"""
Date utilities: finding latest dates from GeoJSON files, parsing date strings.
"""
import glob
import re
from pathlib import Path

from fastapi import HTTPException

from config import DATA_DIR, DATE_FORMAT_GEOJSON


def get_latest_date() -> str:
    """Get latest available date from GeoJSON files in DATA_DIR."""
    pattern = str(DATA_DIR / "risk_*.geojson")
    files = glob.glob(pattern)
    if not files:
        raise HTTPException(status_code=500, detail="No risk data files found")

    dates = []
    for f in files:
        match = re.search(r"risk_(\d{8})\.geojson", f)
        if match:
            dates.append(match.group(1))

    if not dates:
        raise HTTPException(status_code=500, detail="No valid risk data files found")

    return max(dates)


def get_available_dates(days: int = 30) -> list[str]:
    """Get list of available dates, most recent first."""
    pattern = str(DATA_DIR / "risk_*.geojson")
    files = glob.glob(pattern)

    dates: list[str] = []
    for f in files:
        match = re.search(r"risk_(\d{8})\.geojson", f)
        if match:
            dates.append(match.group(1))

    dates.sort(reverse=True)
    return dates[:days]


def validate_date_format(date: str) -> bool:
    """Check if date string matches YYYYMMDD format."""
    import re
    return bool(re.compile(r"^\d{8}$").match(date))