from datetime import (
    datetime,
    timedelta,
)

import pytest

from pandas import (
    DatetimeIndex,
    NaT,
    Timestamp,
)
import pandas._testing as tm


@pytest.mark.parametrize(
    "arr, expected",
    [
        (DatetimeIndex(["2017", "2017"]), DatetimeIndex(["2017"])),
        (
            DatetimeIndex(["2017", "2017"], tz="US/Eastern"),
            DatetimeIndex(["2017"], tz="US/Eastern"),
        ),
    ],
)
def test_unique(arr, expected):
    result = arr.unique()
    tm.assert_index_equal(result, expected)
    # GH#21737
    # Ensure the underlying data is consistent
    assert result[0] == expected[0]


def test_index_unique(rand_series_with_duplicate_datetimeindex):
    dups = rand_series_with_duplicate_datetimeindex
    index = dups.index

    uniques = index.unique()
    expected = DatetimeIndex(
        [
            datetime(2000, 1, 2),
            datetime(2000, 1, 3),
            datetime(2000, 1, 4),
            datetime(2000, 1, 5),
        ]
    )
    assert uniques.dtype == "M8[ns]"  # sanity
    tm.assert_index_equal(uniques, expected)
    assert index.nunique() == 4

    # GH#2563
    assert isinstance(uniques, DatetimeIndex)

    dups_local = index.tz_localize("US/Eastern")
    dups_local.name = "foo"
    result = dups_local.unique()
    expected = DatetimeIndex(expected, name="foo")
    expected = expected.tz_localize("US/Eastern")
    assert result.tz is not None
    assert result.name == "foo"
    tm.assert_index_equal(result, expected)

    # NaT, note this is excluded
    arr = [1370745748 + t for t in range(20)] + [NaT.value]
    idx = DatetimeIndex(arr * 3)
    tm.assert_index_equal(idx.unique(), DatetimeIndex(arr))
    assert idx.nunique() == 20
    assert idx.nunique(dropna=False) == 21

    arr = [
        Timestamp("2013-06-09 02:42:28") + timedelta(seconds=t) for t in range(20)
    ] + [NaT]
    idx = DatetimeIndex(arr * 3)
    tm.assert_index_equal(idx.unique(), DatetimeIndex(arr))
    assert idx.nunique() == 20
    assert idx.nunique(dropna=False) == 21


def test_is_unique_monotonic(rand_series_with_duplicate_datetimeindex):
    index = rand_series_with_duplicate_datetimeindex.index
    assert not index.is_unique