from datetime import datetime, date

import pytest
from freezegun import freeze_time

from app.utils import (
    get_london_midnight_in_utc,
    get_midnight_for_day_before,
    midnight_n_days_ago,
    last_n_days
)


@pytest.mark.parametrize('date, expected_date', [
    (datetime(2016, 1, 15, 0, 30), datetime(2016, 1, 15, 0, 0)),
    (datetime(2016, 6, 15, 0, 0), datetime(2016, 6, 14, 23, 0)),
    (datetime(2016, 9, 15, 11, 59), datetime(2016, 9, 14, 23, 0)),
    # works for both dates and datetimes
    (date(2016, 1, 15), datetime(2016, 1, 15, 0, 0)),
    (date(2016, 6, 15), datetime(2016, 6, 14, 23, 0)),
])
def test_get_london_midnight_in_utc_returns_expected_date(date, expected_date):
    assert get_london_midnight_in_utc(date) == expected_date


@pytest.mark.parametrize('date, expected_date', [
    (datetime(2016, 1, 15, 0, 30), datetime(2016, 1, 14, 0, 0)),
    (datetime(2016, 7, 15, 0, 0), datetime(2016, 7, 13, 23, 0)),
    (datetime(2016, 8, 23, 11, 59), datetime(2016, 8, 21, 23, 0)),
])
def test_get_midnight_for_day_before_returns_expected_date(date, expected_date):
    assert get_midnight_for_day_before(date) == expected_date


@pytest.mark.parametrize('current_time, arg, expected_datetime', [
    # winter
    ('2018-01-10 23:59', 1, datetime(2018, 1, 9, 0, 0)),
    ('2018-01-11 00:00', 1, datetime(2018, 1, 10, 0, 0)),

    # bst switchover at 1am 25th
    ('2018-03-25 10:00', 1, datetime(2018, 3, 24, 0, 0)),
    ('2018-03-26 10:00', 1, datetime(2018, 3, 25, 0, 0)),
    ('2018-03-27 10:00', 1, datetime(2018, 3, 25, 23, 0)),

    # summer
    ('2018-06-05 10:00', 1, datetime(2018, 6, 3, 23, 0)),

    # zero days ago
    ('2018-01-11 00:00', 0, datetime(2018, 1, 11, 0, 0)),
    ('2018-06-05 10:00', 0, datetime(2018, 6, 4, 23, 0)),
])
def test_midnight_n_days_ago(current_time, arg, expected_datetime):
    with freeze_time(current_time):
        assert midnight_n_days_ago(arg) == expected_datetime


def test_last_n_days():
    with freeze_time('2018-03-27 12:00'):
        res = last_n_days(5)

    assert res == [
        datetime(2018, 3, 23, 0, 0),
        datetime(2018, 3, 24, 0, 0),
        datetime(2018, 3, 25, 0, 0),
        datetime(2018, 3, 26, 0, 0),
        datetime(2018, 3, 27, 0, 0)
    ]


@pytest.mark.parametrize('arg', [0, -1])
def test_last_n_days_invalid_arg(arg):
    assert last_n_days(arg) == []