#include <kapi/system.hpp>

#include <kapi/cpu.hpp>

#include <kstd/print.hpp>
#include <kstd/system_error.hpp>

#include <source_location>
#include <string_view>

namespace kapi::system
{

  namespace
  {

    auto panic_write(kstd::error_code error) -> void
    {
      kstd::print(kstd::print_sink::stderr, " ({}) ", error);
    }

  }  // namespace

  namespace detail
  {

    panic_buffer::~panic_buffer()
    {
      flush();
    }

    void panic_buffer::append(char character)
    {
      m_buffer[m_written++] = character;
      if (m_written == m_buffer.size())
      {
        flush();
      }
    }

    void panic_buffer::flush()
    {
      if (m_written > 0)
      {
        panic_write(std::string_view{m_buffer.data(), m_written});
        m_written = 0;
      }
    }

    panic_iterator::panic_iterator(panic_buffer & buffer)
        : m_buffer(&buffer)
    {}

    auto panic_iterator::operator*() noexcept -> panic_iterator &
    {
      return *this;
    }

    auto panic_iterator::operator=(char character) -> panic_iterator &
    {
      m_buffer->append(character);
      return *this;
    }

    auto panic_iterator::operator++() -> panic_iterator &
    {
      return *this;
    }

    auto panic_iterator::operator++(int) -> panic_iterator
    {
      return *this;
    }

  }  // namespace detail

  [[gnu::weak]]
  auto panic(std::string_view message, std::source_location location) -> void
  {
    panic_start(location);
    panic_write(message);
    panic_finish(location);
  }

  [[gnu::weak]]
  auto panic(std::string_view message, kstd::error_code error, std::source_location location) -> void
  {
    panic_start(location);
    panic_write(message);
    panic_write(error);
    panic_finish(location);
  }

  auto panic_start(std::source_location location) -> void
  {
    kstd::print(kstd::print_sink::stderr, "[PANIC] in '{}': ", location.function_name());
  }

  auto panic_write(std::string_view message) -> void
  {
    kstd::print(kstd::print_sink::stderr, "{}", message);
  }

  auto panic_finish(std::source_location location) -> void
  {
    kstd::println(kstd::print_sink::stderr, " @ {}:{}", location.file_name(), location.line());
    cpu::halt();
  }

}  // namespace kapi::system