using System;
using System.IO;
using Microsoft.SqlServer.Server;
using Microsoft.SqlServer.Types;

/* 
 * I make no claim of copyright ownership of all the code listed below - the original authors of each code
 * are idenfied
 * 
 * Place this file in C:\assemblies, then compile it to C:\assemblies\Aggregate.dll 
 * via the Command Prompt using this command (you may need to modify for your environment)
 
 c:\windows\microsoft.net\framework\v3.5\csc /t:library /r:Microsoft.SqlServer.Types.dll C:\assemblies\aggregate.cs
 
 * Then in SQL Server 2008 (Katmai) Management Studio run these commands
 
 CREATE ASSEMBLY SpatialAggregate FROM 'c:\assemblies\Aggregate.dll' 
 go 
 CREATE AGGREGATE EnvelopeAggregate(@input GEOMETRY) RETURNS GEOMETRY 
 external name [SpatialAggregate].[SilverlightEarth.Geoquery.SqlClr.EnvelopeAggregate] 
 go 
 CREATE AGGREGATE UnionAggregate(@input GEOMETRY) RETURNS GEOMETRY 
 external name [SpatialAggregate].[SilverlightEarth.Geoquery.SqlClr.UnionAggregate] 
 go 

 sp_configure 'clr enabled', 1; 
 go 
 RECONFIGURE; 
 go
 
 */
namespace SilverlightEarth.Geoquery.SqlClr
{
    /// <summary>
    /// 
    /// </summary>
    /// <remarks>
    /// Author: Steven Hemingray
    /// Source: MSDN Forums
    /// Link: http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=2527689&SiteID=17
    /// </remarks>
    [Serializable]
    [Microsoft.SqlServer.Server.SqlUserDefinedAggregate(Format.Native)]
    public struct EnvelopeAggregate
    {
        public double minX;
        public double minY;
        public double maxX;
        public double maxY;
        public void Init()
        {
            minX = double.MaxValue;
            minY = double.MaxValue;
            maxX = double.MinValue;
            maxY = double.MinValue;
        }

        public void Accumulate(SqlGeometry value)
        {
            if (value != null && !value.IsNull && !value.STIsEmpty())
            {
                SqlGeometry envelope = value.STEnvelope();
                if (envelope.STPointN(1).STX.Value < minX)
                    minX = envelope.STPointN(1).STX.Value;
                if (envelope.STPointN(1).STY.Value < minY)
                    minY = envelope.STPointN(1).STY.Value;
                if (envelope.STPointN(3).STX.Value > maxX)
                    maxX = envelope.STPointN(3).STX.Value;
                if (envelope.STPointN(3).STY.Value > maxY)
                    maxY = envelope.STPointN(3).STY.Value;
            }
        }

        public void Merge(EnvelopeAggregate group)
        {
            if (group.minX < minX)
                minX = group.minX;
            if (group.minY < minY)
                minY = group.minY;
            if (group.maxX > maxX)
                maxX = group.maxX;
            if (group.maxY > maxY)
                maxY = group.maxY;
        }

        public SqlGeometry Terminate()
        {
            if (minX == double.MaxValue) //All inputs were null or empty
                return SqlGeometry.Null;
            return SqlGeometry.Parse(String.Format("POLYGON (({0} {1}, {2} {1}, {2} {3}, {0} {3}, {0} {1}))", minX, minY, maxX, maxY));
        }

    } // EnvelopeAggregate


    /// <summary>
    /// 
    /// </summary>
    /// <remarks>
    /// Author: Steven Hemingray
    /// Source: MSDN Forums
    /// Link: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=2508004&SiteID=1
    /// </remarks>
    [Serializable]
    [Microsoft.SqlServer.Server.SqlUserDefinedAggregate(Format.UserDefined, MaxByteSize = -1)]
    public struct UnionAggregate : IBinarySerialize
    {
        public SqlGeometry union;
        public void Init()
        {
            union = new SqlGeometry();
        }

        public void Accumulate(SqlGeometry value)
        {
            if (union.IsNull || union.STIsEmpty())
                union = value;
            else
                union = union.STUnion(value);
        }

        public void Merge(UnionAggregate group)
        {
            if (union.IsNull || union.STIsEmpty())
                union = group.union;
            else
                union = union.STUnion(group.union);
        }

        public SqlGeometry Terminate()
        {
            return union;
        }

        public void Read(BinaryReader r)
        {
            union = new SqlGeometry();
            union.Read(r);
        }

        public void Write(BinaryWriter w)
        {
            union.Write(w);
        }
    } // UnionAggregate  
}