"""Redis client for GPS and IMU data."""
import json
import redis

_client = None


def get_client():
    """Get Redis connection."""
    global _client
    if _client is None:
        _client = redis.Redis(host="localhost", port=6379, decode_responses=True)
    return _client


def get_latest_gnss():
    """Get latest GPS fix from GNSSFusion30Hz ZSET."""
    client = get_client()
    try:
        # Get the most recent entry (highest score = most recent timestamp)
        results = client.zrevrange("GNSSFusion30Hz", 0, 0, withscores=True)
        if results:
            data = json.loads(results[0][0])
            return {
                "lat_deg": data.get("lat_deg"),
                "lon_deg": data.get("lon_deg"),
                "alt_m": data.get("alt_m"),
                "unix_milliseconds": int(data.get("unix_milliseconds", 0)),
                "hdop": data.get("hdop"),
                "num_satellites": data.get("num_satellites", 0),
            }
    except (redis.RedisError, json.JSONDecodeError):
        pass
    return None


def has_gps_lock():
    """Check if we have a valid GPS lock."""
    gnss = get_latest_gnss()
    return gnss is not None and gnss.get("num_satellites", 0) >= 4