import datetime
from typing import Optional
from zoneinfo import ZoneInfo

from dateutil.parser import parse
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from database.schemas import Deadline, UforaCourse

__all__ = ["add_deadline", "get_deadlines"]


async def add_deadline(session: AsyncSession, course_id: int, name: str, date_str: str):
    """Add a new deadline"""
    date_dt = parse(date_str, dayfirst=True).replace(tzinfo=ZoneInfo("Europe/Brussels"))

    # If we only have a day, assume it's the end of the day
    if date_dt.hour == date_dt.minute == date_dt.second == 0:
        date_dt.replace(hour=23, minute=59, second=59)

    deadline = Deadline(course_id=course_id, name=name, deadline=date_dt)
    session.add(deadline)
    await session.commit()


async def get_deadlines(
    session: AsyncSession, *, after: Optional[datetime.date] = None, course: Optional[UforaCourse] = None
) -> list[Deadline]:
    """Get a list of all upcoming deadlines"""
    statement = select(Deadline)

    if after is not None:
        statement = statement.where(Deadline.deadline > after)

    if course is not None:
        statement = statement.where(Deadline.course_id == course.course_id)

    statement = statement.options(selectinload(Deadline.course))
    return list((await session.execute(statement)).scalars().all())