#ifndef MATADOR_COLLECTION_PROXY_HPP
#define MATADOR_COLLECTION_PROXY_HPP


#include "matador/object/collection_resolver.hpp"

#include "matador/utils/identifier.hpp"

#include <atomic>
#include <mutex>
#include <vector>

namespace matador::object {


template<typename Type>
class collection_proxy final {
public:
  collection_proxy() = default;

  // Lazy
  collection_proxy(std::weak_ptr<collection_resolver<Type>> resolver, utils::identifier owner_id)
  : owner_id_(std::move(owner_id)), resolver_(std::move(resolver)) {}

  // Eager
  collection_proxy(std::weak_ptr<collection_resolver<Type>> resolver, std::vector<Type> items)
  : items_(std::move(items)), resolver_(std::move(resolver)) {}

  // Transient
  explicit collection_proxy(std::vector<Type> items)
  : items_(std::move(items)) {}

  [[nodiscard]] const utils::identifier& owner_id() const {
    return owner_id_;
  }
  const std::vector<Type>& items() const {
    resolve();
    return items_;
  }
  std::vector<Type>& items() {
    resolve();
    return items_;
  }
private:
  void resolve() {
    if (loaded_) {
      return;
    }

    std::lock_guard lock(mutex_);
    auto resolver = resolver_.lock();
    if (!resolver) {
      return;
      // Todo: Add states (Detached, Attached, Transient) - if attached an no resolver is available throw runtime exception
      // throw std::runtime_error("Detached proxy (session expired)");
    }

    items_ = resolver->resolve(owner_id_);
    loaded_ = true;
  }

private:
  const utils::identifier owner_id_;
  std::atomic_bool loaded_{false};
  std::vector<Type> items_;
  std::weak_ptr<collection_resolver<Type>> resolver_{};
  mutable std::mutex mutex_{};
};
}
#endif //MATADOR_COLLECTION_PROXY_HPP