"""Utility functions to build calendar rules."""

from icalendar.prop import vRecur
from recurrence import serialize


def build_rrule(  # noqa
    count=None,
    interval=None,
    bysecond=None,
    byminute=None,
    byhour=None,
    byweekno=None,
    bymonthday=None,
    byyearday=None,
    bymonth=None,
    until=None,
    bysetpos=None,
    wkst=None,
    byday=None,
    freq=None,
):
    """
    Build rrule dictionary for vRecur class.

    :param count: int
    :param interval: int
    :param bysecond: int
    :param byminute: int
    :param byhour: int
    :param byweekno: int
    :param bymonthday: int
    :param byyearday: int
    :param bymonth: int
    :param until: datetime
    :param bysetpos: int
    :param wkst: str, two-letter weekday
    :param byday: weekday
    :param freq: str, frequency name ('WEEK', 'MONTH', etc)
    :return: dict
    """
    result = {}

    if count is not None:
        result["COUNT"] = count

    if interval is not None:
        result["INTERVAL"] = interval

    if bysecond is not None:
        result["BYSECOND"] = bysecond

    if byminute is not None:
        result["BYMINUTE"] = byminute

    if byhour is not None:
        result["BYHOUR"] = byhour

    if byweekno is not None:
        result["BYWEEKNO"] = byweekno

    if bymonthday is not None:
        result["BYMONTHDAY"] = bymonthday

    if byyearday is not None:
        result["BYYEARDAY"] = byyearday

    if bymonth is not None:
        result["BYMONTH"] = bymonth

    if until is not None:
        result["UNTIL"] = until

    if bysetpos is not None:
        result["BYSETPOS"] = bysetpos

    if wkst is not None:
        result["WKST"] = wkst

    if byday is not None:
        result["BYDAY"] = byday

    if freq is not None:
        if freq not in vRecur.frequencies:
            raise ValueError(
                "Frequency value should be one of: {0}".format(vRecur.frequencies)
            )
        result["FREQ"] = freq

    return result


def build_rrule_from_text(rrule_str):
    """Build an rrule from a serialzed RRULE string."""
    recurr = vRecur()
    return recurr.from_ical(rrule_str)


def build_rrule_from_recurrences_rrule(rule):
    """
    Build rrule dictionary for vRecur class from a django_recurrences rrule.

    django_recurrences is a popular implementation for recurrences in django.
    https://pypi.org/project/django-recurrence/
    this is a shortcut to interface between recurrences and icalendar.
    """
    line = serialize(rule)
    if line.startswith("RRULE:"):
        line = line[6:]
    return build_rrule_from_text(line)


def build_rrule_from_dateutil_rrule(rule):
    """
    Build rrule dictionary for vRecur class from a dateutil rrule.

    Dateutils rrule is a popular implementation of rrule in python.
    https://pypi.org/project/python-dateutil/
    this is a shortcut to interface between dateutil and icalendar.
    """
    lines = str(rule).splitlines()
    for line in lines:
        if line.startswith("DTSTART:"):
            continue
        if line.startswith("RRULE:"):
            line = line[6:]
        return build_rrule_from_text(line)