"""Birthdays."""

from datetime import date

import yaml

from .types import Event

YEAR_NOT_KNOWN = 1900


def next_birthday(from_date: date, birth_date: date) -> tuple[date, int | None]:
    """Calculate the date of the next birthday based on a given birth date."""
    next_birthday_date = birth_date.replace(year=from_date.year)

    if from_date > next_birthday_date:
        next_birthday_date = birth_date.replace(year=from_date.year + 1)

    if birth_date.year != YEAR_NOT_KNOWN:
        age_at_next_birthday = next_birthday_date.year - birth_date.year
    else:
        age_at_next_birthday = None

    return next_birthday_date, age_at_next_birthday


def get_birthdays(from_date: date, filepath: str) -> list[Event]:
    """Get birthdays from config."""
    events = []
    with open(filepath) as f:
        entities = yaml.safe_load(f)

    for entity in entities:
        if "year" in entity["birthday"]:
            birthday = date(**entity["birthday"])
        else:
            birthday = date(year=YEAR_NOT_KNOWN, **entity["birthday"])
        bday, age = next_birthday(from_date, birthday)
        for offset in range(2):
            display_age = f"aged {age + offset}" if age is not None else "age unknown"
            events.append(
                Event(
                    date=bday.replace(year=bday.year + offset),
                    name="birthday",
                    title=f'🎈 {entity["label"]} ({display_age})',
                )
            )

    return events