// code adapted from: https://github.com/awcoats/mapstache
namespace SharpMap.Demo.Wms.Controllers
{
 using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
 using System.Web.Mvc;

 using GeoAPI.Geometries;

 using Mapstache;

 using GeoAPI.CoordinateSystems.Transformations;

 using SharpMap.Converters.GeoJSON;
 using SharpMap.Data;
 using SharpMap.Demo.Wms.Helpers;
 using SharpMap.Layers;

 public class UtfGridController : Controller
 {
 private readonly ICoordinateTransformation projection;

 public UtfGridController()
 {
 this.projection = ProjHelper.LatLonToGoogle();
 }

 const int UtfGridResolution = 2;

 private Envelope GetBoundingBoxInLatLngWithMargin(int tileX, int tileY, int zoom)
 {
 Point px1 = new Point((tileX * 256), (tileY * 256));
 Point px2 = new Point(((tileX + 1) * 256), ((tileY + 1) * 256));

 PointF ll1 = TileSystemHelper.PixelXYToLatLong(px1, zoom);
 PointF ll2 = TileSystemHelper.PixelXYToLatLong(px2, zoom);

 double[] prj1 = this.projection.MathTransform.Transform(new double[] { ll1.X, ll1.Y });
 double[] prj2 = this.projection.MathTransform.Transform(new double[] { ll2.X, ll2.Y });

 Envelope bbox = new Envelope();
 bbox.ExpandToInclude(prj1[0], prj1[1]);
 bbox.ExpandToInclude(prj2[0], prj2[1]);
 return bbox;
 }

 public JsonResult GetData(string layer, int z, int x, int y)
 {
 if (String.IsNullOrEmpty(layer))
 throw new ArgumentNullException("layer");

 Map map = ShapefileHelper.Spherical();
 IQueryable<VectorLayer> coll = map.Layers
 .AsQueryable()
 .OfType<VectorLayer>()
 .Where(l => l.Enabled && l.IsQueryEnabled)
 .Where(l => String.Equals(l.LayerName, layer));
 VectorLayer query = coll.SingleOrDefault();
 if (query == null)
 throw new ArgumentException("Layer not found: " + layer);

 if (query.SRID != 4326)
 throw new ArgumentException("Only EPSG:4326 supported");

 using (Utf8Grid grid = new Utf8Grid(UtfGridResolution, x, y, z))
 {
 Envelope bbox = this.GetBoundingBoxInLatLngWithMargin(x, y, z);
 FeatureDataSet ds = new FeatureDataSet();
 query.ExecuteIntersectionQuery(bbox, ds);
 IEnumerable<GeoJSON> data = GeoJSONHelper.GetData(ds);

 int i = 1;
 foreach (GeoJSON val in data)
 {
 IGeometry geom = val.Geometry;
 IDictionary<string, object> dict = val.Values;
 grid.FillPolygon(geom, i, dict);
 i = i + 1;
 }

 Utf8GridResults results = grid.CreateUtfGridJson();
 return this.Json(new { keys = results.Keys, data = results.Data, grid = results.Grid, }, JsonRequestBehavior.AllowGet);
 }
 }
 }
}