directions.py

"""
Google Directions API
"""

import urllib2
import urllib
import json

class Modes:
    DRIVING="driving"
    WALKING="walking"
    BICYCLING="bicycling"
    TRANSIT="transit"

class Avoid:
    TOLLS="tolls"
    HIGHWAYS="highways"

class Units:
    METRIC="metric"
    IMPERIAL="imperial"

class Region:
    """Not exhaustive, any two-character ccTLD top level domain value works."""
    Canada="ca"
    UnitedStates="us"

class DirectionsException(Exception):
    def __init__(self, response):
        Exception.__init__(self, response['status'])
        self.response = response
        self.status = response['status']

def directions(origin, destination, region=None, units=None, mode=None, avoid=None, departure_time=None, arrival_time=None, sensor=False):
    options = dict(origin=origin,
                   destination=destination,
                   sensor="true" if sensor else "false")
    if region:
        options["region"] = region
    if units:
        options["units"] = units
    if mode:
        options["mode"] = mode
    if avoid:
        options["avoid"] = avoid
    if departure_time:
        options["departure_time"] = departure_time
    if arrival_time:
        options["arrival_time"] = arrival_time

    url = "http://maps.googleapis.com/maps/api/directions/json?" + urllib.urlencode(options)
    try:
        conn = urllib2.urlopen(url, None)
        try:
            response = json.loads(conn.read())
        finally:
            conn.close()
    except urllib2.HTTPError as error:
        try:
            raise DirectionsException(json.loads(error.read()))
        except ValueError:
            raise DirectionsException({'status': "cannot decode JSON, bad connection?"})

    if response['status'] != "OK":
        raise DirectionsException(response)

    return response