#include "Types.hpp"
#include <array>
#include <cassert>
#include <queue>

#ifndef WINDOW_H
#define WINDOW_H

class EntityManager
{
private:
    // Queue of unused entity IDs
    std::queue<Entity> mAvailableEntities{};

    // Array of signatures where the index corresponds to the entity ID
    std::array<Signature, MAX_ENTITIES> mSignatures{};

    // Total living entities - used to keep limits on how many exist
    uint32_t mLivingEntityCount{};

public:
    EntityManager()
    {
        // Initialize the queue with all possible entity IDs
        for (Entity entity = 0; entity < MAX_ENTITIES; ++entity)
        {
            mAvailableEntities.push(entity);
        }
    }

    Entity 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 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 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 GetSignature(Entity entity)
    {
        assert(entity < MAX_ENTITIES && "Entity out of range.");

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

#endif