"""
Test the consistency of the groupby API, both internally and with other pandas objects.
"""

import inspect

import pytest

from pandas import (
    DataFrame,
    Series,
)
from pandas.core.groupby.generic import (
    DataFrameGroupBy,
    SeriesGroupBy,
)


def test_frame_consistency(request, groupby_func):
    # GH#48028
    if groupby_func in ("first", "last"):
        msg = "first and last are entirely different between frame and groupby"
        request.node.add_marker(pytest.mark.xfail(reason=msg))
    if groupby_func in ("cumcount",):
        msg = "DataFrame has no such method"
        request.node.add_marker(pytest.mark.xfail(reason=msg))

    if groupby_func == "ngroup":
        assert not hasattr(DataFrame, groupby_func)
        return

    frame_method = getattr(DataFrame, groupby_func)
    gb_method = getattr(DataFrameGroupBy, groupby_func)
    result = set(inspect.signature(gb_method).parameters)
    if groupby_func == "size":
        # "size" is a method on GroupBy but property on DataFrame:
        expected = {"self"}
    else:
        expected = set(inspect.signature(frame_method).parameters)

    # Exclude certain arguments from result and expected depending on the operation
    # Some of these may be purposeful inconsistencies between the APIs
    exclude_expected, exclude_result = set(), set()
    if groupby_func in ("any", "all"):
        exclude_expected = {"kwargs", "bool_only", "axis"}
    elif groupby_func in ("count",):
        exclude_expected = {"numeric_only", "axis"}
    elif groupby_func in ("nunique",):
        exclude_expected = {"axis"}
    elif groupby_func in ("max", "min"):
        exclude_expected = {"axis", "kwargs", "skipna"}
        exclude_result = {"min_count", "engine", "engine_kwargs"}
    elif groupby_func in ("mean", "std", "sum", "var"):
        exclude_expected = {"axis", "kwargs", "skipna"}
        exclude_result = {"engine", "engine_kwargs"}
    elif groupby_func in ("median", "prod", "sem"):
        exclude_expected = {"axis", "kwargs", "skipna"}
    elif groupby_func in ("backfill", "bfill", "ffill", "pad"):
        exclude_expected = {"downcast", "inplace", "axis"}
    elif groupby_func in ("cummax", "cummin"):
        exclude_expected = {"skipna", "args"}
        exclude_result = {"numeric_only"}
    elif groupby_func in ("cumprod", "cumsum"):
        exclude_expected = {"skipna"}
    elif groupby_func in ("pct_change",):
        exclude_expected = {"kwargs"}
        exclude_result = {"axis"}
    elif groupby_func in ("rank",):
        exclude_expected = {"numeric_only"}
    elif groupby_func in ("quantile",):
        exclude_expected = {"method", "axis"}

    # Ensure excluded arguments are actually in the signatures
    assert result & exclude_result == exclude_result
    assert expected & exclude_expected == exclude_expected

    result -= exclude_result
    expected -= exclude_expected
    assert result == expected


def test_series_consistency(request, groupby_func):
    # GH#48028
    if groupby_func in ("first", "last"):
        msg = "first and last are entirely different between Series and groupby"
        request.node.add_marker(pytest.mark.xfail(reason=msg))
    if groupby_func in ("cumcount", "corrwith"):
        msg = "Series has no such method"
        request.node.add_marker(pytest.mark.xfail(reason=msg))

    if groupby_func == "ngroup":
        assert not hasattr(Series, groupby_func)
        return

    series_method = getattr(Series, groupby_func)
    gb_method = getattr(SeriesGroupBy, groupby_func)
    result = set(inspect.signature(gb_method).parameters)
    if groupby_func == "size":
        # "size" is a method on GroupBy but property on Series
        expected = {"self"}
    else:
        expected = set(inspect.signature(series_method).parameters)

    # Exclude certain arguments from result and expected depending on the operation
    # Some of these may be purposeful inconsistencies between the APIs
    exclude_expected, exclude_result = set(), set()
    if groupby_func in ("any", "all"):
        exclude_expected = {"kwargs", "bool_only", "axis"}
    elif groupby_func in ("diff",):
        exclude_result = {"axis"}
    elif groupby_func in ("max", "min"):
        exclude_expected = {"axis", "kwargs", "skipna"}
        exclude_result = {"min_count", "engine", "engine_kwargs"}
    elif groupby_func in ("mean", "std", "sum", "var"):
        exclude_expected = {"axis", "kwargs", "skipna"}
        exclude_result = {"engine", "engine_kwargs"}
    elif groupby_func in ("median", "prod", "sem"):
        exclude_expected = {"axis", "kwargs", "skipna"}
    elif groupby_func in ("backfill", "bfill", "ffill", "pad"):
        exclude_expected = {"downcast", "inplace", "axis"}
    elif groupby_func in ("cummax", "cummin"):
        exclude_expected = {"skipna", "args"}
        exclude_result = {"numeric_only"}
    elif groupby_func in ("cumprod", "cumsum"):
        exclude_expected = {"skipna"}
    elif groupby_func in ("pct_change",):
        exclude_expected = {"kwargs"}
        exclude_result = {"axis"}
    elif groupby_func in ("rank",):
        exclude_expected = {"numeric_only"}
    elif groupby_func in ("idxmin", "idxmax"):
        exclude_expected = {"args", "kwargs"}
    elif groupby_func in ("quantile",):
        exclude_result = {"numeric_only"}

    # Ensure excluded arguments are actually in the signatures
    assert result & exclude_result == exclude_result
    assert expected & exclude_expected == exclude_expected

    result -= exclude_result
    expected -= exclude_expected
    assert result == expected