from itertools import product

import numpy as np
import pytest

from pandas._libs import hashtable

from pandas import DatetimeIndex, MultiIndex
import pandas._testing as tm


@pytest.mark.parametrize("names", [None, ["first", "second"]])
def test_unique(names):
    mi = MultiIndex.from_arrays([[1, 2, 1, 2], [1, 1, 1, 2]], names=names)

    res = mi.unique()
    exp = MultiIndex.from_arrays([[1, 2, 2], [1, 1, 2]], names=mi.names)
    tm.assert_index_equal(res, exp)

    mi = MultiIndex.from_arrays([list("aaaa"), list("abab")], names=names)
    res = mi.unique()
    exp = MultiIndex.from_arrays([list("aa"), list("ab")], names=mi.names)
    tm.assert_index_equal(res, exp)

    mi = MultiIndex.from_arrays([list("aaaa"), list("aaaa")], names=names)
    res = mi.unique()
    exp = MultiIndex.from_arrays([["a"], ["a"]], names=mi.names)
    tm.assert_index_equal(res, exp)

    # GH #20568 - empty MI
    mi = MultiIndex.from_arrays([[], []], names=names)
    res = mi.unique()
    tm.assert_index_equal(mi, res)


def test_unique_datetimelike():
    idx1 = DatetimeIndex(
        ["2015-01-01", "2015-01-01", "2015-01-01", "2015-01-01", "NaT", "NaT"]
    )
    idx2 = DatetimeIndex(
        ["2015-01-01", "2015-01-01", "2015-01-02", "2015-01-02", "NaT", "2015-01-01"],
        tz="Asia/Tokyo",
    )
    result = MultiIndex.from_arrays([idx1, idx2]).unique()

    eidx1 = DatetimeIndex(["2015-01-01", "2015-01-01", "NaT", "NaT"])
    eidx2 = DatetimeIndex(
        ["2015-01-01", "2015-01-02", "NaT", "2015-01-01"], tz="Asia/Tokyo"
    )
    exp = MultiIndex.from_arrays([eidx1, eidx2])
    tm.assert_index_equal(result, exp)


@pytest.mark.parametrize("level", [0, "first", 1, "second"])
def test_unique_level(idx, level):
    # GH #17896 - with level= argument
    result = idx.unique(level=level)
    expected = idx.get_level_values(level).unique()
    tm.assert_index_equal(result, expected)

    # With already unique level
    mi = MultiIndex.from_arrays([[1, 3, 2, 4], [1, 3, 2, 5]], names=["first", "second"])
    result = mi.unique(level=level)
    expected = mi.get_level_values(level)
    tm.assert_index_equal(result, expected)

    # With empty MI
    mi = MultiIndex.from_arrays([[], []], names=["first", "second"])
    result = mi.unique(level=level)
    expected = mi.get_level_values(level)


@pytest.mark.parametrize("dropna", [True, False])
def test_get_unique_index(idx, dropna):
    mi = idx[[0, 1, 0, 1, 1, 0, 0]]
    expected = mi._shallow_copy(mi[[0, 1]])

    result = mi._get_unique_index(dropna=dropna)
    assert result.unique
    tm.assert_index_equal(result, expected)


def test_duplicate_multiindex_codes():
    # GH 17464
    # Make sure that a MultiIndex with duplicate levels throws a ValueError
    with pytest.raises(ValueError):
        mi = MultiIndex([["A"] * 10, range(10)], [[0] * 10, range(10)])

    # And that using set_levels with duplicate levels fails
    mi = MultiIndex.from_arrays([["A", "A", "B", "B", "B"], [1, 2, 1, 2, 3]])
    with pytest.raises(ValueError):
        mi.set_levels([["A", "B", "A", "A", "B"], [2, 1, 3, -2, 5]], inplace=True)


@pytest.mark.parametrize("names", [["a", "b", "a"], [1, 1, 2], [1, "a", 1]])
def test_duplicate_level_names(names):
    # GH18872, GH19029
    mi = MultiIndex.from_product([[0, 1]] * 3, names=names)
    assert mi.names == names

    # With .rename()
    mi = MultiIndex.from_product([[0, 1]] * 3)
    mi = mi.rename(names)
    assert mi.names == names

    # With .rename(., level=)
    mi.rename(names[1], level=1, inplace=True)
    mi = mi.rename([names[0], names[2]], level=[0, 2])
    assert mi.names == names


def test_duplicate_meta_data():
    # GH 10115
    mi = MultiIndex(
        levels=[[0, 1], [0, 1, 2]], codes=[[0, 0, 0, 0, 1, 1, 1], [0, 1, 2, 0, 0, 1, 2]]
    )

    for idx in [
        mi,
        mi.set_names([None, None]),
        mi.set_names([None, "Num"]),
        mi.set_names(["Upper", "Num"]),
    ]:
        assert idx.has_duplicates
        assert idx.drop_duplicates().names == idx.names


def test_has_duplicates(idx, idx_dup):
    # see fixtures
    assert idx.is_unique is True
    assert idx.has_duplicates is False
    assert idx_dup.is_unique is False
    assert idx_dup.has_duplicates is True

    mi = MultiIndex(
        levels=[[0, 1], [0, 1, 2]], codes=[[0, 0, 0, 0, 1, 1, 1], [0, 1, 2, 0, 0, 1, 2]]
    )
    assert mi.is_unique is False
    assert mi.has_duplicates is True

    # single instance of NaN
    mi_nan = MultiIndex(
        levels=[["a", "b"], [0, 1]], codes=[[-1, 0, 0, 1, 1], [-1, 0, 1, 0, 1]]
    )
    assert mi_nan.is_unique is True
    assert mi_nan.has_duplicates is False

    # multiple instances of NaN
    mi_nan_dup = MultiIndex(
        levels=[["a", "b"], [0, 1]], codes=[[-1, -1, 0, 0, 1, 1], [-1, -1, 0, 1, 0, 1]]
    )
    assert mi_nan_dup.is_unique is False
    assert mi_nan_dup.has_duplicates is True


def test_has_duplicates_from_tuples():
    # GH 9075
    t = [
        ("x", "out", "z", 5, "y", "in", "z", 169),
        ("x", "out", "z", 7, "y", "in", "z", 119),
        ("x", "out", "z", 9, "y", "in", "z", 135),
        ("x", "out", "z", 13, "y", "in", "z", 145),
        ("x", "out", "z", 14, "y", "in", "z", 158),
        ("x", "out", "z", 16, "y", "in", "z", 122),
        ("x", "out", "z", 17, "y", "in", "z", 160),
        ("x", "out", "z", 18, "y", "in", "z", 180),
        ("x", "out", "z", 20, "y", "in", "z", 143),
        ("x", "out", "z", 21, "y", "in", "z", 128),
        ("x", "out", "z", 22, "y", "in", "z", 129),
        ("x", "out", "z", 25, "y", "in", "z", 111),
        ("x", "out", "z", 28, "y", "in", "z", 114),
        ("x", "out", "z", 29, "y", "in", "z", 121),
        ("x", "out", "z", 31, "y", "in", "z", 126),
        ("x", "out", "z", 32, "y", "in", "z", 155),
        ("x", "out", "z", 33, "y", "in", "z", 123),
        ("x", "out", "z", 12, "y", "in", "z", 144),
    ]

    mi = MultiIndex.from_tuples(t)
    assert not mi.has_duplicates


def test_has_duplicates_overflow():
    # handle int64 overflow if possible
    def check(nlevels, with_nulls):
        codes = np.tile(np.arange(500), 2)
        level = np.arange(500)

        if with_nulls:  # inject some null values
            codes[500] = -1  # common nan value
            codes = [codes.copy() for i in range(nlevels)]
            for i in range(nlevels):
                codes[i][500 + i - nlevels // 2] = -1

            codes += [np.array([-1, 1]).repeat(500)]
        else:
            codes = [codes] * nlevels + [np.arange(2).repeat(500)]

        levels = [level] * nlevels + [[0, 1]]

        # no dups
        mi = MultiIndex(levels=levels, codes=codes)
        assert not mi.has_duplicates

        # with a dup
        if with_nulls:

            def f(a):
                return np.insert(a, 1000, a[0])

            codes = list(map(f, codes))
            mi = MultiIndex(levels=levels, codes=codes)
        else:
            values = mi.values.tolist()
            mi = MultiIndex.from_tuples(values + [values[0]])

        assert mi.has_duplicates

    # no overflow
    check(4, False)
    check(4, True)

    # overflow possible
    check(8, False)
    check(8, True)


@pytest.mark.parametrize(
    "keep, expected",
    [
        ("first", np.array([False, False, False, True, True, False])),
        ("last", np.array([False, True, True, False, False, False])),
        (False, np.array([False, True, True, True, True, False])),
    ],
)
def test_duplicated(idx_dup, keep, expected):
    result = idx_dup.duplicated(keep=keep)
    tm.assert_numpy_array_equal(result, expected)


@pytest.mark.parametrize("keep", ["first", "last", False])
def test_duplicated_large(keep):
    # GH 9125
    n, k = 200, 5000
    levels = [np.arange(n), tm.makeStringIndex(n), 1000 + np.arange(n)]
    codes = [np.random.choice(n, k * n) for lev in levels]
    mi = MultiIndex(levels=levels, codes=codes)

    result = mi.duplicated(keep=keep)
    expected = hashtable.duplicated_object(mi.values, keep=keep)
    tm.assert_numpy_array_equal(result, expected)


def test_duplicated2():
    # TODO: more informative test name
    # GH5873
    for a in [101, 102]:
        mi = MultiIndex.from_arrays([[101, a], [3.5, np.nan]])
        assert not mi.has_duplicates

        tm.assert_numpy_array_equal(mi.duplicated(), np.zeros(2, dtype="bool"))

    for n in range(1, 6):  # 1st level shape
        for m in range(1, 5):  # 2nd level shape
            # all possible unique combinations, including nan
            codes = product(range(-1, n), range(-1, m))
            mi = MultiIndex(
                levels=[list("abcde")[:n], list("WXYZ")[:m]],
                codes=np.random.permutation(list(codes)).T,
            )
            assert len(mi) == (n + 1) * (m + 1)
            assert not mi.has_duplicates

            tm.assert_numpy_array_equal(
                mi.duplicated(), np.zeros(len(mi), dtype="bool")
            )
