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

#include "kapi/system.hpp"

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

#include <algorithm>
#include <cstddef>
#include <cstdint>

namespace kernel::filesystem::ext2
{
  inode::inode(filesystem * fs)
      : kernel::filesystem::inode(inode_kind::regular)
      , m_filesystem(fs)
  {
    if (!m_filesystem)
    {
      kapi::system::panic("[EXT2] ext2::inode constructed with filesystem null pointer");
    }
  }

  auto inode::read(void * buffer, size_t offset, size_t size) const -> size_t
  {
    auto block_index = offset / m_filesystem->get_block_size();
    auto in_block_offset = offset % m_filesystem->get_block_size();

    auto bytes_read = 0uz;

    while (bytes_read < size)
    {
      auto const block_number = m_filesystem->map_inode_block_index_to_global_block_number(block_index, m_data);
      if (block_number == 0)  // TODO BA-FS26 really correct?
      {
        break;
      }

      auto const block_start_offset = block_number * m_filesystem->get_block_size();
      auto const read_offset = block_start_offset + in_block_offset;
      auto const bytes_to_read = std::min(size - bytes_read, m_filesystem->get_block_size() - in_block_offset);

      bytes_read += kernel::devices::block_device_utils::read(
          m_filesystem->device(), static_cast<uint8_t *>(buffer) + bytes_read, read_offset, bytes_to_read);

      block_index++;
      in_block_offset = 0;  // After the first block, we always start at the beginning of the block
    }

    return bytes_read;
  }

  auto inode::write(void const * /*buffer*/, size_t /*offset*/, size_t /*size*/) -> size_t
  {
    // TODO BA-FS26 implement
    return 0;
  }
}  // namespace kernel::filesystem::ext2