"""Shared utilities for scraper run statistics and listing validation."""
from __future__ import annotations

import json
import logging
import os
from pathlib import Path

HERE = Path(__file__).parent
DATA_DIR = Path(os.environ.get("DATA_DIR", HERE))

_val_log = logging.getLogger(__name__)

_REQUIRED_FIELDS = ("hash_id", "price", "locality", "lat", "lon", "url", "source")


def validate_listing(listing: dict, context: str = "") -> bool:
    """
    Validate a listing dict before it is written to the output JSON.
    Returns True if valid, False if the listing should be skipped.
    Logs a warning for each invalid listing.
    """
    prefix = f"[{context}] " if context else ""

    for field in _REQUIRED_FIELDS:
        val = listing.get(field)
        if val is None or val == "":
            _val_log.warning(f"{prefix}Skipping listing — missing field '{field}': {listing.get('hash_id', '?')}")
            return False

    price = listing.get("price")
    if not isinstance(price, (int, float)) or price <= 0:
        _val_log.warning(f"{prefix}Skipping listing — invalid price={price!r}: {listing.get('hash_id', '?')}")
        return False

    lat, lon = listing.get("lat"), listing.get("lon")
    if not isinstance(lat, (int, float)) or not isinstance(lon, (int, float)):
        _val_log.warning(f"{prefix}Skipping listing — non-numeric GPS lat={lat!r} lon={lon!r}: {listing.get('hash_id', '?')}")
        return False
    if not (47.0 <= lat <= 52.0) or not (12.0 <= lon <= 19.0):
        _val_log.warning(f"{prefix}Skipping listing — GPS outside Czech Republic lat={lat} lon={lon}: {listing.get('hash_id', '?')}")
        return False

    area = listing.get("area")
    if area is not None and (not isinstance(area, (int, float)) or area <= 0):
        _val_log.warning(f"{prefix}Skipping listing — invalid area={area!r}: {listing.get('hash_id', '?')}")
        return False

    return True


def write_stats(filename: str, stats: dict) -> None:
    """Write scraper run stats dict to the data directory."""
    path = DATA_DIR / filename
    path.write_text(json.dumps(stats, ensure_ascii=False, indent=2), encoding="utf-8")