namespace SharpMap.Demo.Wms.Controllers
{
 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using System.Web.Mvc;

 using GeoAPI.Geometries;

 using NetTopologySuite.Geometries;
 using NetTopologySuite.Geometries.Utilities;
 using NetTopologySuite.IO;
 using NetTopologySuite.Operation.Linemerge;
 using NetTopologySuite.Operation.Polygonize;
 using NetTopologySuite.Operation.Union;
 using NetTopologySuite.Simplify;

 using SharpMap.Converters.GeoJSON;

 public class ProcessController : Controller
 {
 private readonly IGeometryFactory factory = GeometryFactory.Default;

 private IGeometryCollection ValidateGeo(string geo)
 {
 if (String.IsNullOrEmpty(geo))
 throw new ArgumentException("invalid argument 'geo': empty string");

 WKTReader reader = new WKTReader(this.factory);
 IGeometry data = reader.Read(geo);

 // we should expect a GeometryCollection object
 if (data is IGeometryCollection)
 return data as IGeometryCollection;
 throw new ArgumentException("invalid argument 'geo': IGeometryCollection expected");
 }

 private ILineString ValidateCut(string cut)
 {
 if (String.IsNullOrEmpty(cut))
 throw new ArgumentException("invalid argument 'cut': empty string");

 WKTReader reader = new WKTReader(this.factory);
 IGeometry data = reader.Read(cut);

 // we should expect a GeometryCollection object
 if (data is ILineString)
 return data as ILineString;
 throw new ArgumentException("invalid argument 'cut': ILineString expected");
 }

 private ActionResult MakeResponse(IEnumerable<IGeometry> geometries)
 {
 if (geometries == null)
 throw new ArgumentNullException("geometries");

 // we should return a GeometryCollection object
 IGeometry[] array = geometries.ToArray();
 IGeometryCollection result = this.factory.CreateGeometryCollection(array);
 StringWriter writer = new StringWriter();
 GeoJSONWriter.Write(result, writer);
 return this.Json(new { geo = writer.ToString() });
 }

 private static IEnumerable<IGeometry> GetItems(IGeometry coll)
 {
 if (coll == null) 
 throw new ArgumentNullException("coll");

 for (int i = 0; i < coll.NumGeometries; i++)
 yield return coll.GetGeometryN(i);
 }

 [HttpPost]
 public ActionResult Clean(string geo)
 {
 IGeometryCollection coll = this.ValidateGeo(geo);
 IEnumerable<IGeometry> data = DoClean(coll);
 return this.MakeResponse(data);
 }

 private static IEnumerable<IGeometry> DoClean(IGeometryCollection coll)
 {
 if (coll == null)
 throw new ArgumentNullException("coll");

 IEnumerable<IGeometry> items = GetItems(coll);
 foreach (IGeometry geom in items)
 {
 DouglasPeuckerSimplifier simplifier = new DouglasPeuckerSimplifier(geom);
 IGeometry clean = simplifier.GetResultGeometry();
 yield return clean;
 }
 } 

 [HttpPost]
 public ActionResult Merge(string geo)
 {
 IGeometryCollection coll = this.ValidateGeo(geo);
 IEnumerable<IGeometry> data = DoMerge(coll);
 return this.MakeResponse(data);
 }

 private static IEnumerable<IGeometry> DoMerge(IGeometryCollection coll)
 {
 if (coll == null)
 throw new ArgumentNullException("coll");

 IEnumerable<IGeometry> items = GetItems(coll);
 yield return UnaryUnionOp.Union(items.ToArray());
 }

 [HttpPost]
 public ActionResult Split(string geo, string cut)
 {
 IGeometryCollection coll = this.ValidateGeo(geo);
 ILineString split = this.ValidateCut(cut);
 IEnumerable<IGeometry> data = DoSplit(coll, split);
 return this.MakeResponse(data);
 }

 public static IGeometry Polygonize(IGeometry geometry)
 {
 if (geometry == null)
 throw new ArgumentNullException("geometry");

 var lines = LineStringExtracter.GetLines(geometry);
 var geoms = lines.ToList();

 var polygonizer = new Polygonizer(); 
 polygonizer.Add(geoms);
 var polys = polygonizer.GetPolygons();
 return geometry.Factory.BuildGeometry(polys);
 }

 private static IEnumerable<IGeometry> DoSplit(IGeometryCollection coll, ILineString cut)
 {
 if (coll == null)
 throw new ArgumentNullException("coll");
 if (cut == null)
 throw new ArgumentNullException("cut");

 // adapted from 'SplitPolygon WPS' GeoServer extension:
 // https://github.com/mdavisog/wps-splitpoly/tree/master/src

 IList<IGeometry> output = new List<IGeometry>();
 IEnumerable<IGeometry> items = GetItems(coll);
 IEnumerable<IGeometry> valid = items.Where(i => i is IPolygon);
 foreach (IGeometry item in valid)
 {
 IGeometry nodedLinework = item.Boundary.Union(cut);
 IGeometry polygons = Polygonize(nodedLinework);

 // only keep polygons which are inside the input 
 for (int i = 0; i < polygons.NumGeometries; i++)
 {
 IPolygon candpoly = (IPolygon)polygons.GetGeometryN(i);
 if (item.Contains(candpoly.InteriorPoint))
 output.Add(candpoly);
 } 
 }
 return output;

 /*
 IEnumerable<IGeometry> items = GetItems(coll);
 LineMerger merger = new LineMerger(); 
 merger.Add(items);
 merger.Add(cut);
 IList<IGeometry> list = merger.GetMergedLineStrings();

 IGeometry union = UnaryUnionOp.Union(list);

 Polygonizer polygonizer = new Polygonizer();
 polygonizer.Add(union);
 ICollection<IGeometry> split = polygonizer.GetPolygons();
 return split;
 * */
 }
 }
}