helm/bin/time-in

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2017-04-20 18:37:22 -07:00
#!/usr/bin/env python3
# Retrieves the time (and time difference) at a location (can be an address,
# postal code, country name, etc). Uses Google Maps APIs to map locations to
# coordinates, and coordinates to timezones.
#
# Requires: pytz. tzlocal
# Usage: time-in Copenhagen "Toronto, ON" Vancouver
import sys
import os
import json
from base64 import b64encode
from datetime import datetime
from urllib import request
from pytz import timezone
from tzlocal import get_localzone
URL_BASE = "https://maps.googleapis.com/maps/api/"
URL_TZ = URL_BASE + "timezone/json?location={},{}&timestamp={}"
URL_GEOCODE = URL_BASE + "geocode/json?address={}"
CACHE_FILE = "/tmp/time-in"
CACHE = {}
#
def _generate_url(url, *args):
return url.format(*map(request.quote, map(str, args)))
def get_timezone(lat, lng, timestamp):
try:
url = _generate_url(URL_TZ, lat, lng, timestamp)
resp = request.urlopen(url).read()
result = json.loads(resp.decode('utf-8'))
if result['status'] == 'OK':
return result['timeZoneId']
elif result['status'] != 'UNKNOWN_ERROR':
raise Exception(result['error_message'])
except IOError:
print("IOError")
def get_coords(desc):
try:
url = _generate_url(URL_GEOCODE, desc)
resp = request.urlopen(url).read()
result = json.loads(resp.decode('utf-8'))
if result['status'] == 'OK':
if result['results']:
return {
"lat": result['results'][0]['geometry']['location']['lat'],
"lng": result['results'][0]['geometry']['location']['lng'],
"name": result['results'][0]['formatted_address']
}
else:
return None
elif result['status'] != 'UNKNOWN_ERROR':
raise Exception(result['error_message'])
except IOError:
print("IOError")
def cache(key, fn, ttl):
if key in CACHE and CACHE[key]['time'] < CACHE[key]['time'] + ttl:
return CACHE[key]['value']
value = fn()
if value is not None:
CACHE[key] = {
'time': datetime.now().timestamp(),
'value': fn()
}
return value
def diff(a, b):
a = a.replace(tzinfo=None)
b = b.replace(tzinfo=None)
return max(a, b) - min(a, b)
def encode(s):
return str(b64encode(s.encode('ascii')))
#
if __name__ == '__main__':
if not sys.argv[1:]:
print("Usage: {} [LOCATION]".format(sys.argv[0]))
sys.exit(1)
if os.path.isfile(CACHE_FILE):
with open(CACHE_FILE, 'r') as f:
CACHE = json.load(f)
here = get_localzone().localize(datetime.now())
for location in sys.argv[1:]:
d_coords = cache("coords-" + encode(location), lambda: get_coords(location), 86400)
if d_coords:
d_tzname = cache(
"tz-" + encode(location),
lambda: get_timezone(d_coords['lat'], d_coords['lng'], here.timestamp()),
1800
)
then = here.astimezone(timezone(d_tzname))
diff = diff(here, then)
print("{:30}{} ({} {})".format(
d_coords['name'],
then.isoformat(),
diff,
"ago" if then < here else "ahead"
))
else:
print("Couldn't find {}".format(location))
with open(CACHE_FILE, 'w') as f:
json.dump(CACHE, f)
sys.exit(0)