from typing import Callable, Optional, TypeVar

from reactivex import Observable, compose
from reactivex import operators as ops
from reactivex import typing
from reactivex.internal.basic import default_comparer

_T = TypeVar("_T")


def contains_(
    value: _T, comparer: Optional[typing.Comparer[_T]] = None
) -> Callable[[Observable[_T]], Observable[bool]]:
    comparer_ = comparer or default_comparer

    def predicate(v: _T) -> bool:
        return comparer_(v, value)

    return compose(
        ops.filter(predicate),
        ops.some(),
    )


__all__ = ["contains_"]