from __future__ import annotations

import re
from datetime import date
from pathlib import Path


def parse_dates_text(text: str) -> list[date]:
    dates: list[date] = []
    for line in text.splitlines():
        line = line.strip()
        if not line or line.startswith("#"):
            continue
        for token in re.split(r"[\s,;]+", line):
            token = token.strip()
            if token:
                dates.append(date.fromisoformat(token))
    return sorted(set(dates))


def parse_dates_file(path: str | Path) -> list[date]:
    content = Path(path).read_text(encoding="utf-8")
    dates = parse_dates_text(content)
    if not dates:
        raise ValueError(f"No dates found in {path}")
    return dates