public ActionResult <IEnumerable <TrackResult> > GetTracks([FromQuery] TracksByBoundingBox request)
{
// Due to a bug in the CosmosDb client, we need to specify the invariant-culture here.
// The cosmos-db query will be created using the current culture settings.
// When querying on a double, the decimal point could otherwise be a comma instead of a point
// which would lead to syntax-errors.
// (see https://github.com/Azure/azure-cosmos-dotnet-v2/issues/651 )
System.Threading.Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
var searchKeys = CalculateSearchKeys(request);
// First coordinate in the boundingbox-polygon should be the upper left corner.
// From there, add the points counter-clockwise and finish by repeating the first location again.
// Points must appear counter-clockwise so that st_within will know that we're interested in
// the area inside the polygon.
var bbox = new Polygon(
new[]
{
new Microsoft.Azure.Documents.Spatial.Position(request.MinLongitude, request.MaxLatitude),
new Microsoft.Azure.Documents.Spatial.Position(request.MinLongitude, request.MinLatitude),
new Microsoft.Azure.Documents.Spatial.Position(request.MaxLongitude, request.MinLatitude),
new Microsoft.Azure.Documents.Spatial.Position(request.MaxLongitude, request.MaxLatitude),
new Microsoft.Azure.Documents.Spatial.Position(request.MinLongitude, request.MaxLatitude),
});
var query = DbClient.CreateDocumentQuery <VesselGeoPosition>(TracksGeoCollectionUri, new FeedOptions()
{
EnableCrossPartitionQuery = true
})
.Where(p => searchKeys.Contains(p.GeoHash_Date) &&
p.Position.Within(bbox) &&
p.Timestamp >= request.StartDate &&
p.Timestamp <= request.EndDate);
var searchResults = query.ToList();
var groupedByVesselId = new Dictionary <long, List <VesselGeoPosition> >();
foreach (var kvp in searchResults)
{
if (groupedByVesselId.ContainsKey(kvp.ObjectId) == false)
{
groupedByVesselId.Add(kvp.ObjectId, new List <VesselGeoPosition>());
}
groupedByVesselId[kvp.ObjectId].Add(kvp);
}
return(Ok(groupedByVesselId.Select(kvp => new TrackResult
{
ObjectId = kvp.Key,
Positions = kvp.Value.Select(p => new Position()
{
Location = p.Position, Timestamp = p.Timestamp
})
}).ToArray()));
}
private static IEnumerable <string> CalculateSearchKeys(TracksByBoundingBox request)
{
var geohashes = NGeoHash.GeoHash.Bboxes(request.MinLatitude, request.MinLongitude, request.MaxLatitude, request.MaxLongitude, 3);
var numberOfDays = request.EndDate - request.StartDate;
for (int i = 0; i <= numberOfDays.Days; i++)
{
foreach (var geohash in geohashes)
{
yield return($"{geohash}_{request.StartDate.AddDays(i):yyyyMMdd}");
}
}
}
