# utils.py
import numpy as np
from config import EARTH_RADIUS_KM

def deg_to_rad(degrees):
    return degrees * (np.pi / 180)

def distcalculate(lat1, lon1, lat2, lon2):
    d_lat = deg_to_rad(lat2 - lat1)
    d_lon = deg_to_rad(lon2 - lon1)
    a = np.sin(d_lat / 2)**2 + np.cos(deg_to_rad(lat1)) * np.cos(deg_to_rad(lat2)) * np.sin(d_lon / 2)**2
    c = 2 * np.arctan2(np.sqrt(a), np.sqrt(1 - a))
    return EARTH_RADIUS_KM * c