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"""
Module with location helpers.
detect_location_info and elevation are mocked by default during tests.
"""
import collections
import math
from typing import Any, Optional, Tuple, Dict
import requests
ELEVATION_URL = 'http://maps.googleapis.com/maps/api/elevation/json'
FREEGEO_API = 'https://freegeoip.net/json/'
IP_API = 'http://ip-api.com/json'
# Constants from https://github.com/maurycyp/vincenty
# Earth ellipsoid according to WGS 84
# Axis a of the ellipsoid (Radius of the earth in meters)
AXIS_A = 6378137
# Flattening f = (a-b) / a
FLATTENING = 1 / 298.257223563
# Axis b of the ellipsoid in meters.
AXIS_B = 6356752.314245
MILES_PER_KILOMETER = 0.621371
MAX_ITERATIONS = 200
CONVERGENCE_THRESHOLD = 1e-12
LocationInfo = collections.namedtuple(
"LocationInfo",
['ip', 'country_code', 'country_name', 'region_code', 'region_name',
'city', 'zip_code', 'time_zone', 'latitude', 'longitude',
'use_metric'])
def detect_location_info() -> Optional[LocationInfo]:
"""Detect location information."""
data = _get_freegeoip()
if data is None:
data = _get_ip_api()
if data is None:
return None
data['use_metric'] = data['country_code'] not in (
'US', 'MM', 'LR')
return LocationInfo(**data)
def distance(lat1: Optional[float], lon1: Optional[float],
lat2: float, lon2: float) -> Optional[float]:
"""Calculate the distance in meters between two points.
Async friendly.
"""
if lat1 is None or lon1 is None:
return None
result = vincenty((lat1, lon1), (lat2, lon2))
if result is None:
return None
return result * 1000
def elevation(latitude: float, longitude: float) -> int:
"""Return elevation for given latitude and longitude."""
try:
req = requests.get(
ELEVATION_URL,
params={
'locations': '{},{}'.format(latitude, longitude),
'sensor': 'false',
},
timeout=10)
except requests.RequestException:
return 0
if req.status_code != 200:
return 0
try:
return int(float(req.json()['results'][0]['elevation']))
except (ValueError, KeyError, IndexError):
return 0
# Author: https://github.com/maurycyp
# Source: https://github.com/maurycyp/vincenty
# License: https://github.com/maurycyp/vincenty/blob/master/LICENSE
# pylint: disable=invalid-name
def vincenty(point1: Tuple[float, float], point2: Tuple[float, float],
miles: bool = False) -> Optional[float]:
"""
Vincenty formula (inverse method) to calculate the distance.
Result in kilometers or miles between two points on the surface of a
spheroid.
Async friendly.
"""
# short-circuit coincident points
if point1[0] == point2[0] and point1[1] == point2[1]:
return 0.0
U1 = math.atan((1 - FLATTENING) * math.tan(math.radians(point1[0])))
U2 = math.atan((1 - FLATTENING) * math.tan(math.radians(point2[0])))
L = math.radians(point2[1] - point1[1])
Lambda = L
sinU1 = math.sin(U1)
cosU1 = math.cos(U1)
sinU2 = math.sin(U2)
cosU2 = math.cos(U2)
for _ in range(MAX_ITERATIONS):
sinLambda = math.sin(Lambda)
cosLambda = math.cos(Lambda)
sinSigma = math.sqrt((cosU2 * sinLambda) ** 2 +
(cosU1 * sinU2 - sinU1 * cosU2 * cosLambda) ** 2)
if sinSigma == 0:
return 0.0 # coincident points
cosSigma = sinU1 * sinU2 + cosU1 * cosU2 * cosLambda
sigma = math.atan2(sinSigma, cosSigma)
sinAlpha = cosU1 * cosU2 * sinLambda / sinSigma
cosSqAlpha = 1 - sinAlpha ** 2
try:
cos2SigmaM = cosSigma - 2 * sinU1 * sinU2 / cosSqAlpha
except ZeroDivisionError:
cos2SigmaM = 0
C = FLATTENING / 16 * cosSqAlpha * (4 + FLATTENING * (4 - 3 *
cosSqAlpha))
LambdaPrev = Lambda
Lambda = L + (1 - C) * FLATTENING * sinAlpha * (sigma + C * sinSigma *
(cos2SigmaM + C *
cosSigma *
(-1 + 2 *
cos2SigmaM ** 2)))
if abs(Lambda - LambdaPrev) < CONVERGENCE_THRESHOLD:
break # successful convergence
else:
return None # failure to converge
uSq = cosSqAlpha * (AXIS_A ** 2 - AXIS_B ** 2) / (AXIS_B ** 2)
A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)))
B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)))
deltaSigma = B * sinSigma * (cos2SigmaM +
B / 4 * (cosSigma * (-1 + 2 *
cos2SigmaM ** 2) -
B / 6 * cos2SigmaM *
(-3 + 4 * sinSigma ** 2) *
(-3 + 4 * cos2SigmaM ** 2)))
s = AXIS_B * A * (sigma - deltaSigma)
s /= 1000 # Conversion of meters to kilometers
if miles:
s *= MILES_PER_KILOMETER # kilometers to miles
return round(s, 6)
def _get_freegeoip() -> Optional[Dict[str, Any]]:
"""Query freegeoip.io for location data."""
try:
raw_info = requests.get(FREEGEO_API, timeout=5).json()
except (requests.RequestException, ValueError):
return None
return {
'ip': raw_info.get('ip'),
'country_code': raw_info.get('country_code'),
'country_name': raw_info.get('country_name'),
'region_code': raw_info.get('region_code'),
'region_name': raw_info.get('region_name'),
'city': raw_info.get('city'),
'zip_code': raw_info.get('zip_code'),
'time_zone': raw_info.get('time_zone'),
'latitude': raw_info.get('latitude'),
'longitude': raw_info.get('longitude'),
}
def _get_ip_api() -> Optional[Dict[str, Any]]:
"""Query ip-api.com for location data."""
try:
raw_info = requests.get(IP_API, timeout=5).json()
except (requests.RequestException, ValueError):
return None
return {
'ip': raw_info.get('query'),
'country_code': raw_info.get('countryCode'),
'country_name': raw_info.get('country'),
'region_code': raw_info.get('region'),
'region_name': raw_info.get('regionName'),
'city': raw_info.get('city'),
'zip_code': raw_info.get('zip'),
'time_zone': raw_info.get('timezone'),
'latitude': raw_info.get('lat'),
'longitude': raw_info.get('lon'),
}