#include "kernel/memory.hpp"

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

#include "kernel/memory/block_list_allocator.hpp"
#include "kernel/memory/heap_allocator.hpp"

#include <kstd/print>
#include <kstd/units>

#include <atomic>
#include <optional>

namespace kernel::memory
{

  namespace
  {
    struct null_allocator : heap_allocator
    {
      null_allocator static instance;

      [[nodiscard]] auto allocate(kstd::units::bytes, kstd::units::bytes) noexcept -> void * override
      {
        kstd::print(kstd::print_sink::stderr, "Tried to allocate memory without an active heap!");
        return nullptr;
      }

      auto deallocate(void *) noexcept -> void override
      {
        kstd::print(kstd::print_sink::stderr, "Tried to deallocate memory without an active heap!");
      }
    };

    constinit null_allocator null_allocator::instance{};

    auto constinit active_heap_allocator = std::optional<heap_allocator *>{&null_allocator::instance};
    auto constinit basic_allocator = std::optional<block_list_allocator>{};
  }  // namespace

  auto get_heap_allocator() -> heap_allocator &
  {
    return *active_heap_allocator.value();
  }

  auto init_heap(kapi::memory::linear_address base) -> void
  {
    auto static constinit is_initialized = std::atomic_flag{};

    if (is_initialized.test_and_set())
    {
      kapi::system::panic("[OS:MEM] The heap has already been initialized.");
    }

    auto & instance = basic_allocator.emplace(base);
    active_heap_allocator = &instance;
    kstd::println("[OS:MEM] Heap initialized. Dynamic memory available.");
  }

}  // namespace kernel::memory