/// <summary>
/// Get the last known location and calculate speed. Then Publish back to the MQTT Broker.
/// </summary>
/// <param name="mqttClient">The MQTT Client</param>
/// <param name="topic">The most recent topic</param>
/// <returns>A Task which performs the operation</returns>
public async Task Work(IManagedMqttClient mqttClient, CarCoordinates topic)
{
try
{
// Get lastCoordinate from key
var carInformation = _carCache.Read(topic.CarIndex);
// Get Geo coordinate
var lastGeoCoordinate = new GeoCoordinate(carInformation.LastLocation.Latitude, carInformation.LastLocation.Longitude);
var currentGeoCoordinate = new GeoCoordinate(topic.Location.Latitude, topic.Location.Longitude);
// Calculate the distance and the speed
var distance = lastGeoCoordinate.GetDistanceTo(currentGeoCoordinate);
var speed = Speedometer.CalculateSpeedMph(distance, carInformation.LastRecordedTimestamp,
topic.TimeStamp);
// using the total distance driven
var carValues = _carCache.Values().ToList();
var position = carValues.OrderByDescending(x => x.TotalDistanceTraveled)
.Select(x => x.CarIndex).ToList().IndexOf(topic.CarIndex) + 1;
// has the car position changed
if (position != carInformation.Position)
{
// who is now in that position?
var carInPreviousPos = carValues.FirstOrDefault(x => x.Position == position);
if (carInPreviousPos != null)
{
var eventStatus = new EventMessage()
{
Timestamp = topic.TimeStamp,
Text =
$"Car {carInPreviousPos.CarIndex} races ahead of Car {carInformation.CarIndex} in a dramatic overtake."
};
var messageEvent = MessageBuilder.CreateMessage(eventStatus);
// send event for the overtake
await mqttClient.PublishAsync(messageEvent);
}
}
// Set information car information
carInformation.TotalDistanceTraveled += distance;
carInformation.LastRecordedTimestamp = topic.TimeStamp;
carInformation.LastLocation = topic.Location;
carInformation.Position = position;
_carCache.AddOrUpdate(topic.CarIndex, carInformation);
// The response
var messageSpeed = MessageBuilder.CreateMessage(CarStatus.SpeedStatus(topic, speed));
var messagePosition = MessageBuilder.CreateMessage(CarStatus.PositionStatus(topic, position));
await mqttClient.PublishAsync(messageSpeed);
await mqttClient.PublishAsync(messagePosition);
}
catch (KeyNotFoundException)
{
// Must be first time round, add topic to dictionary
var carInformation = new CarInformation()
{
LastLocation = topic.Location,
LastRecordedTimestamp = topic.TimeStamp,
Position = 0,
TotalDistanceTraveled = 0,
CarIndex = topic.CarIndex
};
_carCache.AddOrUpdate(topic.CarIndex, carInformation);
}
catch (Exception ex)
{
_logger.LogError(ex.ToString());
}
}