//
// Created by erki on 24/10/23.
//

#pragma once

#include <type_traits>
#include <array>
#include <cstring>
#include <memory>

namespace cpptick
{

template<typename T>
concept TrivialClass = std::is_trivial_v<T> && std::is_trivially_destructible_v<T>;

template<typename T>
concept CopyableClass = !TrivialClass<T> && std::copy_constructible<T>;

template<typename T>
concept SlotArgument = TrivialClass<T> || CopyableClass<T>;

struct ArgStorage
{
  std::array<char, sizeof(int) * 12> buffer;
  std::array<char*, 12> pointer_buffer;
  std::array<char*, 12>::iterator pointer_buffer_head;
  std::size_t space_remaining;

  ArgStorage() = default;
  ArgStorage(const ArgStorage&) = default;
  ArgStorage(ArgStorage&&) = default;

  void reset()
  {
    space_remaining = buffer.size();
    pointer_buffer_head = pointer_buffer.begin();
    *pointer_buffer_head = buffer.data();
  }

  template<TrivialClass T>
  void pushArg(T&& arg)
  {
    if (pointer_buffer_head == pointer_buffer.end() || space_remaining == 0)
      std::exit(1);

    void* memory_location = *pointer_buffer_head;

    if (std::align(alignof(T), sizeof(T), memory_location, space_remaining) == nullptr)
      std::exit(2);

    std::memcpy(memory_location, &arg, sizeof(T));
    pointer_buffer_head++;
    if (pointer_buffer_head != pointer_buffer.end())
    {
      *pointer_buffer_head = (char*)memory_location + sizeof(T);
      space_remaining -= sizeof(T);
    }
  }

  template<CopyableClass T>
  void pushArg(T&& arg)
  {
    if (pointer_buffer_head == pointer_buffer.end() || space_remaining == 0)
      std::exit(1);

    void* memory_location = *pointer_buffer_head;

    if (std::align(alignof(T), sizeof(T), memory_location, space_remaining) == nullptr)
      std::exit(2);

    new (memory_location) T{arg};
    pointer_buffer_head++;
    if (pointer_buffer_head != pointer_buffer.end())
    {
      *pointer_buffer_head = (char*)memory_location + sizeof(T);
      space_remaining -= sizeof(T);
    }
  }

  template<TrivialClass T>
  void cleanUp(const std::size_t)
  { }

  template<CopyableClass T>
  void cleanUp(const std::size_t index)
  {
    T* item = reinterpret_cast<T*>(pointer_buffer[index]);
    item->~T();
  }

  template<typename... Args, size_t... Is>
  void cleanUp(std::index_sequence<Is...>)
  {
    (cleanUp<Args>(Is), ...);
  }

  template<typename... Args>
  void cleanUp()
  {
    cleanUp<Args...>(std::make_index_sequence<sizeof...(Args)>{});
  }

  template<SlotArgument T>
  T& at(const std::size_t idx)
  {
    return *((T*)pointer_buffer[idx]);
  }

  template<SlotArgument T>
  const T& at(const std::size_t idx) const
  {
    return *((T*)pointer_buffer[idx]);
  }
};

}