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using System;
using Autodesk.Revit;
using Autodesk.Revit.Elements;
using Autodesk.Revit.Geometry;
using Autodesk.Revit.Parameters;
using Element = Autodesk.Revit.Element;
using GElement = Autodesk.Revit.Geometry.Element;

namespace Revit.SDK.Samples.WindowWizard.CS
{
    /// <summary>
    /// A object to help locating with geometry data.
    /// </summary>
    public class GeoHelper
    {
        /// <summary>
        /// store the const precision
        /// </summary>
        private const double Precision = 0.0001;

        /// <summary>
        /// The method is used to get the wall face along the specified parameters
        /// </summary>
        /// <param name="wall">the wall</param>
        /// <param name="view">the options view</param>
        /// <param name="ExtOrInt">if true indicate that get exterior wall face, else false get the interior wall face</param>
        /// <returns>the face</returns>
        static public Face GetWallFace(Wall wall, View view, bool ExtOrInt)
        {
            FaceArray faces = null;
            Face face = null;
            Options options = new Options();
            options.ComputeReferences = true;
            options.View = view;
            if (wall != null)
            {
                GeometryObjectArray geoArr = wall.get_Geometry(options).Objects;
                foreach (GeometryObject geoObj in geoArr)
                {
                    if (geoObj is Solid)
                    {
                        Solid s = geoObj as Solid;
                        faces = s.Faces;
                    }
                }
            }
            if (ExtOrInt)
                face = GetExteriorFace(faces);
            else
                face = GetInteriorFace(faces);
            return face;
        }

        /// <summary>
        /// The method is used to get extrusion's face along to the specified parameters
        /// </summary>
        /// <param name="extrusion">the extrusion</param>
        /// <param name="view">options view</param>
        /// <param name="ExtOrInt">If true indicate getting exterior extrusion face, else getting interior extrusion face</param>
        /// <returns>the face</returns>
        static public Face GetExtrusionFace(Extrusion extrusion, View view, bool ExtOrInt)
        {
            Face face = null;
            FaceArray faces = null;
            if (extrusion.IsSolid)
            {
                Options options = new Options();
                options.ComputeReferences = true;
                options.View = view;
                GeometryObjectArray geoArr = extrusion.get_Geometry(options).Objects;
                foreach (GeometryObject geoObj in geoArr)
                {
                    if (geoObj is Solid)
                    {
                        Solid s = geoObj as Solid;
                        faces = s.Faces;
                    }
                }
                if (ExtOrInt)
                    face = GetExteriorFace(faces);
                else
                    face = GetInteriorFace(faces);
            }
            return face;
        }

        /// <summary>
        /// The assistant method is used for getting wall face and getting extrusion face
        /// </summary>
        /// <param name="faces">faces array</param>
        /// <returns>the face</returns>
        static private Face GetExteriorFace(FaceArray faces)
        {
            double elevation = 0;
            double tempElevation = 0;
            Mesh mesh = null;
            Face face = null;
            foreach (Face f in faces)
            {
                tempElevation = 0;
                mesh = f.Triangulate();
                foreach (XYZ xyz in mesh.Vertices)
                {
                    tempElevation = tempElevation + xyz.Y;
                }
                tempElevation = tempElevation / mesh.Vertices.Size;
                if (elevation < tempElevation || null == face)
                {                   
                    face = f;
                    elevation = tempElevation;
                }
            }
            return face;
        }

        /// <summary>
        /// The assistant method is used for getting wall face and getting extrusion face
        /// </summary>
        /// <param name="faces">faces array</param>
        /// <returns>the face</returns>
        static private Face GetInteriorFace(FaceArray faces)
        {
            double elevation = 0;
            double tempElevation = 0;
            Mesh mesh = null;
            Face face = null;
            foreach (Face f in faces)
            {
                tempElevation = 0;
                mesh = f.Triangulate();
                foreach (XYZ xyz in mesh.Vertices)
                {
                    tempElevation = tempElevation + xyz.Y;
                }
                tempElevation = tempElevation / mesh.Vertices.Size;
                if (elevation > tempElevation || null == face)
                {
                    face = f;
                    elevation = tempElevation;
                }
            }
            return face;
        }

        /// <summary>
        /// Find out the three points which made of a plane.
        /// </summary>
        /// <param name="mesh">A mesh contains many points.</param>
        /// <param name="startPoint">Create a new instance of ReferencePlane.</param>
        /// <param name="endPoint">The free end apply to reference plane.</param>
        /// <param name="thirdPnt">A third point needed to define the reference plane.</param>
        static public void Distribute(Mesh mesh, ref XYZ startPoint, ref XYZ endPoint, ref XYZ thirdPnt)
        {
            int count = mesh.Vertices.Size;
            startPoint = mesh.Vertices.get_Item(0);
            endPoint = mesh.Vertices.get_Item((int)(count / 3));
            thirdPnt = mesh.Vertices.get_Item((int)(count / 3 * 2));
        }              

        /// <summary>
        /// Determines whether a edge is vertical.
        /// </summary>
        /// <param name="edge">The edge to be determined.</param>
        /// <returns>Return true if this edge is vertical, or else return false.</returns>
        static public bool IsVerticalEdge(Edge edge)
        {
            XYZArray polyline = edge.Tessellate();
            XYZ verticalVct = new XYZ(0, 0, 1);
            XYZ pointBuffer = polyline.get_Item(0);

            for (int i = 1; i < polyline.Size; i = i + 1)
            {
                XYZ temp = polyline.get_Item(i);
                XYZ vector = GetVector(pointBuffer, temp);
                if (Equal(vector, verticalVct))
                {
                    return true;
                }
                else
                {
                    continue;
                }
            }
            return false;
        }

        /// <summary>
        /// Get the vector between two points.
        /// </summary>
        /// <param name="startPoint">The start point.</param>
        /// <param name="endPoint">The end point.</param>
        /// <returns>The vector between two points.</returns>
        static public XYZ GetVector(XYZ startPoint, XYZ endPoint)
        {
            return new XYZ(endPoint.X - startPoint.X,
                endPoint.Y - startPoint.Y, endPoint.Z - startPoint.Z);
        }

        /// <summary>
        /// Determines whether two vector are equal in x and y axis.
        /// </summary>
        /// <param name="vectorA">The vector A.</param>
        /// <param name="vectorB">The vector B.</param>
        /// <returns>Return true if two vector are equals, or else return false.</returns>
        static public bool Equal(XYZ vectorA, XYZ vectorB)
        {
            bool isNotEqual = (Precision < Math.Abs(vectorA.X - vectorB.X)) ||
                (Precision < Math.Abs(vectorA.Y - vectorB.Y));
            return isNotEqual ? false : true;
        }
    }
}