# -*- coding: utf-8 -*-
"""
Tests for helper functions in the cython tslibs.offsets
"""
from datetime import datetime

import pytest

from pandas import Timestamp

import pandas._libs.tslibs.offsets as liboffsets
from pandas._libs.tslibs.offsets import roll_qtrday


def test_get_lastbday():
    dt = datetime(2017, 11, 30)
    assert dt.weekday() == 3  # i.e. this is a business day
    assert liboffsets.get_lastbday(dt.year, dt.month) == 30

    dt = datetime(1993, 10, 31)
    assert dt.weekday() == 6  # i.e. this is not a business day
    assert liboffsets.get_lastbday(dt.year, dt.month) == 29


def test_get_firstbday():
    dt = datetime(2017, 4, 1)
    assert dt.weekday() == 5  # i.e. not a weekday
    assert liboffsets.get_firstbday(dt.year, dt.month) == 3

    dt = datetime(1993, 10, 1)
    assert dt.weekday() == 4  # i.e. a business day
    assert liboffsets.get_firstbday(dt.year, dt.month) == 1


def test_shift_month():
    dt = datetime(2017, 11, 30)
    assert liboffsets.shift_month(dt, 0, 'business_end') == dt
    assert liboffsets.shift_month(dt, 0,
                                  'business_start') == datetime(2017, 11, 1)

    ts = Timestamp('1929-05-05')
    assert liboffsets.shift_month(ts, 1, 'start') == Timestamp('1929-06-01')
    assert liboffsets.shift_month(ts, -3, 'end') == Timestamp('1929-02-28')

    assert liboffsets.shift_month(ts, 25, None) == Timestamp('1931-06-5')

    # Try to shift to April 31, then shift back to Apr 30 to get a real date
    assert liboffsets.shift_month(ts, -1, 31) == Timestamp('1929-04-30')

    dt = datetime(2017, 11, 15)

    assert liboffsets.shift_month(dt, 0, day_opt=None) == dt
    assert liboffsets.shift_month(dt, 0, day_opt=15) == dt

    assert liboffsets.shift_month(dt, 1,
                                  day_opt='start') == datetime(2017, 12, 1)

    assert liboffsets.shift_month(dt, -145,
                                  day_opt='end') == datetime(2005, 10, 31)

    with pytest.raises(ValueError):
        liboffsets.shift_month(dt, 3, day_opt='this should raise')


def test_get_day_of_month():
    # get_day_of_month is not directly exposed; we test it via roll_yearday
    dt = datetime(2017, 11, 15)

    with pytest.raises(ValueError):
        # To hit the raising case we need month == dt.month and n > 0
        liboffsets.roll_yearday(dt, n=3, month=11, day_opt='foo')


def test_roll_yearday():
    # Copied from doctest examples
    month = 3
    day_opt = 'start'              # `other` will be compared to March 1
    other = datetime(2017, 2, 10)  # before March 1
    assert liboffsets.roll_yearday(other, 2, month, day_opt) == 1
    assert liboffsets.roll_yearday(other, -7, month, day_opt) == -7
    assert liboffsets.roll_yearday(other, 0, month, day_opt) == 0

    other = Timestamp('2014-03-15', tz='US/Eastern')  # after March 1
    assert liboffsets.roll_yearday(other, 2, month, day_opt) == 2
    assert liboffsets.roll_yearday(other, -7, month, day_opt) == -6
    assert liboffsets.roll_yearday(other, 0, month, day_opt) == 1

    month = 6
    day_opt = 'end'                # `other` will be compared to June 30
    other = datetime(1999, 6, 29)  # before June 30
    assert liboffsets.roll_yearday(other, 5, month, day_opt) == 4
    assert liboffsets.roll_yearday(other, -7, month, day_opt) == -7
    assert liboffsets.roll_yearday(other, 0, month, day_opt) == 0

    other = Timestamp(2072, 8, 24, 6, 17, 18)  # after June 30
    assert liboffsets.roll_yearday(other, 5, month, day_opt) == 5
    assert liboffsets.roll_yearday(other, -7, month, day_opt) == -6
    assert liboffsets.roll_yearday(other, 0, month, day_opt) == 1


def test_roll_qtrday():
    other = Timestamp(2072, 10, 1, 6, 17, 18)  # Saturday
    for day_opt in ['start', 'end', 'business_start', 'business_end']:
        # as long as (other.month % 3) != (month % 3), day_opt is irrelevant
        # the `day_opt` doesn't matter.
        month = 5  # (other.month % 3) < (month % 3)
        assert roll_qtrday(other, 4, month, day_opt, modby=3) == 3
        assert roll_qtrday(other, -3, month, day_opt, modby=3) == -3

        month = 3  # (other.month % 3) > (month % 3)
        assert roll_qtrday(other, 4, month, day_opt, modby=3) == 4
        assert roll_qtrday(other, -3, month, day_opt, modby=3) == -2

    month = 2
    other = datetime(1999, 5, 31)  # Monday
    # has (other.month % 3) == (month % 3)

    n = 2
    assert roll_qtrday(other, n, month, 'start', modby=3) == n
    assert roll_qtrday(other, n, month, 'end', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_start', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_end', modby=3) == n

    n = -1
    assert roll_qtrday(other, n, month, 'start', modby=3) == n + 1
    assert roll_qtrday(other, n, month, 'end', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_start', modby=3) == n + 1
    assert roll_qtrday(other, n, month, 'business_end', modby=3) == n

    other = Timestamp(2072, 10, 1, 6, 17, 18)  # Saturday
    month = 4  # (other.month % 3) == (month % 3)
    n = 2
    assert roll_qtrday(other, n, month, 'start', modby=3) == n
    assert roll_qtrday(other, n, month, 'end', modby=3) == n - 1
    assert roll_qtrday(other, n, month, 'business_start', modby=3) == n - 1
    assert roll_qtrday(other, n, month, 'business_end', modby=3) == n - 1

    n = -1
    assert roll_qtrday(other, n, month, 'start', modby=3) == n
    assert roll_qtrday(other, n, month, 'end', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_start', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_end', modby=3) == n

    other = Timestamp(2072, 10, 3, 6, 17, 18)  # First businessday
    month = 4  # (other.month % 3) == (month % 3)
    n = 2
    assert roll_qtrday(other, n, month, 'start', modby=3) == n
    assert roll_qtrday(other, n, month, 'end', modby=3) == n - 1
    assert roll_qtrday(other, n, month, 'business_start', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_end', modby=3) == n - 1

    n = -1
    assert roll_qtrday(other, n, month, 'start', modby=3) == n + 1
    assert roll_qtrday(other, n, month, 'end', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_start', modby=3) == n
    assert roll_qtrday(other, n, month, 'business_end', modby=3) == n


def test_roll_convention():
    other = 29
    before = 1
    after = 31

    n = 42
    assert liboffsets.roll_convention(other, n, other) == n
    assert liboffsets.roll_convention(other, n, before) == n
    assert liboffsets.roll_convention(other, n, after) == n - 1

    n = -4
    assert liboffsets.roll_convention(other, n, other) == n
    assert liboffsets.roll_convention(other, n, before) == n + 1
    assert liboffsets.roll_convention(other, n, after) == n