#include "kernel/test_support/simulated_memory.hpp"

#include "kapi/memory.hpp"

#include <kstd/units>

#include <cstddef>
#include <cstring>
#include <stdexcept>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>

using namespace kstd::units_literals;

namespace kernel::tests
{
  namespace
  {
    constexpr auto virtual_size = 1_GiB;
  }

  simulated_memory::simulated_memory(kstd::units::bytes size)
      : m_memory_descriptor{memfd_create("teachos_simulated_memory", 0)}
      , m_size{size}
  {
    if (m_memory_descriptor < 0)
    {
      throw std::runtime_error("Failed to create simulated memory");
    }

    if (ftruncate(m_memory_descriptor, static_cast<off_t>(m_size.value)) < 0)
    {
      throw std::runtime_error("Failed to resize simulated memory");
    }

    auto mapped_pointer = mmap(nullptr, m_size.value, PROT_READ | PROT_WRITE, MAP_SHARED, m_memory_descriptor, 0);
    if (mapped_pointer == MAP_FAILED)
    {
      throw std::runtime_error("Failed to map simulated memory");
    }

    m_physical_base = static_cast<std::byte *>(mapped_pointer);

    auto virtual_pointer = mmap(nullptr, virtual_size.value, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (virtual_pointer == MAP_FAILED)
    {
      throw std::runtime_error("Failed to map simulated memory");
    }

    m_virtual_base = static_cast<std::byte *>(virtual_pointer);

    clear();
  }

  simulated_memory::~simulated_memory()
  {
    munmap(m_physical_base, m_size.value);
    munmap(m_virtual_base, virtual_size.value);
    close(m_memory_descriptor);
  }

  auto simulated_memory::clear() -> void
  {
    std::memset(m_physical_base, 0, m_size.value);
  }

  auto simulated_memory::ram_base() noexcept -> std::byte *
  {
    return m_physical_base;
  }

  auto simulated_memory::ram_base() const noexcept -> std::byte const *
  {
    return m_physical_base;
  }

  auto simulated_memory::heap_base() const noexcept -> kapi::memory::linear_address
  {
    return kapi::memory::linear_address{m_virtual_base};
  }

  auto simulated_memory::heap_size() const noexcept -> kstd::units::bytes
  {
    return virtual_size;
  }

  auto simulated_memory::memory_descriptor() const noexcept -> int
  {
    return m_memory_descriptor;
  }

}  // namespace kernel::tests