#include "entity.hpp"
#include <cassert>

EntityManager::EntityManager() {
  // Initialize the queue with all possible entity IDs
  for (Entity entity = 0; entity < MAX_ENTITIES; ++entity) {
    mAvailableEntities.push(entity);
  }
}
Entity EntityManager::CreateEntity() {
  assert(mLivingEntityCount < MAX_ENTITIES &&
         "Too many entities in existence.");

  // Take an ID from the front of the queue
  Entity id = mAvailableEntities.front();
  mAvailableEntities.pop();
  ++mLivingEntityCount;

  return id;
}
void EntityManager::DestroyEntity(Entity entity) {
  assert(entity < MAX_ENTITIES && "Entity out of range.");

  // Invalidate the destroyed entity's signature
  mSignatures[entity].reset();

  // Put the destroyed ID at the back of the queue
  mAvailableEntities.push(entity);
  --mLivingEntityCount;
}
void EntityManager::SetSignature(Entity entity, Signature signature) {
  assert(entity < MAX_ENTITIES && "Entity out of range.");

  // Put this entity's signature into the array
  mSignatures[entity] = signature;
}
Signature EntityManager::GetSignature(Entity entity) {
  assert(entity < MAX_ENTITIES && "Entity out of range.");

  // Get this entity's signature from the array
  return mSignatures[entity];
}