// Copyright (C) Stichting Deltares 2020. All rights reserved.
//
// This file is part of the Layer On Slope Tool.
//
// The Layer On Slope Tool is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
// All names, logos, and references to "Deltares" are registered trademarks of
// Stichting Deltares and remain full property of Stichting Deltares at all times.
// All rights reserved.

using System;
using Deltares.LayerOnSlopeTool.Data;

namespace Deltares.LayerOnSlopeTool.LayerCreator
{
    /// <summary></summary>
    public class SurfaceLineProcessor
    {
        private const double Tolerance = 1e-4;
        private const double HorizontalOffset = 0.01;
        private readonly SurfaceLine surfaceLine;
        private readonly SurfaceLinePoint dikeTopPolder;
        private readonly SurfaceLinePoint dikeToePolder;

        /// <summary>Initializes a new instance of the <see cref="SurfaceLineProcessor"/> class.</summary>
        /// <param name="orgSurfaceLine">The org surface line.</param>
        public SurfaceLineProcessor(SurfaceLine orgSurfaceLine)
        {
            surfaceLine = orgSurfaceLine;
            dikeTopPolder = surfaceLine.GetSurfaceLinePointByType(CharacteristicPointType.DikeTopAtPolder);
            if (dikeTopPolder == null)
            {
                throw new Exception(string.Format("Surface line {0} has no Dike Top.", surfaceLine.SurfaceLineId));
            }
            dikeToePolder = surfaceLine.GetSurfaceLinePointByType(CharacteristicPointType.DikeToeAtPolder);
            if (dikeToePolder == null)
            {
                throw new Exception(string.Format("Surface line {0} has no Dike Toe.", surfaceLine.SurfaceLineId));
            }
        }

        /// <summary>Creates the lowered surface line.</summary>
        /// <param name="layerThickness">The layer thickness.</param>
        /// <returns></returns>
        public SurfaceLine CreateLoweredSurfaceLine(double layerThickness)
        {
            var loweredSurfaceLine = new SurfaceLine();
            foreach (var point in surfaceLine.SurfaceLinePoints)
            {
                if (point.XCoordinate <= dikeTopPolder.XCoordinate)
                {
                    HandlePointsUpToAndIncludingDikeTopPolder(layerThickness, point, loweredSurfaceLine);
                }
                else
                {
                    if (point.XCoordinate > dikeTopPolder.XCoordinate + HorizontalOffset && 
                        point.XCoordinate < dikeToePolder.XCoordinate - HorizontalOffset)
                    {
                        HandlePointsBetweenDikeTopPolderAndDikeToePolder(layerThickness, point, loweredSurfaceLine);
                    }
                    else
                    {
                        HandlePointsAtDikeToePolderAndBeyond(layerThickness, point, loweredSurfaceLine);
                    }
                }
            }
            loweredSurfaceLine.SurfaceLineId = surfaceLine.SurfaceLineId + "_low";
            return loweredSurfaceLine;
        }

        private static void HandlePointsBetweenDikeTopPolderAndDikeToePolder(double layerThickness, 
            SurfaceLinePoint point, SurfaceLine loweredSurfaceLine)
        {
            var newPointLowered = new SurfaceLinePoint
            {
                XCoordinate = point.XCoordinate,
                ZCoordinate = point.ZCoordinate - layerThickness,
                PointType = point.PointType
            };
            loweredSurfaceLine.SurfaceLinePoints.Add(newPointLowered);
        }

        private void HandlePointsAtDikeToePolderAndBeyond(double layerThickness, 
            SurfaceLinePoint point, SurfaceLine loweredSurfaceLine)
        {
            if (Math.Abs(point.XCoordinate - dikeToePolder.XCoordinate) < Tolerance)
            {
                var newPointAtDikeToe = new SurfaceLinePoint
                {
                    XCoordinate = point.XCoordinate - HorizontalOffset,
                    ZCoordinate = point.ZCoordinate - layerThickness,
                    PointType = CharacteristicPointType.None
                };
                loweredSurfaceLine.SurfaceLinePoints.Add(newPointAtDikeToe);
            }

            if (point.XCoordinate >= dikeToePolder.XCoordinate)
            {
                var newPointBeyondDikeToe = new SurfaceLinePoint
                {
                    XCoordinate = point.XCoordinate,
                    ZCoordinate = point.ZCoordinate,
                    PointType = point.PointType
                };
                loweredSurfaceLine.SurfaceLinePoints.Add(newPointBeyondDikeToe);
            }
        }

        private void HandlePointsUpToAndIncludingDikeTopPolder(double layerThickness, SurfaceLinePoint point,
            SurfaceLine loweredSurfaceLine)
        {
            var newPointUpToDikeTop = new SurfaceLinePoint
            {
                XCoordinate = point.XCoordinate,
                ZCoordinate = point.ZCoordinate,
                PointType = point.PointType
            };
            loweredSurfaceLine.SurfaceLinePoints.Add(newPointUpToDikeTop);
            if (Math.Abs(point.XCoordinate - dikeTopPolder.XCoordinate) < Tolerance)
            {
                var newPointAtDikeTop = new SurfaceLinePoint
                {
                    XCoordinate = point.XCoordinate + HorizontalOffset,
                    ZCoordinate = point.ZCoordinate - layerThickness,
                    PointType = CharacteristicPointType.None
                };
                loweredSurfaceLine.SurfaceLinePoints.Add(newPointAtDikeTop);
            }
        }
    }
}