ordigi/elodie/geolocation.py

from os import path
from ConfigParser import ConfigParser
import fractions
import pyexiv2

import math
import requests
import sys
import urllib

from elodie import constants
from elodie.localstorage import Db

class Fraction(fractions.Fraction):
    """Only create Fractions from floats.
    >>> Fraction(0.3)
    Fraction(3, 10)
    >>> Fraction(1.1)
    Fraction(11, 10)
    """
    def __new__(cls, value, ignore=None):
        """Should be compatible with Python 2.6, though untested."""
        return fractions.Fraction.from_float(value).limit_denominator(99999)

def coordinates_by_name(name):
    # Try to get cached location first
    db = Db()
    cached_coordinates = db.get_location_coordinates(name)
    if(cached_coordinates is not None):
        return {
                'latitude': cached_coordinates[0],
                'longitude': cached_coordinates[1]
        }

    # If the name is not cached then we go ahead with an API lookup
    geolocation_info = lookup(name)

    if(geolocation_info is not None):
        if('results' in geolocation_info and len(geolocation_info['results']) != 0 and 
                'locations' in geolocation_info['results'][0] and len(geolocation_info['results'][0]['locations']) != 0):

            # By default we use the first entry unless we find one with geocodeQuality=city.
            use_location = geolocation_info['results'][0]['locations'][0]['latLng']
            # Loop over the locations to see if we come accross a geocodeQuality=city.
            # If we find a city we set that to the use_location and break
            for location in geolocation_info['results'][0]['locations']:
                if('latLng' in location and 'lat' in location['latLng'] and 'lng' in location['latLng'] and location['geocodeQuality'].lower() == 'city'):
                    use_location = location['latLng']
                    break
                    
            return {
                    'latitude': use_location['lat'],
                    'longitude': use_location['lng']
            }
                    
    return None

def decimal_to_dms(decimal, signed=True):
    # if decimal is negative we need to make the degrees and minutes negative also
    sign = 1
    if(decimal < 0):
        sign = -1

    # http://anothergisblog.blogspot.com/2011/11/convert-decimal-degree-to-degrees.html
    degrees = int(decimal)
    subminutes = abs((decimal - int(decimal)) * 60)
    minutes = int(subminutes) * sign
    subseconds = abs((subminutes - int(subminutes)) * 60) * sign
    subseconds_fraction = Fraction(subseconds)

    if(signed == False):
        degrees = abs(degrees)
        minutes = abs(minutes)
        subseconds_fraction = Fraction(abs(subseconds))

    return (pyexiv2.Rational(degrees, 1), pyexiv2.Rational(minutes, 1), pyexiv2.Rational(subseconds_fraction.numerator, subseconds_fraction.denominator))

def dms_to_decimal(degrees, minutes, seconds, sign=' '):
    return (-1 if sign[0] in 'SWsw' else 1) * (
        float(degrees)        +
        float(minutes) / 60   +
        float(seconds) / 3600
    )

def get_key():
    config_file = '%s/config.ini' % constants.application_directory
    if not path.exists(config_file):
        return None
        
    config = ConfigParser()
    config.read(config_file)
    if('MapQuest' not in config.sections()):
        return None

    return config.get('MapQuest', 'key')

def place_name(lat, lon):

    # Try to get cached location first
    db = Db()
    # 3km distace radious for a match
    cached_place_name = db.get_location_name(lat, lon,3000)
    if(cached_place_name is not None):
        return cached_place_name

    lookup_place_name = None;
    geolocation_info = reverse_lookup(lat, lon)
    if(geolocation_info is not None):
        if('address' in geolocation_info):
            address = geolocation_info['address']
            if('city' in address):
                lookup_place_name = address['city']
            elif('state' in address):
                lookup_place_name = address['state']
            elif('country' in address):
                lookup_place_name = address['country']

    if(lookup_place_name is not None):
        db.add_location(lat, lon, lookup_place_name)
        # TODO: Maybe this should only be done on exit and not for every write.
        db.update_location_db()
    return lookup_place_name


def reverse_lookup(lat, lon):
    if(lat is None or lon is None):
        return None

    key = get_key()

    try:
        params = {'format': 'json', 'key': key, 'lat': lat, 'lon': lon}
        r = requests.get('http://open.mapquestapi.com/nominatim/v1/reverse.php?%s' % urllib.urlencode(params))
        return r.json()
    except requests.exceptions.RequestException as e:
        if(constants.debug == True):
            print e
        return None
    except ValueError as e:
        if(constants.debug == True):
            print r.text
            print e
        return None

def lookup(name):
    if(name is None or len(name) == 0):
        return None

    key = get_key()

    try:
        params = {'format': 'json', 'key': key, 'location': name}
        if(constants.debug == True):
            print 'http://open.mapquestapi.com/geocoding/v1/address?%s' % urllib.urlencode(params)
        r = requests.get('http://open.mapquestapi.com/geocoding/v1/address?%s' % urllib.urlencode(params))
        return r.json()
    except requests.exceptions.RequestException as e:
        if(constants.debug == True):
            print e
        return None
    except ValueError as e:
        if(constants.debug == True):
            print r.text
            print e
        return None