#include "kapi/acpi.hpp"

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

#include "kernel/acpi/manager.hpp"

#include <kstd/units>

#include <algorithm>
#include <atomic>
#include <bit>
#include <cstddef>
#include <cstdint>
#include <optional>
#include <span>
#include <string_view>

namespace kapi::acpi
{

  namespace
  {
    auto constinit manager = std::optional<kernel::acpi::manager>{};
  }  // namespace

  auto root_system_description_pointer::oem_id() const noexcept -> std::string_view
  {
    return {m_oem_id.data(), m_oem_id.size()};
  }

  auto root_system_description_pointer::revision() const noexcept -> std::uint8_t
  {
    return m_revision;
  }

  auto root_system_description_pointer::signature() const noexcept -> std::string_view
  {
    return {m_signature.data(), m_signature.size()};
  }

  auto root_system_description_pointer::table_address() const noexcept -> memory::physical_address
  {
    auto raw = std::bit_cast<std::uint32_t>(m_rsdt_address);
    return memory::physical_address{static_cast<std::uintptr_t>(raw)};
  }

  auto root_system_description_pointer::validate() const noexcept -> bool
  {
    return validate_checksum({reinterpret_cast<std::byte const *>(this), sizeof(root_system_description_pointer)});
  }

  auto extended_system_description_pointer::length() const noexcept -> kstd::units::bytes
  {
    return kstd::units::bytes{m_length};
  }

  auto extended_system_description_pointer::table_address() const noexcept -> memory::physical_address
  {
    return memory::physical_address{std::bit_cast<std::uintptr_t>(m_xsdt_address)};
  }

  auto extended_system_description_pointer::validate() const noexcept -> bool
  {
    return validate_checksum({reinterpret_cast<std::byte const *>(this), m_length});
  }

  auto init(root_system_description_pointer const & sdp) -> bool
  {
    auto static constinit initialized = std::atomic_flag{};
    if (initialized.test_and_set())
    {
      system::panic("[OS::ACPI] The ACPI manager has already been initialized!");
    }

    manager.emplace(sdp);
    return manager->load_tables();
  }

  auto validate_checksum(std::span<std::byte const> data) -> bool
  {
    auto sum = std::ranges::fold_left(data, std::uint8_t{}, [](auto acc, auto byte) {
      return static_cast<std::uint8_t>(acc + static_cast<std::uint8_t>(byte));
    });
    return sum == 0;
  }

};  // namespace kapi::acpi