#include "kernel/test_support/page_mapper.hpp"

#include "kapi/memory.hpp"

#include <kstd/units>

#include <cstddef>
#include <format>
#include <stdexcept>
#include <sys/mman.h>

namespace kernel::tests
{

  page_mapper::page_mapper(kstd::units::bytes memory_size)
      : memory{memory_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 sandbox_start = memory.heap_base();
    auto sandbox_end = sandbox_start + memory.heap_size();

    if (page_address >= sandbox_start && page_address < sandbox_end)
    {
      auto virtual_target = static_cast<std::byte *>(page_address);
      auto physical_offset = frame.number() * kapi::memory::frame::size;
      auto mapped_ptr = mmap(virtual_target, kapi::memory::page::size.value, PROT_READ | PROT_WRITE,
                             MAP_SHARED | MAP_FIXED, memory.memory_descriptor(), physical_offset.value);
      if (mapped_ptr == MAP_FAILED)
      {
        throw std::runtime_error("Failed to map page");
      }

      return static_cast<std::byte *>(mapped_ptr);
    }
    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.ram_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