//
// Created by atdunbg on 2026/9/22.
//

#include <Engine/ECS/Scene.h>
#include <Engine/ECS/EntityHandle.h>
#include <Engine/Core/Log.h>

namespace Engine::ECS {

    EntityHandle Scene::CreateEntity(std::string name)
    {
        Entity e = m_Registry.create();
        // IdComponent 自动挂载：每个实体出生即有稳定 UUID
        m_Registry.emplace<IdComponent>(e, IdComponent{UUID::New()});
        if (!name.empty()) {
            m_Registry.emplace<NameComponent>(e, NameComponent{std::move(name)});
        }
        return EntityHandle{this, e};
    }

    Entity Scene::FindEntityByUUID(UUID uuid)
    {
        if (!uuid.Valid()) return entt::null;

        Entity found = entt::null;
        m_Registry.view<IdComponent>().each([&](Entity e, IdComponent& id) {
            if (found == entt::null && id.uuid == uuid) found = e;
        });
        return found;
    }

    void Scene::DestroyEntity(Entity e)
    {
        if (!m_Registry.valid(e)) {
            ENGINE_FATAL("Scene::DestroyEntity: stale entity ({})",
                         static_cast<u32>(e));
        }
        // 延迟到帧尾，保证遍历期间池结构不变
        m_PendingDestroy.push_back(e);
    }

    void Scene::FlushDestroyQueue()
    {
        if (m_PendingDestroy.empty()) return;

        for (Entity e : m_PendingDestroy) {
            if (m_Registry.valid(e)) {
                m_Registry.destroy(e);   // entt 自动回收槽位并递增版本号
            }
        }
        m_PendingDestroy.clear();
    }

    CameraComponent* Scene::GetPrimaryCamera()
    {
        CameraComponent* found = nullptr;
        m_Registry.view<CameraComponent>().each([&](Entity, CameraComponent& cc) {
            if (!found && cc.primary) found = &cc;
        });
        return found;
    }

} // namespace Engine::ECS