static string _url = "http://lightningmaps.org/live/"; // Setting the url for the external lightning strike database
// A method to obtain lightning strike data
public async Task <LightningList> GetLightningDataAsync()
{
HttpClient client = new HttpClient();
HttpResponseMessage response = await client.GetAsync(_url);
response.EnsureSuccessStatusCode();
string results = await response.Content.ReadAsStringAsync();
LightningList lightningDataList = JsonConvert.DeserializeObject <LightningList>(results); // Converting the JSON results to the LightnignList object
return(lightningDataList);
}
// The timer_Elapsed method is called every 2 min. This method accesses the external API's, so it is made asynchronous to prevent any thread blocking.
static async void timer_Elapsed(object sender, ElapsedEventArgs e)
{
try
{
Task <LightningList> lightningResults = lightningData.GetLightningDataAsync();
LightningList lightningLocationData = lightningResults.Result; // The results from the lightning strike database.
IList <UserLocation> userLocationsList = userLocation.ListLocations().ToList(); // The list of User specified locations to be compared against the lightning strike locations.
foreach (var lightning in lightningLocationData.d)
{
foreach (var userLocation in userLocationsList)
{
float userRad = userLocation.Radius; // The detection threshold radius.
float userLat = userLocation.Latitude; // The user-specified latitude.
float userLon = userLocation.Longitude; // The user-specified longitude.
float lightningLat = lightning.lat; // The latitude of the lightning strike
float lightningLon = lightning.lon; // The longitude of the lightning strike
TimeSpan?timeDiff = DateTime.Now - userLocation.LastEmailTime; // Computes the length of time since the last alert email was sent.
//try {
if (timeDiff.Value.TotalMinutes > 59.00) // Test if the email was send within the last 59 min.
{
double dist = Math.Pow(((userLat - lightningLat) * 68.9318), 2) + Math.Pow(((userLon - lightningLon) * Math.Cos(userLat) * 69.1742), 2); // Computing the square of the distance between the user-specified location and the lightning strike location using the Pythagorean theorem.
double rad = Math.Pow(userRad, 2); // Computing the square of the detection threshold radius.
if (dist < rad) // Test if the userLocation and the lightningLocation distance is within the radius.
{
Task <Weather> weatherResult = weatherData.GetWeatherConditionAsync(userLat, userLon); // Fetching the weather condition at the userLocation.
int weatherCondition = weatherResult.Result.weather.Select(w => w.id).FirstOrDefault(); // Getting the weather condition id from the weather results.
if ((weatherCondition >= 800) && (weatherCondition <= 804)) // Test if the weather condition is non-precipitating. The weather condition id's between 800 and 804 correspond to sunny and cloudy.
{
userLocation.LastEmailTime = DateTime.Now; // Setting the last email time in memory to now. The eager-loading prevents the LastEmailTime to be updated even after the UpdateLastEmailTime method is called.
emailTime.UpdateLastEmailTime(userLocation.UserLocationId); // Calling the method to update the LastEmailTime in the database.
string userEmail = userLocation.User.Email; // Setting the user's email.
await sendEmail.SendEmailAsync(userEmail, userLocation.UserLocationName); // Calling the SendEmailAsync method to send the alert email to the user.
}
}
}
}
}
}
catch (AggregateException ex)
{
// Ignore if error occurs.
}
}
