/// <summary>
/// Returns the traveling distance in miles using the Google Maps API.
/// </summary>
public static double?CalculateTravelDistance(string fromPostCode, string toPostCode, string countryCode = "GB")
{
var fromLocation = GetPostcodeLocation(fromPostCode, countryCode).Get(x => x.Latitude + "," + x.Longitude);
var toLocation = GetPostcodeLocation(toPostCode, countryCode).Get(x => x.Latitude + "," + x.Longitude);
var url = DIRECTION_URL.AsUri()
.AddQueryString("origins", fromLocation)
.AddQueryString("destinations", toLocation);
if (GoogleClientKey.HasValue())
{
url = url.AddQueryString("key".OnlyWhen(GoogleSignatureKey.IsEmpty()).Or("client"), GoogleClientKey);
}
if (GoogleSignatureKey.HasValue())
{
url = url.AddQueryString("signature", GoogleSignatureKey);
}
var response = url.Download().To <XElement>();
var status = response.GetValue <string>("status");
if (status == "ZERO_RESULTS")
{
return(null);
}
if (status != "OK")
{
throw new Exception("Google API Error: " + status + "\r\n\r\n" + response);
}
var miles = response.Element("row").Get(r => r.Element("element").Get(e => e.Element("distance")).Get(d => d.Element("text")));
if (miles == null)
{
throw new Exception("Unexpected result from Google API: \r\n\r\n" + response);
}
var result = miles.Value.Split(' ').FirstOrDefault().TryParseAs <double>();
if (result == null)
{
throw new Exception("Unexpected result format from Google API: \r\n\r\n" + response);
}
return(result);
}
/// <summary>
/// Gets the Geo Location of a specified postcode using Google API.
/// This method has daily usage limit of 25000 calls.
/// </summary>
public static GeoLocation GetPostcodeLocation(string postcode, string countryCode = "GB")
{
var fullAddress = postcode + "," + countryCode;
return(CachedLocations.GetOrAdd(fullAddress, address =>
{
var clientParameter = "key".OnlyWhen(GoogleSignatureKey.IsEmpty()).Or("client");
var url = "https://maps.googleapis.com/maps/api/geocode/xml?address=" + address + "&sensor=false" +
GoogleClientKey.UrlEncode().WithPrefix("&" + clientParameter + "=") +
GoogleSignatureKey.UrlEncode().WithPrefix("&signature=");
var response = new WebClient().DownloadString(url).To <XElement>();
var status = response.GetValue <string>("status");
if (status == "ZERO_RESULTS")
{
return null;
}
if (status != "OK")
{
throw new Exception("Google API Error: " + status + "\r\n\r\n" + response);
}
var location = response.Element("result").Get(x => x.Element("geometry")).Get(x => x.Element("location"));
if (location == null)
{
throw new Exception("Unexpected result from Google API: \r\n\r\n" + response);
}
return new GeoLocation
{
Latitude = location.GetValue <string>("lat").To <double>(),
Longitude = location.GetValue <string>("lng").To <double>()
};
}));
}
