import argparse
import datetime


def get_latest_event_year() -> int:
    now = datetime.datetime.now()
    year = now.year

    if now.month < 12:
        year -= 1

    return year


def argument_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(description="aoc")

    subcli = parser.add_subparsers(title="command", required=True, dest="command")

    solve = subcli.add_parser("solve", help="solve a given day's puzzle")
    solve.add_argument(
        "-e",
        "--example",
        action="store_true",
        required=False,
        help="use example input file instead of real input file",
    )
    solve.add_argument(
        "-y",
        "--year",
        type=int,
        required=False,
        help="year of the puzzle (default: current year)",
        default=get_latest_event_year(),
    )
    solve.add_argument("day", type=int, help="day of the puzzle (1-25)")

    create = subcli.add_parser(
        "create", help="create template and input files for a given day's puzzle"
    )
    create.add_argument(
        "-y",
        "--year",
        type=int,
        required=False,
        help="year of the puzzle (default: current year)",
        default=get_latest_event_year(),
    )
    create.add_argument("day", type=int, help="day of the puzzle (1-25)")

    download = subcli.add_parser(
        "download", help="download input file for a given day's puzzle"
    )
    download.add_argument(
        "-f",
        "--force",
        action="store_true",
        required=False,
        help="force re-download even if input file already exists",
    )
    download.add_argument(
        "-y",
        "--year",
        type=int,
        required=False,
        help="year of the puzzle (default: current year)",
        default=get_latest_event_year(),
    )
    download.add_argument("day", type=int, help="day of the puzzle (1-25)")

    return parser