#include "kapi/memory.hpp"

#include "kapi/memory/frame.hpp"
#include "kapi/memory/frame_allocator.hpp"
#include "kapi/system.hpp"

#include "x86_64/boot/boot.hpp"
#include "x86_64/boot/ld.hpp"
#include "x86_64/cpu/registers.hpp"
#include "x86_64/memory/region_allocator.hpp"

#include <multiboot2/information.hpp>

#include <atomic>

namespace teachos::memory
{
  std::size_t const PLATFORM_FRAME_SIZE{4096};

  namespace
  {
    auto constinit is_initialized = std::atomic_flag{};
    auto constinit allocator = static_cast<frame_allocator *>(nullptr);

    auto create_memory_information() -> x86_64::region_allocator::memory_information
    {
      auto const & mbi = boot::x86_64::multiboot_information_pointer.get();
      auto map = mbi->memory_map();

      return {std::make_pair(physical_address{&boot::x86_64::_start_physical},
                             physical_address{&boot::x86_64::_end_physical}),
              std::make_pair(physical_address{std::bit_cast<std::byte *>(&mbi)},
                             physical_address{std::bit_cast<std::byte *>(&mbi) + mbi->size_bytes()}),
              map};
    };
  }  // namespace

  auto active_allocator() -> frame_allocator &
  {
    if (!allocator)
    {
      system::panic("[x86_64] The frame allocator has not been set yet.");
    }

    return *allocator;
  }

  auto init() -> void
  {
    if (is_initialized.test_and_set())
    {
      system::panic("[x86_64] Memory management has already been initialized.");
    }

    auto memory_map = boot::x86_64::multiboot_information_pointer->maybe_memory_map();
    if (!memory_map)
    {
      system::panic("[x86_64] No memory map available.");
    }

    auto mem_info = create_memory_information();
    auto allocator = x86_64::region_allocator{mem_info};

    static_cast<void>(allocator);

    cpu::x86_64::set_cr0_bit(cpu::x86_64::cr0_flags::WRITE_PROTECT);

    // set_efer_bit(efer_flags::NXE);

    // paging::kernel_mapper kernel(allocator, memory_information);
    // kernel.remap_kernel();
    // video::vga::text::write("Kernel remapping successful", video::vga::text::common_attributes::green_on_black);
    // video::vga::text::newline();

    // remap_heap(heap::KERNEL_HEAP_START, heap::KERNEL_HEAP_SIZE);
    // video::vga::text::write("Heap remapping successful", video::vga::text::common_attributes::green_on_black);
    // video::vga::text::newline();
  }

}  // namespace teachos::memory