from datetime import datetime
from dateutil.relativedelta import relativedelta as reldelta
from django.utils.timezone import timedelta as delta

CALENDAR_FREQUENCIES = {
    "daily": delta(days=1),
    "weekly": reldelta(weeks=1),
    "monthly": reldelta(months=1),
    "yearly": reldelta(years=1)
}

# Espera date en UTC
def get_next_calendar_date(date: datetime, frequency: str):
    base_date: datetime = date.replace(hour=2, minute=59, second=59, microsecond=0) + delta(days=1)
    if frequency == "daily":
        return base_date
    if frequency == "weekly":
        days_ahead = -date.weekday() + 6 # Lunes
        return base_date + delta(days=days_ahead)
    if frequency == "monthly":
        return (base_date.replace(day=1) + reldelta(months=1))
    if frequency == "yearly":
        return (base_date.replace(day=1, month=1) + reldelta(years=1))
    return None

# Espera date en UTC
def get_previous_calendar_date(date: datetime, frequency: str):
    base_date: datetime = date.replace(hour=2, minute=59, second=59, microsecond=0)
    if frequency == "daily":
        return base_date
    if frequency == "weekly":
        days_ahead = date.weekday()
        return base_date - delta(days=days_ahead)
    if frequency == "monthly":
        return base_date.replace(day=1)
    if frequency == "yearly":
        return base_date.replace(day=1, month=1)
    return None