#include "kernel/filesystem/ext2/filesystem.hpp"

#include "kapi/devices/device.hpp"

#include "kernel/devices/block_device_utils.hpp"
#include "kernel/filesystem/ext2/block_group_descriptor.hpp"
#include "kernel/filesystem/ext2/inode.hpp"
#include "kernel/filesystem/ext2/superblock.hpp"
#include "kernel/filesystem/filesystem.hpp"
#include "kernel/filesystem/inode.hpp"

#include <kstd/memory>
#include <kstd/vector>

#include <cstddef>
#include <cstdint>
#include <string_view>

namespace kernel::filesystem::ext2
{
  namespace
  {
    constexpr size_t SUPERBLOCK_OFFSET = 1024;
    constexpr uint16_t EXT2_MAGIC = 0xEF53;

    // Mode bits
    // constexpr uint16_t S_IFMT = 0xF000;
    // constexpr uint16_t S_IFREG = 0x8000;
    // constexpr uint16_t S_IFDIR = 0x4000;

    // auto S_ISREG(uint16_t mode) -> bool
    // {
    //   return (mode & S_IFMT) == S_IFREG;
    // }
    // auto S_ISDIR(uint16_t mode) -> bool
    // {
    //   return (mode & S_IFMT) == S_IFDIR;
    // }
  }  // namespace

  auto filesystem::mount(kstd::shared_ptr<kapi::devices::device> const & device) -> int
  {
    kernel::filesystem::filesystem::mount(device);

    kernel::devices::block_device_utils::read(m_device, &m_superblock, SUPERBLOCK_OFFSET, sizeof(m_superblock));

    if (m_superblock.magic != EXT2_MAGIC)
    {
      return -1;
    }

    auto const block_size = get_block_size();
    auto const blocks_per_group = m_superblock.blocks_per_group;
    auto const num_block_groups = (m_superblock.blocks_count + blocks_per_group - 1) / blocks_per_group;

    m_block_group_descriptors = kstd::vector<block_group_descriptor>(num_block_groups);

    auto const block_group_descriptor_table_offset = block_size == 1024 ? 2 * block_size : block_size;
    kernel::devices::block_device_utils::read(m_device, m_block_group_descriptors.data(),
                                              block_group_descriptor_table_offset,
                                              num_block_groups * sizeof(block_group_descriptor));

    // TODO BA-FS26 load proper root inode from ext2 metadata
    // m_root_inode = inode{inode_kind::directory};

    // TODO BA-FS26 implement
    m_root_inode = kstd::make_shared<inode>();
    // devices::block_device_utils::read(device, nullptr, 0, 0);  // TODO BA-FS26 just for testing
    return 0;
  }

  auto filesystem::lookup(kstd::shared_ptr<kernel::filesystem::inode> const & /*parent*/, std::string_view name)
      -> kstd::shared_ptr<kernel::filesystem::inode>
  {
    // TODO BA-FS26 implement ext2 directory traversal and inode loading
    if (name == "dev")
    {
      // TODO BA-FS26 just for testing
      return nullptr;
    }

    return kstd::make_shared<inode>();
  }

  auto filesystem::get_block_size() -> size_t
  {
    return 1024U << m_superblock.log_block_size;
  }

  auto filesystem::get_inode_size() -> size_t
  {
    return m_superblock.rev_level == 0 ? 128 : m_superblock.inode_size;
  }
}  // namespace kernel::filesystem::ext2