import pandas as pd
from typing import Iterable, NamedTuple

SplitUniqueKeys = dict[str:str]


class SplitUniqueResult(NamedTuple):
    keys: SplitUniqueKeys
    data: pd.DataFrame


def split(
    data: pd.DataFrame,
    columns: str | Iterable[str],
    *,
    prevkeys: SplitUniqueKeys = None
) -> Iterable[SplitUniqueResult]:
    if isinstance(columns, str):
        columns = [columns]
    if prevkeys is None:
        prevkeys = {}
    current, *rest = columns
    for value in data[current].unique():
        selection = data[current] == value
        selected = data.loc[selection].copy()
        keys = prevkeys | {current: value}
        if rest:
            yield from split(selected, rest, prevkeys=keys)
        else:
            yield SplitUniqueResult(keys, selected)