#include "arch/memory/main.hpp"

#include "arch/exception_handling/assert.hpp"
#include "arch/kernel/cpu/control_register.hpp"
#include "arch/kernel/cpu/msr.hpp"
#include "arch/memory/allocator/area_frame_allocator.hpp"
#include "arch/memory/allocator/concept.hpp"
#include "arch/memory/heap/global_heap_allocator.hpp"
#include "arch/memory/paging/active_page_table.hpp"
#include "arch/memory/paging/kernel_mapper.hpp"

#include <optional>

namespace teachos::arch::memory
{
  namespace
  {
    static std::optional<allocator::area_frame_allocator> frame_allocator;

    auto create_frame_allocator(multiboot::memory_information const & memory_information)
        -> allocator::area_frame_allocator
    {
      frame_allocator.emplace(memory_information);
      return frame_allocator.value();
    }

    auto get_frame_allocator() -> allocator::area_frame_allocator
    {
      exception_handling::assert(frame_allocator.has_value(), "[Memory main] Frame allocator has not been created yet");
      return frame_allocator.value();
    }
  }  // namespace

  auto remap_heap(std::size_t heap_start, std::size_t heap_size, paging::entry::bitset additional_flags = {}) -> void
  {
    auto allocator = get_frame_allocator();
    decltype(auto) active_table = paging::active_page_table::create_or_get();
    auto const start_page = paging::virtual_page::containing_address(heap_start);
    auto const end_page = ++(paging::virtual_page::containing_address(heap_start + heap_size - 1));

    paging::page_container::iterator const begin{start_page};
    paging::page_container::iterator const end{end_page};
    paging::page_container const pages{begin, end};

    constexpr auto base_flags = paging::entry::WRITABLE;
    auto const flags = base_flags | additional_flags;

    for (auto const & page : pages)
    {
      active_table.map_page_to_next_free_frame(allocator, page, flags);
    }
  }

  auto initialize_memory_management() -> void
  {
    static bool has_been_called = false;
    arch::exception_handling::assert(!has_been_called,
                                     "[Initialization] Memory management has already been initialized");
    has_been_called = true;

    auto const memory_information = multiboot::read_multiboot2();
    auto allocator = create_frame_allocator(memory_information);

    kernel::cpu::set_cr0_bit(kernel::cpu::cr0_flags::WRITE_PROTECT);
    kernel::cpu::set_efer_bit(kernel::cpu::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 kernel heap
    remap_heap(heap::KERNEL_HEAP_START, heap::KERNEL_HEAP_SIZE);
    // Remap user heap
    remap_heap(heap::USER_HEAP_SIZE, heap::USER_HEAP_SIZE, paging::entry::USER_ACCESSIBLE);

    video::vga::text::write("Heap remapping successful", video::vga::text::common_attributes::green_on_black);
    video::vga::text::newline();
  }
}  // namespace teachos::arch::memory