from __future__ import annotations

import re
from datetime import datetime, timedelta
from pathlib import Path


ORDERED_TIMESTAMP_STEM_RE = re.compile(r"^(?P<timestamp>\d{8}_\d{6})-[1-9]\d*$")


def naive_wall_time(dt: datetime) -> datetime:
    return dt.replace(tzinfo=None)


def format_filename_stem(dt: datetime) -> str:
    return naive_wall_time(dt).strftime("%Y%m%d_%H%M%S")


def round_datetime_to_second(dt: datetime) -> datetime:
    rounded = dt.replace(microsecond=0)
    if dt.microsecond >= 500_000:
        rounded += timedelta(seconds=1)
    return rounded


def format_rounded_filename_stem(dt: datetime) -> str:
    rounded = round_datetime_to_second(dt)
    return format_filename_stem(rounded)


def normalized_extension(path: Path) -> str:
    return path.suffix.lower()


def group_stem_from_name(name: str) -> str:
    stem = Path(name).stem
    match = ORDERED_TIMESTAMP_STEM_RE.match(stem)
    if match:
        return match.group("timestamp")
    return stem


def group_stem(path: Path) -> str:
    return group_stem_from_name(path.name)