//-----------------------------------------------------------------------
// <copyright file="OvertoppingErosionCalculator.cs" company="Deltares">
//  Copyright (c) 2009 Deltares. All rights reserved.
// </copyright>
// <author>B.S.T.I.M. The</author>
// <email>tom.the@deltares.nl</email>
// <date>07-07-2009</date>
// <summary>Calculates the remaining grass strength when overtopping occurs</summary>
//-----------------------------------------------------------------------

using Deltares.Geometry;
using Deltares.Geotechnics;
using Deltares.Geotechnics.SurfaceLines;

namespace Deltares.Dam.Data
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Runtime.Serialization;

    [global::System.Serializable]
    public class OvertoppingErosionCalculatorException : Exception
    {
        //
        // For guidelines regarding the creation of new exception types, see
        //    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/cpconerrorraisinghandlingguidelines.asp
        // and
        //    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dncscol/html/csharp07192001.asp
        //

        public OvertoppingErosionCalculatorException() { }
        public OvertoppingErosionCalculatorException(string message) : base(message) { }
        public OvertoppingErosionCalculatorException(string message, Exception inner) : base(message, inner) { }
        protected OvertoppingErosionCalculatorException(
          SerializationInfo info,
          StreamingContext context)
            : base(info, context) { }
    }

    public class OvertoppingErosionCalculator
    {
        public double TimeStepInHours { get; set; }
        public double GrassQualityFactor { get; set; }
        public Location Location { get; set; }

        public OvertoppingErosionCalculator()
        {
            TimeStepInHours = 1.0;
            GrassQualityFactor = 0.9;
        }

        public double Calculate(double overtoppingRate)
        {
            double dikeSlopeAtPolder = DetermineDikeSlopeAtPolder();
            return CalculateRemainingStrength(TimeStepInHours, dikeSlopeAtPolder, GrassQualityFactor, overtoppingRate);
        }

        /// <summary>
        /// Calculates the remaining strength of grass as a factor between 0.0 and 1.0
        /// </summary>
        /// <param name="OvertoppingRate"></param>
        /// <returns></returns>
        public double CalculateRemainingStrength(double timeStepInHour, double dikeSlopeAtPolder, double grassQualityFactor, double OvertoppingRate)
        {
            const double roughnessFactor = 0.015;            
           
            if(grassQualityFactor==0)
                throw new OvertoppingErosionCalculatorException("grassQualityFactor can not be zero");

            double criticalFlowSpeed = Math.Pow(((OvertoppingRate / 1000.0) * 125 * Math.Pow(Math.Tan(dikeSlopeAtPolder), 0.75)) / Math.Pow(roughnessFactor, 0.25), 0.4);            
            double criticalFlowTime = Math.Pow(10,( (((grassQualityFactor * 3.8) / criticalFlowSpeed) - 1) / Math.Pow(0.8,10.0)));

            if (criticalFlowTime == 0)
                throw new OvertoppingErosionCalculatorException("Division byte zero when calculating GrassDecay");     

            double grassDecay = (timeStepInHour * 3600)/ criticalFlowTime;
            return (grassDecay > 1.0 ? 0.0 :  1 - grassDecay);
        }

        /// <summary>
        /// Determines the slope at Polder side
        /// </summary>
        /// <returns>Angle in radians</returns>
        private double DetermineDikeSlopeAtPolder()
        {
            GeometryPoint dikeTopAtPolderPoint = dikeTopAtPolderPoint = GetDikeTopAtPolder();
            GeometryPoint insteekShoulderInsidePoint = Location.LocalXZSurfaceLine2.GetDikeToeInward();            

            double dx = insteekShoulderInsidePoint.X - dikeTopAtPolderPoint.X;
            double dz = dikeTopAtPolderPoint.Z - insteekShoulderInsidePoint.Z;

            if (dx == 0)
                throw new OvertoppingErosionCalculatorException("Division by zero when calculating tan alpha");

            return Math.Atan(dz/dx);
        }
        
        /// <summary>
        /// Retrieve the CharacteristicPoint DikeTopAtPolder.
        /// </summary>
        /// <returns></returns>
        private GeometryPoint GetDikeTopAtPolder()
        {
            GeometryPoint dikeTopAtPolderPoint = null;

            var dikeTopAtPolder = Location.LocalXZSurfaceLine2.CharacteristicPoints.GetGeometryPoint(CharacteristicPointType.DikeTopAtPolder);
            if (dikeTopAtPolder != null)
            {
                dikeTopAtPolderPoint = dikeTopAtPolder;
            }
            else
                throw new OvertoppingErosionCalculatorException("Could not find the required charactersisticpoints in surfaceline");

            return dikeTopAtPolderPoint;
        }
    }
}