#pragma once

#include <cstdint>
#include <utility>
#include "span.hpp"

namespace hv
{
  typedef std::uint8_t byte;
  struct memory_map
  {
    /// Create a copy-on-write memory map to a file descriptor
    inline static memory_map cow(std::uint64_t size, int&& fd) noexcept
    {
      return memory_map(size, std::move(fd), true);
    }
    /// Create a copy-on-write memory map to a file by name
    inline static memory_map cow(std::uint64_t size, const char* file) noexcept
    {
      return memory_map(size, file, true);
    }
    memory_map(std::uint64_t size, const char* const filename) noexcept;
    memory_map(std::uint64_t size, int&& fd) noexcept;
    ~memory_map();

    inline byte& operator[](std::size_t index)
    {
      if (index>=size) std::terminate();
      return ((byte*)block0)[index];
    }
    inline const byte& operator[](std::size_t index) const
    {
      if (index>=size) std::terminate();
      return ((byte*)block0)[index];
    }

    inline hv::span<byte> span()
    {
      return hv::span((byte*)block0, size);
    }
    
    inline void* base()
    {
      return block0;
    }
    inline const void* base() const
    {
      return block0;
    }
    const bool is_cow;
    const std::uint64_t size;
  private:
    memory_map(std::uint64_t size, int&& fd, bool _cow) noexcept;
    memory_map(std::uint64_t size, const char* filename, bool _cow) noexcept;
    const int fd;
    void* const block0;
  };
  
  struct const_memory_map
  {
    const_memory_map(std::uint64_t size, const char* const filename) noexcept;
    const_memory_map(std::uint64_t size, int&& fd) noexcept;
    ~const_memory_map();

    inline const byte& operator[](std::size_t index) const
    {
      if (index>=size) std::terminate();
      return ((byte*)block0)[index];
    }
    
    inline const void* base() const
    {
      return block0;
    }
    const std::uint64_t size; 
  private:
    const int fd;
    const void* const block0;
  };
}