//
// (C) Copyright 2003-2019 by Autodesk, Inc.
//
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using System;
using System.Collections.Generic;
using System.Text;

using Autodesk.Revit;
using Autodesk.Revit.DB;

namespace Revit.SDK.Samples.NewRebar.CS
{
   using GeoElement = Autodesk.Revit.DB.GeometryElement;
   using GeoSolid = Autodesk.Revit.DB.Solid;
   using Element = Autodesk.Revit.DB.Element;


   /// <summary>
   /// The class which gives the base geometry operation, it is a static class.
   /// </summary>
   static class GeomUtil
   {
      // Private members
      const double Precision = 0.00001;    //precision when judge whether two doubles are equal

      /// <summary>
      /// Judge whether the two double data are equal
      /// </summary>
      /// <param name="d1">The first double data</param>
      /// <param name="d2">The second double data</param>
      /// <returns>true if two double data is equal, otherwise false</returns>
      public static bool IsEqual(double d1, double d2)
      {
         //get the absolute value;
         double diff = Math.Abs(d1 - d2);
         return diff < Precision;
      }

      /// <summary>
      /// Judge whether the two Autodesk.Revit.DB.XYZ point are equal
      /// </summary>
      /// <param name="first">The first Autodesk.Revit.DB.XYZ point</param>
      /// <param name="second">The second Autodesk.Revit.DB.XYZ point</param>
      /// <returns>true if two Autodesk.Revit.DB.XYZ point is equal, otherwise false</returns>
      public static bool IsEqual(Autodesk.Revit.DB.XYZ first, Autodesk.Revit.DB.XYZ second)
      {
         bool flag = true;
         flag = flag && IsEqual(first.X, second.X);
         flag = flag && IsEqual(first.Y, second.Y);
         flag = flag && IsEqual(first.Z, second.Z);
         return flag;
      }

      /// <summary>
      /// Judge whether the line is perpendicular to the face
      /// </summary>
      /// <param name="face">The face reference</param>
      /// <param name="line">The line reference</param>
      /// <param name="faceTrans">The transform for the face</param>
      /// <param name="lineTrans">The transform for the line</param>
      /// <returns>True if line is perpendicular to the face, otherwise false</returns>
      public static bool IsVertical(Face face, Line line,
                                              Transform faceTrans, Transform lineTrans)
      {
         //get points which the face contains
          List<XYZ> points = face.Triangulate().Vertices as List<XYZ>;
         if (3 > points.Count)    // face's point number should be above 2
         {
            return false;
         }

         // get three points from the face points
         Autodesk.Revit.DB.XYZ first = points[0];
         Autodesk.Revit.DB.XYZ second = points[1];
         Autodesk.Revit.DB.XYZ third = points[2];

         // get start and end point of line
         Autodesk.Revit.DB.XYZ lineStart = line.GetEndPoint(0);
         Autodesk.Revit.DB.XYZ lineEnd = line.GetEndPoint(1);

         // transForm the three points if necessary
         if (null != faceTrans)
         {
            first = TransformPoint(first, faceTrans);
            second = TransformPoint(second, faceTrans);
            third = TransformPoint(third, faceTrans);
         }

         // transform the start and end points if necessary
         if (null != lineTrans)
         {
            lineStart = TransformPoint(lineStart, lineTrans);
            lineEnd = TransformPoint(lineEnd, lineTrans);
         }

         // form two vectors from the face and a vector stand for the line
         // Use SubXYZ() method to get the vectors
         Autodesk.Revit.DB.XYZ vector1 = SubXYZ(first, second);    // first vector of face
         Autodesk.Revit.DB.XYZ vector2 = SubXYZ(first, third);     // second vector of face
         Autodesk.Revit.DB.XYZ vector3 = SubXYZ(lineStart, lineEnd);   // line vector

         // get two dot products of the face vectors and line vector
         double result1 = DotMatrix(vector1, vector3);
         double result2 = DotMatrix(vector2, vector3);

         // if two dot products are all zero, the line is perpendicular to the face
         return (IsEqual(result1, 0) && IsEqual(result2, 0));
      }

      /// <summary>
      /// Judge whether the two vectors have the same direction
      /// </summary>
      /// <param name="firstVec">The first vector</param>
      /// <param name="secondVec">The second vector</param>
      /// <returns>True if the two vector is in same direction, otherwise false</returns>
      public static bool IsSameDirection(Autodesk.Revit.DB.XYZ firstVec, Autodesk.Revit.DB.XYZ secondVec)
      {
         // get the unit vector for two vectors
         Autodesk.Revit.DB.XYZ first = UnitVector(firstVec);
         Autodesk.Revit.DB.XYZ second = UnitVector(secondVec);

         // if the dot product of two unit vectors is equal to 1, return true
         double dot = DotMatrix(first, second);
         return (IsEqual(dot, 1));
      }

      /// <summary>
      /// Judge whether the two vectors have the opposite direction
      /// </summary>
      /// <param name="firstVec">The first vector</param>
      /// <param name="secondVec">The second vector</param>
      /// <returns>True if the two vector is in opposite direction, otherwise false</returns>
      public static bool IsOppositeDirection(Autodesk.Revit.DB.XYZ firstVec, Autodesk.Revit.DB.XYZ secondVec)
      {
         // get the unit vector for two vectors
         Autodesk.Revit.DB.XYZ first = UnitVector(firstVec);
         Autodesk.Revit.DB.XYZ second = UnitVector(secondVec);

         // if the dot product of two unit vectors is equal to -1, return true
         double dot = DotMatrix(first, second);
         return (IsEqual(dot, -1));
      }

      /// <summary>
      /// Set the vector into unit length
      /// </summary>
      /// <param name="vector">The input vector</param>
      /// <returns>The vector in unit length</returns>
      public static Autodesk.Revit.DB.XYZ UnitVector(Autodesk.Revit.DB.XYZ vector)
      {
         // calculate the distance from grid origin to the XYZ
         double length = GetLength(vector);

         // changed the vector into the unit length
         double x = vector.X / length;
         double y = vector.Y / length;
         double z = vector.Z / length;
         return new Autodesk.Revit.DB.XYZ (x, y, z);
      }

      /// <summary>
      /// Calculate the distance from grid origin to the XYZ(vector length)
      /// </summary>
      /// <param name="vector">The input vector</param>
      /// <returns>The length of the vector</returns>
      public static double GetLength(Autodesk.Revit.DB.XYZ vector)
      {
         double x = vector.X;
         double y = vector.Y;
         double z = vector.Z;
         return Math.Sqrt(x * x + y * y + z * z);
      }

      /// <summary>
      /// Subtraction of two points(or vectors), get a new vector 
      /// </summary>
      /// <param name="p1">The first point(vector)</param>
      /// <param name="p2">The second point(vector)</param>
      /// <returns>Return a new vector from point p2 to p1</returns>
      public static Autodesk.Revit.DB.XYZ SubXYZ(Autodesk.Revit.DB.XYZ p1, Autodesk.Revit.DB.XYZ p2)
      {
         double x = p1.X - p2.X;
         double y = p1.Y - p2.Y;
         double z = p1.Z - p2.Z;

         return new Autodesk.Revit.DB.XYZ (x, y, z);
      }

      /// <summary>
      /// Add of two points(or vectors), get a new point(vector) 
      /// </summary>
      /// <param name="p1">The first point(vector)</param>
      /// <param name="p2">The first point(vector)</param>
      /// <returns>A new vector(point)</returns>
      public static Autodesk.Revit.DB.XYZ AddXYZ(Autodesk.Revit.DB.XYZ p1, Autodesk.Revit.DB.XYZ p2)
      {
         double x = p1.X + p2.X;
         double y = p1.Y + p2.Y;
         double z = p1.Z + p2.Z;

         return new Autodesk.Revit.DB.XYZ (x, y, z);
      }

      /// <summary>
      /// Multiply a vector with a number
      /// </summary>
      /// <param name="vector">A vector</param>
      /// <param name="rate">The rate number</param>
      /// <returns></returns>
      public static Autodesk.Revit.DB.XYZ MultiplyVector(Autodesk.Revit.DB.XYZ vector, double rate)
      {
         double x = vector.X * rate;
         double y = vector.Y * rate;
         double z = vector.Z * rate;

         return new Autodesk.Revit.DB.XYZ (x, y, z);
      }

      /// <summary>
      /// Transform old coordinate system in the new coordinate system 
      /// </summary>
      /// <param name="point">The Autodesk.Revit.DB.XYZ which need to be transformed</param>
      /// <param name="transform">The value of the coordinate system to be transformed</param>
      /// <returns>The new Autodesk.Revit.DB.XYZ which has been transformed</returns>
      public static Autodesk.Revit.DB.XYZ TransformPoint(Autodesk.Revit.DB.XYZ point, Transform transform)
      {
         //get the coordinate value in X, Y, Z axis
         double x = point.X;
         double y = point.Y;
         double z = point.Z;

         //transform basis of the old coordinate system in the new coordinate system
         Autodesk.Revit.DB.XYZ b0 = transform.get_Basis(0);
         Autodesk.Revit.DB.XYZ b1 = transform.get_Basis(1);
         Autodesk.Revit.DB.XYZ b2 = transform.get_Basis(2);
         Autodesk.Revit.DB.XYZ origin = transform.Origin;

         //transform the origin of the old coordinate system in the new coordinate system
         double xTemp = x * b0.X + y * b1.X + z * b2.X + origin.X;
         double yTemp = x * b0.Y + y * b1.Y + z * b2.Y + origin.Y;
         double zTemp = x * b0.Z + y * b1.Z + z * b2.Z + origin.Z;

         return new Autodesk.Revit.DB.XYZ (xTemp, yTemp, zTemp);
      }

      /// <summary>
      /// Move a point a give offset along a given direction
      /// </summary>
      /// <param name="point">The point need to move</param>
      /// <param name="direction">The direction the point move to</param>
      /// <param name="offset">Tndicate how long to move</param>
      /// <returns>The moved point</returns>
      public static Autodesk.Revit.DB.XYZ OffsetPoint(Autodesk.Revit.DB.XYZ point, Autodesk.Revit.DB.XYZ direction, double offset)
      {
         Autodesk.Revit.DB.XYZ directUnit = UnitVector(direction);
         Autodesk.Revit.DB.XYZ offsetVect = MultiplyVector(directUnit, offset);
         return AddXYZ(point, offsetVect);
      }
       


      /// <summary>
      /// Dot product of two Autodesk.Revit.DB.XYZ as Matrix
      /// </summary>
      /// <param name="p1">The first XYZ</param>
      /// <param name="p2">The second XYZ</param>
      /// <returns>The cosine value of the angle between vector p1 an p2</returns>
      private static double DotMatrix(Autodesk.Revit.DB.XYZ p1, Autodesk.Revit.DB.XYZ p2)
      {
         //get the coordinate of the Autodesk.Revit.DB.XYZ 
         double v1 = p1.X;
         double v2 = p1.Y;
         double v3 = p1.Z;

         double u1 = p2.X;
         double u2 = p2.Y;
         double u3 = p2.Z;

         return v1 * u1 + v2 * u2 + v3 * u3;
      }
   }
}