entity> entities;
    static UMapPtr<std::type_index, Resource> resources;
    static UMapVecPtr<std::type_index, Component> components;
 
    /* Iterate over all systems and run them */
    template <typename Tuple, std::size_t... Is>
    static void for_each_impl(Tuple &&tuple, std::index_sequence<Is...>)
    {
        (..., process(std::get<Is>(std::forward<Tuple>(tuple))));
    }
    template <typename Tuple> static void for_each(Tuple &&tuple)
    {
        for_each_impl(std::forward<Tuple>(tuple),
                      std::make_index_sequence<
                          std::tuple_size_v<std::remove_reference_t<Tuple>>>{});
    }
    template <typename... T>
    static std::vector<ECS::Entity> QueryComponentsTuple(std::tuple<T...>)
    {
        return QueryComponents<T...>();
    }
    template <typename System> static void process(const System &system)
    {
        using Dependencies = typename System::dependencies;
        std::vector<ECS::Entity> matches = QueryComponentsTuple(Dependencies{});
        system.run(matches);
    }
 
    template <typename C, typename... Components, typename N = None>
    static std::vector<Entity> QueryComponents()
    {
        if (!World::components)
        {
            ERROR("Cannot query: world not initialized");
            return {};
        }
 
        std::vector<Entity> matched;
 
        if (!components->count(std::type_index(typeid(C))))
        {
            return matched;
        }
 
        for (auto component : components->at(std::type_index(typeid(C))))
        {
            matched.push_back(component->entity);
        }
 
        if (matched.empty())
            return matched;
        if (sizeof...(Components) == 0)
            return matched;
 
        QueryComponentsRec<Components..., None>(&matched);
 
        return matched;
    }
 
    template <typename C, typename... Components>
    static void QueryComponentsRec(std::vector<Entity> *entities)
    {
        if (entities->empty())
            return;
        std::vector<Entity> matched;
 
        if (!components->count(std::type_index(typeid(C))))
        {
            *entities = matched;
            return;
        }
        for (auto component : components->at(std::type_index(typeid(C))))
        {
            if (std::find(entities->begin(), entities->end(),
                          (int &) component->entity)
                != entities->end())
            {
                matched.push_back(component->entity);
            }
        }
        *entities = matched;
 
        if (sizeof...(Components) == 0)
            return;
 
        (QueryComponentsRec<Components>(entities), ...);
    }
};
 
} // namespace ECS
 
} // namespace Brenta