#include "kapi/cio.hpp"

#include <kstd/bits/format/output_buffer.hpp>
#include <kstd/format>
#include <kstd/os/print.hpp>
#include <kstd/print>

#include <algorithm>
#include <array>
#include <cstddef>
#include <string_view>

namespace kstd::os
{

  namespace
  {
    struct write_buffer final : kstd::bits::format::output_buffer
    {
      using output_stream = kapi::cio::output_stream;

      constexpr auto static size = 128uz;

      write_buffer(write_buffer const &) = delete;
      write_buffer(write_buffer &&) = delete;
      auto operator=(write_buffer const &) -> write_buffer & = delete;
      auto operator=(write_buffer &&) -> write_buffer & = delete;

      explicit write_buffer(output_stream stream)
          : m_stream{stream}
      {}

      ~write_buffer() noexcept final
      {
        flush();
      }

      auto push(std::string_view text) -> void final
      {
        std::ranges::for_each(text, [this](auto c) { this->push(c); });
      }

      auto push(char character) -> void final
      {
        if (m_position >= size)
        {
          flush();
        }
        m_buffer.at(m_position++) = character;
      }

    private:
      auto flush() noexcept -> void
      {
        if (m_position > 0)
        {
          std::string_view chunk{m_buffer.data(), m_position};
          kapi::cio::write(m_stream, chunk);
          m_position = 0;
        }
      }

      output_stream m_stream;
      std::array<char, size> m_buffer{};
      std::size_t m_position{};
    };

  }  // namespace

  auto vprint(print_sink sink, std::string_view format, kstd::format_args args) -> void
  {
    auto writer = write_buffer{(sink == print_sink::stderr) ? kapi::cio::output_stream::stderr
                                                            : kapi::cio::output_stream::stdout};
    kstd::bits::format::vformat_to(writer, format, args);
  }

}  // namespace kstd::os