#include "kernel/test_support/page_mapper.hpp"

#include "kapi/memory.hpp"

#include <kstd/units>

#include <cstddef>
#include <format>
#include <stdexcept>

namespace kernel::tests
{

  page_mapper::page_mapper(kstd::units::bytes physical_size, kstd::units::bytes virtual_size)
      : memory{physical_size, virtual_size}
  {}

  auto page_mapper::map(kapi::memory::page page, kapi::memory::frame frame, flags) -> std::byte *
  {
    auto result = page_mappings.insert({page.number(), frame});
    if (!result.second)
    {
      auto error = std::format("Page {} was already mapped!", page.number());
      throw std::invalid_argument{error};
    }

    auto page_address = page.start_address();
    auto virtual_base = memory.virtual_base();
    auto virtual_end = virtual_base + memory.virtual_size();

    if (page_address >= virtual_base && page_address < virtual_end)
    {
      auto virtual_target = static_cast<std::byte *>(page_address);
      auto physical_offset = frame.number() * kapi::memory::frame::size;
      return memory.map(kapi::memory::page::size, virtual_target, physical_offset.value);
    }
    else if (page_address >= kapi::memory::mmio_base)
    {
      throw std::runtime_error("MMIO mapping not yet supported in testing!");
    }
    else if (page_address >= kapi::memory::higher_half_direct_map_base)
    {
      auto offset = frame.number() * kapi::memory::frame::size;
      return memory.physical_base() + offset;
    }

    return nullptr;
  }

  auto page_mapper::unmap(kapi::memory::page page) -> void
  {
    if (!try_unmap(page))
    {
      auto error = std::format("Page {} was never mapped!", page.number());
      throw std::invalid_argument{error};
    }
  }

  auto page_mapper::try_unmap(kapi::memory::page page) noexcept -> bool
  {
    if (page_mappings.contains(page.number()))
    {
      page_mappings.erase(page.number());
      return true;
    }

    return false;
  }

}  // namespace kernel::tests