from typing import Union

import torch

_STR_DTYPE_TO_TORCH_DTYPE = {
    'half': torch.half,
    'float': torch.float,
    'float16': torch.float16,
    'float32': torch.float32,
}


def get_torch_dtype(dtype: Union[torch.dtype, str]) -> torch.dtype:
    if isinstance(dtype, str):
        torch_dtype = _STR_DTYPE_TO_TORCH_DTYPE[dtype.lower()]
    else:
        torch_dtype = dtype
    return torch_dtype


def get_dtype_size(dtype: Union[torch.dtype, str]) -> int:
    torch_dtype = get_torch_dtype(dtype)
    return torch.tensor([], dtype=torch_dtype).element_size()