public async Task<JsonResult> Get(double latitude, double longitude, double radius)
{
var latLng = new LatLng(latitude, longitude);
var tweets = await _tweetManager.GetAllTweets();
var exportableTweets = new List<ExportableTweet>();
foreach (var tweet in tweets)
{
if (tweet.Latitude > 0 && tweet.Longitude > 0)
{
var tweetLatLng = new LatLng(tweet.Latitude, tweet.Longitude);
if (LatLngHelper.IsWithinRadius(latLng, tweetLatLng, radius))
{
var tweetUser = await _userManager.FindByIdAsync(tweet.UserId.ToString());
exportableTweets.Add(new ExportableTweet()
{
TweetId = tweet.Id.ToString(),
UserName = tweetUser.UserName,
Text = tweet.Content,
Latitude = tweet.Latitude,
Longitude = tweet.Longitude,
ImageUrl = string.IsNullOrEmpty(tweet.FilePath) ? string.Empty : string.Format("http://{0}{1}", HttpContext.Request.Host, tweet.FilePath),
CreatedOn = tweet.CreatedOn
});
}
}
}
return Json(exportableTweets);
}
/// <summary>
/// Returns the distance in miles or kilometers of any two latitude / longitude points.
/// </summary>
/// <param name="pos1">Location 1</param>
/// <param name="pos2">Location 2</param>
/// <returns>Distance in kilometers</returns>
public static double GetDistance(LatLng pos1, LatLng pos2)
{
double r = 6371;
var lat = (pos2.Latitude - pos1.Latitude).ToRadians();
var lng = (pos2.Longitude - pos1.Longitude).ToRadians();
var h1 = Math.Sin(lat / 2) * Math.Sin(lat / 2) + Math.Cos(pos1.Latitude.ToRadians()) * Math.Cos(pos2.Latitude.ToRadians()) * Math.Sin(lng / 2) * Math.Sin(lng / 2);
var h2 = 2 * Math.Asin(Math.Min(1, Math.Sqrt(h1)));
return r * h2;
}
public static bool IsWithinRadius(LatLng pos1, LatLng pos2, double radius)
{
return GetDistance(pos1, pos2) <= radius;
}
