"""Unit tests for datetime utility functions."""
import pytest

from analytics.consts import models as model_consts
from analytics.utils import date


def test_get_date():
    """Test transformation of a date string into a datetime obj."""
    dates = [date.get('2014-10-01'), date.get('10-01-2014', format='%m-%d-%Y')]
    for current_date in dates:
        assert current_date.year == 2014
        assert current_date.month == 10
        assert current_date.day == 1


def test_get_wrong_date():
    """
    Test get_wrong_date.

    Dates that do not match the format returns empty.
    """
    assert not date.get('2015-20-01')


def test_create_empty_date_ranges():
    """Test creating empty date ranges."""
    ranges = date.create_empty_date_ranges('2015-10-01', '2015-11-01')
    assert len(ranges) == 32  # includes 2015-11-01.


def test_month_difference():
    """Test difference between two dates in months."""
    m = date.month_difference(date.get('2014-10-01'), date.get('2015-02-01'))
    assert m == 5


def test_generator_month_between_dates():
    """The generator return one month at a time between two dates."""
    dates = list(date.generator_month_between_dates(
        date.get('2014-10-01'),
        date.get('2015-02-01')))

    assert len(dates) == 5
    assert dates[0] == date.get('2014-10-01')
    assert dates[1] == date.get('2014-11-01')
    assert dates[2] == date.get('2014-12-01')
    assert dates[3] == date.get('2015-01-01')
    assert dates[4] == date.get('2015-02-01')


def test_generator_month_chunk_same_date():
    """Test the generator that returns a month range."""
    start_date = date.get('2014-10-01')
    end_date = date.get('2014-10-01')
    dates = list(date.month_chunk(start_date, end_date))[0]
    assert dates[0] == dates[1]


def test_generator_month_chunk_same_month():
    """Test the generator that returns a month range."""
    start_date = date.get('2014-10-01')
    end_date = date.get('2014-10-20')
    dates = list(date.month_chunk(start_date, end_date))[0]
    assert dates[0].day == 1
    assert dates[1].day == 20
    assert dates[0].month == dates[1].month
    assert dates[0].year == dates[1].year


def test_generator_month_chunk():
    """Test the generator that returns a month range."""
    start_date = date.get('2014-10-08')
    end_date = date.get('2015-07-20')
    ranges = list(date.month_chunk(start_date, end_date))

    # oct, nov, dec, jan, feb, march, april, may, june, july
    assert len(ranges) == 10

    # Check it goes through all the dates
    assert ranges[0][0] == start_date

    for i in range(2):
        assert ranges[9][i].year == end_date.year
        assert ranges[9][i].month == end_date.month

    assert ranges[9][1] == end_date


def test_generator_month_chunk_with_size():
    """Test the generator that returns a month range with a different size."""
    start_date = date.get('2014-10-08')
    end_date = date.get('2015-07-20')
    ranges = list(date.month_chunk(start_date, end_date, size=2))

    # (oct, nov),  (dec, jan), (feb, march), (april, may), (june, july)
    assert len(ranges) == 5

    # Check it goes through all the dates
    assert ranges[0][0] == start_date
    assert ranges[4][1] == end_date

    ranges = list(date.month_chunk(start_date, end_date, size=3))

    # (oct, nov, dec), (jan, feb, march), (april, may, june), (july)
    assert len(ranges) == 4

    # Check it goes through all the dates
    assert ranges[0][0] == start_date

    for i in range(2):
        assert ranges[3][i].year == end_date.year
        assert ranges[3][i].month == end_date.month
    assert ranges[3][1] == end_date


@pytest.mark.parametrize(
    'start_date, end_date, period', [
        ('2017-01-01', '2017-01-31', model_consts.MONTH_PERIOD),
        ('2017-01-01', '2017-01-07', model_consts.WEEK_PERIOD),
        ('2016-01-01', '2017-01-01', model_consts.YEAR_PERIOD),
        ('2017-01-01', '2018-01-01', model_consts.YEAR_PERIOD),
        ('2017-01-01', '2018-01-08', model_consts.YEAR_PERIOD)
    ]
)
def test_determine_date_period(start_date, end_date, period):
    """Test the determine period."""
    assert date.determine_date_period(start_date, end_date).message == period


@pytest.mark.parametrize(
    'start_date, end_date', [
        ('2017-01-01', '2017-01-10'),
        ('2017-01-01', '2017-01-02'),
        ('2017-01-01', '2017-03-03'),
        ('2016-01-03', '2017-01-01'),
        ('2017-01-02', '2018-01-01'),
        ('2017-01-01', '2018-01-09')
    ]
)
def test_determine_date_period_invalid_range(start_date, end_date):
    """Test the determine period for invalid date ranges."""
    assert not date.determine_date_period(start_date, end_date)