"""Diffusion utility functions."""

from functools import reduce
from inspect import isfunction
from math import ceil, floor, log2
from typing import Callable, Dict, List, Optional, Sequence, Tuple, TypeVar, Union

import torch
import torch.nn.functional as F
from typing_extensions import TypeGuard

T = TypeVar("T")


def exists(val: Optional[T]) -> TypeGuard[T]:
    return val is not None


def default(val: Optional[T], d: Union[Callable[..., T], T]) -> T:
    if exists(val):
        return val
    return d() if isfunction(d) else d


def rand_bool(shape, proba, device=None):
    if proba == 1:
        return torch.ones(shape, device=device, dtype=torch.bool)
    elif proba == 0:
        return torch.zeros(shape, device=device, dtype=torch.bool)
    else:
        return torch.bernoulli(torch.full(shape, proba, device=device)).to(torch.bool)


def groupby(prefix: str, d: Dict, keep_prefix: bool = False) -> Tuple[Dict, Dict]:
    kwargs_with_prefix = {k: v for k, v in d.items() if k.startswith(prefix)}
    kwargs = {k: v for k, v in d.items() if not k.startswith(prefix)}
    if keep_prefix:
        return kwargs_with_prefix, kwargs
    kwargs_no_prefix = {k[len(prefix):]: v for k, v in kwargs_with_prefix.items()}
    return kwargs_no_prefix, kwargs