#include "system.hpp"

#include <cassert>

template <typename T> std::shared_ptr<T> SystemManager::RegisterSystem() {
  const char *typeName = typeid(T).name();

  assert(mSystems.find(typeName) == mSystems.end() &&
         "Registering system more than once.");

  // Create a pointer to the system and return it so it can be used externally
  auto system = std::make_shared<T>();
  mSystems.insert({typeName, system});
  return system;
}

template <typename T> void SystemManager::SetSignature(Signature signature) {
  const char *typeName = typeid(T).name();

  assert(mSystems.find(typeName) != mSystems.end() &&
         "System used before registered.");

  // Set the signature for this system
  mSignatures.insert({typeName, signature});
}

void SystemManager::EntityDestroyed(Entity entity) {
  // Erase a destroyed entity from all system lists
  // mEntities is a set so no check needed
  for (auto const &pair : mSystems) {
    auto const &system = pair.second;

    system->mEntities.erase(entity);
  }
}

void SystemManager::EntitySignatureChanged(Entity entity,
                                           Signature entitySignature) {
  // Notify each system that an entity's signature changed
  for (auto const &pair : mSystems) {
    auto const &type = pair.first;
    auto const &system = pair.second;
    auto const &systemSignature = mSignatures[type];

    // Entity signature matches system signature - insert into set
    if ((entitySignature & systemSignature) == systemSignature) {
      system->mEntities.insert(entity);
    }
    // Entity signature does not match system signature - erase from set
    else {
      system->mEntities.erase(entity);
    }
  }
}