/* 
   orxonox - the future of 3D-vertical-scrollers

   Copyright (C) 2004 orx

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   ### File Specific:
   main-programmer: Benjamin Grauer
   co-programmer: Patrick Boenzli

   ADD: Patrick Boenzli           B-Spline 


   TODO: 
     local-Time implementation
     NURBS
     tList implementation
     
*/

#define DEBUG_SPECIAL_MODULE DEBUG_MODULE_MATH

#include "curve.h"

#include "debug.h"

#include <math.h>
#include <stdio.h>


/** 
    \brief default constructor for a Curve
*/
Curve::Curve()
{
  nodeCount = 0;
  firstNode = new PathNode;
  currentNode = firstNode;

  firstNode->position = Vector (.0, .0, .0);
  firstNode->number = 0;
  firstNode->next = 0; // not sure if this really points to NULL!!
}

/**
   \brief adds a new Node to the bezier Curve
   \param newNode a Vector to the position of the new node
*/
void Curve::addNode(const Vector& newNode)
{
  if (nodeCount != 0 )
    {
      currentNode = currentNode->next = new PathNode;
    }
  currentNode->position = newNode;
  currentNode->next = 0;
  currentNode->number = (++nodeCount);
  this->rebuild();
  return;
}

/**
   \brief adds a new Node to the bezier Curve
   \param newNode a Vector to the position of the new node
   \param insertPosition after the n-th node the new node will be inserted
*/
void Curve::addNode(const Vector& newNode, unsigned int insertPosition)
{

  if (this->nodeCount == 0 || insertPosition > this->nodeCount)
    return addNode(newNode);

  if (insertPosition == 0)
    insertPosition = 1;

  PathNode* insNode = new PathNode;

  // relinking
  PathNode* tmpNode = this->firstNode;
  if (insertPosition > 1)
    {
      while (tmpNode->next->number != insertPosition)
	tmpNode= tmpNode->next;
      insNode->next = tmpNode->next;
      tmpNode->next = insNode;
    }
  else
    {
      insNode->next = this->firstNode;
      this->firstNode = insNode;
    }
  // renumbering
  insNode->number = insertPosition;
  tmpNode = insNode->next;
  while (tmpNode)
    {
      tmpNode->number++;
      tmpNode = tmpNode->next;
    }

    // finished
  insNode->position = newNode;
  ++nodeCount;
  this->rebuild();
  return;
}

/**
   \brief Finds a Node by its Number, and returns its Position
   \param nodeToFind the n'th node in the List of nodes
   \returns A Vector to the Position of the Node.
*/
Vector Curve::getNode(unsigned int nodeToFind)
{
  if (nodeToFind > this->nodeCount || nodeToFind < 0)
    return Vector(0,0,0);
  PathNode* tmpNode = this->firstNode;
  for (int i = 1; i < nodeToFind; i++)
    tmpNode = tmpNode->next;
  return tmpNode->position;
}

/**
   \brief Outputs information about the state of this Curve
*/
void Curve::debug()
{
  printf("<<-------------------------------\n");
  printf("Curve Information:\n");
  printf("NodeCount: %d\n", this->nodeCount);
  PathNode* tmpNode = this->firstNode;
  while (tmpNode)
    {
      printf("node #%d: %f, %f, %f\n", tmpNode->number, tmpNode->position.x, tmpNode->position.y, tmpNode->position.z);
      tmpNode = tmpNode->next;
    }
  printf("------------------------------->>\n");
}


///////////////////////////////////
/// Bezier Curve //////////////////
///////////////////////////////////

/**
   \brief Creates a new BezierCurve
*/
BezierCurve::BezierCurve ()
{
  this->derivation = 0;
  dirCurve = new BezierCurve(1);
}

/**
   \brief Creates a new BezierCurve-Derivation-Curve
*/
BezierCurve::BezierCurve (int derivation)
{
  this->derivation = derivation;
  dirCurve=NULL;
}

/**
   \brief Deletes a BezierCurve.

   It does this by freeing all the space taken over from the nodes
*/
BezierCurve::~BezierCurve()
{
  PathNode* tmpNode;
  currentNode = firstNode;
  while (tmpNode != 0)
    {
      tmpNode = currentNode;
      currentNode = currentNode->next;
      delete tmpNode;
    }
  if (dirCurve)
    delete dirCurve;
}

/**
   \brief Rebuilds a Curve
*/
void BezierCurve::rebuild()
{
  PathNode* tmpNode = firstNode;

  // rebuilding the Curve itself
  float k=0;
  float n = nodeCount -1;
  float binCoef = 1;
  while(tmpNode)
    {
      tmpNode->factor = binCoef;
      if (tmpNode =tmpNode->next)
	{
	  binCoef *=(n-k)/(k+1);
	  ++k;
	}
    }

  // rebuilding the Derivation curve
  if(this->derivation <= 1)
    {
      tmpNode = firstNode;
      delete dirCurve;
      dirCurve = new BezierCurve(1);
      while(tmpNode->next)
	{
	  Vector tmpVector = (tmpNode->next->position)- (tmpNode->position);
	  tmpVector.x*=(float)nodeCount;
	  tmpVector.y*=(float)nodeCount;
	  tmpVector.z*=(float)nodeCount;
	  tmpVector.normalize();
	  this->dirCurve->addNode(tmpVector);
	  tmpNode = tmpNode->next;
	}
    }
}

/**
   \brief calculates the Position on the curve
   \param t The position on the Curve (0<=t<=1)
   \return the Position on the Path
*/
Vector BezierCurve::calcPos(float t) 
{
  Vector ret = Vector(0.0,0.0,0.0);
  if (this->nodeCount >= 3)
    {
      PathNode* tmpNode = this->firstNode;
      double factor = pow(1.0-t,nodeCount-1);
      while(tmpNode)
	{
	  ret.x += tmpNode->factor * factor * tmpNode->position.x;
	  ret.y += tmpNode->factor * factor * tmpNode->position.y;
	  ret.z += tmpNode->factor * factor * tmpNode->position.z;
	  factor *= t/(1.0-t); // same as pow but much faster.
	  
	  tmpNode = tmpNode->next;
	}
    }
  else if (nodeCount == 2)
    {
      ret = this->firstNode->position *(1.0-t);
      ret = ret + this->firstNode->next->position * t;
    }
  else if (nodeCount == 1)
    ret = this->firstNode->position;
  return ret;
}

/**
   \brief Calulates the direction of the Curve at time t.
   \param t The time at which to evaluate the curve.
   \returns The valuated Vector.
*/
Vector BezierCurve::calcDir (float t)
{
  return this->dirCurve->calcPos(t);
}

/**
   \brief Calulates the acceleration (second derivate) of the Curve at time t.
   \param t The time at which to evaluate the curve.
   \returns The valuated Vector.
*/
Vector BezierCurve::calcAcc (float t)
{
  return this->dirCurve->getDirCurve()->calcPos(t);
}

/**
   \brief Calculates the Quaternion needed for our rotations
   \param t The time at which to evaluate the cuve.
   \returns The evaluated Quaternion.
*/
Quaternion BezierCurve::calcQuat (float t)
{
  return Quaternion (calcDir(t), Vector(0,0,1));
}


/**
  \brief returns the Position of the point calculated on the Curve
  \return a Vector to the calculated position
*/
Vector BezierCurve::getPos() const
{
  return curvePoint;
}